// VulcanizeDB
// Copyright © 2019 Vulcanize

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program 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 Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package eth

import (
	"context"
	"math/big"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/ethereum/go-ethereum/rpc"
	"github.com/ipfs/go-block-format"

	"github.com/vulcanize/vulcanizedb/pkg/super_node/config"
)

// APIName is the namespace for the super node's eth api
const APIName = "eth"

// APIVersion is the version of the super node's eth api
const APIVersion = "0.0.1"

type PublicEthAPI struct {
	b *Backend
}

// NewPublicEthAPI creates a new PublicEthAPI with the provided underlying Backend
func NewPublicEthAPI(b *Backend) *PublicEthAPI {
	return &PublicEthAPI{
		b: b,
	}
}

// BlockNumber returns the block number of the chain head.
func (pea *PublicEthAPI) BlockNumber() hexutil.Uint64 {
	number, _ := pea.b.retriever.RetrieveLastBlockNumber()
	return hexutil.Uint64(number)
}

// GetLogs returns logs matching the given argument that are stored within the state.
//
// https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getlogs
func (pea *PublicEthAPI) GetLogs(ctx context.Context, crit ethereum.FilterQuery) ([]*types.Log, error) {
	// Convert FilterQuery into ReceiptFilter
	addrStrs := make([]string, len(crit.Addresses))
	for i, addr := range crit.Addresses {
		addrStrs[i] = addr.String()
	}
	topicStrSets := make([][]string, 4)
	for i, topicSet := range crit.Topics {
		if i > 3 {
			break
		}
		for _, topic := range topicSet {
			topicStrSets[i] = append(topicStrSets[i], topic.String())
		}
	}
	filter := config.ReceiptFilter{
		Contracts: addrStrs,
		Topics:    topicStrSets,
	}
	tx, err := pea.b.db.Beginx()
	if err != nil {
		return nil, err
	}
	// If we have a blockhash to filter on, fire off single retrieval query
	if crit.BlockHash != nil {
		rctCIDs, err := pea.b.retriever.RetrieveRctCIDs(tx, filter, 0, crit.BlockHash, nil)
		if err != nil {
			return nil, err
		}
		if err := tx.Commit(); err != nil {
			return nil, err
		}
		rctIPLDs, err := pea.b.fetcher.FetchRcts(rctCIDs)
		if err != nil {
			return nil, err
		}
		return extractLogsOfInterest(rctIPLDs, filter.Topics)
	}
	// Otherwise, create block range from criteria
	// nil values are filled in; to request a single block have both ToBlock and FromBlock equal that number
	startingBlock := crit.FromBlock
	endingBlock := crit.ToBlock
	if startingBlock == nil {
		startingBlockInt, err := pea.b.retriever.RetrieveFirstBlockNumber()
		if err != nil {
			return nil, err
		}
		startingBlock = big.NewInt(startingBlockInt)
	}
	if endingBlock == nil {
		endingBlockInt, err := pea.b.retriever.RetrieveLastBlockNumber()
		if err != nil {
			return nil, err
		}
		endingBlock = big.NewInt(endingBlockInt)
	}
	start := startingBlock.Int64()
	end := endingBlock.Int64()
	allRctCIDs := make([]ReceiptModel, 0)
	for i := start; i <= end; i++ {
		rctCIDs, err := pea.b.retriever.RetrieveRctCIDs(tx, filter, i, nil, nil)
		if err != nil {
			return nil, err
		}
		allRctCIDs = append(allRctCIDs, rctCIDs...)
	}
	if err := tx.Commit(); err != nil {
		return nil, err
	}
	rctIPLDs, err := pea.b.fetcher.FetchRcts(allRctCIDs)
	if err != nil {
		return nil, err
	}
	return extractLogsOfInterest(rctIPLDs, filter.Topics)
}

// GetHeaderByNumber returns the requested canonical block header.
// * When blockNr is -1 the chain head is returned.
// * We cannot support pending block calls since we do not have an active miner
func (pea *PublicEthAPI) GetHeaderByNumber(ctx context.Context, number rpc.BlockNumber) (map[string]interface{}, error) {
	header, err := pea.b.HeaderByNumber(ctx, number)
	if header != nil && err == nil {
		return pea.rpcMarshalHeader(header)
	}
	return nil, err
}

// GetBlockByNumber returns the requested canonical block.
// * When blockNr is -1 the chain head is returned.
// * We cannot support pending block calls since we do not have an active miner
// * When fullTx is true all transactions in the block are returned, otherwise
//   only the transaction hash is returned.
func (pea *PublicEthAPI) GetBlockByNumber(ctx context.Context, number rpc.BlockNumber, fullTx bool) (map[string]interface{}, error) {
	block, err := pea.b.BlockByNumber(ctx, number)
	if block != nil && err == nil {
		return pea.rpcMarshalBlock(block, true, fullTx)
	}
	return nil, err
}

