// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package downloader

import (
	"errors"
	"fmt"
	"math/big"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/XinFinOrg/XDPoSChain/core/rawdb"

	"github.com/XinFinOrg/XDPoSChain/common"
	"github.com/XinFinOrg/XDPoSChain/consensus/ethash"
	"github.com/XinFinOrg/XDPoSChain/core"
	"github.com/XinFinOrg/XDPoSChain/core/types"
	"github.com/XinFinOrg/XDPoSChain/crypto"
	"github.com/XinFinOrg/XDPoSChain/ethdb"
	"github.com/XinFinOrg/XDPoSChain/event"
	"github.com/XinFinOrg/XDPoSChain/params"
	"github.com/XinFinOrg/XDPoSChain/trie"
)

var (
	testKey, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
	testAddress = crypto.PubkeyToAddress(testKey.PublicKey)
)

// Reduce some of the parameters to make the tester faster.
func init() {
	MaxForkAncestry = uint64(10000)
	blockCacheItems = 1024
	fsHeaderContCheck = 500 * time.Millisecond
}

// downloadTester is a test simulator for mocking out local block chain.
type downloadTester struct {
	downloader *Downloader

	genesis *types.Block   // Genesis blocks used by the tester and peers
	stateDb ethdb.Database // Database used by the tester for syncing from peers
	peerDb  ethdb.Database // Database of the peers containing all data

	ownHashes   []common.Hash                  // Hash chain belonging to the tester
	ownHeaders  map[common.Hash]*types.Header  // Headers belonging to the tester
	ownBlocks   map[common.Hash]*types.Block   // Blocks belonging to the tester
	ownReceipts map[common.Hash]types.Receipts // Receipts belonging to the tester
	ownChainTd  map[common.Hash]*big.Int       // Total difficulties of the blocks in the local chain

	peerHashes   map[string][]common.Hash                  // Hash chain belonging to different test peers
	peerHeaders  map[string]map[common.Hash]*types.Header  // Headers belonging to different test peers
	peerBlocks   map[string]map[common.Hash]*types.Block   // Blocks belonging to different test peers
	peerReceipts map[string]map[common.Hash]types.Receipts // Receipts belonging to different test peers
	peerChainTds map[string]map[common.Hash]*big.Int       // Total difficulties of the blocks in the peer chains

	peerMissingStates map[string]map[common.Hash]bool // State entries that fast sync should not return

	lock sync.RWMutex
}

// newTester creates a new downloader test mocker.
func newTester() *downloadTester {
	testdb := rawdb.NewMemoryDatabase()
	genesis := core.GenesisBlockForTesting(testdb, testAddress, big.NewInt(1000000000))

	tester := &downloadTester{
		genesis:           genesis,
		peerDb:            testdb,
		ownHashes:         []common.Hash{genesis.Hash()},
		ownHeaders:        map[common.Hash]*types.Header{genesis.Hash(): genesis.Header()},
		ownBlocks:         map[common.Hash]*types.Block{genesis.Hash(): genesis},
		ownReceipts:       map[common.Hash]types.Receipts{genesis.Hash(): nil},
		ownChainTd:        map[common.Hash]*big.Int{genesis.Hash(): genesis.Difficulty()},
		peerHashes:        make(map[string][]common.Hash),
		peerHeaders:       make(map[string]map[common.Hash]*types.Header),
		peerBlocks:        make(map[string]map[common.Hash]*types.Block),
		peerReceipts:      make(map[string]map[common.Hash]types.Receipts),
		peerChainTds:      make(map[string]map[common.Hash]*big.Int),
		peerMissingStates: make(map[string]map[common.Hash]bool),
	}
	tester.stateDb = rawdb.NewMemoryDatabase()
	tester.stateDb.Put(genesis.Root().Bytes(), []byte{0x00})

	tester.downloader = New(FullSync, tester.stateDb, new(event.TypeMux), tester, nil, tester.dropPeer, tester.handleProposedBlock)

	return tester
}

// makeChain creates a chain of n blocks starting at and including parent.
// the returned hash chain is ordered head->parent. In addition, every 3rd block
// contains a transaction and every 5th an uncle to allow testing correct block
// reassembly.
func (dl *downloadTester) makeChain(n int, seed byte, parent *types.Block, parentReceipts types.Receipts, heavy bool) ([]common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]types.Receipts) {
	// Generate the block chain
	blocks, receipts := core.GenerateChain(params.TestChainConfig, parent, ethash.NewFaker(), dl.peerDb, n, func(i int, block *core.BlockGen) {
		block.SetCoinbase(common.Address{seed})

		// If a heavy chain is requested, delay blocks to raise difficulty
		if heavy {
			block.OffsetTime(-1)
		}
		// If the block number is multiple of 3, send a bonus transaction to the miner
		if parent == dl.genesis && i%3 == 0 {
			signer := types.MakeSigner(params.TestChainConfig, block.Number())
			tx, err := types.SignTx(types.NewTransaction(block.TxNonce(testAddress), common.Address{seed}, big.NewInt(1000), params.TxGas, nil, nil), signer, testKey)
			if err != nil {
				panic(err)
			}
			block.AddTx(tx)
		}
		// If the block number is a multiple of 5, add a bonus uncle to the block
		if i > 0 && i%5 == 0 {
			block.AddUncle(&types.Header{
				ParentHash: block.PrevBlock(i - 1).Hash(),
				Number:     big.NewInt(block.Number().Int64() - 1),
			})
		}
	})
	// Convert the block-chain into a hash-chain and header/block maps
	hashes := make([]common.Hash, n+1)
	hashes[len(hashes)-1] = parent.Hash()

	headerm := make(map[common.Hash]*types.Header, n+1)
	headerm[parent.Hash()] = parent.Header()

	blockm := make(map[common.Hash]*types.Block, n+1)
	blockm[parent.Hash()] = parent

	receiptm := make(map[common.Hash]types.Receipts, n+1)
	receiptm[parent.Hash()] = parentReceipts

	for i, b := range blocks {
		hashes[len(hashes)-i-2] = b.Hash()
		headerm[b.Hash()] = b.Header()
		blockm[b.Hash()] = b
		receiptm[b.Hash()] = receipts[i]
	}
	return hashes, headerm, blockm, receiptm
}

// makeChainFork creates two chains of length n, such that h1[:f] and
// h2[:f] are different but have a common suffix of length n-f.
func (dl *downloadTester) makeChainFork(n, f int, parent *types.Block, parentReceipts types.Receipts, balanced bool) ([]common.Hash, []common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]*types.Block, map[common.Hash]types.Receipts, map[common.Hash]types.Receipts) {
	// Create the common suffix
	hashes, headers, blocks, receipts := dl.makeChain(n-f, 0, parent, parentReceipts, false)

	// Create the forks, making the second heavyer if non balanced forks were requested
	hashes1, headers1, blocks1, receipts1 := dl.makeChain(f, 1, blocks[hashes[0]], receipts[hashes[0]], false)
	hashes1 = append(hashes1, hashes[1:]...)

	heavy := false
	if !balanced {
		heavy = true
	}
	hashes2, headers2, blocks2, receipts2 := dl.makeChain(f, 2, blocks[hashes[0]], receipts[hashes[0]], heavy)
	hashes2 = append(hashes2, hashes[1:]...)

	for hash, header := range headers {
		headers1[hash] = header
		headers2[hash] = header
	}
	for hash, block := range blocks {
		blocks1[hash] = block
		blocks2[hash] = block
	}
	for hash, receipt := range receipts {
		receipts1[hash] = receipt
		receipts2[hash] = receipt
	}
	return hashes1, hashes2, headers1, headers2, blocks1, blocks2, receipts1, receipts2
}

// terminate aborts any operations on the embedded downloader and releases all
// held resources.
func (dl *downloadTester) terminate() {
	dl.downloader.Terminate()
}

// sync starts synchronizing with a remote peer, blocking until it completes.
func (dl *downloadTester) sync(id string, td *big.Int, mode SyncMode) error {
	dl.lock.RLock()
	hash := dl.peerHashes[id][0]
	// If no particular TD was requested, load from the peer's blockchain
	if td == nil {
		td = big.NewInt(1)
		if diff, ok := dl.peerChainTds[id][hash]; ok {
			td = diff
		}
	}
	dl.lock.RUnlock()

	// Synchronise with the chosen peer and ensure proper cleanup afterwards
	err := dl.downloader.synchronise(id, hash, td, mode)
	select {
	case <-dl.downloader.cancelCh:
		// Ok, downloader fully cancelled after sync cycle
	default:
		// Downloader is still accepting packets, can block a peer up
		panic("downloader active post sync cycle") // panic will be caught by tester
	}
	return err
}

// HasHeader checks if a header is present in the testers canonical chain.
func (dl *downloadTester) HasHeader(hash common.Hash, number uint64) bool {
	return dl.GetHeaderByHash(hash) != nil
}

// HasBlock checks if a block is present in the testers canonical chain.
func (dl *downloadTester) HasBlock(hash common.Hash, number uint64) bool {
	return dl.GetBlockByHash(hash) != nil
}

// GetHeader retrieves a header from the testers canonical chain.
func (dl *downloadTester) GetHeaderByHash(hash common.Hash) *types.Header {
	dl.lock.RLock()
	defer dl.lock.RUnlock()

	return dl.ownHeaders[hash]
}

// GetBlock retrieves a block from the testers canonical chain.
func (dl *downloadTester) GetBlockByHash(hash common.Hash) *types.Block {
	dl.lock.RLock()
	defer dl.lock.RUnlock()

	return dl.ownBlocks[hash]
}

// CurrentHeader retrieves the current head header from the canonical chain.
func (dl *downloadTester) CurrentHeader() *types.Header {
	dl.lock.RLock()
	defer dl.lock.RUnlock()

	for i := len(dl.ownHashes) - 1; i >= 0; i-- {
		if header := dl.ownHeaders[dl.ownHashes[i]]; header != nil {
			return header
		}
	}
	return dl.genesis.Header()
}

// CurrentBlock retrieves the current head block from the canonical chain.
func (dl *downloadTester) CurrentBlock() *types.Block {
	dl.lock.RLock()
	defer dl.lock.RUnlock()

	for i := len(dl.ownHashes) - 1; i >= 0; i-- {
		if block := dl.ownBlocks[dl.ownHashes[i]]; block != nil {
			if _, err := dl.stateDb.Get(block.Root().Bytes()); err == nil {
				return block
			}
		}
	}
	return dl.genesis
}

