package engine

import (
	"errors"
	"strings"
	"sync/atomic"
	"time"

	"github.com/thrasher-corp/gocryptotrader/currency"
	"github.com/thrasher-corp/gocryptotrader/exchanges/asset"
	"github.com/thrasher-corp/gocryptotrader/exchanges/ticker"
	log "github.com/thrasher-corp/gocryptotrader/logger"
)

// const holds the sync item types
const (
	SyncItemTicker = iota
	SyncItemOrderbook
	SyncItemTrade

	DefaultSyncerWorkers = 15
	DefaultSyncerTimeout = time.Second * 15
)

var (
	createdCounter = 0
	removedCounter = 0
)

// NewCurrencyPairSyncer starts a new CurrencyPairSyncer
func NewCurrencyPairSyncer(c CurrencyPairSyncerConfig) (*ExchangeCurrencyPairSyncer, error) {
	if !c.SyncOrderbook && !c.SyncTicker && !c.SyncTrades {
		return nil, errors.New("no sync items enabled")
	}

	if c.NumWorkers <= 0 {
		c.NumWorkers = DefaultSyncerWorkers
	}

	if c.SyncTimeout <= time.Duration(0) {
		c.SyncTimeout = DefaultSyncerTimeout
	}

	s := ExchangeCurrencyPairSyncer{
		Cfg: CurrencyPairSyncerConfig{
			SyncTicker:       c.SyncTicker,
			SyncOrderbook:    c.SyncOrderbook,
			SyncTrades:       c.SyncTrades,
			SyncContinuously: c.SyncContinuously,
			SyncTimeout:      c.SyncTimeout,
			NumWorkers:       c.NumWorkers,
		},
	}

	s.tickerBatchLastRequested = make(map[string]time.Time)

	log.Debugf(log.SyncMgr,
		"Exchange currency pair syncer config: continuous: %v ticker: %v"+
			" orderbook: %v trades: %v workers: %v verbose: %v timeout: %v\n",
		s.Cfg.SyncContinuously, s.Cfg.SyncTicker, s.Cfg.SyncOrderbook,
		s.Cfg.SyncTrades, s.Cfg.NumWorkers, s.Cfg.Verbose, s.Cfg.SyncTimeout)
	return &s, nil
}

func (e *ExchangeCurrencyPairSyncer) get(exchangeName string, p currency.Pair, a asset.Item) (*CurrencyPairSyncAgent, error) {
	e.mux.Lock()
	defer e.mux.Unlock()

	for x := range e.CurrencyPairs {
		if e.CurrencyPairs[x].Exchange == exchangeName &&
			e.CurrencyPairs[x].Pair.Equal(p) &&
			e.CurrencyPairs[x].AssetType == a {
			return &e.CurrencyPairs[x], nil
		}
	}

	return nil, errors.New("exchange currency pair syncer not found")
}

func (e *ExchangeCurrencyPairSyncer) exists(exchangeName string, p currency.Pair, a asset.Item) bool {
	e.mux.Lock()
	defer e.mux.Unlock()

	for x := range e.CurrencyPairs {
		if e.CurrencyPairs[x].Exchange == exchangeName &&
			e.CurrencyPairs[x].Pair.Equal(p) &&
			e.CurrencyPairs[x].AssetType == a {
			return true
		}
	}
	return false
}

func (e *ExchangeCurrencyPairSyncer) add(c *CurrencyPairSyncAgent) {
	e.mux.Lock()
	defer e.mux.Unlock()

	if e.Cfg.SyncTicker {
		if e.Cfg.Verbose {
			log.Debugf(log.SyncMgr,
				"%s: Added ticker sync item %v: using websocket: %v using REST: %v\n",
				c.Exchange, FormatCurrency(c.Pair).String(), c.Ticker.IsUsingWebsocket,
				c.Ticker.IsUsingREST)
		}
		if atomic.LoadInt32(&e.initSyncCompleted) != 1 {
			e.initSyncWG.Add(1)
			createdCounter++
		}
	}

