package repository

import (
	"context"
	"time"

	"apskel-pos-be/internal/entities"

	"github.com/google/uuid"
	"gorm.io/gorm"
)

type AnalyticsRepository interface {
	GetPaymentMethodAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time) ([]*entities.PaymentMethodAnalytics, error)
	GetSalesAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, groupBy string) ([]*entities.SalesAnalytics, error)
	GetProductAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, limit int) ([]*entities.ProductAnalytics, error)
	GetProductAnalyticsPerCategory(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time) ([]*entities.ProductAnalyticsPerCategory, error)
	GetDashboardOverview(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time) (*entities.DashboardOverview, error)
	GetProfitLossAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, groupBy string) (*entities.ProfitLossAnalytics, error)
}

type AnalyticsRepositoryImpl struct {
	db *gorm.DB
}

func NewAnalyticsRepositoryImpl(db *gorm.DB) *AnalyticsRepositoryImpl {
	return &AnalyticsRepositoryImpl{
		db: db,
	}
}

func (r *AnalyticsRepositoryImpl) resolveOutletID(query *gorm.DB, outletID *uuid.UUID, column string) *gorm.DB {
	if outletID != nil {
		return query.Where(column+" = ?", *outletID)
	}
	return query
}

func (r *AnalyticsRepositoryImpl) GetPaymentMethodAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time) ([]*entities.PaymentMethodAnalytics, error) {
	var results []*entities.PaymentMethodAnalytics

	query := r.db.WithContext(ctx).
		Table("payments p").
		Select(`
			pm.id as payment_method_id,
			pm.name as payment_method_name,
			pm.type as payment_method_type,
			COALESCE(SUM(p.amount), 0) as total_amount,
			COUNT(DISTINCT p.order_id) as order_count,
			COUNT(p.id) as payment_count
		`).
		Joins("JOIN payment_methods pm ON p.payment_method_id = pm.id").
		Joins("JOIN orders o ON p.order_id = o.id").
		Where("o.organization_id = ?", organizationID).
		Where("o.is_void = ?", false).
		Where("o.is_refund = ?", false).
		Where("p.status = ?", entities.PaymentTransactionStatusCompleted).
		Where("o.created_at >= ? AND o.created_at <= ?", dateFrom, dateTo)

	query = r.resolveOutletID(query, outletID, "o.outlet_id")

	err := query.
		Group("pm.id, pm.name, pm.type").
		Order("total_amount DESC").
		Scan(&results).Error

	return results, err
}

func (r *AnalyticsRepositoryImpl) GetSalesAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, groupBy string) ([]*entities.SalesAnalytics, error) {
	var results []*entities.SalesAnalytics

	var dateFormat string
	switch groupBy {
	case "hour":
		dateFormat = "DATE_TRUNC('hour', o.created_at)"
	case "week":
		dateFormat = "DATE_TRUNC('week', o.created_at)"
	case "month":
		dateFormat = "DATE_TRUNC('month', o.created_at)"
	default:
		dateFormat = "DATE(o.created_at)"
	}

	outletFilter := ""
	args := []interface{}{organizationID, false, false, string(entities.PaymentStatusCompleted), dateFrom, dateTo}
	if outletID != nil {
		outletFilter = "AND o.outlet_id = ?"
		args = append(args, *outletID)
	}

	rawQuery := `
		SELECT
			` + dateFormat + ` as date,
			COALESCE(SUM(o.total_amount), 0) as sales,
			COUNT(o.id) as orders,
			COALESCE(SUM(oi_agg.total_items), 0) as items,
			COALESCE(SUM(o.tax_amount), 0) as tax,
			COALESCE(SUM(o.discount_amount), 0) as discount,
			COALESCE(SUM(o.total_amount - o.tax_amount - o.discount_amount), 0) as net_sales
		FROM orders o
		LEFT JOIN (
			SELECT
				oi.order_id,
				SUM(oi.quantity - COALESCE(oi.refund_quantity, 0)) as total_items
			FROM order_items oi
			WHERE oi.status != 'cancelled'
			  AND oi.is_fully_refunded = false
			GROUP BY oi.order_id
		) oi_agg ON oi_agg.order_id = o.id
		WHERE o.organization_id = ?
		  AND o.is_void = ?
		  AND o.is_refund = ?
		  AND o.payment_status = ?
		  AND o.created_at >= ? AND o.created_at <= ?
		  ` + outletFilter + `
		GROUP BY date
		ORDER BY date ASC
	`

