package eth

import (
	"blockbook/bchain"
	"context"
	"encoding/json"
	"math/big"
	"sync"
	"time"

	"github.com/golang/glog"
	"github.com/juju/errors"

	ethcommon "github.com/ethereum/go-ethereum/common"
	ethtypes "github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/ethclient"
)

type EthereumNet uint32

const (
	MainNet EthereumNet = 1
	TestNet EthereumNet = 3
)

// EthRPC is an interface to JSON-RPC eth service.
type EthRPC struct {
	client       *ethclient.Client
	timeout      time.Duration
	rpcURL       string
	Parser       *EthParser
	Testnet      bool
	Network      string
	Mempool      *bchain.Mempool
	bestHeaderMu sync.Mutex
	bestHeader   *ethtypes.Header
}

type configuration struct {
	RPCURL     string `json:"rpcURL"`
	RPCTimeout int    `json:"rpcTimeout"`
}

// NewEthRPC returns new EthRPC instance.
func NewEthRPC(config json.RawMessage, pushHandler func(*bchain.MQMessage)) (bchain.BlockChain, error) {
	var err error
	var c configuration
	err = json.Unmarshal(config, &c)
	if err != nil {
		return nil, errors.Annotatef(err, "Invalid configuration file")
	}
	ec, err := ethclient.Dial(c.RPCURL)
	if err != nil {
		return nil, err
	}
	s := &EthRPC{
		client: ec,
		rpcURL: c.RPCURL,
	}

	// always create parser
	s.Parser = &EthParser{}
	s.timeout = time.Duration(c.RPCTimeout) * time.Second

	return s, nil
}

func (b *EthRPC) Initialize() error {
	ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
	defer cancel()

	id, err := b.client.NetworkID(ctx)
	if err != nil {
		return err
	}

	// parameters for getInfo request
	switch EthereumNet(id.Uint64()) {
	case MainNet:
		b.Testnet = false
		b.Network = "livenet"
		break
	case TestNet:
		b.Testnet = true
		b.Network = "testnet"
		break
	default:
		return errors.Errorf("Unknown network id %v", id)
	}
	glog.Info("rpc: block chain ", b.Network)

	// b.Mempool = bchain.NewMempool(s, metrics)
	return nil
}

func (b *EthRPC) Shutdown() error {
	return nil
}

func (b *EthRPC) IsTestnet() bool {
	return b.Testnet
}

func (b *EthRPC) GetNetworkName() string {
	return b.Network
}

func (b *EthRPC) getBestHeader() (*ethtypes.Header, error) {
	b.bestHeaderMu.Lock()
	defer b.bestHeaderMu.Unlock()
	if b.bestHeader == nil {
		var err error
		ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
		defer cancel()
		b.bestHeader, err = b.client.HeaderByNumber(ctx, nil)
		if err != nil {
			return nil, err
		}
	}
	return b.bestHeader, nil
}

func ethHashToHash(h ethcommon.Hash) string {
	return h.Hex()[2:]
}

func (b *EthRPC) GetBestBlockHash() (string, error) {
	h, err := b.getBestHeader()
	if err != nil {
		return "", err
	}
	return ethHashToHash(h.Hash()), nil
}

func (b *EthRPC) GetBestBlockHeight() (uint32, error) {
	h, err := b.getBestHeader()
	if err != nil {
		return 0, err
	}
	// TODO - can it grow over 2^32 ?
	return uint32(h.Number.Uint64()), nil
}

func (b *EthRPC) GetBlockHash(height uint32) (string, error) {
	var n big.Int
	n.SetUint64(uint64(height))
	ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
	defer cancel()
	h, err := b.client.HeaderByNumber(ctx, &n)
	if err != nil {
		return "", err
	}
	return ethHashToHash(h.Hash()), nil
}

func (b *EthRPC) ethHeaderToBlockHeader(h *ethtypes.Header) (*bchain.BlockHeader, error) {
	bh, err := b.getBestHeader()
	if err != nil {
		return nil, err
	}
	hn := uint32(h.Number.Uint64())
	bn := uint32(bh.Number.Uint64())
	return &bchain.BlockHeader{
		Hash:          ethHashToHash(h.Hash()),
		Height:        hn,
		Confirmations: int(bn - hn),
		// Next
		// Prev

	}, nil
}

func (b *EthRPC) GetBlockHeader(hash string) (*bchain.BlockHeader, error) {
	ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
	defer cancel()
	h, err := b.client.HeaderByHash(ctx, ethcommon.HexToHash(hash))
	if err != nil {
		return nil, err
	}
	return b.ethHeaderToBlockHeader(h)
}

func (b *EthRPC) GetBlock(hash string, height uint32) (*bchain.Block, error) {
	ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
	defer cancel()
	bk, err := b.client.BlockByHash(ctx, ethcommon.HexToHash(hash))
	if err != nil {
		return nil, err
	}
	// TODO maybe not the most optimal way to get the header
	bbh, err := b.ethHeaderToBlockHeader(bk.Header())
	txs := bk.Transactions()
	btxs := make([]bchain.Tx, len(txs))
	for i, tx := range txs {
		btxs[i] = bchain.Tx{
			// Blocktime
			Confirmations: uint32(bbh.Confirmations),
			// Hex
			// LockTime
			// Time
			Txid: ethHashToHash(tx.Hash()),
			// Vin
		}
	}
	bbk := bchain.Block{
		BlockHeader: *bbh,
		Txs:         btxs,
	}
	return &bbk, nil
}

func (b *EthRPC) GetMempool() ([]string, error) {
	panic("not implemented")
}

func (b *EthRPC) GetTransaction(txid string) (*bchain.Tx, error) {
	// bh, err := b.getBestHeader()
	// if err != nil {
	// 	return nil, err
	// }
	ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
	defer cancel()
	tx, _, err := b.client.TransactionByHash(ctx, ethcommon.StringToHash(txid))
	if err != nil {
		return nil, err
	}
	btx := bchain.Tx{
		// Blocktime
		// Confirmations
		// Hex
		// LockTime
		// Time
		Txid: ethHashToHash(tx.Hash()),
		// Vin
		// Vout
	}
	return &btx, nil
}

func (b *EthRPC) EstimateSmartFee(blocks int, conservative bool) (float64, error) {
	panic("not implemented")
}

func (b *EthRPC) SendRawTransaction(tx string) (string, error) {
	panic("not implemented")
}

func (b *EthRPC) ResyncMempool(onNewTxAddr func(txid string, addr string)) error {
	panic("not implemented")
}

func (b *EthRPC) GetMempoolTransactions(address string) ([]string, error) {
	panic("not implemented")
}

func (b *EthRPC) GetMempoolSpentOutput(outputTxid string, vout uint32) string {
	panic("not implemented")
}

func (b *EthRPC) GetMempoolEntry(txid string) (*bchain.MempoolEntry, error) {
	panic("not implemented")
}

func (b *EthRPC) GetChainParser() bchain.BlockChainParser {
	return b.Parser
}