	if e.Cfg.SyncOrderbook {
		if e.Cfg.Verbose {
			log.Debugf(log.SyncMgr,
				"%s: Added orderbook sync item %v: using websocket: %v using REST: %v\n",
				c.Exchange, FormatCurrency(c.Pair).String(), c.Orderbook.IsUsingWebsocket,
				c.Orderbook.IsUsingREST)
		}
		if atomic.LoadInt32(&e.initSyncCompleted) != 1 {
			e.initSyncWG.Add(1)
			createdCounter++
		}
	}

	if e.Cfg.SyncTrades {
		if e.Cfg.Verbose {
			log.Debugf(log.SyncMgr,
				"%s: Added trade sync item %v: using websocket: %v using REST: %v\n",
				c.Exchange, FormatCurrency(c.Pair).String(), c.Trade.IsUsingWebsocket,
				c.Trade.IsUsingREST)
		}
		if atomic.LoadInt32(&e.initSyncCompleted) != 1 {
			e.initSyncWG.Add(1)
			createdCounter++
		}
	}

	c.Created = time.Now()
	e.CurrencyPairs = append(e.CurrencyPairs, *c)
}

func (e *ExchangeCurrencyPairSyncer) remove(c *CurrencyPairSyncAgent) {
	e.mux.Lock()
	defer e.mux.Unlock()

	for x := range e.CurrencyPairs {
		if e.CurrencyPairs[x].Exchange == c.Exchange &&
			e.CurrencyPairs[x].Pair.Equal(c.Pair) &&
			e.CurrencyPairs[x].AssetType == c.AssetType {
			e.CurrencyPairs = append(e.CurrencyPairs[:x], e.CurrencyPairs[x+1:]...)
			return
		}
	}
}

func (e *ExchangeCurrencyPairSyncer) isProcessing(exchangeName string, p currency.Pair, a asset.Item, syncType int) bool {
	e.mux.Lock()
	defer e.mux.Unlock()

	for x := range e.CurrencyPairs {
		if e.CurrencyPairs[x].Exchange == exchangeName &&
			e.CurrencyPairs[x].Pair.Equal(p) &&
			e.CurrencyPairs[x].AssetType == a {
			switch syncType {
			case SyncItemTicker:
				return e.CurrencyPairs[x].Ticker.IsProcessing
			case SyncItemOrderbook:
				return e.CurrencyPairs[x].Orderbook.IsProcessing
			case SyncItemTrade:
				return e.CurrencyPairs[x].Trade.IsProcessing
			}
		}
	}

	return false
}

func (e *ExchangeCurrencyPairSyncer) setProcessing(exchangeName string, p currency.Pair, a asset.Item, syncType int, processing bool) {
	e.mux.Lock()
	defer e.mux.Unlock()

	for x := range e.CurrencyPairs {
		if e.CurrencyPairs[x].Exchange == exchangeName &&
			e.CurrencyPairs[x].Pair.Equal(p) &&
			e.CurrencyPairs[x].AssetType == a {
			switch syncType {
			case SyncItemTicker:
				e.CurrencyPairs[x].Ticker.IsProcessing = processing
			case SyncItemOrderbook:
				e.CurrencyPairs[x].Orderbook.IsProcessing = processing
			case SyncItemTrade:
				e.CurrencyPairs[x].Trade.IsProcessing = processing
			}
		}
	}
}

func (e *ExchangeCurrencyPairSyncer) update(exchangeName string, p currency.Pair, a asset.Item, syncType int, err error) {
	if atomic.LoadInt32(&e.initSyncStarted) != 1 {
		return
	}

	switch syncType {
	case SyncItemOrderbook, SyncItemTrade, SyncItemTicker:
		if !e.Cfg.SyncOrderbook && syncType == SyncItemOrderbook {
			return
		}

