package store

import (
	"fmt"
	"math"
	"strconv"
	"strings"
	"time"

	"gorm.io/gorm"
)

// adaptivePriceRound rounds a price based on its magnitude to preserve meaningful precision.
// For small prices (like meme coins), it preserves more decimal places.
// It detects the number of decimal places needed from the reference price(s).
func adaptivePriceRound(price float64, referencePrices ...float64) float64 {
	if price == 0 {
		return 0
	}

	// Find the minimum magnitude among all prices (including the price itself)
	minMagnitude := math.Abs(price)
	for _, ref := range referencePrices {
		if ref > 0 && ref < minMagnitude {
			minMagnitude = ref
		}
	}

	// Determine decimal places needed based on price magnitude
	// For price 0.000000541, we need ~15 decimal places
	// For price 0.0001, we need ~8 decimal places
	// For price 1.0, we need ~4 decimal places
	var multiplier float64
	switch {
	case minMagnitude < 0.000001: // Ultra small (meme coins like CHEEMS, SHIB)
		multiplier = 1e15 // 15 decimal places
	case minMagnitude < 0.0001: // Very small (PEPE, FLOKI)
		multiplier = 1e12 // 12 decimal places
	case minMagnitude < 0.01: // Small
		multiplier = 1e10 // 10 decimal places
	case minMagnitude < 1: // Medium
		multiplier = 1e8 // 8 decimal places
	default: // Large
		multiplier = 1e6 // 6 decimal places
	}

	return math.Round(price*multiplier) / multiplier
}

// getPriceDecimalPlaces returns the number of decimal places in a price string
func getPriceDecimalPlaces(price float64) int {
	if price == 0 {
		return 0
	}
	s := strconv.FormatFloat(price, 'f', -1, 64)
	idx := strings.Index(s, ".")
	if idx == -1 {
		return 0
	}
	return len(s) - idx - 1
}

// formatDuration formats a duration
func formatDuration(d time.Duration) string {
	return formatDurationMs(d.Milliseconds())
}

// formatDurationMs formats a duration in milliseconds
func formatDurationMs(ms int64) string {
	seconds := ms / 1000
	minutes := seconds / 60
	hours := minutes / 60
	days := hours / 24

	if seconds < 60 {
		return fmt.Sprintf("%ds", seconds)
	}
	if minutes < 60 {
		return fmt.Sprintf("%dm", minutes)
	}
	if hours < 24 {
		remainingMins := minutes % 60
		if remainingMins == 0 {
			return fmt.Sprintf("%dh", hours)
		}
		return fmt.Sprintf("%dh%dm", hours, remainingMins)
	}
	remainingHours := hours % 24
	if remainingHours == 0 {
		return fmt.Sprintf("%dd", days)
	}
	return fmt.Sprintf("%dd%dh", days, remainingHours)
}

// TraderPosition position record
// All time fields use int64 millisecond timestamps (UTC) to avoid timezone issues
type TraderPosition struct {
	ID                 int64   `gorm:"primaryKey;autoIncrement" json:"id"`
	TraderID           string  `gorm:"column:trader_id;not null;index:idx_positions_trader" json:"trader_id"`
	ExchangeID         string  `gorm:"column:exchange_id;not null;default:'';index:idx_positions_exchange" json:"exchange_id"`
	ExchangeType       string  `gorm:"column:exchange_type;not null;default:''" json:"exchange_type"`
	ExchangePositionID string  `gorm:"column:exchange_position_id;not null;default:''" json:"exchange_position_id"`
	Symbol             string  `gorm:"column:symbol;not null" json:"symbol"`
	Side               string  `gorm:"column:side;not null" json:"side"`
	EntryQuantity      float64 `gorm:"column:entry_quantity;default:0" json:"entry_quantity"`
	Quantity           float64 `gorm:"column:quantity;not null" json:"quantity"`
	EntryPrice         float64 `gorm:"column:entry_price;not null" json:"entry_price"`
	EntryOrderID       string  `gorm:"column:entry_order_id;default:''" json:"entry_order_id"`
	EntryTime          int64   `gorm:"column:entry_time;not null;index:idx_positions_entry" json:"entry_time"` // Unix milliseconds UTC
	ExitPrice          float64 `gorm:"column:exit_price;default:0" json:"exit_price"`
	ExitOrderID        string  `gorm:"column:exit_order_id;default:''" json:"exit_order_id"`
	ExitTime           int64   `gorm:"column:exit_time;index:idx_positions_exit" json:"exit_time"` // Unix milliseconds UTC, 0 means not set
	RealizedPnL        float64 `gorm:"column:realized_pnl;default:0" json:"realized_pnl"`
	Fee                float64 `gorm:"column:fee;default:0" json:"fee"`
	Leverage           int     `gorm:"column:leverage;default:1" json:"leverage"`
	Status             string  `gorm:"column:status;default:OPEN;index:idx_positions_status" json:"status"`
	CloseReason        string  `gorm:"column:close_reason;default:''" json:"close_reason"`
	Source             string  `gorm:"column:source;default:system" json:"source"`
	CreatedAt          int64   `gorm:"column:created_at" json:"created_at"`   // Unix milliseconds UTC
	UpdatedAt          int64   `gorm:"column:updated_at" json:"updated_at"`   // Unix milliseconds UTC
}

