package requests

import (
	"encoding/json"
	"fmt"
	"strconv"
	"strings"

	libcommon "github.com/ledgerwatch/erigon-lib/common"
	"github.com/ledgerwatch/erigon-lib/common/hexutility"
	"github.com/ledgerwatch/erigon/common/hexutil"
	"github.com/ledgerwatch/log/v3"
)

// Log represents a contract log event. These events are generated by the LOG opcode and
// stored/indexed by the node.
type Log struct { //nolint
	// Consensus fields:
	// address of the contract that generated the event
	Address libcommon.Address `json:"address" gencodec:"required"`
	// list of topics provided by the contract.
	Topics []libcommon.Hash `json:"topics" gencodec:"required"`
	// supplied by the contract, usually ABI-encoded
	Data hexutility.Bytes `json:"data" gencodec:"required"`

	// Derived fields. These fields are filled in by the node
	// but not secured by consensus.
	// block in which the transaction was included
	BlockNumber hexutil.Uint64 `json:"blockNumber"`
	// hash of the transaction
	TxHash libcommon.Hash `json:"transactionHash" gencodec:"required"`
	// index of the transaction in the block
	TxIndex hexutil.Uint `json:"transactionIndex" gencodec:"required"`
	// hash of the block in which the transaction was included
	BlockHash libcommon.Hash `json:"blockHash"`
	// index of the log in the receipt
	Index hexutil.Uint `json:"logIndex" gencodec:"required"`

	// The Removed field is true if this log was reverted due to a chain reorganisation.
	// You must pay attention to this field if you receive logs through a filter query.
	Removed bool `json:"removed"`
}

type EthGetLogs struct {
	CommonResponse
	Result []Log `json:"result"`
}

func BuildLog(hash libcommon.Hash, blockNum string, address libcommon.Address, topics []libcommon.Hash, data hexutility.Bytes, txIndex hexutil.Uint, blockHash libcommon.Hash, index hexutil.Uint, removed bool) Log {
	return Log{
		Address:     address,
		Topics:      topics,
		Data:        data,
		BlockNumber: hexutil.Uint64(HexToInt(blockNum)),
		TxHash:      hash,
		TxIndex:     txIndex,
		BlockHash:   blockHash,
		Index:       index,
		Removed:     removed,
	}
}

// HexToInt converts a hexadecimal string to uint64
func HexToInt(hexStr string) uint64 {
	cleaned := strings.ReplaceAll(hexStr, "0x", "") // remove the 0x prefix
	result, _ := strconv.ParseUint(cleaned, 16, 64)
	return result
}

func (reqGen *RequestGenerator) GetAndCompareLogs(fromBlock uint64, toBlock uint64, expected Log) error {
	reqGen.logger.Info("GETTING AND COMPARING LOGS")
	var b EthGetLogs

	method, body := reqGen.getLogs(fromBlock, toBlock, expected.Address)
	if res := reqGen.call(method, body, &b); res.Err != nil {
		return fmt.Errorf("failed to fetch logs: %v", res.Err)
	}

	if len(b.Result) == 0 {
		return fmt.Errorf("logs result should not be empty")
	}

	eventLog := b.Result[0]

	actual := BuildLog(eventLog.TxHash, strconv.FormatUint(uint64(eventLog.BlockNumber), 10),
		eventLog.Address, eventLog.Topics, eventLog.Data, eventLog.TxIndex, eventLog.BlockHash, eventLog.Index,
		eventLog.Removed)

	// compare the log events
	errs, ok := compareLogEvents(expected, actual)
	if !ok {
		reqGen.logger.Error("Log result is incorrect", "errors", errs)
		return fmt.Errorf("incorrect logs: %v", errs)
	}

	_, err := parseResponse(b)
	if err != nil {
		return fmt.Errorf("error parsing response: %v", err)
	}

	log.Info("SUCCESS => Logs compared successfully, no discrepancies")

	return nil
}

// ParseResponse converts any of the models interfaces to a string for readability
func parseResponse(resp interface{}) (string, error) {
	result, err := json.Marshal(resp)
	if err != nil {
		return "", fmt.Errorf("error trying to marshal response: %v", err)
	}

	return string(result), nil
}

func compareLogEvents(expected, actual Log) ([]error, bool) {
	var errs []error

	switch {
	case expected.Address != actual.Address:
		errs = append(errs, fmt.Errorf("expected address: %v, actual address %v", expected.Address, actual.Address))
	case expected.TxHash != actual.TxHash:
		errs = append(errs, fmt.Errorf("expected txhash: %v, actual txhash %v", expected.TxHash, actual.TxHash))
	case expected.BlockHash != actual.BlockHash:
		errs = append(errs, fmt.Errorf("expected blockHash: %v, actual blockHash %v", expected.BlockHash, actual.BlockHash))
	case expected.BlockNumber != actual.BlockNumber:
		errs = append(errs, fmt.Errorf("expected blockNumber: %v, actual blockNumber %v", expected.BlockNumber, actual.BlockNumber))
	case expected.TxIndex != actual.TxIndex:
		errs = append(errs, fmt.Errorf("expected txIndex: %v, actual txIndex %v", expected.TxIndex, actual.TxIndex))
	case !hashSlicesAreEqual(expected.Topics, actual.Topics):
		errs = append(errs, fmt.Errorf("expected topics: %v, actual topics %v", expected.Topics, actual.Topics))
	}

	return errs, len(errs) == 0
}

func hashSlicesAreEqual(s1, s2 []libcommon.Hash) bool {
	if len(s1) != len(s2) {
		return false
	}

	for i := 0; i < len(s1); i++ {
		if s1[i] != s2[i] {
			return false
		}
	}

	return true
}

func (req *RequestGenerator) getLogs(fromBlock, toBlock uint64, address libcommon.Address) (RPCMethod, string) {
	const template = `{"jsonrpc":"2.0","method":%q,"params":[{"fromBlock":"0x%x","toBlock":"0x%x","address":"0x%x"}],"id":%d}`
	return Methods.ETHGetLogs, fmt.Sprintf(template, Methods.ETHGetLogs, fromBlock, toBlock, address, req.reqID)
}