package commands

import (
	"context"
	"errors"
	"fmt"
	"math/big"

	"github.com/ledgerwatch/turbo-geth/common"
	"github.com/ledgerwatch/turbo-geth/common/hexutil"
	"github.com/ledgerwatch/turbo-geth/core"
	"github.com/ledgerwatch/turbo-geth/core/bloombits"
	"github.com/ledgerwatch/turbo-geth/core/rawdb"
	"github.com/ledgerwatch/turbo-geth/core/types"
	"github.com/ledgerwatch/turbo-geth/core/vm"
	"github.com/ledgerwatch/turbo-geth/eth/filters"
	"github.com/ledgerwatch/turbo-geth/ethdb"
	"github.com/ledgerwatch/turbo-geth/params"
	"github.com/ledgerwatch/turbo-geth/rpc"
	"github.com/ledgerwatch/turbo-geth/turbo/adapter"
	"github.com/ledgerwatch/turbo-geth/turbo/transactions"
)

func GetReceipts(ctx context.Context, db rawdb.DatabaseReader, cfg *params.ChainConfig, hash common.Hash) (types.Receipts, error) {
	number := rawdb.ReadHeaderNumber(db, hash)
	if number == nil {
		return nil, fmt.Errorf("block not found: %x", hash)
	}

	block := rawdb.ReadBlock(db, hash, *number)
	if cached := rawdb.ReadReceipts(db, block.Hash(), block.NumberU64(), cfg); cached != nil {
		return cached, nil
	}

	cc := adapter.NewChainContext(db)
	bc := adapter.NewBlockGetter(db)
	chainConfig := getChainConfig(db)
	_, _, ibs, dbstate, err := transactions.ComputeTxEnv(ctx, bc, chainConfig, cc, db.(ethdb.HasKV).KV(), hash, 0)
	if err != nil {
		return nil, err
	}

	var receipts types.Receipts
	gp := new(core.GasPool).AddGas(block.GasLimit())
	var usedGas = new(uint64)
	for i, tx := range block.Transactions() {
		ibs.Prepare(tx.Hash(), block.Hash(), i)

		header := rawdb.ReadHeader(db, hash, *number)
		receipt, err := core.ApplyTransaction(chainConfig, cc, nil, gp, ibs, dbstate, header, tx, usedGas, vm.Config{})
		if err != nil {
			return nil, err
		}
		receipts = append(receipts, receipt)
	}

	return receipts, nil
}

func (api *APIImpl) GetLogsByHash(ctx context.Context, hash common.Hash) ([][]*types.Log, error) {
	number := rawdb.ReadHeaderNumber(api.dbReader, hash)
	if number == nil {
		return nil, fmt.Errorf("block not found: %x", hash)
	}
	genesisHash := rawdb.ReadBlockByNumber(api.dbReader, 0).Hash()
	chainConfig := rawdb.ReadChainConfig(api.dbReader, genesisHash)

	receipts, err := GetReceipts(ctx, api.dbReader, chainConfig, hash)
	if err != nil {
		return nil, fmt.Errorf("getReceipt error: %v", err)
	}
	logs := make([][]*types.Log, len(receipts))
	for i, receipt := range receipts {
		logs[i] = receipt.Logs
	}
	return logs, nil
}

// Filter can be used to retrieve and filter logs.
type Filter struct {
	addresses []common.Address
	topics    [][]common.Hash

	block      common.Hash // Block hash if filtering a single block
	begin, end int64       // Range interval if filtering multiple blocks

	matcher *bloombits.Matcher
}

func NewBlockFilter(block common.Hash, addresses []common.Address, topics [][]common.Hash) *Filter {
	// Create a generic filter and convert it into a block filter
	filter := newFilter(addresses, topics)
	filter.block = block
	return filter
}

// newFilter creates a generic filter that can either filter based on a block hash,
// or based on range queries. The search criteria needs to be explicitly set.
func newFilter(addresses []common.Address, topics [][]common.Hash) *Filter {
	return &Filter{
		addresses: addresses,
		topics:    topics,
	}
}

// GetLogs returns logs matching the given argument that are stored within the state.
func (api *APIImpl) GetLogs(ctx context.Context, crit filters.FilterCriteria) ([]*types.Log, error) {
	var filter *Filter
	if crit.BlockHash != nil {
		// Block filter requested, construct a single-shot filter
		filter = NewBlockFilter(*crit.BlockHash, crit.Addresses, crit.Topics)
	} else {
		// Convert the RPC block numbers into internal representations
		latest, err := getLatestBlockNumber(api.dbReader)
		if err != nil {
			return nil, err
		}

		begin := int64(latest)
		if crit.FromBlock != nil {
			begin = crit.FromBlock.Int64()
		}
		end := int64(latest)
		if crit.ToBlock != nil {
			end = crit.ToBlock.Int64()
		}

		filter = NewRangeFilter(begin, end, crit.Addresses, crit.Topics)
	}
	// Run the filter and return all the logs
	logs, err := filter.Logs(ctx, api)
	if err != nil {
		return nil, err
	}
	return returnLogs(logs), err
}

