package evm

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

	"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/pkg/errors"
	"github.com/rs/zerolog/log"
	"github.com/shopspring/decimal"
)

type Client interface {
	bind.ContractBackend
	PublicAddress() common.Address
	PublicAddressAsHexString() string
	PendingNonce(context.Context) (uint64, error)
	NewTransactor() (*bind.TransactOpts, error)
	Execute(context.Context, func(context.Context, *TransactOpts) (*types.Transaction, error), ...ExecutionOption) (Transaction, error)
	ExecuteAndWait(context.Context, func(context.Context) (Transaction, error)) error
	NativeTokenBalance(context.Context) (decimal.Decimal, error)
	CurrentBlockNumber(context.Context) (uint64, error)
	CurrentBlock(context.Context) (*types.Block, error)
	TransactionByHash(context.Context, common.Hash) (*types.Transaction, bool, error)

	TokenService() TokenService
}

type ClientOption func(c *client) (*client, error)

func WithPendingTransactionWaitResolution(duration time.Duration) ClientOption {
	return func(c *client) (*client, error) {
		c.pendingTransactionCheckPeriod = duration
		return c, nil
	}
}

type client struct {
	*ethclient.Client
	ts                            TokenService
	pendingTransactionCheckPeriod time.Duration
	fromAddress                   common.Address
	transactionlock               *sync.Mutex
	privateKey                    *ecdsa.PrivateKey
	chainId                       *big.Int

	defaultTimeout time.Duration
}

func (c *client) TokenService() TokenService {
	return c.ts
}

func NewClient(ctx context.Context, rpcurl string, privatekey string, tm TokenMapper, options ...ClientOption) (Client, error) {
	c, err := ethclient.Dial(rpcurl)
	if err != nil {
		return nil, errors.Wrapf(err, "dialing rpc url %s", rpcurl)
	}

	ecdsaprivatekey, publicaddress, err := GetPrivateKeyAndPublicAddressFromString(privatekey)
	if err != nil {
		return nil, errors.Wrap(err, "reading private key")
	}

	res := &client{
		Client: c,

		pendingTransactionCheckPeriod: 2 * time.Second,
		privateKey:                    ecdsaprivatekey,
		fromAddress:                   publicaddress,
		transactionlock:               &sync.Mutex{},

		defaultTimeout: 15 * time.Minute,
	}
	res.ts = NewTokenService(res, tm)
	res.chainId, err = c.ChainID(ctx)
	if err != nil {
		return nil, errors.Wrap(err, "retrieving chain id")
	}

	for _, option := range options {
		res, err = option(res)
		if err != nil {
			return nil, errors.Wrap(err, "applying option")
		}
	}
	return res, nil
}

func (c *client) PublicAddress() common.Address {
	return c.fromAddress
}

func (c *client) PendingNonce(ctx context.Context) (uint64, error) {
	return c.PendingNonceAt(ctx, c.PublicAddress())
}

func (c *client) PublicAddressAsHexString() string {
	return c.PublicAddress().Hex()
}

func (c *client) NewTransactor() (*bind.TransactOpts, error) {
	return bind.NewKeyedTransactorWithChainID(c.privateKey, c.chainId)
}

func (c *client) Execute(ctx context.Context, action func(context.Context, *TransactOpts) (*types.Transaction, error), opts ...ExecutionOption) (Transaction, error) {
	c.transactionlock.Lock()
	defer c.transactionlock.Unlock()
	localctx, cancel := context.WithTimeout(ctx, c.defaultTimeout)
	defer cancel()
	auth, err := NewTransactOpts(localctx, c)
	if err != nil {
		return nil, errors.Wrap(err, "init transaction options")
	}
	for _, opt := range opts {
		auth = opt(auth)
	}
	tx, err := action(localctx, auth)
	if err != nil {
		return nil, errors.Wrap(err, "executing waitable action")
	}
	log.Debug().Msgf("//TX// tx started / hash: %s / gasprice: %s / gaslimit: %d", tx.Hash().Hex(), decimal.NewFromBigInt(tx.GasPrice(), -9), tx.Gas())
	return NewTransaction(c, c.pendingTransactionCheckPeriod, tx), nil
}

func (c *client) ExecuteAndWait(ctx context.Context, action func(context.Context) (Transaction, error)) error {
	tx, err := action(ctx)
	if err != nil {
		return errors.Wrap(err, "executing waitable action")
	}
	return tx.Wait(ctx)
}

func (c *client) GetTransactionsForAddressInBlock(ctx context.Context, a string, b int64) {
	block, err := c.BlockByNumber(ctx, big.NewInt(b))
	if err != nil {
		panic(err)
	}
	txcount, err := c.TransactionCount(ctx, block.Hash())
	if err != nil {
		panic(err)
	}
	for i := 0; i < int(txcount); i++ {
		tx, err := c.TransactionInBlock(ctx, block.Hash(), uint(i))
		if err != nil {
			panic(err)
		}
		if strings.ToLower(tx.To().Hex()) == strings.ToLower(a) {
			log.Debug().Msgf("%d // %s // %s -> %s", b, decimal.NewFromBigInt(tx.Value(), -18), "", tx.To())
		}
	}
}

func (c *client) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
	return c.Client.SuggestGasPrice(ctx)
}

func (c *client) CurrentBlockNumber(ctx context.Context) (uint64, error) {
	block, err := c.BlockNumber(ctx)
	if err != nil {
		return 0, err
	}
	return block, nil
}

func (c *client) CurrentBlock(ctx context.Context) (*types.Block, error) {
	number, err := c.CurrentBlockNumber(ctx)
	if err != nil {
		return nil, errors.Wrap(err, "getting current block number")
	}
	block, err := c.BlockByNumber(ctx, big.NewInt(int64(number)))
	if err != nil {
		return nil, errors.Wrapf(err, "getting block %d", number)
	}
	return block, nil
}

func (c *client) NativeTokenBalance(ctx context.Context) (decimal.Decimal, error) {
	return c.BalanceFromAddress(ctx, c.PublicAddress())
}

func (c *client) BalanceFromAddress(ctx context.Context, address common.Address) (decimal.Decimal, error) {
	b, err := c.PendingBalanceAt(ctx, address)
	if err != nil {
		return decimal.Zero, errors.Wrap(err, "getting balance")
	}
	return decimal.NewFromBigInt(b, -18), nil
}

func GetPrivateKeyAndPublicAddressFromString(privatekey string) (*ecdsa.PrivateKey, common.Address, error) {
	privateKeyECDSA, err := crypto.HexToECDSA(privatekey)
	if err != nil {
		return nil, common.Address{}, errors.Wrap(err, "converting hex private key to ecdsa")
	}
	publicKeyECDSA, ok := privateKeyECDSA.Public().(*ecdsa.PublicKey)
	if !ok {
		return nil, common.Address{}, errors.New("cannot assert type: publicKey is not of type *ecdsa.PublicKey")
	}
	return privateKeyECDSA, crypto.PubkeyToAddress(*publicKeyECDSA), nil
}