package expiry

import (
	"errors"
	"io"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"wx_service/internal/middleware"
)

// Handler 负责 HTTP 层处理。
type Handler struct {
	service *Service
}

func NewHandler(service *Service) *Handler {
	return &Handler{service: service}
}

// Healthz 用于 expiry 模块健康检查。
func (h *Handler) Healthz(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{
		"code":    0,
		"message": "success",
		"data": gin.H{
			"module": "expiry",
			"status": "ok",
		},
	})
}

type createOrUpdateItemRequest struct {
	Name           string `json:"name"`
	Category       string `json:"category"`
	ProductionDate string `json:"production_date"`
	ExpiryDate     string `json:"expiry_date"`
	ShelfLifeDays  *int   `json:"shelf_life_days"`
	Quantity       *int   `json:"quantity"`
	Location       string `json:"location"`
	Remark         string `json:"remark"`
}

type updateStatusRequest struct {
	Status string `json:"status"`
}

type updateSettingsRequest struct {
	RemindDays []int `json:"remind_days"`
}

const expiryDateLayout = "2006-01-02"

// GetSummary 获取首页汇总统计。
func (h *Handler) GetSummary(c *gin.Context) {
	user := middleware.MustCurrentUser(c)
	resp, err := h.service.GetSummary(user.ID)
	if err != nil {
		writeExpiryServerError(c)
		return
	}
	writeExpirySuccess(c, "success", resp)
}

// GetItems 获取物品列表。
func (h *Handler) GetItems(c *gin.Context) {
	user := middleware.MustCurrentUser(c)

	page := parseIntWithDefault(c.Query("page"), 1)
	pageSize := parseIntWithDefault(c.Query("page_size"), 20)
	filters := ItemFilters{
		Status:   strings.TrimSpace(c.DefaultQuery("status", "all")),
		Category: strings.TrimSpace(c.DefaultQuery("category", "all")),
		Sort:     strings.TrimSpace(c.DefaultQuery("sort", "expiry_date")),
		Page:     page,
		PageSize: pageSize,
	}

	resp, err := h.service.GetItems(user.ID, filters)
	if err != nil {
		if isExpiryBadRequestError(err) {
			writeExpiryError(c, http.StatusBadRequest, err.Error())
			return
		}
		writeExpiryServerError(c)
		return
	}

	writeExpirySuccess(c, "success", resp)
}

// CreateItem 添加物品。
func (h *Handler) CreateItem(c *gin.Context) {
	user := middleware.MustCurrentUser(c)

	var req createOrUpdateItemRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		writeExpiryError(c, http.StatusBadRequest, "请求参数错误")
		return
	}

	serviceReq, err := h.toCreateItemRequest(user.MiniProgramID, req)
	if err != nil {
		writeExpiryError(c, http.StatusBadRequest, err.Error())
		return
	}

	item, err := h.service.CreateItem(user.ID, serviceReq)
	if err != nil {
		if isExpiryBadRequestError(err) {
			writeExpiryError(c, http.StatusBadRequest, err.Error())
			return
		}
		writeExpiryServerError(c)
		return
	}

	writeExpirySuccess(c, "添加成功", toItemView(*item))
}

// UpdateItem 更新物品。
func (h *Handler) UpdateItem(c *gin.Context) {
	user := middleware.MustCurrentUser(c)
	id, ok := parseItemID(c)
	if !ok {
		return
	}

	var req createOrUpdateItemRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		writeExpiryError(c, http.StatusBadRequest, "请求参数错误")
		return
	}

	serviceReq, err := h.toCreateItemRequest(user.MiniProgramID, req)
	if err != nil {
		writeExpiryError(c, http.StatusBadRequest, err.Error())
		return
	}

	item, err := h.service.UpdateItem(id, user.ID, serviceReq)
	if err != nil {
		if errors.Is(err, ErrExpiryItemNotFound) {
			writeExpiryError(c, http.StatusNotFound, "物品不存在")
			return
		}
		if isExpiryBadRequestError(err) {
			writeExpiryError(c, http.StatusBadRequest, err.Error())
			return
		}
		writeExpiryServerError(c)
		return
	}

	writeExpirySuccess(c, "更新成功", toItemView(*item))
}

// DeleteItem 删除物品。
func (h *Handler) DeleteItem(c *gin.Context) {
	user := middleware.MustCurrentUser(c)
	id, ok := parseItemID(c)
	if !ok {
		return
	}

	err := h.service.DeleteItem(id, user.ID)
	if err != nil {
		if errors.Is(err, ErrExpiryItemNotFound) {
			writeExpiryError(c, http.StatusNotFound, "物品不存在")
			return
		}
		writeExpiryServerError(c)
		return
	}

	writeExpirySuccess(c, "删除成功", nil)
}

// UpdateStatus 标记物品状态（used/discarded）。
func (h *Handler) UpdateStatus(c *gin.Context) {
	user := middleware.MustCurrentUser(c)
	id, ok := parseItemID(c)
	if !ok {
		return
	}

	var req updateStatusRequest
	if err := c.ShouldBindJSON(&req); err != nil && !errors.Is(err, io.EOF) {
		writeExpiryError(c, http.StatusBadRequest, "请求参数错误")
		return
	}

