// Copyright 2018 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 rawdb

import (
	"github.com/XinFinOrg/XDPoSChain/common"
	"github.com/XinFinOrg/XDPoSChain/core/types"
	"github.com/XinFinOrg/XDPoSChain/ethdb"
	"github.com/XinFinOrg/XDPoSChain/log"
	"github.com/XinFinOrg/XDPoSChain/params"
	"github.com/XinFinOrg/XDPoSChain/rlp"
)

type TxLookupEntry struct {
	BlockHash  common.Hash
	BlockIndex uint64
	Index      uint64
}

// ReadTxLookupEntry retrieves the positional metadata associated with a transaction
// hash to allow retrieving the transaction or receipt by hash.
func ReadTxLookupEntry(db ethdb.Reader, hash common.Hash) (common.Hash, uint64, uint64) {
	// Load the positional metadata from disk and bail if it fails
	data, _ := db.Get(txLookupKey(hash))
	if len(data) == 0 {
		return common.Hash{}, 0, 0
	}
	// Parse and return the contents of the lookup entry
	var entry TxLookupEntry
	if err := rlp.DecodeBytes(data, &entry); err != nil {
		log.Error("Invalid lookup entry RLP", "hash", hash, "err", err)
		return common.Hash{}, 0, 0
	}
	return entry.BlockHash, entry.BlockIndex, entry.Index
}

// WriteTxLookupEntriesByBlock stores a positional metadata for every transaction from
// a block, enabling hash based transaction and receipt lookups.
func WriteTxLookupEntriesByBlock(db ethdb.KeyValueWriter, block *types.Block) {
	// Iterate over each transaction and encode its metadata
	for i, tx := range block.Transactions() {
		entry := TxLookupEntry{
			BlockHash:  block.Hash(),
			BlockIndex: block.NumberU64(),
			Index:      uint64(i),
		}
		data, err := rlp.EncodeToBytes(entry)
		if err != nil {
			log.Crit("Failed to RLP encode TxLookupEntry", "err", err)
		}
		if err := db.Put(txLookupKey(tx.Hash()), data); err != nil {
			log.Crit("Failed to store tx lookup entry", "err", err)
		}
	}
}

// DeleteTxLookupEntry removes all transaction data associated with a hash.
func DeleteTxLookupEntry(db ethdb.KeyValueWriter, hash common.Hash) {
	db.Delete(txLookupKey(hash))
}

// ReadTransaction retrieves a specific transaction from the database, along with
// its added positional metadata.
func ReadTransaction(db ethdb.Reader, hash common.Hash) (*types.Transaction, common.Hash, uint64, uint64) {
	// Retrieve the lookup metadata and resolve the transaction from the body
	blockHash, blockNumber, txIndex := ReadTxLookupEntry(db, hash)

	if blockHash != (common.Hash{}) {
		body := ReadBody(db, blockHash, blockNumber)
		if body == nil || len(body.Transactions) <= int(txIndex) {
			log.Error("Transaction referenced missing", "number", blockNumber, "hash", blockHash, "index", txIndex)
			return nil, common.Hash{}, 0, 0
		}
		return body.Transactions[txIndex], blockHash, blockNumber, txIndex
	}
	// Old transaction representation, load the transaction and it's metadata separately
	data, _ := db.Get(hash.Bytes())
	if len(data) == 0 {
		return nil, common.Hash{}, 0, 0
	}
	var tx types.Transaction
	if err := rlp.DecodeBytes(data, &tx); err != nil {
		return nil, common.Hash{}, 0, 0
	}
	// Retrieve the blockchain positional metadata
	data, _ = db.Get(append(hash.Bytes(), oldTxMetaSuffix...))
	if len(data) == 0 {
		return nil, common.Hash{}, 0, 0
	}
	var entry TxLookupEntry
	if err := rlp.DecodeBytes(data, &entry); err != nil {
		return nil, common.Hash{}, 0, 0
	}
	return &tx, entry.BlockHash, entry.BlockIndex, entry.Index
}

// ReadReceipt retrieves a specific transaction receipt from the database, along with
// its added positional metadata.
func ReadReceipt(db ethdb.Reader, hash common.Hash, config *params.ChainConfig) (*types.Receipt, common.Hash, uint64, uint64) {
	// Retrieve the lookup metadata and resolve the receipt from the receipts
	blockHash, blockNumber, receiptIndex := ReadTxLookupEntry(db, hash)

	if blockHash != (common.Hash{}) {
		receipts := ReadReceipts(db, blockHash, blockNumber, config)
		if len(receipts) <= int(receiptIndex) {
			log.Error("Receipt refereced missing", "number", blockNumber, "hash", blockHash, "index", receiptIndex)
			return nil, common.Hash{}, 0, 0
		}
		return receipts[receiptIndex], blockHash, blockNumber, receiptIndex
	}
	// Old receipt representation, load the receipt and set an unknown metadata
	data, _ := db.Get(append(oldReceiptsPrefix, hash[:]...))
	if len(data) == 0 {
		return nil, common.Hash{}, 0, 0
	}
	var receipt types.ReceiptForStorage
	err := rlp.DecodeBytes(data, &receipt)
	if err != nil {
		log.Error("Invalid receipt RLP", "hash", hash, "err", err)
	}
	return (*types.Receipt)(&receipt), common.Hash{}, 0, 0
}

// ReadBloomBits retrieves the compressed bloom bit vector belonging to the given
// section and bit index from the.
func ReadBloomBits(db ethdb.KeyValueReader, bit uint, section uint64, head common.Hash) ([]byte, error) {
	return db.Get(bloomBitsKey(bit, section, head))
}

// WriteBloomBits writes the compressed bloom bits vector belonging to the given
// section and bit index.
func WriteBloomBits(db ethdb.KeyValueWriter, bit uint, section uint64, head common.Hash, bits []byte) {
	if err := db.Put(bloomBitsKey(bit, section, head), bits); err != nil {
		log.Crit("Failed to store bloom bits", "err", err)
	}
}

// FindCommonAncestor returns the last common ancestor of two block headers
func FindCommonAncestor(db ethdb.Reader, a, b *types.Header) *types.Header {
	for bn := b.Number.Uint64(); a.Number.Uint64() > bn; {
		a = ReadHeader(db, a.ParentHash, a.Number.Uint64()-1)
		if a == nil {
			return nil
		}
	}
	for an := a.Number.Uint64(); an < b.Number.Uint64(); {
		b = ReadHeader(db, b.ParentHash, b.Number.Uint64()-1)
		if b == nil {
			return nil
		}
	}
	for a.Hash() != b.Hash() {
		a = ReadHeader(db, a.ParentHash, a.Number.Uint64()-1)
		if a == nil {
			return nil
		}
		b = ReadHeader(db, b.ParentHash, b.Number.Uint64()-1)
		if b == nil {
			return nil
		}
	}
	return a
}