// TableName returns the table name
func (TraderPosition) TableName() string {
	return "trader_positions"
}

// PositionStore position storage
type PositionStore struct {
	db *gorm.DB
}

// NewPositionStore creates position storage instance
func NewPositionStore(db *gorm.DB) *PositionStore {
	return &PositionStore{db: db}
}

// isPostgres checks if the database is PostgreSQL
func (s *PositionStore) isPostgres() bool {
	return s.db.Dialector.Name() == "postgres"
}

// InitTables initializes position tables
func (s *PositionStore) InitTables() error {
	// For PostgreSQL with existing table, skip AutoMigrate
	if s.isPostgres() {
		var tableExists int64
		s.db.Raw(`SELECT COUNT(*) FROM information_schema.tables WHERE table_name = 'trader_positions'`).Scan(&tableExists)
		if tableExists > 0 {
			// Migrate timestamp columns to bigint (Unix milliseconds UTC)
			// Check if column is still timestamp type before migrating
			timestampColumns := []string{"entry_time", "exit_time", "created_at", "updated_at"}
			for _, col := range timestampColumns {
				var dataType string
				s.db.Raw(`SELECT data_type FROM information_schema.columns WHERE table_name = 'trader_positions' AND column_name = ?`, col).Scan(&dataType)
				if dataType == "timestamp with time zone" || dataType == "timestamp without time zone" {
					// Convert timestamp to Unix milliseconds (bigint)
					s.db.Exec(fmt.Sprintf(`ALTER TABLE trader_positions ALTER COLUMN %s TYPE BIGINT USING EXTRACT(EPOCH FROM %s) * 1000`, col, col))
				}
			}

			// Just ensure index exists
			s.db.Exec(`CREATE UNIQUE INDEX IF NOT EXISTS idx_positions_exchange_pos_unique ON trader_positions(exchange_id, exchange_position_id) WHERE exchange_position_id != ''`)
			return nil
		}
	}

	if err := s.db.AutoMigrate(&TraderPosition{}); err != nil {
		return fmt.Errorf("failed to migrate trader_positions table: %w", err)
	}

	// Create unique partial index for exchange position deduplication
	var indexSQL string
	if s.isPostgres() {
		indexSQL = `CREATE UNIQUE INDEX IF NOT EXISTS idx_positions_exchange_pos_unique ON trader_positions(exchange_id, exchange_position_id) WHERE exchange_position_id != ''`
	} else {
		indexSQL = `CREATE UNIQUE INDEX IF NOT EXISTS idx_positions_exchange_pos_unique ON trader_positions(exchange_id, exchange_position_id) WHERE exchange_position_id != ''`
	}
	if err := s.db.Exec(indexSQL).Error; err != nil {
		if !strings.Contains(err.Error(), "already exists") && !strings.Contains(err.Error(), "UNIQUE constraint failed") {
			return fmt.Errorf("failed to create unique index: %w", err)
		}
	}

	return nil
}

// Create creates position record
func (s *PositionStore) Create(pos *TraderPosition) error {
	pos.Status = "OPEN"
	if pos.EntryQuantity == 0 {
		pos.EntryQuantity = pos.Quantity
	}
	return s.db.Create(pos).Error
}

