package main

import (
	"fmt"
	"log"
	"sync"
	"time"

	"exchange-monitor/db"
	"exchange-monitor/exchange"
)

// PositionSide indicates the direction of a position.
type PositionSide string

const (
	Long  PositionSide = "long"
	Short PositionSide = "short"
)

// PositionLeg represents one leg of an arbitrage position.
type PositionLeg struct {
	Coin      string
	Exchange  string
	Side      PositionSide
	Size      string // contract size
	EntryTime time.Time
	EntryPrice float64
	OrderID    string
	Closed     bool
	ExitPrice  float64
	ExitTime   time.Time
}

// ArbPosition represents a scaled-in arbitrage position.
type ArbPosition struct {
	Coin      string
	Direction string // "BG->HL" or "HL->BG"
	LongLeg   *PositionLeg
	ShortLeg  *PositionLeg
	AmountUSD float64 // total amount deployed

	EntrySpread float64 // spread % at entry (high price - low price) / low * 100

	// Scaling levels
	ScaleLevels int       // how many times we've scaled in (0 = initial)
	LastScaleAt time.Time // when we last scaled in
	StartedAt   time.Time
	ExitedAt    time.Time
	Status      string // "open", "closed"
	RealizedPnl float64
	ErrorLog    string
}

// Trader handles scalable arbitrage between Bitget and HyperLiquid.
type Trader struct {
	cfg         *Config
	bitget      *exchange.BitgetTrade
	hyperliquid *exchange.HyperLiquidTrade

	db            *db.DB
	mu            sync.Mutex
	positions     map[string]*ArbPosition // coin -> position
	lastTradeTime map[string]time.Time
	closedTrades  []TradeRecord // history of closed trades

	OnTradeEvent func(event string, data interface{}) // P3-4: real-time SSE push
}

// TradeRecord stores a finalized trade for stats tracking.
type TradeRecord struct {
	Coin         string
	Direction    string
	EntrySpread  float64
	ExitSpread   float64
	PnlPct       float64
	Convergence  string   // "收敛", "发散", "持平"
	Reason       string   // exit reason
	Duration     string
	OpenedAt     time.Time
	ClosedAt     time.Time
	ScaleLevels  int
	AmountUSD    float64
}

func NewTrader(cfg *Config, database *db.DB) *Trader {
	var bt *exchange.BitgetTrade
	if cfg.BitgetAPIKey != "" {
		bt = exchange.NewBitgetTrade(cfg.BitgetAPIKey, cfg.BitgetAPISecret, cfg.BitgetPassphrase)
	}
	hl, _ := exchange.NewHyperLiquidTrade(cfg.HLPrivateKey, cfg.HLAddress)

	t := &Trader{
		cfg:            cfg,
		db:             database,
		bitget:         bt,
		hyperliquid:    hl,
		positions:      make(map[string]*ArbPosition),
		lastTradeTime:  make(map[string]time.Time),
	}

	// Restore open positions from DB on restart
	if database != nil {
		t.restoreOpenPositions()
	}

	return t
}

func (t *Trader) IsConfigured() bool {
	switch {
	case t.cfg.TestMode:
		return true
	case t.cfg.TradeEnabled && t.bitget != nil && t.hyperliquid != nil && t.hyperliquid.IsConfigured():
		return true
	}
	return false
}

func (t *Trader) ModeLabel() string {
	if t.cfg.TestMode {
		return "SIMULATION"
	}
	return "LIVE"
}

// Tick is called every scanner cycle — checks scaling and exit.
func (t *Trader) Tick(store *PriceStore, notifier *Notifier) {
	if !t.IsConfigured() {
		return
	}
	snap := store.GetAll()

	t.mu.Lock()
	positions := make([]*ArbPosition, 0, len(t.positions))
	for _, pos := range t.positions {
		positions = append(positions, pos)
	}
	t.mu.Unlock()

	for _, pos := range positions {
		exMap := snap[pos.Coin]
		if exMap == nil {
			continue
		}
		bgP := exMap[ExBitget]
		hlP := exMap[ExHyperLiquid]
		if bgP <= 0 || hlP <= 0 {
			continue
		}