		if !e.Cfg.SyncTicker && syncType == SyncItemTicker {
			return
		}

		if !e.Cfg.SyncTrades && syncType == SyncItemTrade {
			return
		}
	default:
		log.Warnf(log.SyncMgr, "ExchangeCurrencyPairSyncer: unknown sync item %v\n", syncType)
		return
	}

	e.mux.Lock()
	defer e.mux.Unlock()

	for x := range e.CurrencyPairs {
		if e.CurrencyPairs[x].Exchange == exchangeName &&
			e.CurrencyPairs[x].Pair.Equal(p) &&
			e.CurrencyPairs[x].AssetType == a {
			switch syncType {
			case SyncItemTicker:
				origHadData := e.CurrencyPairs[x].Ticker.HaveData
				e.CurrencyPairs[x].Ticker.LastUpdated = time.Now()
				if err != nil {
					e.CurrencyPairs[x].Ticker.NumErrors++
				}
				e.CurrencyPairs[x].Ticker.HaveData = true
				e.CurrencyPairs[x].Ticker.IsProcessing = false
				if atomic.LoadInt32(&e.initSyncCompleted) != 1 && !origHadData {
					removedCounter++
					log.Debugf(log.SyncMgr, "%s ticker sync complete %v [%d/%d].\n",
						exchangeName, FormatCurrency(p).String(), removedCounter, createdCounter)
					e.initSyncWG.Done()
				}

			case SyncItemOrderbook:
				origHadData := e.CurrencyPairs[x].Orderbook.HaveData
				e.CurrencyPairs[x].Orderbook.LastUpdated = time.Now()
				if err != nil {
					e.CurrencyPairs[x].Orderbook.NumErrors++
				}
				e.CurrencyPairs[x].Orderbook.HaveData = true
				e.CurrencyPairs[x].Orderbook.IsProcessing = false
				if atomic.LoadInt32(&e.initSyncCompleted) != 1 && !origHadData {
					removedCounter++
					log.Debugf(log.SyncMgr, "%s orderbook sync complete %v [%d/%d].\n",
						exchangeName, FormatCurrency(p).String(), removedCounter, createdCounter)
					e.initSyncWG.Done()
				}

			case SyncItemTrade:
				origHadData := e.CurrencyPairs[x].Trade.HaveData
				e.CurrencyPairs[x].Trade.LastUpdated = time.Now()
				if err != nil {
					e.CurrencyPairs[x].Trade.NumErrors++
				}
				e.CurrencyPairs[x].Trade.HaveData = true
				e.CurrencyPairs[x].Trade.IsProcessing = false
				if atomic.LoadInt32(&e.initSyncCompleted) != 1 && !origHadData {
					removedCounter++
					log.Debugf(log.SyncMgr, "%s trade sync complete %v [%d/%d].\n",
						exchangeName, FormatCurrency(p).String(), removedCounter, createdCounter)
					e.initSyncWG.Done()
				}
			}
		}
	}
}

func (e *ExchangeCurrencyPairSyncer) worker() {
	cleanup := func() {
		log.Debugln(log.SyncMgr, "Exchange CurrencyPairSyncer worker shutting down.")
	}
	defer cleanup()

	for atomic.LoadInt32(&e.shutdown) != 1 {
		for x := range Bot.Exchanges {
			if !Bot.Exchanges[x].IsEnabled() {
				continue
			}

			exchangeName := Bot.Exchanges[x].GetName()
			assetTypes := Bot.Exchanges[x].GetAssetTypes()
			supportsREST := Bot.Exchanges[x].SupportsREST()
			supportsRESTTickerBatching := Bot.Exchanges[x].SupportsRESTTickerBatchUpdates()
			var usingREST bool
			var usingWebsocket bool
			var switchedToRest bool
			if Bot.Exchanges[x].SupportsWebsocket() && Bot.Exchanges[x].IsWebsocketEnabled() {
				ws, err := Bot.Exchanges[x].GetWebsocket()
				if err != nil {
					log.Errorf(log.SyncMgr, "%s unable to get websocket pointer. Err: %s\n",
						exchangeName, err)
					usingREST = true
				}

