package handler

import (
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"net/http"
	"strings"
	"time"

	"gpt-manager-go/internal/middleware"
	"gpt-manager-go/internal/models"
	"gpt-manager-go/internal/repository"
)

// CardKeyHandler 卡密处理器
type CardKeyHandler struct {
	repo *repository.CardKeyRepository
}

// NewCardKeyHandler 创建处理器
func NewCardKeyHandler(repo *repository.CardKeyRepository) *CardKeyHandler {
	return &CardKeyHandler{repo: repo}
}

// CreateCardKeyRequest 创建卡密请求
type CreateCardKeyRequest struct {
	ValidityDays int `json:"validity_days"` // 有效期天数，默认30
	MaxUses      int `json:"max_uses"`      // 最大使用次数，默认1
}

// BatchCreateCardKeyRequest 批量创建卡密请求
type BatchCreateCardKeyRequest struct {
	Count        int `json:"count"`         // 创建数量
	ValidityDays int `json:"validity_days"` // 有效期天数，默认30
	MaxUses      int `json:"max_uses"`      // 最大使用次数，默认1
}

// CardKeyResponse 卡密响应
type CardKeyResponse struct {
	Success bool              `json:"success"`
	Message string            `json:"message"`
	Data    *models.CardKey   `json:"data,omitempty"`
	Keys    []*models.CardKey `json:"keys,omitempty"`
}

// Handle 处理卡密接口 (GET: 列表, POST: 创建)
func (h *CardKeyHandler) Handle(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		h.list(w, r)
	case http.MethodPost:
		h.create(w, r)
	default:
		respondJSON(w, http.StatusMethodNotAllowed, CardKeyResponse{
			Success: false,
			Message: "Method not allowed",
		})
	}
}

// create 创建单个卡密
func (h *CardKeyHandler) create(w http.ResponseWriter, r *http.Request) {

	var req CreateCardKeyRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		// 允许空请求体，使用默认值
		req = CreateCardKeyRequest{}
	}

	// 设置默认值
	if req.ValidityDays <= 0 {
		req.ValidityDays = 30
	}
	if req.MaxUses <= 0 {
		req.MaxUses = 1
	}

	// 获取当前用户
	claims := middleware.GetUserFromContext(r.Context())

	// 生成卡密
	cardKey := &models.CardKey{
		Key:          generateCardKey(),
		MaxUses:      req.MaxUses,
		UsedCount:    0,
		ValidityType: "custom",
		ExpiresAt:    time.Now().AddDate(0, 0, req.ValidityDays),
		IsActive:     true,
		CreatedByID:  claims.UserID,
		CreatedAt:    time.Now(),
	}

	if err := h.repo.Create(cardKey); err != nil {
		respondJSON(w, http.StatusInternalServerError, CardKeyResponse{
			Success: false,
			Message: "Failed to create card key: " + err.Error(),
		})
		return
	}

	respondJSON(w, http.StatusCreated, CardKeyResponse{
		Success: true,
		Message: "Card key created successfully",
		Data:    cardKey,
	})
}

// BatchCreate 批量创建卡密 (POST /api/cardkeys/batch)
func (h *CardKeyHandler) BatchCreate(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		respondJSON(w, http.StatusMethodNotAllowed, CardKeyResponse{
			Success: false,
			Message: "Method not allowed",
		})
		return
	}

	var req BatchCreateCardKeyRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		respondJSON(w, http.StatusBadRequest, CardKeyResponse{
			Success: false,
			Message: "Invalid request body",
		})
		return
	}

	// 验证和设置默认值
	if req.Count <= 0 {
		respondJSON(w, http.StatusBadRequest, CardKeyResponse{
			Success: false,
			Message: "Count must be greater than 0",
		})
		return
	}
	if req.Count > 100 {
		respondJSON(w, http.StatusBadRequest, CardKeyResponse{
			Success: false,
			Message: "Count cannot exceed 100",
		})
		return
	}
	if req.ValidityDays <= 0 {
		req.ValidityDays = 30
	}
	if req.MaxUses <= 0 {
		req.MaxUses = 1
	}

	// 获取当前用户
	claims := middleware.GetUserFromContext(r.Context())

	// 批量创建
	var createdKeys []*models.CardKey
	expiresAt := time.Now().AddDate(0, 0, req.ValidityDays)

	for i := 0; i < req.Count; i++ {
		cardKey := &models.CardKey{
			Key:          generateCardKey(),
			MaxUses:      req.MaxUses,
			UsedCount:    0,
			ValidityType: "custom",
			ExpiresAt:    expiresAt,
			IsActive:     true,
			CreatedByID:  claims.UserID,
			CreatedAt:    time.Now(),
		}

		if err := h.repo.Create(cardKey); err != nil {
			// 如果创建失败，返回已创建的卡密
			respondJSON(w, http.StatusInternalServerError, CardKeyResponse{
				Success: false,
				Message: "Failed to create some card keys",
				Keys:    createdKeys,
			})
			return
		}
		createdKeys = append(createdKeys, cardKey)
	}

	respondJSON(w, http.StatusCreated, CardKeyResponse{
		Success: true,
		Message: "Card keys created successfully",
		Keys:    createdKeys,
	})
}

// list 获取卡密列表
func (h *CardKeyHandler) list(w http.ResponseWriter, r *http.Request) {

	cardKeys, err := h.repo.FindAll()
	if err != nil {
		respondJSON(w, http.StatusInternalServerError, CardKeyResponse{
			Success: false,
			Message: "Failed to fetch card keys",
		})
		return
	}

	respondJSON(w, http.StatusOK, CardKeyResponse{
		Success: true,
		Message: "OK",
		Keys:    cardKeys,
	})
}

// generateCardKey 生成卡密格式: XXXX-XXXX-XXXX-XXXX
func generateCardKey() string {
	bytes := make([]byte, 8)
	rand.Read(bytes)
	hex := strings.ToUpper(hex.EncodeToString(bytes))
	return hex[0:4] + "-" + hex[4:8] + "-" + hex[8:12] + "-" + hex[12:16]
}