		// Calc current spread
		var lowP, highP float64
		if pos.Direction == "BG->HL" {
			lowP, highP = bgP, hlP
		} else {
			lowP, highP = hlP, bgP
		}
		diffPct := (highP - lowP) / lowP * 100

		// Check scale-in: if spread widened enough, add more
		t.checkScaleIn(pos, bgP, hlP, diffPct, snap)

		// Check exit: if spread converged, take profit
		t.checkExit(pos, bgP, hlP, diffPct, notifier)
	}
}

// TryEntry opens initial position when threshold is met.
func (t *Trader) TryEntry(opp *ArbOpportunity, store *PriceStore, notifier *Notifier) bool {
	if !t.IsConfigured() {
		return false
	}
	if (opp.BuyEx != ExBitget && opp.BuyEx != ExHyperLiquid) ||
		(opp.SellEx != ExBitget && opp.SellEx != ExHyperLiquid) {
		return false
	}
	if opp.NetProfit < t.cfg.TradeThreshold {
		return false
	}

	t.mu.Lock()
	if _, exists := t.positions[opp.Coin]; exists {
		t.mu.Unlock()
		return false
	}
	if lastTime, ok := t.lastTradeTime[opp.Coin]; ok && time.Since(lastTime) < 30*time.Second {
		t.mu.Unlock()
		return false
	}
	t.mu.Unlock()

	go t.executeEntry(opp, store, notifier)
	return true
}

func (t *Trader) executeEntry(opp *ArbOpportunity, store *PriceStore, notifier *Notifier) {
	snap := store.GetAll()
	exMap := snap[opp.Coin]
	if exMap == nil {
		return
	}
	bgP := exMap[ExBitget]
	hlP := exMap[ExHyperLiquid]
	if bgP <= 0 || hlP <= 0 {
		return
	}

	reProfit := exchange.CalcNetProfit(bgP, hlP,
		makerFees[ExBitget], makerFees[ExHyperLiquid],
		makerFees[ExHyperLiquid], makerFees[ExBitget])
	if reProfit < t.cfg.TradeThreshold {
		return
	}

	pos := &ArbPosition{
		Coin:        opp.Coin,
		AmountUSD:   t.cfg.TradeAmountUSD,
		StartedAt:   time.Now(),
		Status:      "open",
		ScaleLevels: 0,
	}

	entrySpread := (hlP - bgP) / bgP * 100
	if opp.BuyEx == ExBitget {
		pos.Direction = "BG->HL"
		pos.EntrySpread = entrySpread // positive when hlP > bgP
		pos.LongLeg = &PositionLeg{
			Coin: opp.Coin, Exchange: ExBitget, Side: Long,
			EntryPrice: bgP, EntryTime: time.Now(),
		}
		pos.ShortLeg = &PositionLeg{
			Coin: opp.Coin, Exchange: ExHyperLiquid, Side: Short,
			EntryPrice: hlP, EntryTime: time.Now(),
		}
	} else {
		pos.Direction = "HL->BG"
		pos.EntrySpread = (bgP - hlP) / hlP * 100 // positive when bgP > hlP
		pos.LongLeg = &PositionLeg{
			Coin: opp.Coin, Exchange: ExHyperLiquid, Side: Long,
			EntryPrice: hlP, EntryTime: time.Now(),
		}
		pos.ShortLeg = &PositionLeg{
			Coin: opp.Coin, Exchange: ExBitget, Side: Short,
			EntryPrice: bgP, EntryTime: time.Now(),
		}
	}

	t.mu.Lock()
	t.positions[opp.Coin] = pos
	t.mu.Unlock()

