package wallet

import (
	"context"
	"errors"
	"math/big"
	"sync"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/ethclient"
	"github.com/ethereum/go-ethereum/event"

	"github.com/status-im/status-go/services/rpcstats"
)

var (
	erc20BatchSize    = big.NewInt(100000)
	errAlreadyRunning = errors.New("already running")
)

// HeaderReader interface for reading headers using block number or hash.
type HeaderReader interface {
	HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error)
	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
}

// BalanceReader interface for reading balance at a specifeid address.
type BalanceReader interface {
	BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error)
	NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error)
	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
}

type walletClient struct {
	client *ethclient.Client
}

func (rc *walletClient) HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error) {
	rpcstats.CountCall("eth_getBlockByHash")
	return rc.client.HeaderByHash(ctx, hash)
}

func (rc *walletClient) HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error) {
	rpcstats.CountCall("eth_getBlockByNumber")
	return rc.client.HeaderByNumber(ctx, number)
}

func (rc *walletClient) BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error) {
	rpcstats.CountCall("eth_getBlockByHash")
	return rc.client.BlockByHash(ctx, hash)
}

func (rc *walletClient) BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error) {
	rpcstats.CountCall("eth_getBlockByNumber")
	return rc.client.BlockByNumber(ctx, number)
}

func (rc *walletClient) BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error) {
	rpcstats.CountCall("eth_getBalance")
	return rc.client.BalanceAt(ctx, account, blockNumber)
}

func (rc *walletClient) NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error) {
	rpcstats.CountCall("eth_getTransactionCount")
	return rc.client.NonceAt(ctx, account, blockNumber)
}

func (rc *walletClient) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
	rpcstats.CountCall("eth_getTransactionReceipt")
	return rc.client.TransactionReceipt(ctx, txHash)
}

func (rc *walletClient) TransactionByHash(ctx context.Context, hash common.Hash) (tx *types.Transaction, isPending bool, err error) {
	rpcstats.CountCall("eth_getTransactionByHash")
	return rc.client.TransactionByHash(ctx, hash)
}

func (rc *walletClient) FilterLogs(ctx context.Context, q ethereum.FilterQuery) ([]types.Log, error) {
	rpcstats.CountCall("eth_getLogs")
	return rc.client.FilterLogs(ctx, q)
}

func (rc *walletClient) CodeAt(ctx context.Context, contract common.Address, blockNumber *big.Int) ([]byte, error) {
	rpcstats.CountCall("eth_getCode")
	return rc.client.CodeAt(ctx, contract, blockNumber)
}

func (rc *walletClient) CallContract(ctx context.Context, call ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
	rpcstats.CountCall("eth_call")
	return rc.client.CallContract(ctx, call, blockNumber)
}

// NewReactor creates instance of the Reactor.
func NewReactor(db *Database, feed *event.Feed, client *ethclient.Client, chain *big.Int) *Reactor {
	return &Reactor{
		db:     db,
		client: client,
		feed:   feed,
		chain:  chain,
	}
}

// Reactor listens to new blocks and stores transfers into the database.
type Reactor struct {
	client *ethclient.Client
	db     *Database
	feed   *event.Feed
	chain  *big.Int

	mu    sync.Mutex
	group *Group
}

func (r *Reactor) newControlCommand(accounts []common.Address) *controlCommand {
	signer := types.NewEIP155Signer(r.chain)
	client := &walletClient{client: r.client}
	ctl := &controlCommand{
		db:       r.db,
		chain:    r.chain,
		client:   client,
		accounts: accounts,
		eth: &ETHTransferDownloader{
			chain:    r.chain,
			client:   client,
			accounts: accounts,
			signer:   signer,
			db:       r.db,
		},
		erc20:       NewERC20TransfersDownloader(client, accounts, signer),
		feed:        r.feed,
		errorsCount: 0,
	}

	return ctl
}

// Start runs reactor loop in background.
func (r *Reactor) Start(accounts []common.Address) error {
	r.mu.Lock()
	defer r.mu.Unlock()
	if r.group != nil {
		return errAlreadyRunning
	}
	r.group = NewGroup(context.Background())
	ctl := r.newControlCommand(accounts)
	r.group.Add(ctl.Command())
	return nil
}

// Stop stops reactor loop and waits till it exits.
func (r *Reactor) Stop() {
	r.mu.Lock()
	defer r.mu.Unlock()
	if r.group == nil {
		return
	}
	r.group.Stop()
	r.group.Wait()
	r.group = nil
}