	if err := h.service.UpdateItemStatus(id, user.ID, strings.TrimSpace(req.Status)); err != nil {
		if errors.Is(err, ErrExpiryItemNotFound) {
			writeExpiryError(c, http.StatusNotFound, "物品不存在")
			return
		}
		if isExpiryBadRequestError(err) {
			writeExpiryError(c, http.StatusBadRequest, err.Error())
			return
		}
		writeExpiryServerError(c)
		return
	}

	item, err := h.service.GetItem(id, user.ID)
	if err != nil {
		writeExpiryServerError(c)
		return
	}

	writeExpirySuccess(c, "标记成功", gin.H{
		"id":         item.ID,
		"status":     item.Status,
		"updated_at": item.UpdatedAt,
	})
}

// GetSettings 获取用户提醒设置。
func (h *Handler) GetSettings(c *gin.Context) {
	user := middleware.MustCurrentUser(c)

	resp, err := h.service.GetSettings(user.ID)
	if err != nil {
		writeExpiryServerError(c)
		return
	}

	writeExpirySuccess(c, "success", resp)
}

// UpdateSettings 更新用户提醒设置。
func (h *Handler) UpdateSettings(c *gin.Context) {
	user := middleware.MustCurrentUser(c)

	var req updateSettingsRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		writeExpiryError(c, http.StatusBadRequest, "请求参数错误")
		return
	}

	resp, err := h.service.UpdateSettings(user.ID, req.RemindDays)
	if err != nil {
		if isExpiryBadRequestError(err) {
			writeExpiryError(c, http.StatusBadRequest, err.Error())
			return
		}
		writeExpiryServerError(c)
		return
	}

	writeExpirySuccess(c, "更新成功", resp)
}

func (h *Handler) toCreateItemRequest(miniProgramID uint, req createOrUpdateItemRequest) (CreateItemRequest, error) {
	productionDate, err := parseDateString(req.ProductionDate)
	if err != nil {
		return CreateItemRequest{}, errors.New("production_date 格式错误，应为 YYYY-MM-DD")
	}

	expiryDate, err := parseDateString(req.ExpiryDate)
	if err != nil {
		return CreateItemRequest{}, errors.New("expiry_date 格式错误，应为 YYYY-MM-DD")
	}

	quantity := 1
	if req.Quantity != nil {
		quantity = *req.Quantity
	}

	return CreateItemRequest{
		MiniProgramID:  miniProgramID,
		Name:           req.Name,
		Category:       req.Category,
		ProductionDate: productionDate,
		ExpiryDate:     expiryDate,
		ShelfLifeDays:  req.ShelfLifeDays,
		Quantity:       quantity,
		Location:       req.Location,
		Remark:         req.Remark,
	}, nil
}

func parseDateString(v string) (*time.Time, error) {
	v = strings.TrimSpace(v)
	if v == "" {
		return nil, nil
	}
	parsed, err := time.ParseInLocation(expiryDateLayout, v, time.Local)
	if err != nil {
		return nil, err
	}
	return &parsed, nil
}

func parseIntWithDefault(v string, defaultValue int) int {
	if strings.TrimSpace(v) == "" {
		return defaultValue
	}
	parsed, err := strconv.Atoi(v)
	if err != nil {
		return defaultValue
	}
	return parsed
}

func parseItemID(c *gin.Context) (uint, bool) {
	id, err := strconv.Atoi(c.Param("id"))
	if err != nil || id <= 0 {
		writeExpiryError(c, http.StatusBadRequest, "id 参数错误")
		return 0, false
	}
	return uint(id), true
}

func isExpiryBadRequestError(err error) bool {
	return errors.Is(err, ErrExpiryNameInvalid) ||
		errors.Is(err, ErrExpiryCategoryInvalid) ||
		errors.Is(err, ErrExpiryMiniProgramRequired) ||
		errors.Is(err, ErrExpiryQuantityInvalid) ||
		errors.Is(err, ErrExpiryLocationTooLong) ||
		errors.Is(err, ErrExpiryRemarkTooLong) ||
		errors.Is(err, ErrExpiryDateRequired) ||
		errors.Is(err, ErrExpiryShelfLifeDaysInvalid) ||
		errors.Is(err, ErrExpiryFilterStatusInvalid) ||
		errors.Is(err, ErrExpiryFilterCategoryInvalid) ||
		errors.Is(err, ErrExpiryFilterSortInvalid) ||
		errors.Is(err, ErrExpiryStatusInvalid) ||
		errors.Is(err, ErrExpiryRemindDaysInvalid)
}

func writeExpirySuccess(c *gin.Context, message string, data interface{}) {
	resp := gin.H{
		"code":    0,
		"message": message,
	}
	if data != nil {
		resp["data"] = data
	}
	c.JSON(http.StatusOK, resp)
}

func writeExpiryError(c *gin.Context, code int, message string) {
	c.JSON(code, gin.H{
		"code":    code,
		"message": message,
	})
}

func writeExpiryServerError(c *gin.Context) {
	writeExpiryError(c, http.StatusInternalServerError, "服务器错误")
}