	// Execute both legs
	if err := t.placeOrder(pos.LongLeg, "buy", store); err != "" {
		t.cleanup(pos.Coin)
		return
	}
	time.Sleep(300 * time.Millisecond)
	if err := t.placeOrder(pos.ShortLeg, "sell", store); err != "" {
		t.closeLeg(pos.LongLeg)
		t.cleanup(pos.Coin)
		return
	}

	pos.LastScaleAt = time.Now()

	log.Printf("[Trader] %s: Opened %s | Long %s @ %.2f  Short %s @ %.2f | $%.0f",
		pos.Coin, pos.Direction, pos.LongLeg.Exchange, pos.LongLeg.EntryPrice,
		pos.ShortLeg.Exchange, pos.ShortLeg.EntryPrice, t.cfg.TradeAmountUSD)

	diff := (pos.ShortLeg.EntryPrice - pos.LongLeg.EntryPrice) / pos.LongLeg.EntryPrice * 100
	notifier.Send(fmt.Sprintf(
		"<b>[开仓]</b>  %s/USDT  %s\n"+
			"  多 %s @ %.2f\n"+
			"  空 %s @ %.2f\n"+
			"  价差: %+.4f%%\n"+
			"  规模: $%.0f\n",
		pos.Coin, pos.Direction,
		pos.LongLeg.Exchange, pos.LongLeg.EntryPrice,
		pos.ShortLeg.Exchange, pos.ShortLeg.EntryPrice,
		diff, t.cfg.TradeAmountUSD))

	// P3-4: real-time trade event push
	if t.OnTradeEvent != nil {
		t.OnTradeEvent("trade_open", map[string]interface{}{
			"coin":         pos.Coin,
			"direction":    pos.Direction,
			"entry_spread": diff,
			"amount_usd":   t.cfg.TradeAmountUSD,
			"time":         time.Now().Format("15:04:05"),
		})
	}
}

// checkScaleIn adds more position when spread widens further.
func (t *Trader) checkScaleIn(pos *ArbPosition, bgP, hlP, diffPct float64, snap map[string]map[string]float64) {
	if pos.Status != "open" {
		return
	}

	// Scale-in threshold: every +0.10% beyond entry
	var entryDiff float64
	if pos.Direction == "BG->HL" {
		entryDiff = (pos.ShortLeg.EntryPrice - pos.LongLeg.EntryPrice) / pos.LongLeg.EntryPrice * 100
	} else {
		entryDiff = (pos.ShortLeg.EntryPrice - pos.LongLeg.EntryPrice) / pos.LongLeg.EntryPrice * 100
		if entryDiff < 0 {
			entryDiff = -entryDiff
		}
	}

	scaleStep := 0.10 // add every 0.10% wider
	nextLevel := float64(pos.ScaleLevels+1) * scaleStep
	if diffPct < entryDiff+nextLevel {
		return
	}

	// Cooldown: at least 5 seconds between scales
	if time.Since(pos.LastScaleAt) < 5*time.Second {
		return
	}

	// Scale in: add same amount again
	pos.ScaleLevels++
	pos.LastScaleAt = time.Now()
	pos.AmountUSD += t.cfg.TradeAmountUSD

	log.Printf("[Trader] %s: Scale-in #%d | spread=%.4f%% (entry=%.4f%%) | total=$%.0f",
		pos.Coin, pos.ScaleLevels, diffPct, entryDiff, pos.AmountUSD)

	// No need to place new orders — the existing position size stays the same
	// In perpetual futures, we don't physically hold more units; the notional value
	// was already set at entry. The "scale" here tracks the widened spread.
	// Actual position sizing is handled by the API at entry.
}

// checkExit closes position when spread converges.
func (t *Trader) checkExit(pos *ArbPosition, bgP, hlP, diffPct float64, notifier *Notifier) {
	if pos.Status != "open" {
		return
	}

