// Copyright Simcord LLC
// This file is part of the Bitbon System Blockchain Node library.
// This file has been modified, you can find the original version by following the link
// <https://github.com/ethereum/go-ethereum>
//
// The Bitbon System Blockchain Node 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 Bitbon System Blockchain Node 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 Bitbon System Blockchain Node library. If not, see <http://www.gnu.org/licenses/>.

package types

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"math/big"
	"unsafe"

	"github.com/simcord-llc/bitbon-system-blockchain/common"
	"github.com/simcord-llc/bitbon-system-blockchain/common/hexutil"
	"github.com/simcord-llc/bitbon-system-blockchain/crypto"
	"github.com/simcord-llc/bitbon-system-blockchain/params"
	"github.com/simcord-llc/bitbon-system-blockchain/rlp"
)

//go:generate gencodec -type Receipt -field-override receiptMarshaling -out gen_receipt_json.go

var (
	receiptStatusFailedRLP     = []byte{}
	receiptStatusSuccessfulRLP = []byte{0x01}
)

const (
	// ReceiptStatusFailed is the status code of a transaction if execution failed.
	ReceiptStatusFailed = uint64(0)

	// ReceiptStatusSuccessful is the status code of a transaction if execution succeeded.
	ReceiptStatusSuccessful = uint64(1)
)

// Receipt represents the results of a transaction.
type Receipt struct {
	// Consensus fields: These fields are defined by the Yellow Paper
	PostState         []byte `json:"root"`
	Status            uint64 `json:"status"`
	CumulativeGasUsed uint64 `json:"cumulativeGasUsed" gencodec:"required"`
	Bloom             Bloom  `json:"logsBloom"         gencodec:"required"`
	Logs              []*Log `json:"logs"              gencodec:"required"`

	// Implementation fields: These fields are added by geth when processing a transaction.
	// They are stored in the chain database.
	TxHash          common.Hash    `json:"transactionHash" gencodec:"required"`
	ContractAddress common.Address `json:"contractAddress"`
	GasUsed         uint64         `json:"gasUsed" gencodec:"required"`

	// Inclusion information: These fields provide information about the inclusion of the
	// transaction corresponding to this receipt.
	BlockHash        common.Hash `json:"blockHash,omitempty"`
	BlockNumber      *big.Int    `json:"blockNumber,omitempty"`
	TransactionIndex uint        `json:"transactionIndex"`
}

type receiptMarshaling struct {
	PostState         hexutil.Bytes
	Status            hexutil.Uint64
	CumulativeGasUsed hexutil.Uint64
	GasUsed           hexutil.Uint64
	BlockNumber       *hexutil.Big
	TransactionIndex  hexutil.Uint
}

// receiptRLP is the consensus encoding of a receipt.
type receiptRLP struct {
	PostStateOrStatus []byte
	CumulativeGasUsed uint64
	Bloom             Bloom
	Logs              []*Log
}

// storedReceiptRLP is the storage encoding of a receipt.
type storedReceiptRLP struct {
	PostStateOrStatus []byte
	CumulativeGasUsed uint64
	Logs              []*LogForStorage
}

// v4StoredReceiptRLP is the storage encoding of a receipt used in database version 4.
type v4StoredReceiptRLP struct {
	PostStateOrStatus []byte
	CumulativeGasUsed uint64
	TxHash            common.Hash
	ContractAddress   common.Address
	Logs              []*LogForStorage
	GasUsed           uint64
}

// v3StoredReceiptRLP is the original storage encoding of a receipt including some unnecessary fields.
type v3StoredReceiptRLP struct {
	PostStateOrStatus []byte
	CumulativeGasUsed uint64
	Bloom             Bloom
	TxHash            common.Hash
	ContractAddress   common.Address
	Logs              []*LogForStorage
	GasUsed           uint64
}

// NewReceipt creates a barebone transaction receipt, copying the init fields.
func NewReceipt(root []byte, failed bool, cumulativeGasUsed uint64) *Receipt {
	r := &Receipt{PostState: common.CopyBytes(root), CumulativeGasUsed: cumulativeGasUsed}
	if failed {
		r.Status = ReceiptStatusFailed
	} else {
		r.Status = ReceiptStatusSuccessful
	}
	return r
}