// CurrentFastBlock retrieves the current head fast-sync block from the canonical chain.
func (dl *downloadTester) CurrentFastBlock() *types.Block {
	dl.lock.RLock()
	defer dl.lock.RUnlock()

	for i := len(dl.ownHashes) - 1; i >= 0; i-- {
		if block := dl.ownBlocks[dl.ownHashes[i]]; block != nil {
			return block
		}
	}
	return dl.genesis
}

// FastSyncCommitHead manually sets the head block to a given hash.
func (dl *downloadTester) FastSyncCommitHead(hash common.Hash) error {
	// For now only check that the state trie is correct
	if block := dl.GetBlockByHash(hash); block != nil {
		_, err := trie.NewSecure(block.Root(), trie.NewDatabase(dl.stateDb))
		return err
	}
	return fmt.Errorf("non existent block: %x", hash[:4])
}

// GetTd retrieves the block's total difficulty from the canonical chain.
func (dl *downloadTester) GetTd(hash common.Hash, number uint64) *big.Int {
	dl.lock.RLock()
	defer dl.lock.RUnlock()

	return dl.ownChainTd[hash]
}

// InsertHeaderChain injects a new batch of headers into the simulated chain.
func (dl *downloadTester) InsertHeaderChain(headers []*types.Header, checkFreq int) (int, error) {
	dl.lock.Lock()
	defer dl.lock.Unlock()

	// Do a quick check, as the blockchain.InsertHeaderChain doesn't insert anything in case of errors
	if _, ok := dl.ownHeaders[headers[0].ParentHash]; !ok {
		return 0, errors.New("unknown parent")
	}
	for i := 1; i < len(headers); i++ {
		if headers[i].ParentHash != headers[i-1].Hash() {
			return i, errors.New("unknown parent")
		}
	}
	// Do a full insert if pre-checks passed
	for i, header := range headers {
		if _, ok := dl.ownHeaders[header.Hash()]; ok {
			continue
		}
		if _, ok := dl.ownHeaders[header.ParentHash]; !ok {
			return i, errors.New("unknown parent")
		}
		dl.ownHashes = append(dl.ownHashes, header.Hash())
		dl.ownHeaders[header.Hash()] = header
		dl.ownChainTd[header.Hash()] = new(big.Int).Add(dl.ownChainTd[header.ParentHash], header.Difficulty)
	}
	return len(headers), nil
}

// InsertChain injects a new batch of blocks into the simulated chain.
func (dl *downloadTester) InsertChain(blocks types.Blocks) (int, error) {
	dl.lock.Lock()
	defer dl.lock.Unlock()

	for i, block := range blocks {
		if parent, ok := dl.ownBlocks[block.ParentHash()]; !ok {
			return i, errors.New("unknown parent")
		} else if _, err := dl.stateDb.Get(parent.Root().Bytes()); err != nil {
			return i, fmt.Errorf("unknown parent state %x: %v", parent.Root(), err)
		}
		if _, ok := dl.ownHeaders[block.Hash()]; !ok {
			dl.ownHashes = append(dl.ownHashes, block.Hash())
			dl.ownHeaders[block.Hash()] = block.Header()
		}
		dl.ownBlocks[block.Hash()] = block
		dl.stateDb.Put(block.Root().Bytes(), []byte{0x00})
		dl.ownChainTd[block.Hash()] = new(big.Int).Add(dl.ownChainTd[block.ParentHash()], block.Difficulty())
	}
	return len(blocks), nil
}

// InsertReceiptChain injects a new batch of receipts into the simulated chain.
func (dl *downloadTester) InsertReceiptChain(blocks types.Blocks, receipts []types.Receipts) (int, error) {
	dl.lock.Lock()
	defer dl.lock.Unlock()

	for i := 0; i < len(blocks) && i < len(receipts); i++ {
		if _, ok := dl.ownHeaders[blocks[i].Hash()]; !ok {
			return i, errors.New("unknown owner")
		}
		if _, ok := dl.ownBlocks[blocks[i].ParentHash()]; !ok {
			return i, errors.New("unknown parent")
		}
		dl.ownBlocks[blocks[i].Hash()] = blocks[i]
		dl.ownReceipts[blocks[i].Hash()] = receipts[i]
	}
	return len(blocks), nil
}

// Rollback removes some recently added elements from the chain.
func (dl *downloadTester) Rollback(hashes []common.Hash) {
	dl.lock.Lock()
	defer dl.lock.Unlock()

	for i := len(hashes) - 1; i >= 0; i-- {
		if dl.ownHashes[len(dl.ownHashes)-1] == hashes[i] {
			dl.ownHashes = dl.ownHashes[:len(dl.ownHashes)-1]
		}
		delete(dl.ownChainTd, hashes[i])
		delete(dl.ownHeaders, hashes[i])
		delete(dl.ownReceipts, hashes[i])
		delete(dl.ownBlocks, hashes[i])
	}
}

// newPeer registers a new block download source into the downloader.
func (dl *downloadTester) newPeer(id string, version int, hashes []common.Hash, headers map[common.Hash]*types.Header, blocks map[common.Hash]*types.Block, receipts map[common.Hash]types.Receipts) error {
	return dl.newSlowPeer(id, version, hashes, headers, blocks, receipts, 0)
}

// newSlowPeer registers a new block download source into the downloader, with a
// specific delay time on processing the network packets sent to it, simulating
// potentially slow network IO.
func (dl *downloadTester) newSlowPeer(id string, version int, hashes []common.Hash, headers map[common.Hash]*types.Header, blocks map[common.Hash]*types.Block, receipts map[common.Hash]types.Receipts, delay time.Duration) error {
	dl.lock.Lock()
	defer dl.lock.Unlock()

	var err = dl.downloader.RegisterPeer(id, version, &downloadTesterPeer{dl: dl, id: id, delay: delay})
	if err == nil {
		// Assign the owned hashes, headers and blocks to the peer (deep copy)
		dl.peerHashes[id] = make([]common.Hash, len(hashes))
		copy(dl.peerHashes[id], hashes)

		dl.peerHeaders[id] = make(map[common.Hash]*types.Header)
		dl.peerBlocks[id] = make(map[common.Hash]*types.Block)
		dl.peerReceipts[id] = make(map[common.Hash]types.Receipts)
		dl.peerChainTds[id] = make(map[common.Hash]*big.Int)
		dl.peerMissingStates[id] = make(map[common.Hash]bool)

		genesis := hashes[len(hashes)-1]
		if header := headers[genesis]; header != nil {
			dl.peerHeaders[id][genesis] = header
			dl.peerChainTds[id][genesis] = header.Difficulty
		}
		if block := blocks[genesis]; block != nil {
			dl.peerBlocks[id][genesis] = block
			dl.peerChainTds[id][genesis] = block.Difficulty()
		}

		for i := len(hashes) - 2; i >= 0; i-- {
			hash := hashes[i]

			if header, ok := headers[hash]; ok {
				dl.peerHeaders[id][hash] = header
				if _, ok := dl.peerHeaders[id][header.ParentHash]; ok {
					dl.peerChainTds[id][hash] = new(big.Int).Add(header.Difficulty, dl.peerChainTds[id][header.ParentHash])
				}
			}
			if block, ok := blocks[hash]; ok {
				dl.peerBlocks[id][hash] = block
				if _, ok := dl.peerBlocks[id][block.ParentHash()]; ok {
					dl.peerChainTds[id][hash] = new(big.Int).Add(block.Difficulty(), dl.peerChainTds[id][block.ParentHash()])
				}
			}
			if receipt, ok := receipts[hash]; ok {
				dl.peerReceipts[id][hash] = receipt
			}
		}
	}
	return err
}

// dropPeer simulates a hard peer removal from the connection pool.
func (dl *downloadTester) dropPeer(id string) {
	dl.lock.Lock()
	defer dl.lock.Unlock()

	delete(dl.peerHashes, id)
	delete(dl.peerHeaders, id)
	delete(dl.peerBlocks, id)
	delete(dl.peerChainTds, id)

	dl.downloader.UnregisterPeer(id)
}

// an empty handleProposedBlock function
func (dl *downloadTester) handleProposedBlock(header *types.Header) error {
	return nil
}

// Config retrieves the blockchain's chain configuration.
func (dl *downloadTester) Config() *params.ChainConfig { return params.TestChainConfig }

type downloadTesterPeer struct {
	dl    *downloadTester
	id    string
	delay time.Duration
	lock  sync.RWMutex
}

// setDelay is a thread safe setter for the network delay value.
func (dlp *downloadTesterPeer) setDelay(delay time.Duration) {
	dlp.lock.Lock()
	defer dlp.lock.Unlock()

	dlp.delay = delay
}

// waitDelay is a thread safe way to sleep for the configured time.
func (dlp *downloadTesterPeer) waitDelay() {
	dlp.lock.RLock()
	delay := dlp.delay
	dlp.lock.RUnlock()

	time.Sleep(delay)
}

// Head constructs a function to retrieve a peer's current head hash
// and total difficulty.
func (dlp *downloadTesterPeer) Head() (common.Hash, *big.Int) {
	dlp.dl.lock.RLock()
	defer dlp.dl.lock.RUnlock()

	return dlp.dl.peerHashes[dlp.id][0], nil
}

// RequestHeadersByHash constructs a GetBlockHeaders function based on a hashed
// origin; associated with a particular peer in the download tester. The returned
// function can be used to retrieve batches of headers from the particular peer.
func (dlp *downloadTesterPeer) RequestHeadersByHash(origin common.Hash, amount int, skip int, reverse bool) error {
	// Find the canonical number of the hash
	dlp.dl.lock.RLock()
	number := uint64(0)
	for num, hash := range dlp.dl.peerHashes[dlp.id] {
		if hash == origin {
			number = uint64(len(dlp.dl.peerHashes[dlp.id]) - num - 1)
			break
		}
	}
	dlp.dl.lock.RUnlock()

	// Use the absolute header fetcher to satisfy the query
	return dlp.RequestHeadersByNumber(number, amount, skip, reverse)
}

// RequestHeadersByNumber constructs a GetBlockHeaders function based on a numbered
// origin; associated with a particular peer in the download tester. The returned
// function can be used to retrieve batches of headers from the particular peer.
func (dlp *downloadTesterPeer) RequestHeadersByNumber(origin uint64, amount int, skip int, reverse bool) error {
	dlp.waitDelay()

	dlp.dl.lock.RLock()
	defer dlp.dl.lock.RUnlock()