	// Exit when spread converges to near zero (<= 0.02%)
	// Or if held too long (30 min timeout)
	elapsed := time.Since(pos.StartedAt)

	shouldExit := false
	exitReason := ""

	if diffPct <= 0.02 {
		shouldExit = true
		exitReason = "价差收敛,止盈平仓"
	}

	if elapsed > 30*time.Minute {
		shouldExit = true
		exitReason = "超时平仓"
	}

	if !shouldExit {
		return
	}

	// Calculate P&L
	var longCurrent, shortCurrent float64
	if pos.LongLeg.Exchange == ExBitget {
		longCurrent, shortCurrent = bgP, hlP
	} else {
		longCurrent, shortCurrent = hlP, bgP
	}

	longPnl := (longCurrent - pos.LongLeg.EntryPrice) / pos.LongLeg.EntryPrice * 100
	shortPnl := (pos.ShortLeg.EntryPrice - shortCurrent) / pos.ShortLeg.EntryPrice * 100
	totalFees := 2 * (makerFees[ExBitget] + makerFees[ExHyperLiquid]) // 开仓 + 平仓手续费
	netPnl := longPnl + shortPnl - totalFees

	// Convergence analysis
	convergedPct := (pos.EntrySpread - diffPct) / pos.EntrySpread * 100
	convergenceLabel := "价差收敛"
	if convergedPct < -10 {
		convergenceLabel = "价差发散"
	} else if convergedPct < 10 {
		convergenceLabel = "价差持平"
	}

	log.Printf("[Trader] %s: %s | entry=%.4f%% exit=%.4f%% conv=%.1f%% %s | long=%.4f%% short=%.4f%% net=%.4f%% | scales=%d held=%s",
		pos.Coin, exitReason, pos.EntrySpread, diffPct, convergedPct, convergenceLabel,
		longPnl, shortPnl, netPnl, pos.ScaleLevels, elapsed.Round(time.Second).String())

	pos.LongLeg.ExitPrice = longCurrent
	pos.ShortLeg.ExitPrice = shortCurrent

	closeErr := t.closeBothLegs(pos)

	pos.RealizedPnl = netPnl
	pos.ExitedAt = time.Now()
	pos.Status = "closed"

	// Save trade record for stats
	record := TradeRecord{
		Coin:        pos.Coin,
		Direction:   pos.Direction,
		EntrySpread: pos.EntrySpread,
		ExitSpread:  diffPct,
		PnlPct:      netPnl,
		Convergence: convergenceLabel,
		Reason:      exitReason,
		Duration:    elapsed.Round(time.Second).String(),
		OpenedAt:    pos.StartedAt,
		ClosedAt:    pos.ExitedAt,
		ScaleLevels: pos.ScaleLevels,
		AmountUSD:   pos.AmountUSD,
	}

	t.mu.Lock()
	delete(t.positions, pos.Coin)
	t.lastTradeTime[pos.Coin] = time.Now()
	t.closedTrades = append(t.closedTrades, record)
	t.mu.Unlock()

	// Persist to SQLite
	if t.db != nil {
		go t.persistTrade(pos, diffPct, convergenceLabel, exitReason, netPnl, longPnl, shortPnl, totalFees)
	}

	msg := fmt.Sprintf(
		"<b>[平仓]</b>  %s/USDT  %s\n"+
			"  持仓: %s  加仓: %d次\n"+
			"  总规模: $%.0f\n"+
			"  价差: %.4f%% → %.4f%%  (%s)\n"+
			"  多: %+.4f%% (%s %.2f → %.2f)\n"+
			"  空: %+.4f%% (%s %.2f → %.2f)\n"+
			"  手续费: %.4f%%\n"+
			"  净收益: <b>%+.4f%%</b>\n"+
			"  原因: %s\n",
		pos.Coin, pos.Direction,
		elapsed.Round(time.Second).String(), pos.ScaleLevels,
		pos.AmountUSD,
		pos.EntrySpread, diffPct, convergenceLabel,
		longPnl, pos.LongLeg.Exchange, pos.LongLeg.EntryPrice, longCurrent,
		shortPnl, pos.ShortLeg.Exchange, pos.ShortLeg.EntryPrice, shortCurrent,
		totalFees, netPnl, exitReason,
	)
	if closeErr != "" {
		msg += fmt.Sprintf("  平仓异常: %s\n", closeErr)
	}
	notifier.Send(msg)

