package ethereum

import (
	"context"
	"crypto/ecdsa"
	"fmt"
	"math/big"
	"strings"
	"time"

	"github.com/ethereum/go-ethereum/accounts/abi"
	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethclient"
	"github.com/ethereum/go-ethereum/rpc"
)

type EthereumClient interface {
	GetEthClient() *ethclient.Client
	GetRPCClient() *rpc.Client
	Close()
	IsConnected(ctx context.Context) error

	NewBoundContract(address common.Address, abi string) (*bind.BoundContract, error)
	// Creates options for sending transactions to the blockchain.
	CreateTransactOpts(ctx context.Context, privateKey string, value *big.Int) (*bind.TransactOpts, error)
	// Creates options for reading from the blockchain.
	CreateCallOpts(ctx context.Context, blockNumber *big.Int) *bind.CallOpts
	// Waits for a transaction to be mined and returns the receipt.
	WaitForTransaction(ctx context.Context, txHash common.Hash) (*types.Receipt, error)
}

type Geth struct {
	ethClient *ethclient.Client
	rpcClient *rpc.Client
	url       string
}

type GethConfig struct {
	URL            string
	RequestTimeout time.Duration
}

func DefaultGethConfig() *GethConfig {
	return &GethConfig{
		RequestTimeout: 30 * time.Second,
	}
}

func NewGeth(clientURL string) (*Geth, error) {
	if clientURL == "" {
		return nil, fmt.Errorf("client URL cannot be empty")
	}

	rpcClient, err := rpc.Dial(clientURL)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to RPC client at %s: %w", clientURL, err)
	}

	ethClient := ethclient.NewClient(rpcClient)

	geth := &Geth{
		ethClient: ethClient,
		rpcClient: rpcClient,
		url:       clientURL,
	}

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	if err := geth.IsConnected(ctx); err != nil {
		geth.Close()
		return nil, fmt.Errorf("connection test failed: %w", err)
	}

	return geth, nil
}

func NewGethWithConfig(config *GethConfig) (*Geth, error) {
	if config == nil {
		return nil, fmt.Errorf("config cannot be nil")
	}

	if config.URL == "" {
		return nil, fmt.Errorf("client URL cannot be empty")
	}

	rpcClient, err := rpc.Dial(config.URL)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to RPC client at %s: %w", config.URL, err)
	}

	ethClient := ethclient.NewClient(rpcClient)

	geth := &Geth{
		ethClient: ethClient,
		rpcClient: rpcClient,
		url:       config.URL,
	}

	ctx, cancel := context.WithTimeout(context.Background(), config.RequestTimeout)
	defer cancel()

	if err := geth.IsConnected(ctx); err != nil {
		geth.Close()
		return nil, fmt.Errorf("connection test failed: %w", err)
	}

	return geth, nil
}

func (g *Geth) GetEthClient() *ethclient.Client {
	return g.ethClient
}

func (g *Geth) GetRPCClient() *rpc.Client {
	return g.rpcClient
}

func (g *Geth) Close() {
	if g.rpcClient != nil {
		g.rpcClient.Close()
	}
}

func (g *Geth) IsConnected(ctx context.Context) error {
	if g.ethClient == nil {
		return fmt.Errorf("ethereum client is not initialized")
	}

	_, err := g.ethClient.NetworkID(ctx)
	if err != nil {
		return fmt.Errorf("failed to get network ID: %w", err)
	}

	return nil
}

func (g *Geth) GetNetworkID(ctx context.Context) (uint64, error) {
	if g.ethClient == nil {
		return 0, fmt.Errorf("ethereum client is not initialized")
	}

	networkID, err := g.ethClient.NetworkID(ctx)
	if err != nil {
		return 0, fmt.Errorf("failed to get network ID: %w", err)
	}

	return networkID.Uint64(), nil
}

func (g *Geth) GetChainID(ctx context.Context) (uint64, error) {
	if g.ethClient == nil {
		return 0, fmt.Errorf("ethereum client is not initialized")
	}

	chainID, err := g.ethClient.ChainID(ctx)
	if err != nil {
		return 0, fmt.Errorf("failed to get chain ID: %w", err)
	}

	return chainID.Uint64(), nil
}

func (g *Geth) GetBlockNumber(ctx context.Context) (uint64, error) {
	if g.ethClient == nil {
		return 0, fmt.Errorf("ethereum client is not initialized")
	}

	blockNumber, err := g.ethClient.BlockNumber(ctx)
	if err != nil {
		return 0, fmt.Errorf("failed to get block number: %w", err)
	}

	return blockNumber, nil
}

func (g *Geth) GetURL() string {
	return g.url
}

func (g *Geth) NewBoundContract(address common.Address, abiJSON string) (*bind.BoundContract, error) {
	if g.ethClient == nil {
		return nil, fmt.Errorf("ethereum client is not initialized")
	}

	parsedABI, err := parseABI(abiJSON)
	if err != nil {
		return nil, fmt.Errorf("failed to parse ABI: %w", err)
	}

	return bind.NewBoundContract(address, parsedABI, g.ethClient, g.ethClient, g.ethClient), nil
}

func (g *Geth) CreateTransactOpts(ctx context.Context, privateKeyHex string, value *big.Int) (*bind.TransactOpts, error) {
	if g.ethClient == nil {
		return nil, fmt.Errorf("ethereum client is not initialized")
	}

	privateKey, err := parsePrivateKey(privateKeyHex)
	if err != nil {
		return nil, fmt.Errorf("failed to parse private key: %w", err)
	}

	chainID, err := g.ethClient.ChainID(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to get chain ID: %w", err)
	}

	opts, err := bind.NewKeyedTransactorWithChainID(privateKey, chainID)
	if err != nil {
		return nil, fmt.Errorf("failed to create transactor: %w", err)
	}

	opts.Context = ctx
	if value != nil {
		opts.Value = value
	}

	return opts, nil
}

func (g *Geth) CreateCallOpts(ctx context.Context, blockNumber *big.Int) *bind.CallOpts {
	return &bind.CallOpts{
		Context:     ctx,
		BlockNumber: blockNumber,
	}
}

func (g *Geth) WaitForTransaction(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
	if g.ethClient == nil {
		return nil, fmt.Errorf("ethereum client is not initialized")
	}

	receipt, err := bind.WaitMined(ctx, g.ethClient, &types.Transaction{})
	if err != nil {
		return nil, fmt.Errorf("failed to wait for transaction: %w", err)
	}

	return receipt, nil
}

func parseABI(abiJSON string) (abi.ABI, error) {
	return abi.JSON(strings.NewReader(abiJSON))
}

func parsePrivateKey(privateKeyHex string) (*ecdsa.PrivateKey, error) {
	privateKeyHex = strings.TrimPrefix(privateKeyHex, "0x")

	return crypto.HexToECDSA(privateKeyHex)
}