// GetBlockByHash returns the requested block. When fullTx is true all transactions in the block are returned in full
// detail, otherwise only the transaction hash is returned.
func (pea *PublicEthAPI) GetBlockByHash(ctx context.Context, hash common.Hash, fullTx bool) (map[string]interface{}, error) {
	block, err := pea.b.BlockByHash(ctx, hash)
	if block != nil {
		return pea.rpcMarshalBlock(block, true, fullTx)
	}
	return nil, err
}

// GetTransactionByHash returns the transaction for the given hash
// SuperNode cannot currently handle pending/tx_pool txs
func (pea *PublicEthAPI) GetTransactionByHash(ctx context.Context, hash common.Hash) (*RPCTransaction, error) {
	// Try to return an already finalized transaction
	tx, blockHash, blockNumber, index, err := pea.b.GetTransaction(ctx, hash)
	if err != nil {
		return nil, err
	}
	if tx != nil {
		return newRPCTransaction(tx, blockHash, blockNumber, index), nil
	}
	// Transaction unknown, return as such
	return nil, nil
}

// extractLogsOfInterest returns logs from the receipt IPLD
func extractLogsOfInterest(rctIPLDs []blocks.Block, wantedTopics [][]string) ([]*types.Log, error) {
	var logs []*types.Log
	for _, rctIPLD := range rctIPLDs {
		rctRLP := rctIPLD.RawData()
		var rct types.Receipt
		if err := rlp.DecodeBytes(rctRLP, &rct); err != nil {
			return nil, err
		}
		for _, log := range rct.Logs {
			if wanted := wantedLog(wantedTopics, log.Topics); wanted == true {
				logs = append(logs, log)
			}
		}
	}
	return logs, nil
}

// returns true if the log matches on the filter
func wantedLog(wantedTopics [][]string, actualTopics []common.Hash) bool {
	// actualTopics will always have length <= 4
	// wantedTopics will always have length == 4
	matches := 0
	for i, actualTopic := range actualTopics {
		// If we have topics in this filter slot, count as a match if the actualTopic matches one of the ones in this filter slot
		if len(wantedTopics[i]) > 0 {
			matches += sliceContainsHash(wantedTopics[i], actualTopic)
		} else {
			// Filter slot is empty, not matching any topics at this slot => counts as a match
			matches++
		}
	}
	if matches == len(actualTopics) {
		return true
	}
	return false
}

// returns 1 if the slice contains the hash, 0 if it does not
func sliceContainsHash(slice []string, hash common.Hash) int {
	for _, str := range slice {
		if str == hash.String() {
			return 1
		}
	}
	return 0
}

// rpcMarshalHeader uses the generalized output filler, then adds the total difficulty field, which requires
// a `PublicEthAPI`.
func (pea *PublicEthAPI) rpcMarshalHeader(header *types.Header) (map[string]interface{}, error) {
	fields := RPCMarshalHeader(header)
	td, err := pea.b.GetTd(header.Hash())
	if err != nil {
		return nil, err
	}
	fields["totalDifficulty"] = (*hexutil.Big)(td)
	return fields, nil
}

// RPCMarshalHeader converts the given header to the RPC output.
// This function is eth/internal so we have to make our own version here...
func RPCMarshalHeader(head *types.Header) map[string]interface{} {
	return map[string]interface{}{
		"number":           (*hexutil.Big)(head.Number),
		"hash":             head.Hash(),
		"parentHash":       head.ParentHash,
		"nonce":            head.Nonce,
		"mixHash":          head.MixDigest,
		"sha3Uncles":       head.UncleHash,
		"logsBloom":        head.Bloom,
		"stateRoot":        head.Root,
		"miner":            head.Coinbase,
		"difficulty":       (*hexutil.Big)(head.Difficulty),
		"extraData":        hexutil.Bytes(head.Extra),
		"size":             hexutil.Uint64(head.Size()),
		"gasLimit":         hexutil.Uint64(head.GasLimit),
		"gasUsed":          hexutil.Uint64(head.GasUsed),
		"timestamp":        hexutil.Uint64(head.Time),
		"transactionsRoot": head.TxHash,
		"receiptsRoot":     head.ReceiptHash,
	}
}