	// Gather the next batch of headers
	hashes := dlp.dl.peerHashes[dlp.id]
	headers := dlp.dl.peerHeaders[dlp.id]
	result := make([]*types.Header, 0, amount)
	for i := 0; i < amount && len(hashes)-int(origin)-1-i*(skip+1) >= 0; i++ {
		if header, ok := headers[hashes[len(hashes)-int(origin)-1-i*(skip+1)]]; ok {
			result = append(result, header)
		}
	}
	// Delay delivery a bit to allow attacks to unfold
	go func() {
		time.Sleep(time.Millisecond)
		dlp.dl.downloader.DeliverHeaders(dlp.id, result)
	}()
	return nil
}

// RequestBodies constructs a getBlockBodies method associated with a particular
// peer in the download tester. The returned function can be used to retrieve
// batches of block bodies from the particularly requested peer.
func (dlp *downloadTesterPeer) RequestBodies(hashes []common.Hash) error {
	dlp.waitDelay()

	dlp.dl.lock.RLock()
	defer dlp.dl.lock.RUnlock()

	blocks := dlp.dl.peerBlocks[dlp.id]

	transactions := make([][]*types.Transaction, 0, len(hashes))
	uncles := make([][]*types.Header, 0, len(hashes))

	for _, hash := range hashes {
		if block, ok := blocks[hash]; ok {
			transactions = append(transactions, block.Transactions())
			uncles = append(uncles, block.Uncles())
		}
	}
	go dlp.dl.downloader.DeliverBodies(dlp.id, transactions, uncles)

	return nil
}

// RequestReceipts constructs a getReceipts method associated with a particular
// peer in the download tester. The returned function can be used to retrieve
// batches of block receipts from the particularly requested peer.
func (dlp *downloadTesterPeer) RequestReceipts(hashes []common.Hash) error {
	dlp.waitDelay()

	dlp.dl.lock.RLock()
	defer dlp.dl.lock.RUnlock()

	receipts := dlp.dl.peerReceipts[dlp.id]

	results := make([][]*types.Receipt, 0, len(hashes))
	for _, hash := range hashes {
		if receipt, ok := receipts[hash]; ok {
			results = append(results, receipt)
		}
	}
	go dlp.dl.downloader.DeliverReceipts(dlp.id, results)

	return nil
}

// RequestNodeData constructs a getNodeData method associated with a particular
// peer in the download tester. The returned function can be used to retrieve
// batches of node state data from the particularly requested peer.
func (dlp *downloadTesterPeer) RequestNodeData(hashes []common.Hash) error {
	dlp.waitDelay()

	dlp.dl.lock.RLock()
	defer dlp.dl.lock.RUnlock()

	results := make([][]byte, 0, len(hashes))
	for _, hash := range hashes {
		if data, err := dlp.dl.peerDb.Get(hash.Bytes()); err == nil {
			if !dlp.dl.peerMissingStates[dlp.id][hash] {
				results = append(results, data)
			}
		}
	}
	go dlp.dl.downloader.DeliverNodeData(dlp.id, results)

	return nil
}

// assertOwnChain checks if the local chain contains the correct number of items
// of the various chain components.
func assertOwnChain(t *testing.T, tester *downloadTester, length int) {
	assertOwnForkedChain(t, tester, 1, []int{length})
}

// assertOwnForkedChain checks if the local forked chain contains the correct
// number of items of the various chain components.
func assertOwnForkedChain(t *testing.T, tester *downloadTester, common int, lengths []int) {
	// Initialize the counters for the first fork
	headers, blocks, receipts := lengths[0], lengths[0], lengths[0]-fsMinFullBlocks

	if receipts < 0 {
		receipts = 1
	}
	// Update the counters for each subsequent fork
	for _, length := range lengths[1:] {
		headers += length - common
		blocks += length - common
		receipts += length - common - fsMinFullBlocks
	}
	switch tester.downloader.mode {
	case FullSync:
		receipts = 1
	case LightSync:
		blocks, receipts = 1, 1
	}
	if hs := len(tester.ownHeaders); hs != headers {
		t.Fatalf("synchronised headers mismatch: have %v, want %v", hs, headers)
	}
	if bs := len(tester.ownBlocks); bs != blocks {
		t.Fatalf("synchronised blocks mismatch: have %v, want %v", bs, blocks)
	}
	if rs := len(tester.ownReceipts); rs != receipts {
		t.Fatalf("synchronised receipts mismatch: have %v, want %v", rs, receipts)
	}
	// Verify the state trie too for fast syncs
	/*if tester.downloader.mode == FastSync {
		pivot := uint64(0)
		var index int
		if pivot := int(tester.downloader.queue.fastSyncPivot); pivot < common {
			index = pivot
		} else {
			index = len(tester.ownHashes) - lengths[len(lengths)-1] + int(tester.downloader.queue.fastSyncPivot)
		}
		if index > 0 {
			if statedb, err := state.New(tester.ownHeaders[tester.ownHashes[index]].Root, state.NewDatabase(trie.NewDatabase(tester.stateDb))); statedb == nil || err != nil {
				t.Fatalf("state reconstruction failed: %v", err)
			}
		}
	}*/
}

// Tests that simple synchronization against a canonical chain works correctly.
// In this test common ancestor lookup should be short circuited and not require
// binary searching.
func TestCanonicalSynchronisation62(t *testing.T)     { testCanonicalSynchronisation(t, 62, FullSync) }
func TestCanonicalSynchronisation63Full(t *testing.T) { testCanonicalSynchronisation(t, 63, FullSync) }
func TestCanonicalSynchronisation63Fast(t *testing.T) { testCanonicalSynchronisation(t, 63, FastSync) }
func TestCanonicalSynchronisation64Full(t *testing.T) { testCanonicalSynchronisation(t, 64, FullSync) }
func TestCanonicalSynchronisation64Fast(t *testing.T) { testCanonicalSynchronisation(t, 64, FastSync) }
func TestCanonicalSynchronisation64Light(t *testing.T) {testCanonicalSynchronisation(t, 64, LightSync)}
func TestCanonicalSynchronisation100Full(t *testing.T) { testCanonicalSynchronisation(t, 100, FullSync) }
func TestCanonicalSynchronisation100Fast(t *testing.T) { testCanonicalSynchronisation(t, 100, FastSync) }
func TestCanonicalSynchronisation101Full(t *testing.T) { testCanonicalSynchronisation(t, 101, FullSync) }
func TestCanonicalSynchronisation101Fast(t *testing.T) { testCanonicalSynchronisation(t, 101, FastSync) }
func TestCanonicalSynchronisation101Light(t *testing.T) {testCanonicalSynchronisation(t, 101, LightSync)}

func testCanonicalSynchronisation(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download
	targetBlocks := blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

	// Synchronise with the peer and make sure all relevant data was retrieved
	if err := tester.sync("peer", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that if a large batch of blocks are being downloaded, it is throttled
// until the cached blocks are retrieved.
func TestThrottling62(t *testing.T)     { testThrottling(t, 62, FullSync) }
func TestThrottling63Full(t *testing.T) { testThrottling(t, 63, FullSync) }
func TestThrottling63Fast(t *testing.T) { testThrottling(t, 63, FastSync) }
func TestThrottling64Full(t *testing.T) { testThrottling(t, 64, FullSync) }
func TestThrottling64Fast(t *testing.T) { testThrottling(t, 64, FastSync) }
func TestThrottling100Full(t *testing.T) { testThrottling(t, 100, FullSync) }
func TestThrottling100Fast(t *testing.T) { testThrottling(t, 100, FastSync) }
func TestThrottling101Full(t *testing.T) { testThrottling(t, 101, FullSync) }
func TestThrottling101Fast(t *testing.T) { testThrottling(t, 101, FastSync) }

func testThrottling(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()
	tester := newTester()
	defer tester.terminate()

	// Create a long block chain to download and the tester
	targetBlocks := 8 * blockCacheItems
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

	// Wrap the importer to allow stepping
	blocked, proceed := uint32(0), make(chan struct{})
	tester.downloader.chainInsertHook = func(results []*fetchResult) {
		atomic.StoreUint32(&blocked, uint32(len(results)))
		<-proceed
	}
	// Start a synchronisation concurrently
	errc := make(chan error)
	go func() {
		errc <- tester.sync("peer", nil, mode)
	}()
	// Iteratively take some blocks, always checking the retrieval count
	for {
		// Check the retrieval count synchronously (! reason for this ugly block)
		tester.lock.RLock()
		retrieved := len(tester.ownBlocks)
		tester.lock.RUnlock()
		if retrieved >= targetBlocks+1 {
			break
		}
		// Wait a bit for sync to throttle itself
		var cached, frozen int
		for start := time.Now(); time.Since(start) < 3*time.Second; {
			time.Sleep(25 * time.Millisecond)

			tester.lock.Lock()
			tester.downloader.queue.lock.Lock()
			cached = len(tester.downloader.queue.blockDonePool)
			if mode == FastSync {
				if receipts := len(tester.downloader.queue.receiptDonePool); receipts < cached {
					//if tester.downloader.queue.resultCache[receipts].Header.Number.Uint64() < tester.downloader.queue.fastSyncPivot {
					cached = receipts
					//}
				}
			}
			frozen = int(atomic.LoadUint32(&blocked))
			retrieved = len(tester.ownBlocks)
			tester.downloader.queue.lock.Unlock()
			tester.lock.Unlock()

			if cached == blockCacheItems || retrieved+cached+frozen == targetBlocks+1 {
				break
			}
		}
		// Make sure we filled up the cache, then exhaust it
		time.Sleep(25 * time.Millisecond) // give it a chance to screw up

		tester.lock.RLock()
		retrieved = len(tester.ownBlocks)
		tester.lock.RUnlock()
		if cached != blockCacheItems && retrieved+cached+frozen != targetBlocks+1 {
			t.Fatalf("block count mismatch: have %v, want %v (owned %v, blocked %v, target %v)", cached, blockCacheItems, retrieved, frozen, targetBlocks+1)
		}
		// Permit the blocked blocks to import
		if atomic.LoadUint32(&blocked) > 0 {
			atomic.StoreUint32(&blocked, uint32(0))
			proceed <- struct{}{}
		}
	}
	// Check that we haven't pulled more blocks than available
	assertOwnChain(t, tester, targetBlocks+1)
	if err := <-errc; err != nil {
		t.Fatalf("block synchronization failed: %v", err)
	}
}