// ClosePosition closes position
func (s *PositionStore) ClosePosition(id int64, exitPrice float64, exitOrderID string, realizedPnL float64, fee float64, closeReason string) error {
	nowMs := time.Now().UTC().UnixMilli()
	return s.db.Model(&TraderPosition{}).Where("id = ?", id).Updates(map[string]interface{}{
		"exit_price":   exitPrice,
		"exit_order_id": exitOrderID,
		"exit_time":    nowMs,
		"realized_pnl": realizedPnL,
		"fee":          fee,
		"status":       "CLOSED",
		"close_reason": closeReason,
		"updated_at":   nowMs,
	}).Error
}

// UpdatePositionQuantityAndPrice updates position quantity and recalculates entry price
func (s *PositionStore) UpdatePositionQuantityAndPrice(id int64, addQty float64, addPrice float64, addFee float64) error {
	var pos TraderPosition
	if err := s.db.First(&pos, id).Error; err != nil {
		return fmt.Errorf("failed to get current position: %w", err)
	}

	currentEntryQty := pos.EntryQuantity
	if currentEntryQty == 0 {
		currentEntryQty = pos.Quantity
	}

	newQty := math.Round((pos.Quantity+addQty)*10000) / 10000
	newEntryQty := math.Round((currentEntryQty+addQty)*10000) / 10000
	newEntryPrice := (pos.EntryPrice*pos.Quantity + addPrice*addQty) / newQty
	// Use adaptive precision based on price magnitude (for meme coins with very small prices)
	newEntryPrice = adaptivePriceRound(newEntryPrice, pos.EntryPrice, addPrice)
	newFee := pos.Fee + addFee
	nowMs := time.Now().UTC().UnixMilli()

	return s.db.Model(&TraderPosition{}).Where("id = ?", id).Updates(map[string]interface{}{
		"quantity":       newQty,
		"entry_quantity": newEntryQty,
		"entry_price":    newEntryPrice,
		"fee":            newFee,
		"updated_at":     nowMs,
	}).Error
}

// ReducePositionQuantity reduces position quantity for partial close
// If quantity reaches 0 (or near 0), automatically closes the position
func (s *PositionStore) ReducePositionQuantity(id int64, reduceQty float64, exitPrice float64, addFee float64, addPnL float64) error {
	var pos TraderPosition
	if err := s.db.First(&pos, id).Error; err != nil {
		return fmt.Errorf("failed to get current position: %w", err)
	}

	newQty := math.Round((pos.Quantity-reduceQty)*10000) / 10000
	newFee := pos.Fee + addFee
	newPnL := pos.RealizedPnL + addPnL

	closedQty := pos.EntryQuantity - pos.Quantity
	newClosedQty := closedQty + reduceQty

	var newExitPrice float64
	if newClosedQty > 0 {
		newExitPrice = (pos.ExitPrice*closedQty + exitPrice*reduceQty) / newClosedQty
		// Use adaptive precision based on price magnitude (for meme coins with very small prices)
		newExitPrice = adaptivePriceRound(newExitPrice, pos.ExitPrice, exitPrice, pos.EntryPrice)
	}

	nowMs := time.Now().UTC().UnixMilli()

	// Check if position should be fully closed (quantity reduced to ~0)
	const QUANTITY_TOLERANCE = 0.0001
	if newQty <= QUANTITY_TOLERANCE {
		// Auto-close: set status to CLOSED
		return s.db.Model(&TraderPosition{}).Where("id = ?", id).Updates(map[string]interface{}{
			"quantity":     0,
			"fee":          newFee,
			"exit_price":   newExitPrice,
			"realized_pnl": newPnL,
			"status":       "CLOSED",
			"exit_time":    nowMs,
			"close_reason": "sync",
			"updated_at":   nowMs,
		}).Error
	}

	return s.db.Model(&TraderPosition{}).Where("id = ?", id).Updates(map[string]interface{}{
		"quantity":     newQty,
		"fee":          newFee,
		"exit_price":   newExitPrice,
		"realized_pnl": newPnL,
		"updated_at":   nowMs,
	}).Error
}