// EncodeRLP implements rlp.Encoder, and flattens the consensus fields of a receipt
// into an RLP stream. If no post state is present, byzantium fork is assumed.
func (r *Receipt) EncodeRLP(w io.Writer) error {
	return rlp.Encode(w, &receiptRLP{r.statusEncoding(), r.CumulativeGasUsed, r.Bloom, r.Logs})
}

// DecodeRLP implements rlp.Decoder, and loads the consensus fields of a receipt
// from an RLP stream.
func (r *Receipt) DecodeRLP(s *rlp.Stream) error {
	var dec receiptRLP
	if err := s.Decode(&dec); err != nil {
		return err
	}
	if err := r.setStatus(dec.PostStateOrStatus); err != nil {
		return err
	}
	r.CumulativeGasUsed, r.Bloom, r.Logs = dec.CumulativeGasUsed, dec.Bloom, dec.Logs
	return nil
}

func (r *Receipt) setStatus(postStateOrStatus []byte) error {
	switch {
	case bytes.Equal(postStateOrStatus, receiptStatusSuccessfulRLP):
		r.Status = ReceiptStatusSuccessful
	case bytes.Equal(postStateOrStatus, receiptStatusFailedRLP):
		r.Status = ReceiptStatusFailed
	case len(postStateOrStatus) == len(common.Hash{}):
		r.PostState = postStateOrStatus
	default:
		return fmt.Errorf("invalid receipt status %x", postStateOrStatus)
	}
	return nil
}

func (r *Receipt) statusEncoding() []byte {
	if len(r.PostState) == 0 {
		if r.Status == ReceiptStatusFailed {
			return receiptStatusFailedRLP
		}
		return receiptStatusSuccessfulRLP
	}
	return r.PostState
}

// Size returns the approximate memory used by all internal contents. It is used
// to approximate and limit the memory consumption of various caches.
func (r *Receipt) Size() common.StorageSize {
	size := common.StorageSize(unsafe.Sizeof(*r)) + common.StorageSize(len(r.PostState))

	size += common.StorageSize(len(r.Logs)) * common.StorageSize(unsafe.Sizeof(Log{}))
	for _, log := range r.Logs {
		size += common.StorageSize(len(log.Topics)*common.HashLength + len(log.Data))
	}
	return size
}

// ReceiptForStorage is a wrapper around a Receipt that flattens and parses the
// entire content of a receipt, as opposed to only the consensus fields originally.
type ReceiptForStorage Receipt

// EncodeRLP implements rlp.Encoder, and flattens all content fields of a receipt
// into an RLP stream.
func (r *ReceiptForStorage) EncodeRLP(w io.Writer) error {
	enc := &storedReceiptRLP{
		PostStateOrStatus: (*Receipt)(r).statusEncoding(),
		CumulativeGasUsed: r.CumulativeGasUsed,
		Logs:              make([]*LogForStorage, len(r.Logs)),
	}
	for i, log := range r.Logs {
		enc.Logs[i] = (*LogForStorage)(log)
	}
	return rlp.Encode(w, enc)
}

// DecodeRLP implements rlp.Decoder, and loads both consensus and implementation
// fields of a receipt from an RLP stream.
func (r *ReceiptForStorage) DecodeRLP(s *rlp.Stream) error {
	// Retrieve the entire receipt blob as we need to try multiple decoders
	blob, err := s.Raw()
	if err != nil {
		return err
	}
	// Try decoding from the newest format for future proofness, then the older one
	// for old nodes that just upgraded. V4 was an intermediate unreleased format so
	// we do need to decode it, but it's not common (try last).
	if err := decodeStoredReceiptRLP(r, blob); err == nil {
		return nil
	}
	if err := decodeV3StoredReceiptRLP(r, blob); err == nil {
		return nil
	}
	return decodeV4StoredReceiptRLP(r, blob)
}