// Tests that simple synchronization against a forked chain works correctly. In
// this test common ancestor lookup should *not* be short circuited, and a full
// binary search should be executed.
func TestForkedSync62(t *testing.T)      { testForkedSync(t, 62, FullSync) }
func TestForkedSync63Full(t *testing.T)  { testForkedSync(t, 63, FullSync) }
func TestForkedSync63Fast(t *testing.T)  { testForkedSync(t, 63, FastSync) }
func TestForkedSync64Full(t *testing.T)  { testForkedSync(t, 64, FullSync) }
func TestForkedSync64Fast(t *testing.T)  { testForkedSync(t, 64, FastSync) }
func TestForkedSync64Light(t *testing.T) { testForkedSync(t, 64, LightSync) }
func TestForkedSync100Full(t *testing.T)  { testForkedSync(t, 100, FullSync) }
func TestForkedSync100Fast(t *testing.T)  { testForkedSync(t, 100, FastSync) }
func TestForkedSync101Full(t *testing.T)  { testForkedSync(t, 101, FullSync) }
func TestForkedSync101Fast(t *testing.T)  { testForkedSync(t, 101, FastSync) }
func TestForkedSync101Light(t *testing.T) { testForkedSync(t, 101, LightSync) }

func testForkedSync(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a long enough forked chain
	common, fork := MaxHashFetch, 2*MaxHashFetch
	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, true)

	tester.newPeer("fork A", protocol, hashesA, headersA, blocksA, receiptsA)
	tester.newPeer("fork B", protocol, hashesB, headersB, blocksB, receiptsB)

	// Synchronise with the peer and make sure all blocks were retrieved
	if err := tester.sync("fork A", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, common+fork+1)

	// Synchronise with the second peer and make sure that fork is pulled too
	if err := tester.sync("fork B", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnForkedChain(t, tester, common+1, []int{common + fork + 1, common + fork + 1})
}

// Tests that synchronising against a much shorter but much heavyer fork works
// corrently and is not dropped.
func TestHeavyForkedSync62(t *testing.T)      { testHeavyForkedSync(t, 62, FullSync) }
func TestHeavyForkedSync63Full(t *testing.T)  { testHeavyForkedSync(t, 63, FullSync) }
func TestHeavyForkedSync63Fast(t *testing.T)  { testHeavyForkedSync(t, 63, FastSync) }
func TestHeavyForkedSync64Full(t *testing.T)  { testHeavyForkedSync(t, 64, FullSync) }
func TestHeavyForkedSync64Fast(t *testing.T)  { testHeavyForkedSync(t, 64, FastSync) }
func TestHeavyForkedSync64Light(t *testing.T) { testHeavyForkedSync(t, 64, LightSync) }
func TestHeavyForkedSync100Full(t *testing.T)  { testHeavyForkedSync(t, 100, FullSync) }
func TestHeavyForkedSync100Fast(t *testing.T)  { testHeavyForkedSync(t, 100, FastSync) }
func TestHeavyForkedSync101Full(t *testing.T)  { testHeavyForkedSync(t, 101, FullSync) }
func TestHeavyForkedSync101Fast(t *testing.T)  { testHeavyForkedSync(t, 101, FastSync) }
func TestHeavyForkedSync101Light(t *testing.T) { testHeavyForkedSync(t, 101, LightSync) }

func testHeavyForkedSync(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a long enough forked chain
	common, fork := MaxHashFetch, 4*MaxHashFetch
	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, false)

	tester.newPeer("light", protocol, hashesA, headersA, blocksA, receiptsA)
	tester.newPeer("heavy", protocol, hashesB[fork/2:], headersB, blocksB, receiptsB)

	// Synchronise with the peer and make sure all blocks were retrieved
	if err := tester.sync("light", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, common+fork+1)

	// Synchronise with the second peer and make sure that fork is pulled too
	if err := tester.sync("heavy", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnForkedChain(t, tester, common+1, []int{common + fork + 1, common + fork/2 + 1})
}

// Tests that chain forks are contained within a certain interval of the current
// chain head, ensuring that malicious peers cannot waste resources by feeding
// long dead chains.
func TestBoundedForkedSync62(t *testing.T)      { testBoundedForkedSync(t, 62, FullSync) }
func TestBoundedForkedSync63Full(t *testing.T)  { testBoundedForkedSync(t, 63, FullSync) }
func TestBoundedForkedSync63Fast(t *testing.T)  { testBoundedForkedSync(t, 63, FastSync) }
func TestBoundedForkedSync64Full(t *testing.T)  { testBoundedForkedSync(t, 64, FullSync) }
func TestBoundedForkedSync64Fast(t *testing.T)  { testBoundedForkedSync(t, 64, FastSync) }
func TestBoundedForkedSync64Light(t *testing.T) { testBoundedForkedSync(t, 64, LightSync) }
func TestBoundedForkedSync100Full(t *testing.T)  { testBoundedForkedSync(t, 100, FullSync) }
func TestBoundedForkedSync100Fast(t *testing.T)  { testBoundedForkedSync(t, 100, FastSync) }
func TestBoundedForkedSync101Full(t *testing.T)  { testBoundedForkedSync(t, 101, FullSync) }
func TestBoundedForkedSync101Fast(t *testing.T)  { testBoundedForkedSync(t, 101, FastSync) }
func TestBoundedForkedSync101Light(t *testing.T) { testBoundedForkedSync(t, 101, LightSync) }

func testBoundedForkedSync(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a long enough forked chain
	common, fork := 13, int(MaxForkAncestry+17)
	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, true)

	tester.newPeer("original", protocol, hashesA, headersA, blocksA, receiptsA)
	tester.newPeer("rewriter", protocol, hashesB, headersB, blocksB, receiptsB)

	// Synchronise with the peer and make sure all blocks were retrieved
	if err := tester.sync("original", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, common+fork+1)

	// Synchronise with the second peer and ensure that the fork is rejected to being too old
	if err := tester.sync("rewriter", nil, mode); err != errInvalidAncestor {
		t.Fatalf("sync failure mismatch: have %v, want %v", err, errInvalidAncestor)
	}
}

// Tests that chain forks are contained within a certain interval of the current
// chain head for short but heavy forks too. These are a bit special because they
// take different ancestor lookup paths.
func TestBoundedHeavyForkedSync62(t *testing.T)       { testBoundedHeavyForkedSync(t, 62, FullSync) }
func TestBoundedHeavyForkedSync63Full(t *testing.T)   { testBoundedHeavyForkedSync(t, 63, FullSync) }
func TestBoundedHeavyForkedSync63Fast(t *testing.T)   { testBoundedHeavyForkedSync(t, 63, FastSync) }
func TestBoundedHeavyForkedSync64Full(t *testing.T)   { testBoundedHeavyForkedSync(t, 64, FullSync) }
func TestBoundedHeavyForkedSync64Fast(t *testing.T)   { testBoundedHeavyForkedSync(t, 64, FastSync) }
func TestBoundedHeavyForkedSync64Light(t *testing.T)  { testBoundedHeavyForkedSync(t, 64, LightSync) }
func TestBoundedHeavyForkedSync100Full(t *testing.T)  { testBoundedHeavyForkedSync(t, 100, FullSync) }
func TestBoundedHeavyForkedSync100Fast(t *testing.T)  { testBoundedHeavyForkedSync(t, 100, FastSync) }
func TestBoundedHeavyForkedSync100Light(t *testing.T) { testBoundedHeavyForkedSync(t, 100, LightSync) }
func TestBoundedHeavyForkedSync101Full(t *testing.T)  { testBoundedHeavyForkedSync(t, 101, FullSync) }
func TestBoundedHeavyForkedSync101Fast(t *testing.T)  { testBoundedHeavyForkedSync(t, 101, FastSync) }
func TestBoundedHeavyForkedSync101Light(t *testing.T) { testBoundedHeavyForkedSync(t, 101, LightSync) }

func testBoundedHeavyForkedSync(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a long enough forked chain
	common, fork := 13, int(MaxForkAncestry+17)
	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, false)

	tester.newPeer("original", protocol, hashesA, headersA, blocksA, receiptsA)
	tester.newPeer("heavy-rewriter", protocol, hashesB[MaxForkAncestry-17:], headersB, blocksB, receiptsB) // Root the fork below the ancestor limit

	// Synchronise with the peer and make sure all blocks were retrieved
	if err := tester.sync("original", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, common+fork+1)

	// Synchronise with the second peer and ensure that the fork is rejected to being too old
	if err := tester.sync("heavy-rewriter", nil, mode); err != errInvalidAncestor {
		t.Fatalf("sync failure mismatch: have %v, want %v", err, errInvalidAncestor)
	}
}

// Tests that an inactive downloader will not accept incoming block headers and
// bodies.
func TestInactiveDownloader62(t *testing.T) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Check that neither block headers nor bodies are accepted
	if err := tester.downloader.DeliverHeaders("bad peer", []*types.Header{}); err != errNoSyncActive {
		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
	}
	if err := tester.downloader.DeliverBodies("bad peer", [][]*types.Transaction{}, [][]*types.Header{}); err != errNoSyncActive {
		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
	}
}

// Tests that an inactive downloader will not accept incoming block headers,
// bodies and receipts.
func TestInactiveDownloader63(t *testing.T) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Check that neither block headers nor bodies are accepted
	if err := tester.downloader.DeliverHeaders("bad peer", []*types.Header{}); err != errNoSyncActive {
		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
	}
	if err := tester.downloader.DeliverBodies("bad peer", [][]*types.Transaction{}, [][]*types.Header{}); err != errNoSyncActive {
		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
	}
	if err := tester.downloader.DeliverReceipts("bad peer", [][]*types.Receipt{}); err != errNoSyncActive {
		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
	}
}

