package handler

import (
	"net/http"

	"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/util"
)

type NumberRuleHandler struct {
	db *gorm.DB
}

func NewNumberRuleHandler(db *gorm.DB) *NumberRuleHandler {
	return &NumberRuleHandler{db: db}
}

var defaultRules = []struct {
	Type       string
	Prefix     string
	Mode       string
	DateFormat string
}{
	{"stock_in", "RK", "date_seq", "YYYYMMDD"},
	{"stock_out", "CK", "date_seq", "YYYYMMDD"},
	{"inventory_check", "PD", "date_seq", "YYYYMMDD"},
	{"product", "SP", "seq", "YYYYMMDD"},
}

// List GET /api/v1/number-rules
func (h *NumberRuleHandler) List(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	rules := make([]model.NumberRule, 0)
	h.db.Where("shop_id = ?", shopID).Order("id").Find(&rules)

	if len(rules) == 0 {
		for _, d := range defaultRules {
			r := model.NumberRule{ShopID: shopID, Type: d.Type, Prefix: d.Prefix, Mode: d.Mode, DateFormat: d.DateFormat}
			h.db.Create(&r)
			rules = append(rules, r)
		}
	}

	util.RespondSuccess(c, rules)
}

// Update PUT /api/v1/number-rules/:id
func (h *NumberRuleHandler) Update(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	id := c.Param("id")

	var rule model.NumberRule
	if err := h.db.Where("id = ? AND shop_id = ?", id, shopID).First(&rule).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
		return
	}

	var req struct {
		Prefix     string `json:"prefix"`
		Mode       string `json:"mode"`
		CurrentNo  *int   `json:"current_no"`
		DateFormat string `json:"date_format"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// 当前序号只能调大、不能调小（防止单号重复）
	if req.CurrentNo != nil && *req.CurrentNo < rule.CurrentNo {
		c.JSON(http.StatusBadRequest, gin.H{"error": "当前序号只能调大，不能调小（防止单号重复）"})
		return
	}
	// 模式仅允许 date_seq / seq
	if req.Mode != "" && req.Mode != "date_seq" && req.Mode != "seq" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "模式只能是 date_seq 或 seq"})
		return
	}

	updates := map[string]any{}
	if req.Prefix != "" {
		updates["prefix"] = req.Prefix
	}
	if req.Mode != "" {
		updates["mode"] = req.Mode
	}
	if req.CurrentNo != nil {
		updates["current_no"] = *req.CurrentNo
	}
	if req.DateFormat != "" {
		updates["date_format"] = req.DateFormat
	}

	if err := h.db.Model(&rule).Updates(updates).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	util.RespondSuccess(c, rule)
}