// UpdatePositionExchangeInfo updates exchange_id and exchange_type
func (s *PositionStore) UpdatePositionExchangeInfo(id int64, exchangeID, exchangeType string) error {
	nowMs := time.Now().UTC().UnixMilli()
	return s.db.Model(&TraderPosition{}).Where("id = ?", id).Updates(map[string]interface{}{
		"exchange_id":   exchangeID,
		"exchange_type": exchangeType,
		"updated_at":    nowMs,
	}).Error
}

// ClosePositionFully marks position as fully closed
// exitTimeMs is Unix milliseconds UTC
func (s *PositionStore) ClosePositionFully(id int64, exitPrice float64, exitOrderID string, exitTimeMs int64, totalRealizedPnL float64, totalFee float64, closeReason string) error {
	var pos TraderPosition
	if err := s.db.First(&pos, id).Error; err != nil {
		return fmt.Errorf("failed to get position: %w", err)
	}

	quantity := pos.Quantity
	if pos.EntryQuantity > 0 {
		quantity = pos.EntryQuantity
	}

	return s.db.Model(&TraderPosition{}).Where("id = ?", id).Updates(map[string]interface{}{
		"quantity":       quantity,
		"exit_price":     exitPrice,
		"exit_order_id":  exitOrderID,
		"exit_time":      exitTimeMs,
		"realized_pnl":   totalRealizedPnL,
		"fee":            totalFee,
		"status":         "CLOSED",
		"close_reason":   closeReason,
		"updated_at":     time.Now().UTC().UnixMilli(),
	}).Error
}

// DeleteAllOpenPositions deletes all OPEN positions for a trader
func (s *PositionStore) DeleteAllOpenPositions(traderID string) error {
	return s.db.Where("trader_id = ? AND status = ?", traderID, "OPEN").Delete(&TraderPosition{}).Error
}

// GetOpenPositions gets all open positions
func (s *PositionStore) GetOpenPositions(traderID string) ([]*TraderPosition, error) {
	var positions []*TraderPosition
	err := s.db.Where("trader_id = ? AND status = ?", traderID, "OPEN").
		Order("entry_time DESC").
		Find(&positions).Error
	if err != nil {
		return nil, fmt.Errorf("failed to query open positions: %w", err)
	}

	// Fix EntryQuantity if it's 0
	for _, pos := range positions {
		if pos.EntryQuantity == 0 {
			pos.EntryQuantity = pos.Quantity
		}
	}
	return positions, nil
}

// GetOpenPositionBySymbol gets open position for specified symbol and direction
func (s *PositionStore) GetOpenPositionBySymbol(traderID, symbol, side string) (*TraderPosition, error) {
	var pos TraderPosition
	err := s.db.Where("trader_id = ? AND symbol = ? AND side = ? AND status = ?", traderID, symbol, side, "OPEN").
		Order("entry_time DESC").
		First(&pos).Error

	if err == nil {
		if pos.EntryQuantity == 0 {
			pos.EntryQuantity = pos.Quantity
		}
		return &pos, nil
	}

	if err == gorm.ErrRecordNotFound {
		// Try without USDT suffix for backward compatibility
		if strings.HasSuffix(symbol, "USDT") {
			baseSymbol := strings.TrimSuffix(symbol, "USDT")
			err = s.db.Where("trader_id = ? AND symbol = ? AND side = ? AND status = ?", traderID, baseSymbol, side, "OPEN").
				Order("entry_time DESC").
				First(&pos).Error
			if err == nil {
				if pos.EntryQuantity == 0 {
					pos.EntryQuantity = pos.Quantity
				}
				return &pos, nil
			}
		}
		return nil, nil
	}
	return nil, err
}

// GetClosedPositions gets closed positions
func (s *PositionStore) GetClosedPositions(traderID string, limit int) ([]*TraderPosition, error) {
	var positions []*TraderPosition
	err := s.db.Where("trader_id = ? AND status = ?", traderID, "CLOSED").
		Order("exit_time DESC").
		Limit(limit).
		Find(&positions).Error
	if err != nil {
		return nil, fmt.Errorf("failed to query closed positions: %w", err)
	}

	for _, pos := range positions {
		if pos.EntryQuantity == 0 {
			pos.EntryQuantity = pos.Quantity
		}
	}
	return positions, nil
}

