package services

import (
	"app/commons/core/redisclient"
	"app/commons/model/entity"
	"context"
	"crypto/rand"
	"encoding/json"
	"errors"
	"fmt"
	"math/big"
	"time"
)

type TgBindService struct {
	CommonService
}

const (
	redisKeyBindToken = "tg_bind_token:%s"       // 绑定令牌
	redisKeyBindLimit = "tg_bind_limit:%d"        // 生成限频
	redisKeyBindCache = "tg_bind_cache:%d"        // 绑定缓存
	bindTokenExpire   = 5 * time.Minute           // 令牌有效期
	bindLimitExpire   = 60 * time.Second          // 限频间隔
	bindCacheExpire   = 1 * time.Hour             // 缓存有效期
)

type bindTokenData struct {
	TelegramId       int64  `json:"telegramId"`
	TelegramUsername string `json:"telegramUsername"`
}

// GenerateBindToken 生成绑定令牌
func (s *TgBindService) GenerateBindToken(telegramId int64, telegramUsername string) (string, error) {
	ctx := context.Background()
	rdb := redisclient.DefaultClient()

	// 限频检查
	limitKey := fmt.Sprintf(redisKeyBindLimit, telegramId)
	if rdb.Exists(ctx, limitKey).Val() > 0 {
		return "", errors.New("请稍后再试（60秒内只能生成一次）")
	}

	// 生成6位码
	token := s.randomAlphanumeric(6)

	// 存 Redis
	tokenKey := fmt.Sprintf(redisKeyBindToken, token)
	data := bindTokenData{
		TelegramId:       telegramId,
		TelegramUsername: telegramUsername,
	}
	jsonBytes, _ := json.Marshal(data)
	rdb.Set(ctx, tokenKey, string(jsonBytes), bindTokenExpire)

	// 存 DB
	bindToken := &entity.TgBindToken{
		Token:            token,
		TelegramId:       telegramId,
		TelegramUsername: telegramUsername,
		Status:           0,
		ExpireAt:         time.Now().Add(bindTokenExpire),
	}
	s.DB().Create(bindToken)

	// 设置限频
	rdb.Set(ctx, limitKey, "1", bindLimitExpire)

	return token, nil
}

// BindTelegramUser 使用令牌绑定 Telegram 用户到平台账户
func (s *TgBindService) BindTelegramUser(userId int64, token string) (*entity.TgUserBind, error) {
	ctx := context.Background()
	rdb := redisclient.DefaultClient()

	// 从 Redis 查令牌
	tokenKey := fmt.Sprintf(redisKeyBindToken, token)
	val, err := rdb.Get(ctx, tokenKey).Result()

	var data bindTokenData
	if err == nil {
		json.Unmarshal([]byte(val), &data)
	} else {
		// Redis 没有，查 DB
		var dbToken entity.TgBindToken
		if err := s.DB().Where("token = ? AND status = 0", token).First(&dbToken).Error; err != nil {
			return nil, errors.New("绑定码无效或已过期")
		}
		if time.Now().After(dbToken.ExpireAt) {
			return nil, errors.New("绑定码已过期")
		}
		data.TelegramId = dbToken.TelegramId
		data.TelegramUsername = dbToken.TelegramUsername
	}

	// 检查 telegramId 是否已绑定其他用户
	var existBind entity.TgUserBind
	err = s.DB().Where("telegram_id = ? AND bind_status = 1", data.TelegramId).First(&existBind).Error
	if err == nil && existBind.UserId != userId {
		return nil, errors.New("该Telegram账户已绑定其他平台账户")
	}
	if err == nil && existBind.UserId == userId {
		// 已绑定同一用户，直接返回
		return &existBind, nil
	}

	// 检查 userId 是否已绑定其他 telegramId
	err = s.DB().Where("user_id = ? AND bind_status = 1", userId).First(&existBind).Error
	if err == nil && existBind.TelegramId != data.TelegramId {
		return nil, errors.New("该平台账户已绑定其他Telegram账户")
	}

	// 创建绑定记录
	bind := &entity.TgUserBind{
		UserId:            userId,
		TelegramId:        data.TelegramId,
		TelegramUsername:  data.TelegramUsername,
		TelegramFirstName: "",
		BindStatus:        1,
		BindTime:          time.Now(),
	}
	if err := s.DB().Create(bind).Error; err != nil {
		return nil, fmt.Errorf("绑定失败: %w", err)
	}

	// 更新令牌状态
	s.DB().Model(&entity.TgBindToken{}).Where("token = ?", token).Updates(map[string]interface{}{
		"status":  1,
		"user_id": userId,
	})

	// 删除 Redis 令牌，设置绑定缓存
	rdb.Del(ctx, tokenKey)
	cacheKey := fmt.Sprintf(redisKeyBindCache, data.TelegramId)
	rdb.Set(ctx, cacheKey, fmt.Sprintf("%d", userId), bindCacheExpire)

	return bind, nil
}

// IsUserBound 检查是否已绑定，返回 (是否绑定, userId)
// 优先用 telegramId 查，查不到时用 telegramUsername 兜底（后台手动绑定场景）
// 兜底匹配成功后自动回填 telegram_id，后续直接用 id 查
func (s *TgBindService) IsUserBound(telegramId int64, telegramUsername ...string) (bool, int64) {
	ctx := context.Background()
	rdb := redisclient.DefaultClient()

	// 查 Redis 缓存
	cacheKey := fmt.Sprintf(redisKeyBindCache, telegramId)
	val, err := rdb.Get(ctx, cacheKey).Result()
	if err == nil && val != "" {
		var userId int64
		fmt.Sscanf(val, "%d", &userId)
		if userId > 0 {
			return true, userId
		}
	}

	// 查 DB —— 优先用 telegram_id
	var bind entity.TgUserBind
	err = s.DB().Where("telegram_id = ? AND bind_status = 1", telegramId).First(&bind).Error
	if err != nil {
		// telegram_id 查不到，用 telegram_username 兜底
		if len(telegramUsername) > 0 && telegramUsername[0] != "" {
			err = s.DB().Where("telegram_username = ? AND bind_status = 1", telegramUsername[0]).First(&bind).Error
			if err == nil {
				// 自动回填 telegram_id，下次直接用 id 查
				s.DB().Model(&bind).Updates(map[string]interface{}{
					"telegram_id": telegramId,
				})
				bind.TelegramId = telegramId
			}
		}
		if err != nil {
			return false, 0
		}
	}

	// 写入缓存
	rdb.Set(ctx, cacheKey, fmt.Sprintf("%d", bind.UserId), bindCacheExpire)
	return true, bind.UserId
}

// GetBindByUserId 根据平台 userId 查询绑定记录
func (s *TgBindService) GetBindByUserId(userId int64) (*entity.TgUserBind, error) {
	var bind entity.TgUserBind
	if err := s.DB().Where("user_id = ? AND bind_status = 1", userId).First(&bind).Error; err != nil {
		return nil, err
	}
	return &bind, nil
}

// randomAlphanumeric 生成 n 位大写字母+数字随机码
func (s *TgBindService) randomAlphanumeric(n int) string {
	const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	result := make([]byte, n)
	for i := range result {
		num, _ := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
		result[i] = charset[num.Int64()]
	}
	return string(result)
}