// Tests that a canceled download wipes all previously accumulated state.
func TestCancel62(t *testing.T)       { testCancel(t, 62, FullSync) }
func TestCancel63Full(t *testing.T)   { testCancel(t, 63, FullSync) }
func TestCancel63Fast(t *testing.T)   { testCancel(t, 63, FastSync) }
func TestCancel64Full(t *testing.T)   { testCancel(t, 64, FullSync) }
func TestCancel64Fast(t *testing.T)   { testCancel(t, 64, FastSync) }
func TestCancel64Light(t *testing.T)  { testCancel(t, 64, LightSync) }
func TestCancel100Full(t *testing.T)  { testCancel(t, 100, FullSync) }
func TestCancel100Fast(t *testing.T)  { testCancel(t, 100, FastSync) }
func TestCancel100Light(t *testing.T) { testCancel(t, 100, LightSync) }
func TestCancel101Full(t *testing.T)  { testCancel(t, 101, FullSync) }
func TestCancel101Fast(t *testing.T)  { testCancel(t, 101, FastSync) }
func TestCancel101Light(t *testing.T) { testCancel(t, 101, LightSync) }

func testCancel(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download and the tester
	targetBlocks := blockCacheItems - 15
	if targetBlocks >= MaxHashFetch {
		targetBlocks = MaxHashFetch - 15
	}
	if targetBlocks >= MaxHeaderFetch {
		targetBlocks = MaxHeaderFetch - 15
	}
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

	// Make sure canceling works with a pristine downloader
	tester.downloader.Cancel()
	if !tester.downloader.queue.Idle() {
		t.Errorf("download queue not idle")
	}
	// Synchronise with the peer, but cancel afterwards
	if err := tester.sync("peer", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	tester.downloader.Cancel()
	if !tester.downloader.queue.Idle() {
		t.Errorf("download queue not idle")
	}
}

// Tests that synchronisation from multiple peers works as intended (multi thread sanity test).
func TestMultiSynchronisation62(t *testing.T)       { testMultiSynchronisation(t, 62, FullSync) }
func TestMultiSynchronisation63Full(t *testing.T)   { testMultiSynchronisation(t, 63, FullSync) }
func TestMultiSynchronisation63Fast(t *testing.T)   { testMultiSynchronisation(t, 63, FastSync) }
func TestMultiSynchronisation64Full(t *testing.T)   { testMultiSynchronisation(t, 64, FullSync) }
func TestMultiSynchronisation64Fast(t *testing.T)   { testMultiSynchronisation(t, 64, FastSync) }
func TestMultiSynchronisation64Light(t *testing.T)  { testMultiSynchronisation(t, 64, LightSync) }
func TestMultiSynchronisation100Full(t *testing.T)  { testMultiSynchronisation(t, 100, FullSync) }
func TestMultiSynchronisation100Fast(t *testing.T)  { testMultiSynchronisation(t, 100, FastSync) }
func TestMultiSynchronisation100Light(t *testing.T) { testMultiSynchronisation(t, 100, LightSync) }
func TestMultiSynchronisation101Full(t *testing.T)  { testMultiSynchronisation(t, 101, FullSync) }
func TestMultiSynchronisation101Fast(t *testing.T)  { testMultiSynchronisation(t, 101, FastSync) }
func TestMultiSynchronisation101Light(t *testing.T) { testMultiSynchronisation(t, 101, LightSync) }

func testMultiSynchronisation(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create various peers with various parts of the chain
	targetPeers := 8
	targetBlocks := targetPeers*blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	for i := 0; i < targetPeers; i++ {
		id := fmt.Sprintf("peer #%d", i)
		tester.newPeer(id, protocol, hashes[i*blockCacheItems:], headers, blocks, receipts)
	}
	if err := tester.sync("peer #0", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that synchronisations behave well in multi-version protocol environments
// and not wreak havoc on other nodes in the network.
func TestMultiProtoSynchronisation62(t *testing.T)       { testMultiProtoSync(t, 62, FullSync) }
func TestMultiProtoSynchronisation63Full(t *testing.T)   { testMultiProtoSync(t, 63, FullSync) }
func TestMultiProtoSynchronisation63Fast(t *testing.T)   { testMultiProtoSync(t, 63, FastSync) }
func TestMultiProtoSynchronisation64Full(t *testing.T)   { testMultiProtoSync(t, 64, FullSync) }
func TestMultiProtoSynchronisation64Fast(t *testing.T)   { testMultiProtoSync(t, 64, FastSync) }
func TestMultiProtoSynchronisation64Light(t *testing.T)  { testMultiProtoSync(t, 64, LightSync) }
func TestMultiProtoSynchronisation100Full(t *testing.T)  { testMultiProtoSync(t, 100, FullSync) }
func TestMultiProtoSynchronisation100Fast(t *testing.T)  { testMultiProtoSync(t, 100, FastSync) }
func TestMultiProtoSynchronisation100Light(t *testing.T) { testMultiProtoSync(t, 100, LightSync) }
func TestMultiProtoSynchronisation101Full(t *testing.T)  { testMultiProtoSync(t, 101, FullSync) }
func TestMultiProtoSynchronisation101Fast(t *testing.T)  { testMultiProtoSync(t, 101, FastSync) }
func TestMultiProtoSynchronisation101Light(t *testing.T) { testMultiProtoSync(t, 101, LightSync) }

func testMultiProtoSync(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download
	targetBlocks := blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	// Create peers of every type
	tester.newPeer("peer 62", 62, hashes, headers, blocks, nil)
	tester.newPeer("peer 63", 63, hashes, headers, blocks, receipts)
	tester.newPeer("peer 64", 64, hashes, headers, blocks, receipts)
	tester.newPeer("peer 100", 100, hashes, headers, blocks, receipts)
	tester.newPeer("peer 101", 101, hashes, headers, blocks, receipts)

	// Synchronise with the requested peer and make sure all blocks were retrieved
	if err := tester.sync(fmt.Sprintf("peer %d", protocol), nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, targetBlocks+1)

	// Check that no peers have been dropped off
	for _, version := range []int{62, 63, 64, 100, 101} {
		peer := fmt.Sprintf("peer %d", version)
		if _, ok := tester.peerHashes[peer]; !ok {
			t.Errorf("%s dropped", peer)
		}
	}
}

// Tests that if a block is empty (e.g. header only), no body request should be
// made, and instead the header should be assembled into a whole block in itself.
func TestEmptyShortCircuit62(t *testing.T)       { testEmptyShortCircuit(t, 62, FullSync) }
func TestEmptyShortCircuit63Full(t *testing.T)   { testEmptyShortCircuit(t, 63, FullSync) }
func TestEmptyShortCircuit63Fast(t *testing.T)   { testEmptyShortCircuit(t, 63, FastSync) }
func TestEmptyShortCircuit64Full(t *testing.T)   { testEmptyShortCircuit(t, 64, FullSync) }
func TestEmptyShortCircuit64Fast(t *testing.T)   { testEmptyShortCircuit(t, 64, FastSync) }
func TestEmptyShortCircuit64Light(t *testing.T)  { testEmptyShortCircuit(t, 64, LightSync) }
func TestEmptyShortCircuit100Full(t *testing.T)  { testEmptyShortCircuit(t, 100, FullSync) }
func TestEmptyShortCircuit100Fast(t *testing.T)  { testEmptyShortCircuit(t, 100, FastSync) }
func TestEmptyShortCircuit100Light(t *testing.T) { testEmptyShortCircuit(t, 100, LightSync) }
func TestEmptyShortCircuit101Full(t *testing.T)  { testEmptyShortCircuit(t, 101, FullSync) }
func TestEmptyShortCircuit101Fast(t *testing.T)  { testEmptyShortCircuit(t, 101, FastSync) }
func TestEmptyShortCircuit101Light(t *testing.T) { testEmptyShortCircuit(t, 101, LightSync) }

func testEmptyShortCircuit(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a block chain to download
	targetBlocks := 2*blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

	// Instrument the downloader to signal body requests
	bodiesHave, receiptsHave := int32(0), int32(0)
	tester.downloader.bodyFetchHook = func(headers []*types.Header) {
		atomic.AddInt32(&bodiesHave, int32(len(headers)))
	}
	tester.downloader.receiptFetchHook = func(headers []*types.Header) {
		atomic.AddInt32(&receiptsHave, int32(len(headers)))
	}
	// Synchronise with the peer and make sure all blocks were retrieved
	if err := tester.sync("peer", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, targetBlocks+1)

	// Validate the number of block bodies that should have been requested
	bodiesNeeded, receiptsNeeded := 0, 0
	for _, block := range blocks {
		if mode != LightSync && block != tester.genesis && (len(block.Transactions()) > 0 || len(block.Uncles()) > 0) {
			bodiesNeeded++
		}
	}
	for _, receipt := range receipts {
		if mode == FastSync && len(receipt) > 0 {
			receiptsNeeded++
		}
	}
	if int(bodiesHave) != bodiesNeeded {
		t.Errorf("body retrieval count mismatch: have %v, want %v", bodiesHave, bodiesNeeded)
	}
	if int(receiptsHave) != receiptsNeeded {
		t.Errorf("receipt retrieval count mismatch: have %v, want %v", receiptsHave, receiptsNeeded)
	}
}

// Tests that headers are enqueued continuously, preventing malicious nodes from
// stalling the downloader by feeding gapped header chains.
func TestMissingHeaderAttack62(t *testing.T)       { testMissingHeaderAttack(t, 62, FullSync) }
func TestMissingHeaderAttack63Full(t *testing.T)   { testMissingHeaderAttack(t, 63, FullSync) }
func TestMissingHeaderAttack63Fast(t *testing.T)   { testMissingHeaderAttack(t, 63, FastSync) }
func TestMissingHeaderAttack64Full(t *testing.T)   { testMissingHeaderAttack(t, 64, FullSync) }
func TestMissingHeaderAttack64Fast(t *testing.T)   { testMissingHeaderAttack(t, 64, FastSync) }
func TestMissingHeaderAttack64Light(t *testing.T)  { testMissingHeaderAttack(t, 64, LightSync) }
func TestMissingHeaderAttack100Full(t *testing.T)  { testMissingHeaderAttack(t, 100, FullSync) }
func TestMissingHeaderAttack100Fast(t *testing.T)  { testMissingHeaderAttack(t, 100, FastSync) }
func TestMissingHeaderAttack100Light(t *testing.T) { testMissingHeaderAttack(t, 100, LightSync) }
func TestMissingHeaderAttack101Full(t *testing.T)  { testMissingHeaderAttack(t, 101, FullSync) }
func TestMissingHeaderAttack101Fast(t *testing.T)  { testMissingHeaderAttack(t, 101, FastSync) }
func TestMissingHeaderAttack101Light(t *testing.T) { testMissingHeaderAttack(t, 101, LightSync) }

