// 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"
	"encoding/json"
	"fmt"
	"math/big"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/rpc"

	"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/vulcanize/ipld-eth-indexer/pkg/ipfs"
)

// 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 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
}

// RPCMarshalBlockWithUncleHashes marshals the block with the provided uncle hashes
func RPCMarshalBlockWithUncleHashes(block *types.Block, uncleHashes []common.Hash, 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
	}
	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
}

// 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()), // somehow this is ending up `nil`
		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
}

type rpcBlock struct {
	Hash         common.Hash      `json:"hash"`
	Transactions []rpcTransaction `json:"transactions"`
	UncleHashes  []common.Hash    `json:"uncles"`
}

type rpcTransaction struct {
	tx *types.Transaction
	txExtraInfo
}

type txExtraInfo struct {
	BlockNumber *string         `json:"blockNumber,omitempty"`
	BlockHash   *common.Hash    `json:"blockHash,omitempty"`
	From        *common.Address `json:"from,omitempty"`
}

func (tx *rpcTransaction) UnmarshalJSON(msg []byte) error {
	if err := json.Unmarshal(msg, &tx.tx); err != nil {
		return err
	}
	return json.Unmarshal(msg, &tx.txExtraInfo)
}

func getBlockAndUncleHashes(cli *rpc.Client, ctx context.Context, method string, args ...interface{}) (*types.Block, []common.Hash, error) {
	var raw json.RawMessage
	err := cli.CallContext(ctx, &raw, method, args...)
	if err != nil {
		return nil, nil, err
	} else if len(raw) == 0 {
		return nil, nil, ethereum.NotFound
	}
	// Decode header and transactions.
	var head *types.Header
	var body rpcBlock
	if err := json.Unmarshal(raw, &head); err != nil {
		return nil, nil, err
	}
	if err := json.Unmarshal(raw, &body); err != nil {
		return nil, nil, err
	}
	// Quick-verify transaction and uncle lists. This mostly helps with debugging the server.
	if head.UncleHash == types.EmptyUncleHash && len(body.UncleHashes) > 0 {
		return nil, nil, fmt.Errorf("server returned non-empty uncle list but block header indicates no uncles")
	}
	if head.UncleHash != types.EmptyUncleHash && len(body.UncleHashes) == 0 {
		return nil, nil, fmt.Errorf("server returned empty uncle list but block header indicates uncles")
	}
	if head.TxHash == types.EmptyRootHash && len(body.Transactions) > 0 {
		return nil, nil, fmt.Errorf("server returned non-empty transaction list but block header indicates no transactions")
	}
	if head.TxHash != types.EmptyRootHash && len(body.Transactions) == 0 {
		return nil, nil, fmt.Errorf("server returned empty transaction list but block header indicates transactions")
	}
	txs := make([]*types.Transaction, len(body.Transactions))
	for i, tx := range body.Transactions {
		txs[i] = tx.tx
	}
	return types.NewBlockWithHeader(head).WithBody(txs, nil), body.UncleHashes, nil
}

// newRPCRawTransactionFromBlockIndex returns the bytes of a transaction given a block and a transaction index.
func newRPCRawTransactionFromBlockIndex(b *types.Block, index uint64) hexutil.Bytes {
	txs := b.Transactions()
	if index >= uint64(len(txs)) {
		return nil
	}
	blob, _ := rlp.EncodeToBytes(txs[index])
	return blob
}

// 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)
}

// extractLogsOfInterest returns logs from the receipt IPLD
func extractLogsOfInterest(rctIPLDs []ipfs.BlockModel, wantedTopics [][]string) ([]*types.Log, error) {
	var logs []*types.Log
	for _, rctIPLD := range rctIPLDs {
		rctRLP := rctIPLD
		var rct types.Receipt
		if err := rlp.DecodeBytes(rctRLP.Data, &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
}

func toFilterArg(q ethereum.FilterQuery) (interface{}, error) {
	arg := map[string]interface{}{
		"address": q.Addresses,
		"topics":  q.Topics,
	}
	if q.BlockHash != nil {
		arg["blockHash"] = *q.BlockHash
		if q.FromBlock != nil || q.ToBlock != nil {
			return nil, fmt.Errorf("cannot specify both BlockHash and FromBlock/ToBlock")
		}
	} else {
		if q.FromBlock == nil {
			arg["fromBlock"] = "0x0"
		} else {
			arg["fromBlock"] = toBlockNumArg(q.FromBlock)
		}
		arg["toBlock"] = toBlockNumArg(q.ToBlock)
	}
	return arg, nil
}

func toBlockNumArg(number *big.Int) string {
	if number == nil {
		return "latest"
	}
	return hexutil.EncodeBig(number)
}