package pricing

import (
	"time"

	"github.com/mchus/quoteforge/internal/config"
	"github.com/mchus/quoteforge/internal/models"
	"github.com/mchus/quoteforge/internal/repository"
)

type Service struct {
	componentRepo *repository.ComponentRepository
	priceRepo     *repository.PriceRepository
	config        config.PricingConfig
}

func NewService(
	componentRepo *repository.ComponentRepository,
	priceRepo *repository.PriceRepository,
	cfg config.PricingConfig,
) *Service {
	return &Service{
		componentRepo: componentRepo,
		priceRepo:     priceRepo,
		config:        cfg,
	}
}

// GetEffectivePrice returns the current effective price for a component
// Priority: active override > calculated price > nil
func (s *Service) GetEffectivePrice(lotName string) (*float64, error) {
	// Check for active override first
	override, err := s.priceRepo.GetPriceOverride(lotName)
	if err == nil && override != nil {
		return &override.Price, nil
	}

	// Get component metadata
	component, err := s.componentRepo.GetByLotName(lotName)
	if err != nil {
		return nil, err
	}

	return component.CurrentPrice, nil
}

// CalculatePrice calculates price using the specified method
func (s *Service) CalculatePrice(lotName string, method models.PriceMethod, periodDays int) (float64, error) {
	if periodDays == 0 {
		periodDays = s.config.DefaultPeriodDays
	}

	points, err := s.priceRepo.GetPriceHistory(lotName, periodDays)
	if err != nil {
		return 0, err
	}

	if len(points) == 0 {
		return 0, nil
	}

	prices := make([]float64, len(points))
	for i, p := range points {
		prices[i] = p.Price
	}

	switch method {
	case models.PriceMethodAverage:
		return CalculateAverage(prices), nil
	case models.PriceMethodWeightedMedian:
		return CalculateWeightedMedian(points, s.config.DefaultPeriodDays), nil
	case models.PriceMethodMedian:
		fallthrough
	default:
		return CalculateMedian(prices), nil
	}
}

// UpdateComponentPrice recalculates and updates the price for a component
func (s *Service) UpdateComponentPrice(lotName string) error {
	component, err := s.componentRepo.GetByLotName(lotName)
	if err != nil {
		return err
	}

	price, err := s.CalculatePrice(lotName, component.PriceMethod, component.PricePeriodDays)
	if err != nil {
		return err
	}

	now := time.Now()
	if price > 0 {
		component.CurrentPrice = &price
		component.PriceUpdatedAt = &now
	}

	return s.componentRepo.Update(component)
}

// SetManualPrice sets a manual price override
func (s *Service) SetManualPrice(lotName string, price float64, reason string, userID uint) error {
	override := &models.PriceOverride{
		LotName:   lotName,
		Price:     price,
		ValidFrom: time.Now(),
		Reason:    reason,
		CreatedBy: userID,
	}
	return s.priceRepo.CreatePriceOverride(override)
}

// UpdatePriceMethod changes the pricing method for a component
func (s *Service) UpdatePriceMethod(lotName string, method models.PriceMethod, periodDays int) error {
	component, err := s.componentRepo.GetByLotName(lotName)
	if err != nil {
		return err
	}

	component.PriceMethod = method
	if periodDays > 0 {
		component.PricePeriodDays = periodDays
	}

	if err := s.componentRepo.Update(component); err != nil {
		return err
	}

	return s.UpdateComponentPrice(lotName)
}

// GetPriceStats returns statistics for a component's price history
func (s *Service) GetPriceStats(lotName string, periodDays int) (*PriceStats, error) {
	if periodDays == 0 {
		periodDays = s.config.DefaultPeriodDays
	}

	points, err := s.priceRepo.GetPriceHistory(lotName, periodDays)
	if err != nil {
		return nil, err
	}

	if len(points) == 0 {
		return &PriceStats{QuoteCount: 0}, nil
	}

	prices := make([]float64, len(points))
	for i, p := range points {
		prices[i] = p.Price
	}

	return &PriceStats{
		QuoteCount:    len(points),
		MinPrice:      CalculatePercentile(prices, 0),
		MaxPrice:      CalculatePercentile(prices, 100),
		MedianPrice:   CalculateMedian(prices),
		AveragePrice:  CalculateAverage(prices),
		StdDeviation:  CalculateStdDev(prices),
		LatestPrice:   points[0].Price,
		LatestDate:    points[0].Date,
		OldestDate:    points[len(points)-1].Date,
		Percentile25:  CalculatePercentile(prices, 25),
		Percentile75:  CalculatePercentile(prices, 75),
	}, nil
}

type PriceStats struct {
	QuoteCount   int       `json:"quote_count"`
	MinPrice     float64   `json:"min_price"`
	MaxPrice     float64   `json:"max_price"`
	MedianPrice  float64   `json:"median_price"`
	AveragePrice float64   `json:"average_price"`
	StdDeviation float64   `json:"std_deviation"`
	LatestPrice  float64   `json:"latest_price"`
	LatestDate   time.Time `json:"latest_date"`
	OldestDate   time.Time `json:"oldest_date"`
	Percentile25 float64   `json:"percentile_25"`
	Percentile75 float64   `json:"percentile_75"`
}