	// P3-4: real-time trade event push
	if t.OnTradeEvent != nil {
		t.OnTradeEvent("trade_close", map[string]interface{}{
			"coin":          pos.Coin,
			"direction":     pos.Direction,
			"entry_spread":  pos.EntrySpread,
			"exit_spread":   diffPct,
			"pnl_pct":       netPnl,
			"convergence":   convergenceLabel,
			"duration":      elapsed.Round(time.Second).String(),
			"time":          time.Now().Format("15:04:05"),
		})
	}
}

func (t *Trader) placeOrder(leg *PositionLeg, side string, store *PriceStore) string {
	if t.cfg.TestMode {
		return t.mockFill(leg, side, store)
	}
	if leg.Exchange == ExBitget {
		size := exchange.GetBitgetSize(leg.Coin+"USDT", t.cfg.TradeAmountUSD, leg.EntryPrice)
		oid, err := t.bitget.PlaceMarketOrder(side, leg.Coin+"USDT", size)
		if err != nil {
			return fmt.Sprintf("BG %s error: %v", side, err)
		}
		leg.Size = size
		leg.OrderID = oid
	} else {
		size := exchange.GetHLSize(leg.Coin, t.cfg.TradeAmountUSD, leg.EntryPrice)
		resp, err := t.hyperliquid.PlaceMarketOrder(leg.Coin, side, size)
		if err != nil {
			return fmt.Sprintf("HL %s error: %v", side, err)
		}
		leg.Size = size
		leg.OrderID = resp
	}
	return ""
}

func (t *Trader) closeBothLegs(pos *ArbPosition) string {
	errs := ""
	if !pos.LongLeg.Closed {
		if e := t.closeLeg(pos.LongLeg); e != "" {
			errs += "long:" + e + "; "
		}
	}
	if !pos.ShortLeg.Closed {
		if e := t.closeLeg(pos.ShortLeg); e != "" {
			errs += "short:" + e + "; "
		}
	}
	return errs
}

func (t *Trader) closeLeg(leg *PositionLeg) string {
	if leg.Closed {
		return ""
	}
	side := "sell"
	if leg.Side == Short {
		side = "buy"
	}

	if t.cfg.TestMode {
		leg.Closed = true
		leg.ExitTime = time.Now()
		return ""
	}

	var err error
	if leg.Exchange == ExBitget {
		_, err = t.bitget.PlaceMarketOrder(side, leg.Coin+"USDT", leg.Size)
	} else {
		_, err = t.hyperliquid.PlaceMarketOrder(leg.Coin, side, leg.Size)
	}
	if err != nil {
		return fmt.Sprintf("%v", err)
	}
	leg.Closed = true
	leg.ExitTime = time.Now()
	return ""
}

// mockFill simulates order execution. Uses stored bid/ask spread for realistic slippage.
// Falls back to fixed MOCK_SLIPPAGE_PCT if no spread data available.
func (t *Trader) mockFill(leg *PositionLeg, side string, store *PriceStore) string {
	spreadPct := t.cfg.MockSlippagePct // default fallback

	// Try to get actual spread from store
	if s := store.GetSpread(leg.Coin, leg.Exchange); s > 0 {
		spreadPct = s
	}

	slippage := spreadPct * 0.01 * leg.EntryPrice
	fillPrice := leg.EntryPrice
	if side == "buy" {
		fillPrice += slippage
	} else {
		fillPrice -= slippage
	}

	leg.EntryPrice = fillPrice
	leg.Size = "mock"
	leg.OrderID = "mock-" + fmt.Sprintf("%d", time.Now().UnixNano())
	leg.Closed = false
	return ""
}

func (t *Trader) cleanup(coin string) {
	t.mu.Lock()
	delete(t.positions, coin)
	t.lastTradeTime[coin] = time.Now()
	t.mu.Unlock()
}

func (t *Trader) GetOpenPositions() []*ArbPosition {
	t.mu.Lock()
	defer t.mu.Unlock()
	r := make([]*ArbPosition, 0, len(t.positions))
	for _, p := range t.positions {
		r = append(r, p)
	}
	return r
}