func testMissingHeaderAttack(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download
	targetBlocks := blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	// Attempt a full sync with an attacker feeding gapped headers
	tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
	missing := targetBlocks / 2
	delete(tester.peerHeaders["attack"], hashes[missing])

	if err := tester.sync("attack", nil, mode); err == nil {
		t.Fatalf("succeeded attacker synchronisation")
	}
	// Synchronise with the valid peer and make sure sync succeeds
	tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
	if err := tester.sync("valid", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that if requested headers are shifted (i.e. first is missing), the queue
// detects the invalid numbering.
func TestShiftedHeaderAttack62(t *testing.T)       { testShiftedHeaderAttack(t, 62, FullSync) }
func TestShiftedHeaderAttack63Full(t *testing.T)   { testShiftedHeaderAttack(t, 63, FullSync) }
func TestShiftedHeaderAttack63Fast(t *testing.T)   { testShiftedHeaderAttack(t, 63, FastSync) }
func TestShiftedHeaderAttack64Full(t *testing.T)   { testShiftedHeaderAttack(t, 64, FullSync) }
func TestShiftedHeaderAttack64Fast(t *testing.T)   { testShiftedHeaderAttack(t, 64, FastSync) }
func TestShiftedHeaderAttack64Light(t *testing.T)  { testShiftedHeaderAttack(t, 64, LightSync) }
func TestShiftedHeaderAttack100Full(t *testing.T)  { testShiftedHeaderAttack(t, 100, FullSync) }
func TestShiftedHeaderAttack100Fast(t *testing.T)  { testShiftedHeaderAttack(t, 100, FastSync) }
func TestShiftedHeaderAttack100Light(t *testing.T) { testShiftedHeaderAttack(t, 100, LightSync) }
func TestShiftedHeaderAttack101Full(t *testing.T)  { testShiftedHeaderAttack(t, 101, FullSync) }
func TestShiftedHeaderAttack101Fast(t *testing.T)  { testShiftedHeaderAttack(t, 101, FastSync) }
func TestShiftedHeaderAttack101Light(t *testing.T) { testShiftedHeaderAttack(t, 101, LightSync) }

func testShiftedHeaderAttack(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download
	targetBlocks := blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	// Attempt a full sync with an attacker feeding shifted headers
	tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
	delete(tester.peerHeaders["attack"], hashes[len(hashes)-2])
	delete(tester.peerBlocks["attack"], hashes[len(hashes)-2])
	delete(tester.peerReceipts["attack"], hashes[len(hashes)-2])

	if err := tester.sync("attack", nil, mode); err == nil {
		t.Fatalf("succeeded attacker synchronisation")
	}
	// Synchronise with the valid peer and make sure sync succeeds
	tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
	if err := tester.sync("valid", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that upon detecting an invalid header, the recent ones are rolled back
// for various failure scenarios. Afterwards a full sync is attempted to make
// sure no state was corrupted.
func TestInvalidHeaderRollback63Fast(t *testing.T)   { testInvalidHeaderRollback(t, 63, FastSync) }
func TestInvalidHeaderRollback64Fast(t *testing.T)   { testInvalidHeaderRollback(t, 64, FastSync) }
func TestInvalidHeaderRollback64Light(t *testing.T)  { testInvalidHeaderRollback(t, 64, LightSync) }
func TestInvalidHeaderRollback100Fast(t *testing.T)  { testInvalidHeaderRollback(t, 100, FastSync) }
func TestInvalidHeaderRollback100Light(t *testing.T) { testInvalidHeaderRollback(t, 100, LightSync) }
func TestInvalidHeaderRollback101Fast(t *testing.T)  { testInvalidHeaderRollback(t, 101, FastSync) }
func TestInvalidHeaderRollback101Light(t *testing.T) { testInvalidHeaderRollback(t, 101, LightSync) }

func testInvalidHeaderRollback(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download
	targetBlocks := 3*fsHeaderSafetyNet + 256 + fsMinFullBlocks
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	// Attempt to sync with an attacker that feeds junk during the fast sync phase.
	// This should result in the last fsHeaderSafetyNet headers being rolled back.
	tester.newPeer("fast-attack", protocol, hashes, headers, blocks, receipts)
	missing := fsHeaderSafetyNet + MaxHeaderFetch + 1
	delete(tester.peerHeaders["fast-attack"], hashes[len(hashes)-missing])

	if err := tester.sync("fast-attack", nil, mode); err == nil {
		t.Fatalf("succeeded fast attacker synchronisation")
	}
	if head := tester.CurrentHeader().Number.Int64(); int(head) > MaxHeaderFetch {
		t.Errorf("rollback head mismatch: have %v, want at most %v", head, MaxHeaderFetch)
	}
	// Attempt to sync with an attacker that feeds junk during the block import phase.
	// This should result in both the last fsHeaderSafetyNet number of headers being
	// rolled back, and also the pivot point being reverted to a non-block status.
	tester.newPeer("block-attack", protocol, hashes, headers, blocks, receipts)
	missing = 3*fsHeaderSafetyNet + MaxHeaderFetch + 1
	delete(tester.peerHeaders["fast-attack"], hashes[len(hashes)-missing]) // Make sure the fast-attacker doesn't fill in
	delete(tester.peerHeaders["block-attack"], hashes[len(hashes)-missing])

	if err := tester.sync("block-attack", nil, mode); err == nil {
		t.Fatalf("succeeded block attacker synchronisation")
	}
	if head := tester.CurrentHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
		t.Errorf("rollback head mismatch: have %v, want at most %v", head, 2*fsHeaderSafetyNet+MaxHeaderFetch)
	}
	if mode == FastSync {
		if head := tester.CurrentBlock().NumberU64(); head != 0 {
			t.Errorf("fast sync pivot block #%d not rolled back", head)
		}
	}
	// Attempt to sync with an attacker that withholds promised blocks after the
	// fast sync pivot point. This could be a trial to leave the node with a bad
	// but already imported pivot block.
	tester.newPeer("withhold-attack", protocol, hashes, headers, blocks, receipts)
	missing = 3*fsHeaderSafetyNet + MaxHeaderFetch + 1

	tester.downloader.syncInitHook = func(uint64, uint64) {
		for i := missing; i <= len(hashes); i++ {
			delete(tester.peerHeaders["withhold-attack"], hashes[len(hashes)-i])
		}
		tester.downloader.syncInitHook = nil
	}

	if err := tester.sync("withhold-attack", nil, mode); err == nil {
		t.Fatalf("succeeded withholding attacker synchronisation")
	}
	if head := tester.CurrentHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
		t.Errorf("rollback head mismatch: have %v, want at most %v", head, 2*fsHeaderSafetyNet+MaxHeaderFetch)
	}
	if mode == FastSync {
		if head := tester.CurrentBlock().NumberU64(); head != 0 {
			t.Errorf("fast sync pivot block #%d not rolled back", head)
		}
	}
	// Synchronise with the valid peer and make sure sync succeeds. Since the last
	// rollback should also disable fast syncing for this process, verify that we
	// did a fresh full sync. Note, we can't assert anything about the receipts
	// since we won't purge the database of them, hence we can't use assertOwnChain.
	tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
	if err := tester.sync("valid", nil, mode); err != nil {
		t.Fatalf("failed to synchronise blocks: %v", err)
	}
	if hs := len(tester.ownHeaders); hs != len(headers) {
		t.Fatalf("synchronised headers mismatch: have %v, want %v", hs, len(headers))
	}
	if mode != LightSync {
		if bs := len(tester.ownBlocks); bs != len(blocks) {
			t.Fatalf("synchronised blocks mismatch: have %v, want %v", bs, len(blocks))
		}
	}
}

// Tests that a peer advertising an high TD doesn't get to stall the downloader
// afterwards by not sending any useful hashes.
func TestHighTDStarvationAttack62(t *testing.T)       { testHighTDStarvationAttack(t, 62, FullSync) }
func TestHighTDStarvationAttack63Full(t *testing.T)   { testHighTDStarvationAttack(t, 63, FullSync) }
func TestHighTDStarvationAttack63Fast(t *testing.T)   { testHighTDStarvationAttack(t, 63, FastSync) }
func TestHighTDStarvationAttack64Full(t *testing.T)   { testHighTDStarvationAttack(t, 64, FullSync) }
func TestHighTDStarvationAttack64Fast(t *testing.T)   { testHighTDStarvationAttack(t, 64, FastSync) }
func TestHighTDStarvationAttack64Light(t *testing.T)  { testHighTDStarvationAttack(t, 64, LightSync) }
func TestHighTDStarvationAttack100Full(t *testing.T)  { testHighTDStarvationAttack(t, 100, FullSync) }
func TestHighTDStarvationAttack100Fast(t *testing.T)  { testHighTDStarvationAttack(t, 100, FastSync) }
func TestHighTDStarvationAttack100Light(t *testing.T) { testHighTDStarvationAttack(t, 100, LightSync) }
func TestHighTDStarvationAttack101Full(t *testing.T)  { testHighTDStarvationAttack(t, 101, FullSync) }
func TestHighTDStarvationAttack101Fast(t *testing.T)  { testHighTDStarvationAttack(t, 101, FastSync) }
func TestHighTDStarvationAttack101Light(t *testing.T) { testHighTDStarvationAttack(t, 101, LightSync) }

func testHighTDStarvationAttack(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	hashes, headers, blocks, receipts := tester.makeChain(0, 0, tester.genesis, nil, false)
	tester.newPeer("attack", protocol, []common.Hash{hashes[0]}, headers, blocks, receipts)

	if err := tester.sync("attack", big.NewInt(1000000), mode); err != errStallingPeer {
		t.Fatalf("synchronisation error mismatch: have %v, want %v", err, errStallingPeer)
	}
}

// Tests that misbehaving peers are disconnected, whilst behaving ones are not.
func TestBlockHeaderAttackerDropping62(t *testing.T)  { testBlockHeaderAttackerDropping(t, 62) }
func TestBlockHeaderAttackerDropping63(t *testing.T)  { testBlockHeaderAttackerDropping(t, 63) }
func TestBlockHeaderAttackerDropping64(t *testing.T)  { testBlockHeaderAttackerDropping(t, 64) }
func TestBlockHeaderAttackerDropping100(t *testing.T) { testBlockHeaderAttackerDropping(t, 100) }
func TestBlockHeaderAttackerDropping101(t *testing.T) { testBlockHeaderAttackerDropping(t, 101) }

func testBlockHeaderAttackerDropping(t *testing.T, protocol int) {
	t.Parallel()

