package handler

import (
	"fmt"
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"github.com/wangjia/jiu/backend/internal/middleware"
	"github.com/wangjia/jiu/backend/internal/model"
)

type InventoryHandler struct {
	db *gorm.DB
}

func NewInventoryHandler(db *gorm.DB) *InventoryHandler {
	return &InventoryHandler{db: db}
}

// List GET /api/v1/inventory
func (h *InventoryHandler) List(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	query := h.db.Model(&model.Inventory{}).Where("shop_id = ?", shopID)

	if warehouseID := c.Query("warehouse_id"); warehouseID != "" {
		query = query.Where("warehouse_id = ?", warehouseID)
	}
	if productID := c.Query("product_id"); productID != "" {
		query = query.Where("product_id = ?", productID)
	}
	if c.Query("in_stock") == "1" {
		query = query.Where("quantity > 0")
	}

	var total int64
	query.Count(&total)

	var inventory []model.Inventory
	query.Preload("Product").Preload("Warehouse").
		Offset((page - 1) * pageSize).Limit(pageSize).
		Find(&inventory)

	c.JSON(http.StatusOK, gin.H{"data": inventory, "total": total, "page": page, "page_size": pageSize})
}

// Logs GET /api/v1/inventory/logs
func (h *InventoryHandler) Logs(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	query := h.db.Model(&model.InventoryLog{}).Where("shop_id = ?", shopID)

	if productID := c.Query("product_id"); productID != "" {
		query = query.Where("product_id = ?", productID)
	}

	var total int64
	query.Count(&total)

	var logs []model.InventoryLog
	query.Preload("Product").Preload("Warehouse").Offset((page-1)*pageSize).Limit(pageSize).Order("id DESC").Find(&logs)

	c.JSON(http.StatusOK, gin.H{"data": logs, "total": total, "page": page, "page_size": pageSize})
}

// productTrackingItem is the response shape for GET /api/v1/inventory/products
type productTrackingItem struct {
	model.StockInItem
	CurrentQty float64 `json:"current_qty"`
	Status     string  `json:"status"` // in_stock | sold_out
	BuyerName  string  `json:"buyer_name,omitempty"`
	SoldAt     string  `json:"sold_at,omitempty"`
}

// Products GET /api/v1/inventory/products — 商品追踪：已审核入库单的明细行，附库存状态和买家
func (h *InventoryHandler) Products(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))

	query := h.db.Model(&model.StockInItem{}).
		Joins("JOIN stock_in_orders ON stock_in_orders.id = stock_in_items.order_id").
		Where("stock_in_orders.shop_id = ? AND stock_in_orders.status = 'approved'", shopID)

	if productID := c.Query("product_id"); productID != "" {
		query = query.Where("stock_in_items.product_id = ?", productID)
	}
	if warehouseID := c.Query("warehouse_id"); warehouseID != "" {
		query = query.Where("stock_in_orders.warehouse_id = ?", warehouseID)
	}

	var total int64
	query.Count(&total)

	var items []model.StockInItem
	query.
		Preload("Product").
		Preload("Order", func(db *gorm.DB) *gorm.DB {
			return db.Preload("Warehouse").Preload("Partner")
		}).
		Select("stock_in_items.*").
		Order("stock_in_orders.order_date DESC, stock_in_items.id DESC").
		Offset((page-1)*pageSize).Limit(pageSize).
		Find(&items)

	// 一次查出所有库存，构建 product+warehouse → qty 的 map
	var inventories []model.Inventory
	h.db.Where("shop_id = ?", shopID).Find(&inventories)
	invMap := make(map[string]float64, len(inventories))
	for _, inv := range inventories {
		key := fmt.Sprintf("%d:%d", inv.ProductID, inv.WarehouseID)
		invMap[key] = inv.Quantity
	}

	// 查询每个 product+warehouse 最新的出库买家信息
	type soldRow struct {
		ProductID   uint64 `gorm:"column:product_id"`
		WarehouseID uint64 `gorm:"column:warehouse_id"`
		BuyerName   string `gorm:"column:buyer_name"`
		SoldAt      string `gorm:"column:sold_at"`
	}
	var soldRows []soldRow
	h.db.Raw(`
		SELECT sooi.product_id, soo.warehouse_id,
		       COALESCE(p.name, '') AS buyer_name,
		       CAST(MAX(soo.order_date) AS CHAR) AS sold_at
		FROM stock_out_orders soo
		JOIN stock_out_items sooi ON sooi.order_id = soo.id
		LEFT JOIN partners p ON p.id = soo.partner_id AND p.shop_id = ?
		WHERE soo.shop_id = ? AND soo.status = 'approved'
		GROUP BY sooi.product_id, soo.warehouse_id
	`, shopID, shopID).Scan(&soldRows)
	soldMap := make(map[string]soldRow, len(soldRows))
	for _, r := range soldRows {
		key := fmt.Sprintf("%d:%d", r.ProductID, r.WarehouseID)
		soldMap[key] = r
	}

	result := make([]productTrackingItem, 0, len(items))
	for _, item := range items {
		var warehouseID uint64
		if item.Order != nil {
			warehouseID = item.Order.WarehouseID
		}
		key := fmt.Sprintf("%d:%d", item.ProductID, warehouseID)
		currentQty := invMap[key]

		status := "in_stock"
		buyerName := ""
		soldAt := ""
		if currentQty <= 0 {
			status = "sold_out"
			if si, ok := soldMap[key]; ok {
				buyerName = si.BuyerName
				if len(si.SoldAt) > 10 {
					soldAt = si.SoldAt[:10]
				} else {
					soldAt = si.SoldAt
				}
			}
		}

		result = append(result, productTrackingItem{
			StockInItem: item,
			CurrentQty:  currentQty,
			Status:      status,
			BuyerName:   buyerName,
			SoldAt:      soldAt,
		})
	}

	c.JSON(http.StatusOK, gin.H{"data": result, "total": total, "page": page, "page_size": pageSize})
}

// CreateCheck POST /api/v1/inventory/checks
func (h *InventoryHandler) CreateCheck(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	operatorID := middleware.GetUserID(c)

	var req model.InventoryCheck
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	req.ShopID = shopID
	req.OperatorID = operatorID
	req.Status = "draft"

	// 自动填入系统库存数量
	for i := range req.Items {
		req.Items[i].ShopID = shopID
		var inv model.Inventory
		if err := h.db.Where("shop_id = ? AND warehouse_id = ? AND product_id = ?",
			shopID, req.WarehouseID, req.Items[i].ProductID).First(&inv).Error; err == nil {
			req.Items[i].SystemQty = inv.Quantity
		}
	}

	if err := h.db.Create(&req).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusCreated, gin.H{"data": req})
}

// GetCheck GET /api/v1/inventory/checks/:id
func (h *InventoryHandler) GetCheck(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	var check model.InventoryCheck
	if err := h.db.Preload("Items.Product").
		Where("id = ? AND shop_id = ?", c.Param("id"), shopID).
		First(&check).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
		return
	}
	c.JSON(http.StatusOK, gin.H{"data": check})
}