				if ws.IsConnected() {
					usingWebsocket = true
				} else {
					usingREST = true
				}
			} else if supportsREST {
				usingREST = true
			}

			for y := range assetTypes {
				enabledPairs := Bot.Exchanges[x].GetEnabledPairs(assetTypes[y])
				for i := range enabledPairs {
					if atomic.LoadInt32(&e.shutdown) == 1 {
						return
					}

					if !e.exists(exchangeName, enabledPairs[i], assetTypes[y]) {
						c := CurrencyPairSyncAgent{
							AssetType: assetTypes[y],
							Exchange:  exchangeName,
							Pair:      enabledPairs[i],
						}

						if e.Cfg.SyncTicker {
							c.Ticker = SyncBase{
								IsUsingREST:      usingREST,
								IsUsingWebsocket: usingWebsocket,
							}
						}

						if e.Cfg.SyncOrderbook {
							c.Orderbook = SyncBase{
								IsUsingREST:      usingREST,
								IsUsingWebsocket: usingWebsocket,
							}
						}

						if e.Cfg.SyncTrades {
							c.Trade = SyncBase{
								IsUsingREST:      usingREST,
								IsUsingWebsocket: usingWebsocket,
							}
						}

						e.add(&c)
					}

					c, err := e.get(exchangeName, enabledPairs[i], assetTypes[y])
					if err != nil {
						log.Errorf(log.SyncMgr, "failed to get item. Err: %s\n", err)
						continue
					}
					if switchedToRest && usingWebsocket {
						log.Infof(log.SyncMgr,
							"%s %s: Websocket re-enabled, switching from rest to websocket\n",
							c.Exchange, FormatCurrency(enabledPairs[i]).String())
						switchedToRest = false
					}
					if e.Cfg.SyncTicker {
						if !e.isProcessing(exchangeName, c.Pair, c.AssetType, SyncItemTicker) {
							if c.Ticker.LastUpdated.IsZero() || time.Since(c.Ticker.LastUpdated) > e.Cfg.SyncTimeout {
								if c.Ticker.IsUsingWebsocket {
									if time.Since(c.Created) < e.Cfg.SyncTimeout {
										continue
									}

									if supportsREST {
										e.setProcessing(c.Exchange, c.Pair, c.AssetType, SyncItemTicker, true)
										c.Ticker.IsUsingWebsocket = false
										c.Ticker.IsUsingREST = true
										log.Warnf(log.SyncMgr,
											"%s %s %s: No ticker update after %s, switching from websocket to rest\n",
											c.Exchange,
											FormatCurrency(enabledPairs[i]).String(),
											strings.ToUpper(c.AssetType.String()),
											e.Cfg.SyncTimeout,
										)
										switchedToRest = true
										e.setProcessing(c.Exchange, c.Pair, c.AssetType, SyncItemTicker, false)
									}
								}

								if c.Ticker.IsUsingREST {
									e.setProcessing(c.Exchange, c.Pair, c.AssetType, SyncItemTicker, true)
									var result *ticker.Price
									var err error

									if supportsRESTTickerBatching {
										e.mux.Lock()
										batchLastDone, ok := e.tickerBatchLastRequested[exchangeName]
										if !ok {
											e.tickerBatchLastRequested[exchangeName] = time.Time{}
										}
										e.mux.Unlock()