// GetAllOpenPositions gets all traders' open positions
func (s *PositionStore) GetAllOpenPositions() ([]*TraderPosition, error) {
	var positions []*TraderPosition
	err := s.db.Where("status = ?", "OPEN").
		Order("trader_id, entry_time DESC").
		Find(&positions).Error
	if err != nil {
		return nil, fmt.Errorf("failed to query all open positions: %w", err)
	}

	for _, pos := range positions {
		if pos.EntryQuantity == 0 {
			pos.EntryQuantity = pos.Quantity
		}
	}
	return positions, nil
}

// ExistsWithExchangePositionID checks if a position exists
func (s *PositionStore) ExistsWithExchangePositionID(exchangeID, exchangePositionID string) (bool, error) {
	if exchangePositionID == "" {
		return false, nil
	}

	var count int64
	err := s.db.Model(&TraderPosition{}).
		Where("exchange_id = ? AND exchange_position_id = ?", exchangeID, exchangePositionID).
		Count(&count).Error
	if err != nil {
		return false, fmt.Errorf("failed to check position existence: %w", err)
	}
	return count > 0, nil
}

// GetOpenPositionByExchangePositionID gets an OPEN position by exchange_position_id
func (s *PositionStore) GetOpenPositionByExchangePositionID(exchangeID, exchangePositionID string) (*TraderPosition, error) {
	if exchangePositionID == "" {
		return nil, nil
	}

	var pos TraderPosition
	err := s.db.Where("exchange_id = ? AND exchange_position_id = ? AND status = ?", exchangeID, exchangePositionID, "OPEN").
		First(&pos).Error
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, nil
		}
		return nil, err
	}

	if pos.EntryQuantity == 0 {
		pos.EntryQuantity = pos.Quantity
	}
	return &pos, nil
}

// CreateOpenPosition creates an open position
func (s *PositionStore) CreateOpenPosition(pos *TraderPosition) error {
	if pos.ExchangePositionID != "" && pos.ExchangeID != "" {
		existingPos, err := s.GetOpenPositionByExchangePositionID(pos.ExchangeID, pos.ExchangePositionID)
		if err != nil {
			return err
		}
		if existingPos != nil {
			return s.UpdatePositionQuantityAndPrice(existingPos.ID, pos.Quantity, pos.EntryPrice, pos.Fee)
		}
		exists, err := s.ExistsWithExchangePositionID(pos.ExchangeID, pos.ExchangePositionID)
		if err != nil {
			return err
		}
		if exists {
			return nil
		}
	}

	if pos.Status == "" {
		pos.Status = "OPEN"
	}
	if pos.Source == "" {
		pos.Source = "system"
	}
	if pos.EntryQuantity == 0 {
		pos.EntryQuantity = pos.Quantity
	}

	err := s.db.Create(pos).Error
	if err != nil {
		if strings.Contains(err.Error(), "UNIQUE constraint failed") {
			existingPos, findErr := s.GetOpenPositionByExchangePositionID(pos.ExchangeID, pos.ExchangePositionID)
			if findErr != nil {
				return findErr
			}
			if existingPos != nil {
				return s.UpdatePositionQuantityAndPrice(existingPos.ID, pos.Quantity, pos.EntryPrice, pos.Fee)
			}
			return nil
		}
		return fmt.Errorf("failed to create open position: %w", err)
	}

	return nil
}

// ClosePositionWithAccurateData closes a position with accurate data from exchange
// exitTimeMs is Unix milliseconds UTC
func (s *PositionStore) ClosePositionWithAccurateData(id int64, exitPrice float64, exitOrderID string, exitTimeMs int64, realizedPnL float64, fee float64, closeReason string) error {
	return s.db.Model(&TraderPosition{}).Where("id = ?", id).Updates(map[string]interface{}{
		"exit_price":    exitPrice,
		"exit_order_id": exitOrderID,
		"exit_time":     exitTimeMs,
		"realized_pnl":  realizedPnL,
		"fee":           fee,
		"status":        "CLOSED",
		"close_reason":  closeReason,
		"updated_at":    time.Now().UTC().UnixMilli(),
	}).Error
}