	err := r.db.WithContext(ctx).Raw(rawQuery, args...).Scan(&results).Error
	return results, err
}

func (r *AnalyticsRepositoryImpl) GetProductAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, limit int) ([]*entities.ProductAnalytics, error) {
	var results []*entities.ProductAnalytics

	query := r.db.WithContext(ctx).
		Table("order_items oi").
		Select(`
			p.id as product_id,
			p.name as product_name,
			c.id as category_id,
			c.name as category_name,
			c.order as category_order,
			COALESCE(SUM(oi.quantity), 0) as quantity_sold,
			COALESCE(SUM(oi.total_price), 0) as revenue,
			CASE 
				WHEN SUM(oi.quantity) > 0 THEN COALESCE(SUM(oi.total_price), 0) / SUM(oi.quantity)
				ELSE 0 
			END as average_price,
			COUNT(DISTINCT oi.order_id) as order_count,
			COALESCE((
				SELECT SUM(pr.quantity * (1 + COALESCE(pr.waste_percentage, 0)/100.0) * i.cost)
				FROM product_recipes pr
				JOIN ingredients i ON pr.ingredient_id = i.id
				WHERE pr.product_id = p.id
			), p.cost, 0) as standard_hpp_per_unit,
			COALESCE((
				SELECT SUM(pr.quantity * (1 + COALESCE(pr.waste_percentage, 0)/100.0) * i.cost)
				FROM product_recipes pr
				JOIN ingredients i ON pr.ingredient_id = i.id
				WHERE pr.product_id = p.id
			), p.cost, 0) * COALESCE(SUM(oi.quantity), 0) as standard_hpp_total,
			CASE 
				WHEN SUM(oi.quantity) > 0 THEN COALESCE(SUM(oi.total_cost), 0) / SUM(oi.quantity)
				ELSE 0 
			END as fifo_hpp_per_unit,
			COALESCE(SUM(oi.total_cost), 0) as fifo_hpp_total,
			COALESCE(mahpp.hpp_per_unit, p.cost, 0) as moving_average_hpp_per_unit,
			COALESCE(mahpp.hpp_per_unit, p.cost, 0) * COALESCE(SUM(oi.quantity), 0) as moving_average_hpp_total
		`).
		Joins("JOIN products p ON oi.product_id = p.id").
		Joins("JOIN categories c ON p.category_id = c.id").
		Joins("JOIN orders o ON oi.order_id = o.id").
		Joins("LEFT JOIN (?) mahpp ON mahpp.product_id = p.id",
			r.db.Table("product_recipes pr2").
				Select("pr2.product_id, SUM(pr2.quantity * (1 + COALESCE(pr2.waste_percentage, 0)/100.0) * COALESCE(ma.moving_avg_cost, ing.cost)) as hpp_per_unit").
				Joins("JOIN ingredients ing ON pr2.ingredient_id = ing.id").
				Joins("LEFT JOIN (?) ma ON ma.ingredient_id = pr2.ingredient_id",
					r.db.Table("inventory_movements im").
						Select("im.item_id as ingredient_id, CASE WHEN SUM(im.quantity) > 0 THEN SUM(im.total_cost) / SUM(im.quantity) ELSE 0 END as moving_avg_cost").
						Where("im.movement_type = ?", "purchase").
						Where("im.item_type = ?", "INGREDIENT").
						Where("im.organization_id = ?", organizationID).
						Where("im.created_at <= ?", dateTo).
						Group("im.item_id"),
				).
				Group("pr2.product_id"),
		).
		Where("o.organization_id = ?", organizationID).
		Where("o.is_void = ?", false).
		Where("o.is_refund = ?", false).
		Where("o.payment_status = ?", entities.PaymentStatusCompleted).
		Where("oi.status != ?", entities.OrderItemStatusCancelled).
		Where("o.created_at >= ? AND o.created_at <= ?", dateFrom, dateTo)

	query = r.resolveOutletID(query, outletID, "o.outlet_id")

	err := query.
		Group("p.id, p.name, p.cost, c.id, c.name, c.order, mahpp.hpp_per_unit").
		Order("revenue DESC").
		Limit(limit).
		Scan(&results).Error