										if batchLastDone.IsZero() || time.Since(batchLastDone) > e.Cfg.SyncTimeout {
											e.mux.Lock()
											if e.Cfg.Verbose {
												log.Debugf(log.SyncMgr, "%s Init'ing REST ticker batching\n", exchangeName)
											}
											result, err = Bot.Exchanges[x].UpdateTicker(c.Pair, c.AssetType)
											e.tickerBatchLastRequested[exchangeName] = time.Now()
											e.mux.Unlock()
										} else {
											if e.Cfg.Verbose {
												log.Debugf(log.SyncMgr, "%s Using recent batching cache\n", exchangeName)
											}
											result, err = Bot.Exchanges[x].FetchTicker(c.Pair, c.AssetType)
										}
									} else {
										result, err = Bot.Exchanges[x].UpdateTicker(c.Pair, c.AssetType)
									}
									printTickerSummary(result, c.Pair, c.AssetType, exchangeName, "REST", err)
									if err == nil {
										//nolint:gocritic Bot.CommsRelayer.StageTickerData(exchangeName, c.AssetType, result)
										if Bot.Config.RemoteControl.WebsocketRPC.Enabled {
											relayWebsocketEvent(result, "ticker_update", c.AssetType.String(), exchangeName)
										}
									}
									e.update(c.Exchange, c.Pair, c.AssetType, SyncItemTicker, err)
								}
							} else {
								time.Sleep(time.Millisecond * 50)
							}
						}
					}

					if e.Cfg.SyncOrderbook {
						if !e.isProcessing(exchangeName, c.Pair, c.AssetType, SyncItemOrderbook) {
							if c.Orderbook.LastUpdated.IsZero() || time.Since(c.Orderbook.LastUpdated) > e.Cfg.SyncTimeout {
								if c.Orderbook.IsUsingWebsocket {
									if time.Since(c.Created) < e.Cfg.SyncTimeout {
										continue
									}
									if supportsREST {
										e.setProcessing(c.Exchange, c.Pair, c.AssetType, SyncItemOrderbook, true)
										c.Orderbook.IsUsingWebsocket = false
										c.Orderbook.IsUsingREST = true
										log.Warnf(log.SyncMgr,
											"%s %s %s: No orderbook update after %s, switching from websocket to rest\n",
											c.Exchange,
											FormatCurrency(c.Pair).String(),
											strings.ToUpper(c.AssetType.String()),
											e.Cfg.SyncTimeout,
										)
										switchedToRest = true
										e.setProcessing(c.Exchange, c.Pair, c.AssetType, SyncItemOrderbook, false)
									}
								}

								e.setProcessing(c.Exchange, c.Pair, c.AssetType, SyncItemOrderbook, true)
								result, err := Bot.Exchanges[x].UpdateOrderbook(c.Pair, c.AssetType)
								printOrderbookSummary(result, c.Pair, c.AssetType, exchangeName, "REST", err)
								if err == nil {
									//nolint:gocritic Bot.CommsRelayer.StageOrderbookData(exchangeName, c.AssetType, result)
									if Bot.Config.RemoteControl.WebsocketRPC.Enabled {
										relayWebsocketEvent(result, "orderbook_update", c.AssetType.String(), exchangeName)
									}
								}
								e.update(c.Exchange, c.Pair, c.AssetType, SyncItemOrderbook, err)
							} else {
								time.Sleep(time.Millisecond * 50)
							}
						}
						if e.Cfg.SyncTrades {
							if !e.isProcessing(exchangeName, c.Pair, c.AssetType, SyncItemTrade) {
								if c.Trade.LastUpdated.IsZero() || time.Since(c.Trade.LastUpdated) > e.Cfg.SyncTimeout {
									e.setProcessing(c.Exchange, c.Pair, c.AssetType, SyncItemTrade, true)
									e.update(c.Exchange, c.Pair, c.AssetType, SyncItemTrade, nil)
								}
							}
						}
					}
				}
			}
		}
	}
}

// Start starts an exchange currency pair syncer
func (e *ExchangeCurrencyPairSyncer) Start() {
	log.Debugln(log.SyncMgr, "Exchange CurrencyPairSyncer started.")