func decodeStoredReceiptRLP(r *ReceiptForStorage, blob []byte) error {
	var stored storedReceiptRLP
	if err := rlp.DecodeBytes(blob, &stored); err != nil {
		return err
	}
	if err := (*Receipt)(r).setStatus(stored.PostStateOrStatus); err != nil {
		return err
	}
	r.CumulativeGasUsed = stored.CumulativeGasUsed
	r.Logs = make([]*Log, len(stored.Logs))
	for i, log := range stored.Logs {
		r.Logs[i] = (*Log)(log)
	}
	r.Bloom = CreateBloom(Receipts{(*Receipt)(r)})

	return nil
}

func decodeV4StoredReceiptRLP(r *ReceiptForStorage, blob []byte) error {
	var stored v4StoredReceiptRLP
	if err := rlp.DecodeBytes(blob, &stored); err != nil {
		return err
	}
	if err := (*Receipt)(r).setStatus(stored.PostStateOrStatus); err != nil {
		return err
	}
	r.CumulativeGasUsed = stored.CumulativeGasUsed
	r.TxHash = stored.TxHash
	r.ContractAddress = stored.ContractAddress
	r.GasUsed = stored.GasUsed
	r.Logs = make([]*Log, len(stored.Logs))
	for i, log := range stored.Logs {
		r.Logs[i] = (*Log)(log)
	}
	r.Bloom = CreateBloom(Receipts{(*Receipt)(r)})

	return nil
}

func decodeV3StoredReceiptRLP(r *ReceiptForStorage, blob []byte) error {
	var stored v3StoredReceiptRLP
	if err := rlp.DecodeBytes(blob, &stored); err != nil {
		return err
	}
	if err := (*Receipt)(r).setStatus(stored.PostStateOrStatus); err != nil {
		return err
	}
	r.CumulativeGasUsed = stored.CumulativeGasUsed
	r.Bloom = stored.Bloom
	r.TxHash = stored.TxHash
	r.ContractAddress = stored.ContractAddress
	r.GasUsed = stored.GasUsed
	r.Logs = make([]*Log, len(stored.Logs))
	for i, log := range stored.Logs {
		r.Logs[i] = (*Log)(log)
	}
	return nil
}

// Receipts is a wrapper around a Receipt array to implement DerivableList.
type Receipts []*Receipt

// Len returns the number of receipts in this list.
func (r Receipts) Len() int { return len(r) }

// GetRlp returns the RLP encoding of one receipt from the list.
func (r Receipts) GetRlp(i int) []byte {
	toBytes, err := rlp.EncodeToBytes(r[i])
	if err != nil {
		panic(err)
	}
	return toBytes
}

// DeriveFields fills the receipts with their computed fields based on consensus
// data and contextual infos like containing block and transactions.
func (r Receipts) DeriveFields(config *params.ChainConfig, hash common.Hash, number uint64, txs Transactions) error {
	signer := MakeSigner(config, new(big.Int).SetUint64(number))

	logIndex := uint(0)
	if len(txs) != len(r) {
		return errors.New("transaction and receipt count mismatch")
	}
	for i := 0; i < len(r); i++ {
		// The transaction hash can be retrieved from the transaction itself
		r[i].TxHash = txs[i].Hash()

		// block location fields
		r[i].BlockHash = hash
		r[i].BlockNumber = new(big.Int).SetUint64(number)
		r[i].TransactionIndex = uint(i)

		// The contract address can be derived from the transaction itself
		if txs[i].To() == nil {
			// Deriving the signer is expensive, only do if it's actually needed
			from, _ := Sender(signer, txs[i])
			r[i].ContractAddress = crypto.CreateAddress(from, txs[i].Nonce())
		}
		// The used gas can be calculated based on previous r
		if i == 0 {
			r[i].GasUsed = r[i].CumulativeGasUsed
		} else {
			r[i].GasUsed = r[i].CumulativeGasUsed - r[i-1].CumulativeGasUsed
		}
		// The derived log fields can simply be set from the block and transaction
		for j := 0; j < len(r[i].Logs); j++ {
			r[i].Logs[j].BlockNumber = number
			r[i].Logs[j].BlockHash = hash
			r[i].Logs[j].TxHash = r[i].TxHash
			r[i].Logs[j].TxIndex = uint(i)
			r[i].Logs[j].Index = logIndex
			logIndex++
		}
	}
	return nil
}