	return results, err
}

func (r *AnalyticsRepositoryImpl) GetProductAnalyticsPerCategory(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time) ([]*entities.ProductAnalyticsPerCategory, error) {
	var results []*entities.ProductAnalyticsPerCategory

	query := r.db.WithContext(ctx).
		Table("order_items oi").
		Select(`
			c.id as category_id,
			c.name as category_name,
			COALESCE(SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.total_price - COALESCE(oi.refund_amount, 0) ELSE 0 END), 0) as total_revenue,
			COALESCE(SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.quantity - COALESCE(oi.refund_quantity, 0) ELSE 0 END), 0) as total_quantity,
			COUNT(DISTINCT p.id) as product_count,
			COUNT(DISTINCT oi.order_id) as order_count,
			COALESCE(SUM(CASE WHEN oi.is_fully_refunded = false THEN COALESCE(shpp.hpp_per_unit, p.cost, 0) * (oi.quantity - COALESCE(oi.refund_quantity, 0)) ELSE 0 END), 0) as total_standard_hpp,
			COALESCE(SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.total_cost * ((oi.quantity - COALESCE(oi.refund_quantity, 0))::float / NULLIF(oi.quantity, 0)) ELSE 0 END), 0) as total_fifo_hpp,
			COALESCE(SUM(CASE WHEN oi.is_fully_refunded = false THEN COALESCE(mahpp.hpp_per_unit, p.cost, 0) * (oi.quantity - COALESCE(oi.refund_quantity, 0)) ELSE 0 END), 0) as total_moving_average_hpp
		`).
		Joins("JOIN products p ON oi.product_id = p.id").
		Joins("JOIN categories c ON p.category_id = c.id").
		Joins("JOIN orders o ON oi.order_id = o.id").
		Joins("LEFT JOIN (SELECT pr.product_id, SUM(pr.quantity * (1 + COALESCE(pr.waste_percentage, 0)/100.0) * i.cost) as hpp_per_unit FROM product_recipes pr JOIN ingredients i ON pr.ingredient_id = i.id GROUP BY pr.product_id) shpp ON shpp.product_id = p.id").
		Joins("LEFT JOIN (?) mahpp ON mahpp.product_id = p.id",
			r.db.Table("product_recipes pr2").
				Select("pr2.product_id, SUM(pr2.quantity * (1 + COALESCE(pr2.waste_percentage, 0)/100.0) * COALESCE(ma.moving_avg_cost, ing.cost)) as hpp_per_unit").
				Joins("JOIN ingredients ing ON pr2.ingredient_id = ing.id").
				Joins("LEFT JOIN (?) ma ON ma.ingredient_id = pr2.ingredient_id",
					r.db.Table("inventory_movements im").
						Select("im.item_id as ingredient_id, CASE WHEN SUM(im.quantity) > 0 THEN SUM(im.total_cost) / SUM(im.quantity) ELSE 0 END as moving_avg_cost").
						Where("im.movement_type = ?", "purchase").
						Where("im.item_type = ?", "INGREDIENT").
						Where("im.organization_id = ?", organizationID).
						Where("im.created_at <= ?", dateTo).
						Group("im.item_id"),
				).
				Group("pr2.product_id"),
		).
		Where("o.organization_id = ?", organizationID).
		Where("o.is_void = ?", false).
		Where("o.is_refund = ?", false).
		Where("o.payment_status = ?", entities.PaymentStatusCompleted).
		Where("oi.status != ?", entities.OrderItemStatusCancelled).
		Where("o.created_at >= ? AND o.created_at <= ?", dateFrom, dateTo)

	query = r.resolveOutletID(query, outletID, "o.outlet_id")

	err := query.
		Group("c.id, c.name").
		Order("c.name ASC").
		Scan(&results).Error

	return results, err
}

func (r *AnalyticsRepositoryImpl) GetDashboardOverview(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time) (*entities.DashboardOverview, error) {
	var result entities.DashboardOverview