	for x := range Bot.Exchanges {
		if !Bot.Exchanges[x].IsEnabled() {
			continue
		}

		exchangeName := Bot.Exchanges[x].GetName()
		supportsWebsocket := Bot.Exchanges[x].SupportsWebsocket()
		assetTypes := Bot.Exchanges[x].GetAssetTypes()
		supportsREST := Bot.Exchanges[x].SupportsREST()

		if !supportsREST && !supportsWebsocket {
			log.Warnf(log.SyncMgr,
				"Loaded exchange %s does not support REST or Websocket.\n",
				exchangeName)
			continue
		}

		var usingWebsocket bool
		var usingREST bool

		if supportsWebsocket && Bot.Exchanges[x].IsWebsocketEnabled() {
			ws, err := Bot.Exchanges[x].GetWebsocket()
			if err != nil {
				log.Errorf(log.SyncMgr, "%s failed to get websocket. Err: %s\n",
					exchangeName, err)
				usingREST = true
			}

			if !ws.IsConnected() && !ws.IsConnecting() {
				go WebsocketDataHandler(ws)

				err = ws.Connect()
				if err != nil {
					log.Errorf(log.SyncMgr, "%s websocket failed to connect. Err: %s\n",
						exchangeName, err)
					usingREST = true
				} else {
					usingWebsocket = true
				}
			} else {
				usingWebsocket = true
			}
		} else if supportsREST {
			usingREST = true
		}

		for y := range assetTypes {
			enabledPairs := Bot.Exchanges[x].GetEnabledPairs(assetTypes[y])
			for i := range enabledPairs {
				if e.exists(exchangeName, enabledPairs[i], assetTypes[y]) {
					continue
				}
				c := CurrencyPairSyncAgent{
					AssetType: assetTypes[y],
					Exchange:  exchangeName,
					Pair:      enabledPairs[i],
				}

				if e.Cfg.SyncTicker {
					c.Ticker = SyncBase{
						IsUsingREST:      usingREST,
						IsUsingWebsocket: usingWebsocket,
					}
				}

				if e.Cfg.SyncOrderbook {
					c.Orderbook = SyncBase{
						IsUsingREST:      usingREST,
						IsUsingWebsocket: usingWebsocket,
					}
				}

				if e.Cfg.SyncTrades {
					c.Trade = SyncBase{
						IsUsingREST:      usingREST,
						IsUsingWebsocket: usingWebsocket,
					}
				}

				e.add(&c)
			}
		}
	}

	if atomic.CompareAndSwapInt32(&e.initSyncStarted, 0, 1) {
		log.Debugf(log.SyncMgr,
			"Exchange CurrencyPairSyncer initial sync started. %d items to process.\n",
			createdCounter)
		e.initSyncStartTime = time.Now()
	}

	go func() {
		e.initSyncWG.Wait()
		if atomic.CompareAndSwapInt32(&e.initSyncCompleted, 0, 1) {
			log.Debugf(log.SyncMgr, "Exchange CurrencyPairSyncer initial sync is complete.\n")
			completedTime := time.Now()
			log.Debugf(log.SyncMgr, "Exchange CurrencyPairSyncer initial sync took %v [%v sync items].\n",
				completedTime.Sub(e.initSyncStartTime), createdCounter)

			if !e.Cfg.SyncContinuously {
				log.Debugln(log.SyncMgr, "Exchange CurrencyPairSyncer stopping.")
				e.Stop()
				return
			}
		}
	}()

	if atomic.LoadInt32(&e.initSyncCompleted) == 1 && !e.Cfg.SyncContinuously {
		return
	}

	for i := 0; i < e.Cfg.NumWorkers; i++ {
		go e.worker()
	}
}

// Stop shuts down the exchange currency pair syncer
func (e *ExchangeCurrencyPairSyncer) Stop() {
	stopped := atomic.CompareAndSwapInt32(&e.shutdown, 0, 1)
	if stopped {
		log.Debugln(log.SyncMgr, "Exchange CurrencyPairSyncer stopped.")
	}
}