// NewRangeFilter creates a new filter which uses a bloom filter on blocks to
// figure out whether a particular block is interesting or not.
func NewRangeFilter(begin, end int64, addresses []common.Address, topics [][]common.Hash) *Filter {
	// Flatten the address and topic filter clauses into a single bloombits filter
	// system. Since the bloombits are not positional, nil topics are permitted,
	// which get flattened into a nil byte slice.
	filters := make([][][]byte, 0, len(addresses))
	if len(addresses) > 0 {
		filter := make([][]byte, len(addresses))
		for i, address := range addresses {
			filter[i] = address.Bytes()
		}
		filters = append(filters, filter)
	}
	for _, topicList := range topics {
		filter := make([][]byte, len(topicList))
		for i, topic := range topicList {
			filter[i] = topic.Bytes()
		}
		filters = append(filters, filter)
	}

	// Create a generic filter and convert it into a range filter
	filter := newFilter(addresses, topics)

	filter.matcher = bloombits.NewMatcher(params.BloomBitsBlocks, filters)
	filter.begin = begin
	filter.end = end

	return filter
}

func (api *APIImpl) GetTransactionReceipt(ctx context.Context, hash common.Hash) (map[string]interface{}, error) {
	// Retrieve the transaction and assemble its EVM context
	tx, blockHash, blockNumber, txIndex := rawdb.ReadTransaction(api.dbReader, hash)
	if tx == nil {
		return nil, fmt.Errorf("transaction %#x not found", hash)
	}

	genesisHash := rawdb.ReadBlockByNumber(api.dbReader, 0).Hash()
	chainConfig := rawdb.ReadChainConfig(api.dbReader, genesisHash)

	receipts, err := GetReceipts(ctx, api.dbReader, chainConfig, blockHash)
	if err != nil {
		return nil, fmt.Errorf("getReceipt error: %v", err)
	}
	if len(receipts) <= int(txIndex) {
		return nil, fmt.Errorf("block has less receipts than expected: %d <= %d, block: %d", len(receipts), int(txIndex), blockNumber)
	}
	receipt := receipts[txIndex]

	var signer types.Signer = types.FrontierSigner{}
	if tx.Protected() {
		signer = types.NewEIP155Signer(tx.ChainID().ToBig())
	}
	from, _ := types.Sender(signer, tx)

	// Fill in the derived information in the logs
	if receipt.Logs != nil {
		for i, log := range receipt.Logs {
			log.BlockNumber = blockNumber
			log.TxHash = hash
			log.TxIndex = uint(txIndex)
			log.BlockHash = blockHash
			log.Index = uint(i)
		}
	}

	// Now reconstruct the bloom filter
	fields := map[string]interface{}{
		"blockHash":         blockHash,
		"blockNumber":       hexutil.Uint64(blockNumber),
		"transactionHash":   hash,
		"transactionIndex":  hexutil.Uint64(txIndex),
		"from":              from,
		"to":                tx.To(),
		"gasUsed":           hexutil.Uint64(receipt.GasUsed),
		"cumulativeGasUsed": hexutil.Uint64(receipt.CumulativeGasUsed),
		"contractAddress":   nil,
		"logs":              receipt.Logs,
		"logsBloom":         receipt.Bloom,
	}

	// Assign receipt status or post state.
	if len(receipt.PostState) > 0 {
		fields["root"] = hexutil.Bytes(receipt.PostState)
	} else {
		fields["status"] = hexutil.Uint(receipt.Status)
	}
	if receipt.Logs == nil {
		fields["logs"] = [][]*types.Log{}
	}
	// If the ContractAddress is 20 0x0 bytes, assume it is not a contract creation
	if receipt.ContractAddress != (common.Address{}) {
		fields["contractAddress"] = receipt.ContractAddress
	}
	return fields, nil
}

// Logs searches the blockchain for matching log entries, returning all from the
// first block that contains matches, updating the start of the filter accordingly.
func (f *Filter) Logs(ctx context.Context, api *APIImpl) ([]*types.Log, error) {
	// If we're doing singleton block filtering, execute and return
	if f.block != (common.Hash{}) {
		header, err := api.GetHeaderByHash(ctx, f.block)
		if err != nil {
			return nil, err
		}
		if header == nil {
			return nil, errors.New("unknown block")
		}
		return f.blockLogs(ctx, header, api)
	}

	// Figure out the limits of the filter range
	latest, err := getLatestBlockNumber(api.dbReader)
	if err != nil {
		return nil, err
	}

	if f.begin == -1 {
		f.begin = int64(latest)
	}
	end := uint64(f.end)
	if f.end == -1 {
		end = latest
	}

	// Gather all indexed logs, and finish with non indexed ones
	var logs []*types.Log
	size, sections, _ := api.ethBackend.BloomStatus()

	if indexed := sections * size; indexed > uint64(f.begin) {
		if indexed > end {
			logs, err = f.indexedLogs(ctx, end, api)
		} else {
			logs, err = f.indexedLogs(ctx, indexed-1, api)
		}
		if err != nil {
			return logs, err
		}
	}
	rest, err := f.unindexedLogs(ctx, end, api)
	logs = append(logs, rest...)
	return logs, err
}

