package handler

import (
	"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"
	"github.com/wangjia/jiu/backend/internal/service"
	"github.com/wangjia/jiu/backend/internal/util"
)

type StockOutHandler struct {
	db       *gorm.DB
	stockSvc *service.StockService
}

func NewStockOutHandler(db *gorm.DB, svc *service.StockService) *StockOutHandler {
	return &StockOutHandler{db: db, stockSvc: svc}
}

// List GET /api/v1/stock-out/orders
func (h *StockOutHandler) List(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
	pageSize = util.ValidatePageSize(pageSize, 20, 200)

	query := h.db.Model(&model.StockOutOrder{}).
		Where("shop_id = ? AND deleted_at IS NULL", shopID)

	if status := c.Query("status"); status != "" {
		query = query.Where("status = ?", status)
	}
	if startDate := c.Query("start_date"); startDate != "" {
		query = query.Where("order_date >= ?", startDate)
	}
	if endDate := c.Query("end_date"); endDate != "" {
		query = query.Where("order_date <= ?", endDate)
	}

	var total int64
	query.Count(&total)

	orders := make([]model.StockOutOrder, 0)
	query.Preload("Warehouse").Preload("Partner").Preload("Operator").Preload("Reviewer").
		Offset((page - 1) * pageSize).Limit(pageSize).
		Order("id DESC").Find(&orders)

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

// Get GET /api/v1/stock-out/orders/:id
func (h *StockOutHandler) Get(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	var order model.StockOutOrder
	if err := h.db.Preload("Items.Product").Preload("Warehouse").Preload("Partner").Preload("Operator").Preload("Reviewer").
		Where("id = ? AND shop_id = ? AND deleted_at IS NULL", c.Param("id"), shopID).
		First(&order).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
		return
	}
	util.RespondSuccess(c, order)
}


// Create POST /api/v1/stock-out/orders
func (h *StockOutHandler) Create(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	operatorID := middleware.GetUserID(c)

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

	req.ShopID = shopID
	req.OperatorID = operatorID

	// 状态只允许 draft 或 pending；直接提交审核时校验库存
	if req.Status == "pending" {
		if err := h.stockSvc.CheckInventoryAvailability(shopID, req.WarehouseID, req.Items); err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
			return
		}
	} else {
		req.Status = "draft"
	}

	orderNo, err := h.stockSvc.GenerateOrderNo(shopID, "stock_out")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	req.OrderNo = orderNo

	var total float64
	for i := range req.Items {
		req.Items[i].ShopID = shopID
		req.Items[i].TotalPrice = req.Items[i].Quantity * req.Items[i].UnitPrice
		total += req.Items[i].TotalPrice
	}
	req.TotalAmount = total

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

// Update PUT /api/v1/stock-out/orders/:id （只允许草稿状态）
func (h *StockOutHandler) Update(c *gin.Context) {
	shopID := middleware.GetShopID(c)

	var order model.StockOutOrder
	if err := h.db.Where("id = ? AND shop_id = ? AND status = 'draft' AND deleted_at IS NULL", c.Param("id"), shopID).
		First(&order).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "出库单不存在或不可修改"})
		return
	}

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

	err := h.db.Transaction(func(tx *gorm.DB) error {
		if err := tx.Where("order_id = ?", order.ID).Delete(&model.StockOutItem{}).Error; err != nil {
			return err
		}
		var total float64
		for i := range req.Items {
			req.Items[i].ShopID = shopID
			req.Items[i].OrderID = order.ID
			req.Items[i].TotalPrice = req.Items[i].Quantity * req.Items[i].UnitPrice
			total += req.Items[i].TotalPrice
		}
		updates := map[string]interface{}{
			"warehouse_id": req.WarehouseID,
			"partner_id":   req.PartnerID,
			"order_date":   req.OrderDate,
			"remark":       req.Remark,
			"total_amount": total,
		}
		if err := tx.Model(&order).Updates(updates).Error; err != nil {
			return err
		}
		if len(req.Items) > 0 {
			if err := tx.Create(&req.Items).Error; err != nil {
				return err
			}
		}
		return nil
	})
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"message": "updated"})
}

// Delete DELETE /api/v1/stock-out/orders/:id （只允许草稿状态）
func (h *StockOutHandler) Delete(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	now := timeNow()
	result := h.db.Model(&model.StockOutOrder{}).
		Where("id = ? AND shop_id = ? AND status = 'draft' AND deleted_at IS NULL", c.Param("id"), shopID).
		Update("deleted_at", now)
	if result.RowsAffected == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "出库单不存在或不可删除"})
		return
	}
	c.JSON(http.StatusOK, gin.H{"message": "deleted"})
}

// Submit PUT /api/v1/stock-out/orders/:id/submit
func (h *StockOutHandler) Submit(c *gin.Context) {
	shopID := middleware.GetShopID(c)

	// 加载订单及明细，校验库存后再改状态
	var order model.StockOutOrder
	if err := h.db.Preload("Items").
		Where("id = ? AND shop_id = ? AND status = 'draft'", c.Param("id"), shopID).
		First(&order).Error; err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "order not found or not in draft status"})
		return
	}
	if err := h.stockSvc.CheckInventoryAvailability(shopID, order.WarehouseID, order.Items); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	h.db.Model(&order).Update("status", "pending")
	c.JSON(http.StatusOK, gin.H{"message": "submitted"})
}

// Approve PUT /api/v1/stock-out/orders/:id/approve
func (h *StockOutHandler) Approve(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	reviewerID := middleware.GetUserID(c)

	id, _ := strconv.ParseUint(c.Param("id"), 10, 64)
	if err := h.stockSvc.ApproveStockOut(shopID, id, reviewerID); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"message": "approved"})
}

// Reject PUT /api/v1/stock-out/orders/:id/reject
func (h *StockOutHandler) Reject(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	reviewerID := middleware.GetUserID(c)
	now := timeNow()

	result := h.db.Model(&model.StockOutOrder{}).
		Where("id = ? AND shop_id = ? AND status = 'pending'", c.Param("id"), shopID).
		Updates(map[string]interface{}{
			"status":      "rejected",
			"reviewer_id": reviewerID,
			"reviewed_at": now,
		})
	if result.RowsAffected == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "order not found or not in pending status"})
		return
	}
	c.JSON(http.StatusOK, gin.H{"message": "rejected"})
}