	query := r.db.WithContext(ctx).
		Table("orders o").
		Select(`
			COALESCE(SUM(CASE WHEN o.is_void = false AND o.is_refund = false AND o.payment_status = 'completed' THEN o.total_amount ELSE 0 END), 0) as total_sales,
			COUNT(CASE WHEN o.is_void = false THEN o.id END) as total_orders,
			CASE 
				WHEN COUNT(CASE WHEN o.is_void = false THEN o.id END) > 0 
				THEN COALESCE(SUM(CASE WHEN o.is_void = false THEN o.total_amount ELSE 0 END), 0) / COUNT(CASE WHEN o.is_void = false THEN o.id END)
				ELSE 0 
			END as average_order_value,
			COUNT(DISTINCT o.customer_id) as total_customers,
			COUNT(CASE WHEN o.is_void = true THEN o.id END) as voided_orders,
			COUNT(CASE WHEN o.is_refund = true THEN o.id END) as refunded_orders
		`).
		Where("o.organization_id = ?", organizationID).
		Where("o.created_at >= ? AND o.created_at <= ?", dateFrom, dateTo)

	query = r.resolveOutletID(query, outletID, "o.outlet_id")

	err := query.Scan(&result).Error
	if err != nil {
		return nil, err
	}

	return &result, nil
}

func (r *AnalyticsRepositoryImpl) GetProfitLossAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, groupBy string) (*entities.ProfitLossAnalytics, error) {
	// Summary query
	var summary entities.ProfitLossSummary

	summaryQuery := r.db.WithContext(ctx).
		Table("orders o").
		Select(`
			COALESCE(SUM(o.total_amount), 0) as total_revenue,
			COALESCE(SUM(o.total_cost), 0) as total_cost,
			COALESCE(SUM(o.total_amount - o.total_cost), 0) as gross_profit,
			CASE 
				WHEN SUM(o.total_amount) > 0 
				THEN (SUM(o.total_amount - o.total_cost) / SUM(o.total_amount)) * 100 
				ELSE 0 
			END as gross_profit_margin,
			COALESCE(SUM(o.tax_amount), 0) as total_tax,
			COALESCE(SUM(o.discount_amount), 0) as total_discount,
			COALESCE(SUM(o.total_amount - o.total_cost - o.discount_amount), 0) as net_profit,
			CASE 
				WHEN SUM(o.total_amount) > 0 
				THEN (SUM(o.total_amount - o.total_cost - o.discount_amount) / SUM(o.total_amount)) * 100 
				ELSE 0 
			END as net_profit_margin,
			COUNT(o.id) as total_orders,
			CASE 
				WHEN COUNT(o.id) > 0 
				THEN SUM(o.total_amount - o.total_cost - o.discount_amount) / COUNT(o.id) 
				ELSE 0 
			END as average_profit,
			CASE 
				WHEN SUM(o.total_cost) > 0 
				THEN (SUM(o.total_amount - o.total_cost) / SUM(o.total_cost)) * 100 
				ELSE 0 
			END as profitability_ratio
		`).
		Where("o.organization_id = ?", organizationID).
		Where("o.status = ?", entities.OrderStatusCompleted).
		Where("o.payment_status = ?", entities.PaymentStatusCompleted).
		Where("o.is_void = false AND o.is_refund = false").
		Where("o.created_at >= ? AND o.created_at <= ?", dateFrom, dateTo)

	summaryQuery = r.resolveOutletID(summaryQuery, outletID, "o.outlet_id")

	err := summaryQuery.Scan(&summary).Error
	if err != nil {
		return nil, err
	}

	// Time series data query
	var timeFormat string
	switch groupBy {
	case "hour":
		timeFormat = "DATE_TRUNC('hour', o.created_at)"
	case "week":
		timeFormat = "DATE_TRUNC('week', o.created_at)"
	case "month":
		timeFormat = "DATE_TRUNC('month', o.created_at)"
	default: // day
		timeFormat = "DATE_TRUNC('day', o.created_at)"
	}