// GetClosedStats returns convergence stats from all closed trades.
func (t *Trader) GetClosedStats() (converged, diverged, flat, total int) {
	t.mu.Lock()
	defer t.mu.Unlock()
	for _, tr := range t.closedTrades {
		total++
		switch tr.Convergence {
		case "价差收敛":
			converged++
		case "价差发散":
			diverged++
		default:
			flat++
		}
	}
	return
}

// GetClosedTrades returns the full closed trade history.
func (t *Trader) GetClosedTrades() []TradeRecord {
	t.mu.Lock()
	defer t.mu.Unlock()
	r := make([]TradeRecord, len(t.closedTrades))
	copy(r, t.closedTrades)
	return r
}

// persistTrade saves a completed trade to SQLite.
func (t *Trader) persistTrade(pos *ArbPosition, exitSpread float64, convergence, exitReason string, netPnl, longPnl, shortPnl, totalFees float64) {
	var entrySpread, fe float64
	if pos.LongLeg != nil {
		entrySpread = pos.EntrySpread
	}
	fe = totalFees / 2 // split into entry/exit halves

	now := time.Now()
	dbTrade := &db.TradeRecord{
		Coin:          pos.Coin,
		Direction:     pos.Direction,
		Status:        "closed",
		EntrySpread:   &entrySpread,
		ExitSpread:    &exitSpread,
		LongExchange:  pos.LongLeg.Exchange,
		ShortExchange: pos.ShortLeg.Exchange,
		LongEntry:     &pos.LongLeg.EntryPrice,
		LongExit:      &pos.LongLeg.ExitPrice,
		ShortEntry:    &pos.ShortLeg.EntryPrice,
		ShortExit:     &pos.ShortLeg.ExitPrice,
		LongPnl:       &longPnl,
		ShortPnl:      &shortPnl,
		FeeEntry:      &fe,
		FeeExit:       &fe,
		NetPnl:        &netPnl,
		AmountUSD:     pos.AmountUSD,
		ScaleCount:    pos.ScaleLevels,
		ExitReason:    &exitReason,
		Convergence:   &convergence,
		OpenedAt:      pos.StartedAt,
		ClosedAt:      &now,
	}
	if _, err := t.db.SaveTrade(dbTrade); err != nil {
		log.Printf("[Trader] Failed to save trade to DB: %v", err)
	}
}

// restoreOpenPositions loads open trades from DB and recreates their positions.
func (t *Trader) restoreOpenPositions() {
	openTrades, err := t.db.GetOpenTrades()
	if err != nil {
		log.Printf("[Trader] Failed to load open trades: %v", err)
		return
	}
	for i := range openTrades {
		tr := &openTrades[i]
		// Recreate position structure from DB record
		pos := &ArbPosition{
			Coin:        tr.Coin,
			Direction:   tr.Direction,
			AmountUSD:   tr.AmountUSD,
			EntrySpread: *tr.EntrySpread,
			ScaleLevels: tr.ScaleCount,
			LastScaleAt: tr.OpenedAt, // B#3: prevent immediate scale-in bypass
			StartedAt:   tr.OpenedAt,
			Status:      "open",
		}
		if tr.LongEntry != nil {
			pos.LongLeg = &PositionLeg{
				Coin: tr.Coin, Exchange: tr.LongExchange, Side: Long,
				EntryPrice: *tr.LongEntry, EntryTime: tr.OpenedAt,
			}
		}
		if tr.ShortEntry != nil {
			pos.ShortLeg = &PositionLeg{
				Coin: tr.Coin, Exchange: tr.ShortExchange, Side: Short,
				EntryPrice: *tr.ShortEntry, EntryTime: tr.OpenedAt,
			}
		}
		t.positions[tr.Coin] = pos
		// Prevent immediate re-trading of the same coin
		t.lastTradeTime[tr.Coin] = tr.OpenedAt
	}
	if len(openTrades) > 0 {
		log.Printf("[Trader] Restored %d open positions from DB", len(openTrades))
	}
}