	// Define the disconnection requirement for individual hash fetch errors
	tests := []struct {
		result error
		drop   bool
	}{
		{nil, false},                        // Sync succeeded, all is well
		{errBusy, false},                    // Sync is already in progress, no problem
		{errUnknownPeer, false},             // Peer is unknown, was already dropped, don't double drop
		{errBadPeer, true},                  // Peer was deemed bad for some reason, drop it
		{errStallingPeer, true},             // Peer was detected to be stalling, drop it
		{errNoPeers, false},                 // No peers to download from, soft race, no issue
		{errTimeout, true},                  // No hashes received in due time, drop the peer
		{errEmptyHeaderSet, true},           // No headers were returned as a response, drop as it's a dead end
		{errPeersUnavailable, true},         // Nobody had the advertised blocks, drop the advertiser
		{errInvalidAncestor, true},          // Agreed upon ancestor is not acceptable, drop the chain rewriter
		{errInvalidChain, true},             // Hash chain was detected as invalid, definitely drop
		{errInvalidBlock, false},            // A bad peer was detected, but not the sync origin
		{errInvalidBody, false},             // A bad peer was detected, but not the sync origin
		{errInvalidReceipt, false},          // A bad peer was detected, but not the sync origin
		{errCancelBlockFetch, false},        // Synchronisation was canceled, origin may be innocent, don't drop
		{errCancelHeaderFetch, false},       // Synchronisation was canceled, origin may be innocent, don't drop
		{errCancelBodyFetch, false},         // Synchronisation was canceled, origin may be innocent, don't drop
		{errCancelReceiptFetch, false},      // Synchronisation was canceled, origin may be innocent, don't drop
		{errCancelHeaderProcessing, false},  // Synchronisation was canceled, origin may be innocent, don't drop
		{errCancelContentProcessing, false}, // Synchronisation was canceled, origin may be innocent, don't drop
	}
	// Run the tests and check disconnection status
	tester := newTester()
	defer tester.terminate()

	for i, tt := range tests {
		// Register a new peer and ensure its presence
		id := fmt.Sprintf("test %d", i)
		if err := tester.newPeer(id, protocol, []common.Hash{tester.genesis.Hash()}, nil, nil, nil); err != nil {
			t.Fatalf("test %d: failed to register new peer: %v", i, err)
		}
		if _, ok := tester.peerHashes[id]; !ok {
			t.Fatalf("test %d: registered peer not found", i)
		}
		// Simulate a synchronisation and check the required result
		tester.downloader.synchroniseMock = func(string, common.Hash) error { return tt.result }

		tester.downloader.Synchronise(id, tester.genesis.Hash(), big.NewInt(1000), FullSync)
		if _, ok := tester.peerHashes[id]; !ok != tt.drop {
			t.Errorf("test %d: peer drop mismatch for %v: have %v, want %v", i, tt.result, !ok, tt.drop)
		}
	}
}

// Tests that synchronisation progress (origin block number, current block number
// and highest block number) is tracked and updated correctly.
func TestSyncProgress62(t *testing.T)       { testSyncProgress(t, 62, FullSync) }
func TestSyncProgress63Full(t *testing.T)   { testSyncProgress(t, 63, FullSync) }
func TestSyncProgress63Fast(t *testing.T)   { testSyncProgress(t, 63, FastSync) }
func TestSyncProgress64Full(t *testing.T)   { testSyncProgress(t, 64, FullSync) }
func TestSyncProgress64Fast(t *testing.T)   { testSyncProgress(t, 64, FastSync) }
func TestSyncProgress64Light(t *testing.T)  { testSyncProgress(t, 64, LightSync) }
func TestSyncProgress100Full(t *testing.T)  { testSyncProgress(t, 100, FullSync) }
func TestSyncProgress100Fast(t *testing.T)  { testSyncProgress(t, 100, FastSync) }
func TestSyncProgress100Light(t *testing.T) { testSyncProgress(t, 100, LightSync) }
func TestSyncProgress101Full(t *testing.T)  { testSyncProgress(t, 101, FullSync) }
func TestSyncProgress101Fast(t *testing.T)  { testSyncProgress(t, 101, FastSync) }
func TestSyncProgress101Light(t *testing.T) { testSyncProgress(t, 101, LightSync) }

func testSyncProgress(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download
	targetBlocks := blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	// Set a sync init hook to catch progress changes
	starting := make(chan struct{})
	progress := make(chan struct{})

	tester.downloader.syncInitHook = func(origin, latest uint64) {
		starting <- struct{}{}
		<-progress
	}
	// Retrieve the sync progress and ensure they are zero (pristine sync)
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != 0 {
		t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, 0)
	}
	// Synchronise half the blocks and check initial progress
	tester.newPeer("peer-half", protocol, hashes[targetBlocks/2:], headers, blocks, receipts)
	pending := new(sync.WaitGroup)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("peer-half", nil, mode); err != nil {
			panic(fmt.Sprintf("failed to synchronise blocks: %v", err))
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != uint64(targetBlocks/2+1) {
		t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, targetBlocks/2+1)
	}
	progress <- struct{}{}
	pending.Wait()

	// Synchronise all the blocks and check continuation progress
	tester.newPeer("peer-full", protocol, hashes, headers, blocks, receipts)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("peer-full", nil, mode); err != nil {
			panic(fmt.Sprintf("failed to synchronise blocks: %v", err))
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != uint64(targetBlocks/2+1) || progress.CurrentBlock != uint64(targetBlocks/2+1) || progress.HighestBlock != uint64(targetBlocks) {
		t.Fatalf("Completing progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, targetBlocks/2+1, targetBlocks/2+1, targetBlocks)
	}
	progress <- struct{}{}
	pending.Wait()

	// Check final progress after successful sync
	if progress := tester.downloader.Progress(); progress.StartingBlock != uint64(targetBlocks/2+1) || progress.CurrentBlock != uint64(targetBlocks) || progress.HighestBlock != uint64(targetBlocks) {
		t.Fatalf("Final progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, targetBlocks/2+1, targetBlocks, targetBlocks)
	}
}

// Tests that synchronisation progress (origin block number and highest block
// number) is tracked and updated correctly in case of a fork (or manual head
// revertal).
func TestForkedSyncProgress62(t *testing.T)       { testForkedSyncProgress(t, 62, FullSync) }
func TestForkedSyncProgress63Full(t *testing.T)   { testForkedSyncProgress(t, 63, FullSync) }
func TestForkedSyncProgress63Fast(t *testing.T)   { testForkedSyncProgress(t, 63, FastSync) }
func TestForkedSyncProgress64Full(t *testing.T)   { testForkedSyncProgress(t, 64, FullSync) }
func TestForkedSyncProgress64Fast(t *testing.T)   { testForkedSyncProgress(t, 64, FastSync) }
func TestForkedSyncProgress64Light(t *testing.T)  { testForkedSyncProgress(t, 64, LightSync) }
func TestForkedSyncProgress100Full(t *testing.T)  { testForkedSyncProgress(t, 100, FullSync) }
func TestForkedSyncProgress100Fast(t *testing.T)  { testForkedSyncProgress(t, 100, FastSync) }
func TestForkedSyncProgress100Light(t *testing.T) { testForkedSyncProgress(t, 100, LightSync) }
func TestForkedSyncProgress101Full(t *testing.T)  { testForkedSyncProgress(t, 101, FullSync) }
func TestForkedSyncProgress101Fast(t *testing.T)  { testForkedSyncProgress(t, 101, FastSync) }
func TestForkedSyncProgress101Light(t *testing.T) { testForkedSyncProgress(t, 101, LightSync) }

func testForkedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a forked chain to simulate origin revertal
	common, fork := MaxHashFetch, 2*MaxHashFetch
	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, true)

	// Set a sync init hook to catch progress changes
	starting := make(chan struct{})
	progress := make(chan struct{})

	tester.downloader.syncInitHook = func(origin, latest uint64) {
		starting <- struct{}{}
		<-progress
	}
	// Retrieve the sync progress and ensure they are zero (pristine sync)
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != 0 {
		t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, 0)
	}
	// Synchronise with one of the forks and check progress
	tester.newPeer("fork A", protocol, hashesA, headersA, blocksA, receiptsA)
	pending := new(sync.WaitGroup)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("fork A", nil, mode); err != nil {
			panic(fmt.Sprintf("failed to synchronise blocks: %v", err))
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != uint64(len(hashesA)-1) {
		t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, len(hashesA)-1)
	}
	progress <- struct{}{}
	pending.Wait()

	// Simulate a successful sync above the fork
	tester.downloader.syncStatsChainOrigin = tester.downloader.syncStatsChainHeight

	// Synchronise with the second fork and check progress resets
	tester.newPeer("fork B", protocol, hashesB, headersB, blocksB, receiptsB)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("fork B", nil, mode); err != nil {
			panic(fmt.Sprintf("failed to synchronise blocks: %v", err))
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != uint64(common) || progress.CurrentBlock != uint64(len(hashesA)-1) || progress.HighestBlock != uint64(len(hashesB)-1) {
		t.Fatalf("Forking progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, common, len(hashesA)-1, len(hashesB)-1)
	}
	progress <- struct{}{}
	pending.Wait()

	// Check final progress after successful sync
	if progress := tester.downloader.Progress(); progress.StartingBlock != uint64(common) || progress.CurrentBlock != uint64(len(hashesB)-1) || progress.HighestBlock != uint64(len(hashesB)-1) {
		t.Fatalf("Final progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, common, len(hashesB)-1, len(hashesB)-1)
	}
}

