package miner

import (
	"crypto/rand"
	"errors"
	"math/big"

	"github.com/ethereum/go-ethereum/accounts"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/consensus/bor"
	"github.com/ethereum/go-ethereum/consensus/clique"
	"github.com/ethereum/go-ethereum/consensus/ethash"
	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/core/state"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/params"
)

const (
	// testCode is the testing contract binary code which will initialises some
	// variables in constructor
	testCode = "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"

	// testGas is the gas required for contract deployment.
	testGas = 144109
)

func init() {
	signer := types.LatestSigner(params.TestChainConfig)

	tx1 := types.MustSignNewTx(testBankKey, signer, &types.AccessListTx{
		ChainID:  params.TestChainConfig.ChainID,
		Nonce:    0,
		To:       &testUserAddress,
		Value:    big.NewInt(1000),
		Gas:      params.TxGas,
		GasPrice: big.NewInt(params.InitialBaseFee),
	})

	pendingTxs = append(pendingTxs, tx1)

	tx2 := types.MustSignNewTx(testBankKey, signer, &types.LegacyTx{
		Nonce:    1,
		To:       &testUserAddress,
		Value:    big.NewInt(1000),
		Gas:      params.TxGas,
		GasPrice: big.NewInt(params.InitialBaseFee),
	})

	newTxs = append(newTxs, tx2)
}

// testWorkerBackend implements worker.Backend interfaces and wraps all information needed during the testing.
type testWorkerBackend struct {
	DB         ethdb.Database
	txPool     *core.TxPool
	chain      *core.BlockChain
	Genesis    *core.Genesis
	uncleBlock *types.Block
}

func newTestWorkerBackend(t TensingObject, chainConfig *params.ChainConfig, engine consensus.Engine, db ethdb.Database, n int) *testWorkerBackend {
	var gspec = core.Genesis{
		Config:   chainConfig,
		Alloc:    core.GenesisAlloc{TestBankAddress: {Balance: testBankFunds}},
		GasLimit: 30_000_000,
	}

	switch e := engine.(type) {
	case *bor.Bor:
		gspec.ExtraData = make([]byte, 32+common.AddressLength+crypto.SignatureLength)
		copy(gspec.ExtraData[32:32+common.AddressLength], TestBankAddress.Bytes())
		e.Authorize(TestBankAddress, func(account accounts.Account, s string, data []byte) ([]byte, error) {
			return crypto.Sign(crypto.Keccak256(data), testBankKey)
		})
	case *clique.Clique:
		gspec.ExtraData = make([]byte, 32+common.AddressLength+crypto.SignatureLength)
		copy(gspec.ExtraData[32:32+common.AddressLength], TestBankAddress.Bytes())
		e.Authorize(TestBankAddress, func(account accounts.Account, s string, data []byte) ([]byte, error) {
			return crypto.Sign(crypto.Keccak256(data), testBankKey)
		})
	case *ethash.Ethash:
	default:
		t.Fatalf("unexpected consensus engine type: %T", engine)
	}

	genesis := gspec.MustCommit(db)

	chain, _ := core.NewBlockChain(db, &core.CacheConfig{TrieDirtyDisabled: true}, gspec.Config, engine, vm.Config{}, nil, nil, nil)
	txpool := core.NewTxPool(testTxPoolConfig, chainConfig, chain)

	// Generate a small n-block chain and an uncle block for it
	if n > 0 {
		blocks, _ := core.GenerateChain(chainConfig, genesis, engine, db, n, func(i int, gen *core.BlockGen) {
			gen.SetCoinbase(TestBankAddress)
		})
		if _, err := chain.InsertChain(blocks); err != nil {
			t.Fatalf("failed to insert origin chain: %v", err)
		}
	}

	parent := genesis
	if n > 0 {
		parent = chain.GetBlockByHash(chain.CurrentBlock().ParentHash())
	}

	blocks, _ := core.GenerateChain(chainConfig, parent, engine, db, 1, func(i int, gen *core.BlockGen) {
		gen.SetCoinbase(testUserAddress)
	})

	return &testWorkerBackend{
		DB:         db,
		chain:      chain,
		txPool:     txpool,
		Genesis:    &gspec,
		uncleBlock: blocks[0],
	}
}

func (b *testWorkerBackend) BlockChain() *core.BlockChain { return b.chain }
func (b *testWorkerBackend) TxPool() *core.TxPool         { return b.txPool }
func (b *testWorkerBackend) StateAtBlock(block *types.Block, reexec uint64, base *state.StateDB, checkLive bool, preferDisk bool) (statedb *state.StateDB, err error) {
	return nil, errors.New("not supported")
}

func (b *testWorkerBackend) newRandomUncle() (*types.Block, error) {
	var parent *types.Block

	cur := b.chain.CurrentBlock()

	if cur.NumberU64() == 0 {
		parent = b.chain.Genesis()
	} else {
		parent = b.chain.GetBlockByHash(b.chain.CurrentBlock().ParentHash())
	}

	var err error

	blocks, _ := core.GenerateChain(b.chain.Config(), parent, b.chain.Engine(), b.DB, 1, func(i int, gen *core.BlockGen) {
		var addr = make([]byte, common.AddressLength)

		_, err = rand.Read(addr)
		if err != nil {
			return
		}

		gen.SetCoinbase(common.BytesToAddress(addr))
	})

	return blocks[0], err
}

func (b *testWorkerBackend) newRandomTx(creation bool) *types.Transaction {
	var tx *types.Transaction

	gasPrice := big.NewInt(10 * params.InitialBaseFee)

	if creation {
		tx, _ = types.SignTx(types.NewContractCreation(b.txPool.Nonce(TestBankAddress), big.NewInt(0), testGas, gasPrice, common.FromHex(testCode)), types.HomesteadSigner{}, testBankKey)
	} else {
		tx, _ = types.SignTx(types.NewTransaction(b.txPool.Nonce(TestBankAddress), testUserAddress, big.NewInt(1000), params.TxGas, gasPrice, nil), types.HomesteadSigner{}, testBankKey)
	}

	return tx
}

func NewTestWorker(t TensingObject, chainConfig *params.ChainConfig, engine consensus.Engine, db ethdb.Database, blocks int) (*worker, *testWorkerBackend, func()) {
	backend := newTestWorkerBackend(t, chainConfig, engine, db, blocks)
	backend.txPool.AddLocals(pendingTxs)

	//nolint:staticcheck
	w := newWorker(testConfig, chainConfig, engine, backend, new(event.TypeMux), nil, false)

	w.setEtherbase(TestBankAddress)

	return w, backend, w.close
}