	var data []entities.ProfitLossData

	dataQuery := r.db.WithContext(ctx).
		Table("orders o").
		Select(`
			`+timeFormat+` as date,
			COALESCE(SUM(o.total_amount), 0) as revenue,
			COALESCE(SUM(o.total_cost), 0) as cost,
			COALESCE(SUM(o.total_amount - o.total_cost), 0) as gross_profit,
			CASE 
				WHEN SUM(o.total_amount) > 0 
				THEN (SUM(o.total_amount - o.total_cost) / SUM(o.total_amount)) * 100 
				ELSE 0 
			END as gross_profit_margin,
			COALESCE(SUM(o.tax_amount), 0) as tax,
			COALESCE(SUM(o.discount_amount), 0) as discount,
			COALESCE(SUM(o.total_amount - o.total_cost - o.discount_amount), 0) as net_profit,
			CASE 
				WHEN SUM(o.total_amount) > 0 
				THEN (SUM(o.total_amount - o.total_cost - o.discount_amount) / SUM(o.total_amount)) * 100 
				ELSE 0 
			END as net_profit_margin,
			COUNT(o.id) as orders
		`).
		Where("o.organization_id = ?", organizationID).
		Where("o.status = ?", entities.OrderStatusCompleted).
		Where("o.payment_status = ?", entities.PaymentStatusCompleted).
		Where("o.is_void = false AND o.is_refund = false").
		Where("o.created_at >= ? AND o.created_at <= ?", dateFrom, dateTo).
		Group(timeFormat).
		Order(timeFormat)

	dataQuery = r.resolveOutletID(dataQuery, outletID, "o.outlet_id")

	err = dataQuery.Scan(&data).Error
	if err != nil {
		return nil, err
	}

	// Product profit data query
	var productData []entities.ProductProfitData

	productQuery := r.db.WithContext(ctx).
		Table("order_items oi").
		Select(`
			p.id as product_id,
			p.name as product_name,
			c.id as category_id,
			c.name as category_name,
			SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.quantity - COALESCE(oi.refund_quantity, 0) ELSE 0 END) as quantity_sold,
			SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.total_price - COALESCE(oi.refund_amount, 0) ELSE 0 END) as revenue,
			SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.total_cost * ((oi.quantity - COALESCE(oi.refund_quantity, 0))::float / NULLIF(oi.quantity, 0)) ELSE 0 END) as cost,
			SUM(CASE WHEN oi.is_fully_refunded = false THEN (oi.total_price - COALESCE(oi.refund_amount, 0)) - (oi.total_cost * ((oi.quantity - COALESCE(oi.refund_quantity, 0))::float / NULLIF(oi.quantity, 0))) ELSE 0 END) as gross_profit,
			CASE 
				WHEN SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.total_price - COALESCE(oi.refund_amount, 0) ELSE 0 END) > 0 
				THEN (SUM(CASE WHEN oi.is_fully_refunded = false THEN (oi.total_price - COALESCE(oi.refund_amount, 0)) - (oi.total_cost * ((oi.quantity - COALESCE(oi.refund_quantity, 0))::float / NULLIF(oi.quantity, 0))) ELSE 0 END) / SUM(CASE WHEN oi.is_fully_refunded = false THEN oi.total_price - COALESCE(oi.refund_amount, 0) ELSE 0 END)) * 100 
				ELSE 0 
			END as gross_profit_margin,
			AVG(CASE WHEN oi.is_fully_refunded = false THEN oi.unit_price ELSE NULL END) as average_price,
			AVG(CASE WHEN oi.is_fully_refunded = false THEN oi.unit_cost ELSE NULL END) as average_cost,
			AVG(CASE WHEN oi.is_fully_refunded = false THEN oi.unit_price - oi.unit_cost ELSE NULL END) as profit_per_unit
		`).
		Joins("JOIN orders o ON oi.order_id = o.id").
		Joins("JOIN products p ON oi.product_id = p.id").
		Joins("JOIN categories c ON p.category_id = c.id").
		Where("o.organization_id = ?", organizationID).
		Where("o.status = ?", entities.OrderStatusCompleted).
		Where("o.payment_status = ?", entities.PaymentStatusCompleted).
		Where("o.is_void = false AND o.is_refund = false").
		Where("oi.status != ?", entities.OrderItemStatusCancelled).
		Where("o.created_at >= ? AND o.created_at <= ?", dateFrom, dateTo).
		Group("p.id, p.name, c.id, c.name").
		Order("p.name ASC").
		Limit(1000)

	productQuery = r.resolveOutletID(productQuery, outletID, "o.outlet_id")

	err = productQuery.Scan(&productData).Error
	if err != nil {
		return nil, err
	}

	return &entities.ProfitLossAnalytics{
		Summary:     summary,
		Data:        data,
		ProductData: productData,
	}, nil
}