package controller

import (
	"errors"
	"strconv"
	"strings"
	"time"

	"github.com/QuantumNous/new-api/common"
	"github.com/QuantumNous/new-api/model"

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

type createPromoCodeRequest struct {
	Code              string `json:"code"`
	BonusAmount       int    `json:"bonus_amount"`
	MaxUses           int    `json:"max_uses"`
	MinRechargeAmount int    `json:"min_recharge_amount"`
	ExpiresAt         string `json:"expires_at"`
	Notes             string `json:"notes"`
}

type updatePromoCodeRequest struct {
	Status            *int    `json:"status"`
	MaxUses           *int    `json:"max_uses"`
	MinRechargeAmount *int    `json:"min_recharge_amount"`
	ExpiresAt         *string `json:"expires_at"`
	Notes             *string `json:"notes"`
}

func GetPromoCodes(c *gin.Context) {
	pageInfo := common.GetPageQuery(c)
	keyword := strings.TrimSpace(c.Query("keyword"))

	var status *int
	if statusText := strings.TrimSpace(c.Query("status")); statusText != "" {
		statusValue, err := strconv.Atoi(statusText)
		if err != nil {
			common.ApiErrorMsg(c, "status 参数格式不正确")
			return
		}
		status = &statusValue
	}

	promoCodes, total, err := model.GetPromoCodes(pageInfo.GetPage(), pageInfo.GetPageSize(), status, keyword)
	if err != nil {
		common.ApiError(c, err)
		return
	}
	pageInfo.SetTotal(int(total))
	pageInfo.SetItems(promoCodes)
	common.ApiSuccess(c, pageInfo)
}

func CreatePromoCode(c *gin.Context) {
	var req createPromoCodeRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		common.ApiError(c, err)
		return
	}

	code := normalizePromoCode(req.Code)
	if code == "" {
		common.ApiErrorMsg(c, "优惠码不能为空")
		return
	}
	if len(code) > 32 {
		common.ApiErrorMsg(c, "优惠码长度不能超过 32 个字符")
		return
	}
	if req.BonusAmount <= 0 {
		common.ApiErrorMsg(c, "赠送额度必须大于 0")
		return
	}
	if req.MaxUses < 0 {
		common.ApiErrorMsg(c, "最大使用次数不能小于 0")
		return
	}
	if req.MinRechargeAmount < 0 {
		common.ApiErrorMsg(c, "最低充值金额不能小于 0")
		return
	}

	if _, err := model.GetPromoCodeByCode(code); err == nil {
		common.ApiErrorMsg(c, "优惠码已存在")
		return
	} else if !errors.Is(err, gorm.ErrRecordNotFound) {
		common.ApiError(c, err)
		return
	}

	promoCode := &model.PromoCode{
		Code:              code,
		BonusAmount:       req.BonusAmount,
		MaxUses:           req.MaxUses,
		MinRechargeAmount: req.MinRechargeAmount,
		Notes:             req.Notes,
		Status:            1,
	}
	if strings.TrimSpace(req.ExpiresAt) != "" {
		expiresAt, err := parsePromoCodeExpiresAt(req.ExpiresAt)
		if err != nil {
			common.ApiErrorMsg(c, "expires_at 必须是 RFC3339 格式")
			return
		}
		promoCode.ExpiresAt = expiresAt
	}

	if err := promoCode.Insert(); err != nil {
		common.ApiError(c, err)
		return
	}
	common.ApiSuccess(c, promoCode)
}

func GetPromoCode(c *gin.Context) {
	promoCode, ok := getPromoCodeFromParam(c)
	if !ok {
		return
	}
	common.ApiSuccess(c, promoCode)
}

func UpdatePromoCode(c *gin.Context) {
	promoCode, ok := getPromoCodeFromParam(c)
	if !ok {
		return
	}

	var req updatePromoCodeRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		common.ApiError(c, err)
		return
	}

	if req.Status != nil {
		promoCode.Status = *req.Status
	}
	if req.MaxUses != nil {
		if *req.MaxUses < 0 {
			common.ApiErrorMsg(c, "最大使用次数不能小于 0")
			return
		}
		promoCode.MaxUses = *req.MaxUses
	}
	if req.MinRechargeAmount != nil {
		if *req.MinRechargeAmount < 0 {
			common.ApiErrorMsg(c, "最低充值金额不能小于 0")
			return
		}
		promoCode.MinRechargeAmount = *req.MinRechargeAmount
	}
	if req.ExpiresAt != nil {
		expiresAtText := strings.TrimSpace(*req.ExpiresAt)
		if expiresAtText == "" {
			promoCode.ExpiresAt = nil
		} else {
			expiresAt, err := parsePromoCodeExpiresAt(expiresAtText)
			if err != nil {
				common.ApiErrorMsg(c, "expires_at 必须是 RFC3339 格式")
				return
			}
			promoCode.ExpiresAt = expiresAt
		}
	}
	if req.Notes != nil {
		promoCode.Notes = *req.Notes
	}

	if err := promoCode.Update(); err != nil {
		common.ApiError(c, err)
		return
	}
	common.ApiSuccess(c, promoCode)
}

func DeletePromoCode(c *gin.Context) {
	promoCode, ok := getPromoCodeFromParam(c)
	if !ok {
		return
	}
	promoCode.Status = 0
	if err := promoCode.Update(); err != nil {
		common.ApiError(c, err)
		return
	}
	common.ApiSuccess(c, nil)
}

func GetPromoCodeUsages(c *gin.Context) {
	promoCode, ok := getPromoCodeFromParam(c)
	if !ok {
		return
	}

	pageInfo := common.GetPageQuery(c)
	usages, total, err := model.GetPromoCodeUsages(pageInfo.GetPage(), pageInfo.GetPageSize(), promoCode.Id)
	if err != nil {
		common.ApiError(c, err)
		return
	}
	pageInfo.SetTotal(int(total))
	pageInfo.SetItems(usages)
	common.ApiSuccess(c, pageInfo)
}

func getPromoCodeFromParam(c *gin.Context) (*model.PromoCode, bool) {
	id, err := strconv.Atoi(c.Param("id"))
	if err != nil {
		common.ApiError(c, err)
		return nil, false
	}
	promoCode, err := model.GetPromoCodeByID(id)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			common.ApiErrorMsg(c, "优惠码不存在")
			return nil, false
		}
		common.ApiError(c, err)
		return nil, false
	}
	return promoCode, true
}

func normalizePromoCode(code string) string {
	return strings.ToUpper(strings.TrimSpace(code))
}

func parsePromoCodeExpiresAt(value string) (*time.Time, error) {
	expiresAt, err := time.Parse(time.RFC3339, strings.TrimSpace(value))
	if err != nil {
		return nil, err
	}
	return &expiresAt, nil
}