// indexedLogs returns the logs matching the filter criteria based on the bloom
// bits indexed available locally or via the network.
func (f *Filter) indexedLogs(ctx context.Context, end uint64, api *APIImpl) ([]*types.Log, error) {
	// Iterate over the matches until exhausted or context closed
	var logs []*types.Log

	for num := f.begin; num < int64(end)+1; num++ {
		// Retrieve the suggested block and pull any truly matching logs
		header, err := api.GetHeaderByNumber(ctx, rpc.BlockNumber(num))
		if header == nil || err != nil {
			return logs, err
		}
		found, err := f.checkMatches(ctx, header, api)
		if err != nil {
			return logs, err
		}
		logs = append(logs, found...)
	}

	return logs, nil
}

// unindexedLogs returns the logs matching the filter criteria based on raw block
// iteration and bloom matching.
func (f *Filter) unindexedLogs(ctx context.Context, end uint64, api *APIImpl) ([]*types.Log, error) {
	var logs []*types.Log

	for ; f.begin <= int64(end); f.begin++ {
		header, err := api.GetHeaderByNumber(ctx, rpc.BlockNumber(f.begin))
		if header == nil || err != nil {
			return logs, err
		}
		found, err := f.blockLogs(ctx, header, api)
		if err != nil {
			return logs, err
		}
		logs = append(logs, found...)
	}
	return logs, nil
}

// blockLogs returns the logs matching the filter criteria within a single block.
func (f *Filter) blockLogs(ctx context.Context, header *types.Header, api *APIImpl) (logs []*types.Log, err error) {
	if bloomFilter(header.Bloom, f.addresses, f.topics) {
		found, err := f.checkMatches(ctx, header, api)
		if err != nil {
			return logs, err
		}
		logs = append(logs, found...)
	}
	return logs, nil
}

// checkMatches checks if the receipts belonging to the given header contain any log events that
// match the filter criteria. This function is called when the bloom filter signals a potential match.
func (f *Filter) checkMatches(ctx context.Context, header *types.Header, api *APIImpl) (logs []*types.Log, err error) {
	// Get the logs of the block
	logsList, err := api.GetLogsByHash(ctx, header.Hash())
	if err != nil {
		return nil, err
	}
	unfiltered := make([]*types.Log, 0, len(logsList))
	for _, logs := range logsList {
		unfiltered = append(unfiltered, logs...)
	}
	logs = filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
	if len(logs) > 0 {
		// We have matching logs, check if we need to resolve full logs via the light client
		if logs[0].TxHash == (common.Hash{}) {
			chainConfig := getChainConfig(api.dbReader)
			receipts := rawdb.ReadReceipts(api.dbReader, header.Hash(), header.Number.Uint64(), chainConfig)
			unfiltered = unfiltered[:0]
			for _, receipt := range receipts {
				unfiltered = append(unfiltered, receipt.Logs...)
			}
			logs = filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
		}
		return logs, nil
	}
	return nil, nil
}

func includes(addresses []common.Address, a common.Address) bool {
	for _, addr := range addresses {
		if addr == a {
			return true
		}
	}

	return false
}

// filterLogs creates a slice of logs matching the given criteria.
func filterLogs(logs []*types.Log, fromBlock, toBlock *big.Int, addresses []common.Address, topics [][]common.Hash) []*types.Log {
	var ret []*types.Log
Logs:
	for _, log := range logs {
		if fromBlock != nil && fromBlock.Int64() >= 0 && fromBlock.Uint64() > log.BlockNumber {
			continue
		}
		if toBlock != nil && toBlock.Int64() >= 0 && toBlock.Uint64() < log.BlockNumber {
			continue
		}

		if len(addresses) > 0 && !includes(addresses, log.Address) {
			continue
		}
		// If the to filtered topics is greater than the amount of topics in logs, skip.
		if len(topics) > len(log.Topics) {
			continue Logs
		}
		for i, sub := range topics {
			match := len(sub) == 0 // empty rule set == wildcard
			for _, topic := range sub {
				if log.Topics[i] == topic {
					match = true
					break
				}
			}
			if !match {
				continue Logs
			}
		}
		ret = append(ret, log)
	}
	return ret
}

func bloomFilter(bloom types.Bloom, addresses []common.Address, topics [][]common.Hash) bool {
	if len(addresses) > 0 {
		var included bool
		for _, addr := range addresses {
			if types.BloomLookup(bloom, addr) {
				included = true
				break
			}
		}
		if !included {
			return false
		}
	}

	for _, sub := range topics {
		included := len(sub) == 0 // empty rule set == wildcard
		for _, topic := range sub {
			if types.BloomLookup(bloom, topic) {
				included = true
				break
			}
		}
		if !included {
			return false
		}
	}
	return true
}

func returnLogs(logs []*types.Log) []*types.Log {
	if logs == nil {
		return []*types.Log{}
	}
	return logs
}