// rpcMarshalBlock uses the generalized output filler, then adds the total difficulty field, which requires
// a `PublicBlockchainAPI`.
func (pea *PublicEthAPI) rpcMarshalBlock(b *types.Block, inclTx bool, fullTx bool) (map[string]interface{}, error) {
	fields, err := RPCMarshalBlock(b, inclTx, fullTx)
	if err != nil {
		return nil, err
	}
	td, err := pea.b.GetTd(b.Hash())
	if err != nil {
		return nil, err
	}
	fields["totalDifficulty"] = (*hexutil.Big)(td)
	return fields, err
}

// RPCMarshalBlock converts the given block to the RPC output which depends on fullTx. If inclTx is true transactions are
// returned. When fullTx is true the returned block contains full transaction details, otherwise it will only contain
// transaction hashes.
func RPCMarshalBlock(block *types.Block, inclTx bool, fullTx bool) (map[string]interface{}, error) {
	fields := RPCMarshalHeader(block.Header())
	fields["size"] = hexutil.Uint64(block.Size())

	if inclTx {
		formatTx := func(tx *types.Transaction) (interface{}, error) {
			return tx.Hash(), nil
		}
		if fullTx {
			formatTx = func(tx *types.Transaction) (interface{}, error) {
				return newRPCTransactionFromBlockHash(block, tx.Hash()), nil
			}
		}
		txs := block.Transactions()
		transactions := make([]interface{}, len(txs))
		var err error
		for i, tx := range txs {
			if transactions[i], err = formatTx(tx); err != nil {
				return nil, err
			}
		}
		fields["transactions"] = transactions
	}
	uncles := block.Uncles()
	uncleHashes := make([]common.Hash, len(uncles))
	for i, uncle := range uncles {
		uncleHashes[i] = uncle.Hash()
	}
	fields["uncles"] = uncleHashes

	return fields, nil
}

// newRPCTransactionFromBlockHash returns a transaction that will serialize to the RPC representation.
func newRPCTransactionFromBlockHash(b *types.Block, hash common.Hash) *RPCTransaction {
	for idx, tx := range b.Transactions() {
		if tx.Hash() == hash {
			return newRPCTransactionFromBlockIndex(b, uint64(idx))
		}
	}
	return nil
}

// newRPCTransactionFromBlockIndex returns a transaction that will serialize to the RPC representation.
func newRPCTransactionFromBlockIndex(b *types.Block, index uint64) *RPCTransaction {
	txs := b.Transactions()
	if index >= uint64(len(txs)) {
		return nil
	}
	return newRPCTransaction(txs[index], b.Hash(), b.NumberU64(), index)
}

// RPCTransaction represents a transaction that will serialize to the RPC representation of a transaction
type RPCTransaction struct {
	BlockHash        *common.Hash    `json:"blockHash"`
	BlockNumber      *hexutil.Big    `json:"blockNumber"`
	From             common.Address  `json:"from"`
	Gas              hexutil.Uint64  `json:"gas"`
	GasPrice         *hexutil.Big    `json:"gasPrice"`
	Hash             common.Hash     `json:"hash"`
	Input            hexutil.Bytes   `json:"input"`
	Nonce            hexutil.Uint64  `json:"nonce"`
	To               *common.Address `json:"to"`
	TransactionIndex *hexutil.Uint64 `json:"transactionIndex"`
	Value            *hexutil.Big    `json:"value"`
	V                *hexutil.Big    `json:"v"`
	R                *hexutil.Big    `json:"r"`
	S                *hexutil.Big    `json:"s"`
}

// newRPCTransaction returns a transaction that will serialize to the RPC
// representation, with the given location metadata set (if available).
func newRPCTransaction(tx *types.Transaction, blockHash common.Hash, blockNumber uint64, index uint64) *RPCTransaction {
	var signer types.Signer = types.FrontierSigner{}
	if tx.Protected() {
		signer = types.NewEIP155Signer(tx.ChainId())
	}
	from, _ := types.Sender(signer, tx)
	v, r, s := tx.RawSignatureValues()

	result := &RPCTransaction{
		From:     from,
		Gas:      hexutil.Uint64(tx.Gas()),
		GasPrice: (*hexutil.Big)(tx.GasPrice()),
		Hash:     tx.Hash(),
		Input:    hexutil.Bytes(tx.Data()),
		Nonce:    hexutil.Uint64(tx.Nonce()),
		To:       tx.To(),
		Value:    (*hexutil.Big)(tx.Value()),
		V:        (*hexutil.Big)(v),
		R:        (*hexutil.Big)(r),
		S:        (*hexutil.Big)(s),
	}
	if blockHash != (common.Hash{}) {
		result.BlockHash = &blockHash
		result.BlockNumber = (*hexutil.Big)(new(big.Int).SetUint64(blockNumber))
		result.TransactionIndex = (*hexutil.Uint64)(&index)
	}
	return result
}