// Tests that if synchronisation is aborted due to some failure, then the progress
// origin is not updated in the next sync cycle, as it should be considered the
// continuation of the previous sync and not a new instance.
func TestFailedSyncProgress62(t *testing.T)       { testFailedSyncProgress(t, 62, FullSync) }
func TestFailedSyncProgress63Full(t *testing.T)   { testFailedSyncProgress(t, 63, FullSync) }
func TestFailedSyncProgress63Fast(t *testing.T)   { testFailedSyncProgress(t, 63, FastSync) }
func TestFailedSyncProgress64Full(t *testing.T)   { testFailedSyncProgress(t, 64, FullSync) }
func TestFailedSyncProgress64Fast(t *testing.T)   { testFailedSyncProgress(t, 64, FastSync) }
func TestFailedSyncProgress64Light(t *testing.T)  { testFailedSyncProgress(t, 64, LightSync) }
func TestFailedSyncProgress100Full(t *testing.T)  { testFailedSyncProgress(t, 100, FullSync) }
func TestFailedSyncProgress100Fast(t *testing.T)  { testFailedSyncProgress(t, 100, FastSync) }
func TestFailedSyncProgress100Light(t *testing.T) { testFailedSyncProgress(t, 100, LightSync) }
func TestFailedSyncProgress101Full(t *testing.T)  { testFailedSyncProgress(t, 101, FullSync) }
func TestFailedSyncProgress101Fast(t *testing.T)  { testFailedSyncProgress(t, 101, FastSync) }
func TestFailedSyncProgress101Light(t *testing.T) { testFailedSyncProgress(t, 101, LightSync) }

func testFailedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small enough block chain to download
	targetBlocks := blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)

	// Set a sync init hook to catch progress changes
	starting := make(chan struct{})
	progress := make(chan struct{})

	tester.downloader.syncInitHook = func(origin, latest uint64) {
		starting <- struct{}{}
		<-progress
	}
	// Retrieve the sync progress and ensure they are zero (pristine sync)
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != 0 {
		t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, 0)
	}
	// Attempt a full sync with a faulty peer
	tester.newPeer("faulty", protocol, hashes, headers, blocks, receipts)
	missing := targetBlocks / 2
	delete(tester.peerHeaders["faulty"], hashes[missing])
	delete(tester.peerBlocks["faulty"], hashes[missing])
	delete(tester.peerReceipts["faulty"], hashes[missing])

	pending := new(sync.WaitGroup)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("faulty", nil, mode); err == nil {
			panic("succeeded faulty synchronisation")
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != uint64(targetBlocks) {
		t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, targetBlocks)
	}
	progress <- struct{}{}
	pending.Wait()

	// Synchronise with a good peer and check that the progress origin remind the same after a failure
	tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("valid", nil, mode); err != nil {
			panic(fmt.Sprintf("failed to synchronise blocks: %v", err))
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock > uint64(targetBlocks/2) || progress.HighestBlock != uint64(targetBlocks) {
		t.Fatalf("Completing progress mismatch: have %v/%v/%v, want %v/0-%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, targetBlocks/2, targetBlocks)
	}
	progress <- struct{}{}
	pending.Wait()

	// Check final progress after successful sync
	if progress := tester.downloader.Progress(); progress.StartingBlock > uint64(targetBlocks/2) || progress.CurrentBlock != uint64(targetBlocks) || progress.HighestBlock != uint64(targetBlocks) {
		t.Fatalf("Final progress mismatch: have %v/%v/%v, want 0-%v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, targetBlocks/2, targetBlocks, targetBlocks)
	}
}

// Tests that if an attacker fakes a chain height, after the attack is detected,
// the progress height is successfully reduced at the next sync invocation.
func TestFakedSyncProgress62(t *testing.T)       { testFakedSyncProgress(t, 62, FullSync) }
func TestFakedSyncProgress63Full(t *testing.T)   { testFakedSyncProgress(t, 63, FullSync) }
func TestFakedSyncProgress63Fast(t *testing.T)   { testFakedSyncProgress(t, 63, FastSync) }
func TestFakedSyncProgress64Full(t *testing.T)   { testFakedSyncProgress(t, 64, FullSync) }
func TestFakedSyncProgress64Fast(t *testing.T)   { testFakedSyncProgress(t, 64, FastSync) }
func TestFakedSyncProgress64Light(t *testing.T)  { testFakedSyncProgress(t, 64, LightSync) }
func TestFakedSyncProgress100Full(t *testing.T)  { testFakedSyncProgress(t, 100, FullSync) }
func TestFakedSyncProgress100Fast(t *testing.T)  { testFakedSyncProgress(t, 100, FastSync) }
func TestFakedSyncProgress100Light(t *testing.T) { testFakedSyncProgress(t, 100, LightSync) }
func TestFakedSyncProgress101Full(t *testing.T)  { testFakedSyncProgress(t, 101, FullSync) }
func TestFakedSyncProgress101Fast(t *testing.T)  { testFakedSyncProgress(t, 101, FastSync) }
func TestFakedSyncProgress101Light(t *testing.T) { testFakedSyncProgress(t, 101, LightSync) }

func testFakedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	tester := newTester()
	defer tester.terminate()

	// Create a small block chain
	targetBlocks := blockCacheItems - 15
	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks+3, 0, tester.genesis, nil, false)

	// Set a sync init hook to catch progress changes
	starting := make(chan struct{})
	progress := make(chan struct{})

	tester.downloader.syncInitHook = func(origin, latest uint64) {
		starting <- struct{}{}
		<-progress
	}
	// Retrieve the sync progress and ensure they are zero (pristine sync)
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != 0 {
		t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, 0)
	}
	//  Create and sync with an attacker that promises a higher chain than available
	tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
	for i := 1; i < 3; i++ {
		delete(tester.peerHeaders["attack"], hashes[i])
		delete(tester.peerBlocks["attack"], hashes[i])
		delete(tester.peerReceipts["attack"], hashes[i])
	}

	pending := new(sync.WaitGroup)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("attack", nil, mode); err == nil {
			panic("succeeded attacker synchronisation")
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock != 0 || progress.HighestBlock != uint64(targetBlocks+3) {
		t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, 0, targetBlocks+3)
	}
	progress <- struct{}{}
	pending.Wait()

	// Synchronise with a good peer and check that the progress height has been reduced to the true value
	tester.newPeer("valid", protocol, hashes[3:], headers, blocks, receipts)
	pending.Add(1)

	go func() {
		defer pending.Done()
		if err := tester.sync("valid", nil, mode); err != nil {
			panic(fmt.Sprintf("failed to synchronise blocks: %v", err))
		}
	}()
	<-starting
	if progress := tester.downloader.Progress(); progress.StartingBlock != 0 || progress.CurrentBlock > uint64(targetBlocks) || progress.HighestBlock != uint64(targetBlocks) {
		t.Fatalf("Completing progress mismatch: have %v/%v/%v, want %v/0-%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, 0, targetBlocks, targetBlocks)
	}
	progress <- struct{}{}
	pending.Wait()

	// Check final progress after successful sync
	if progress := tester.downloader.Progress(); progress.StartingBlock > uint64(targetBlocks) || progress.CurrentBlock != uint64(targetBlocks) || progress.HighestBlock != uint64(targetBlocks) {
		t.Fatalf("Final progress mismatch: have %v/%v/%v, want 0-%v/%v/%v", progress.StartingBlock, progress.CurrentBlock, progress.HighestBlock, targetBlocks, targetBlocks, targetBlocks)
	}
}

// This test reproduces an issue where unexpected deliveries would
// block indefinitely if they arrived at the right time.
// We use data driven subtests to manage this so that it will be parallel on its own
// and not with the other tests, avoiding intermittent failures.
func TestDeliverHeadersHang(t *testing.T) {
	t.Skip("This test failed sometimes and is inconsistant result. Disable for now.")

	testCases := []struct {
		protocol int
		syncMode SyncMode
	}{
		{62, FullSync},
		{63, FullSync},
		{63, FastSync},
		{64, FullSync},
		{64, FastSync},
		{64, LightSync},
		{100, FullSync},
		{100, FastSync},
		{100, LightSync},
		{101, FullSync},
		{101, FastSync},
		{101, LightSync},
	}
	for _, tc := range testCases {
		t.Run(fmt.Sprintf("protocol %d mode %v", tc.protocol, tc.syncMode), func(t *testing.T) {
			testDeliverHeadersHang(t, tc.protocol, tc.syncMode)
		})
	}
}

type floodingTestPeer struct {
	peer   Peer
	tester *downloadTester
	pend   sync.WaitGroup
}

func (ftp *floodingTestPeer) Head() (common.Hash, *big.Int) { return ftp.peer.Head() }
func (ftp *floodingTestPeer) RequestHeadersByHash(hash common.Hash, count int, skip int, reverse bool) error {
	return ftp.peer.RequestHeadersByHash(hash, count, skip, reverse)
}
func (ftp *floodingTestPeer) RequestBodies(hashes []common.Hash) error {
	return ftp.peer.RequestBodies(hashes)
}
func (ftp *floodingTestPeer) RequestReceipts(hashes []common.Hash) error {
	return ftp.peer.RequestReceipts(hashes)
}
func (ftp *floodingTestPeer) RequestNodeData(hashes []common.Hash) error {
	return ftp.peer.RequestNodeData(hashes)
}

func (ftp *floodingTestPeer) RequestHeadersByNumber(from uint64, count, skip int, reverse bool) error {
	deliveriesDone := make(chan struct{}, 500)
	for i := 0; i < cap(deliveriesDone); i++ {
		peer := fmt.Sprintf("fake-peer%d", i)
		ftp.pend.Add(1)

		go func() {
			ftp.tester.downloader.DeliverHeaders(peer, []*types.Header{{}, {}, {}, {}})
			deliveriesDone <- struct{}{}
			ftp.pend.Done()
		}()
	}
	// Deliver the actual requested headers.
	go ftp.peer.RequestHeadersByNumber(from, count, skip, reverse)
	// None of the extra deliveries should block.
	timeout := time.After(60 * time.Second)
	for i := 0; i < cap(deliveriesDone); i++ {
		select {
		case <-deliveriesDone:
		case <-timeout:
			panic("blocked")
		}
	}
	return nil
}

func testDeliverHeadersHang(t *testing.T, protocol int, mode SyncMode) {
	t.Parallel()

	master := newTester()
	defer master.terminate()

	hashes, headers, blocks, receipts := master.makeChain(5, 0, master.genesis, nil, false)
	for i := 0; i < 200; i++ {
		tester := newTester()
		tester.peerDb = master.peerDb

		tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
		// Whenever the downloader requests headers, flood it with
		// a lot of unrequested header deliveries.
		tester.downloader.peers.peers["peer"].peer = &floodingTestPeer{
			peer:   tester.downloader.peers.peers["peer"].peer,
			tester: tester,
		}
		if err := tester.sync("peer", nil, mode); err != nil {
			t.Errorf("test %d: sync failed: %v", i, err)
		}
		tester.terminate()

		// Flush all goroutines to prevent messing with subsequent tests
		tester.downloader.peers.peers["peer"].peer.(*floodingTestPeer).pend.Wait()
	}
}