package repository

import (
	"chat/internal/domain/const"
	redisKey "chat/internal/domain/redis"
	domainRepo "chat/internal/domain/repository"
	"chat/internal/utils"
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/redis/go-redis/v9"
)

type matchmakingRepository struct {
	client *redis.Client
}

// NewMatchmakingRepository 創建新的配對 Repository
func NewMatchmakingRepository(client *redis.Client) domainRepo.MatchmakingRepository {
	return &matchmakingRepository{
		client: client,
	}
}

// JoinQueue 加入配對佇列
func (r *matchmakingRepository) JoinQueue(ctx context.Context, uid string) (status string, roomID string, err error) {
	// 檢查使用者是否已經在配對中或已配對
	userKey := redisKey.MatchUserKey(uid)
	currentStatus, err := r.client.Get(ctx, userKey).Result()
	if err != nil && err != redis.Nil {
		return "", "", fmt.Errorf("failed to check user status: %w", err)
	}

	// 如果已經配對，返回房間ID
	if currentStatus != "" && currentStatus != consts.StatusWaiting {
		return consts.StatusMatched, currentStatus, nil
	}

	// 如果正在等待，返回等待狀態
	if currentStatus == consts.StatusWaiting {
		return consts.StatusWaiting, "", nil
	}

	// 嘗試從佇列中取出一個使用者進行配對
	queueKey := redisKey.MatchQueueKey()
	otherUID, err := r.client.LPop(ctx, queueKey).Result()
	if errors.Is(err, redis.Nil) {
		// 佇列為空，將自己加入佇列
		if err := r.client.RPush(ctx, queueKey, uid).Err(); err != nil {
			return "", "", fmt.Errorf("failed to join queue: %w", err)
		}
		// 設置等待狀態，TTL 5 分鐘
		if err := r.client.Set(ctx, userKey, consts.StatusWaiting, 5*time.Minute).Err(); err != nil {
			return "", "", fmt.Errorf("failed to set waiting status: %w", err)
		}
		return consts.StatusWaiting, "", nil
	}
	if err != nil {
		return "", "", fmt.Errorf("failed to pop from queue: %w", err)
	}

	// 配對成功，生成房間ID
	roomID = utils.GenerateRoomID()

	// 設置雙方的房間ID，TTL 1 小時
	roomTTL := 1 * time.Hour
	if err := r.client.Set(ctx, userKey, roomID, roomTTL).Err(); err != nil {
		return "", "", fmt.Errorf("failed to set room for user: %w", err)
	}
	otherUserKey := redisKey.MatchUserKey(otherUID)
	if err := r.client.Set(ctx, otherUserKey, roomID, roomTTL).Err(); err != nil {
		return "", "", fmt.Errorf("failed to set room for other user: %w", err)
	}

	// 建立房間成員 Set
	membersKey := redisKey.RoomMembersKey(roomID)
	if err := r.client.SAdd(ctx, membersKey, uid, otherUID).Err(); err != nil {
		return "", "", fmt.Errorf("failed to create room members: %w", err)
	}
	if err := r.client.Expire(ctx, membersKey, roomTTL).Err(); err != nil {
		return "", "", fmt.Errorf("failed to set room TTL: %w", err)
	}

	return consts.StatusMatched, roomID, nil
}

// GetMatchStatus 查詢使用者的配對狀態
func (r *matchmakingRepository) GetMatchStatus(ctx context.Context, uid string) (status string, roomID string, err error) {
	userKey := redisKey.MatchUserKey(uid)
	value, err := r.client.Get(ctx, userKey).Result()
	if err == redis.Nil {
		// 沒有配對記錄
		return "", "", nil
	}
	if err != nil {
		return "", "", fmt.Errorf("failed to get match status: %w", err)
	}

	if value == consts.StatusWaiting {
		return consts.StatusWaiting, "", nil
	}

	// value 是 roomID
	return consts.StatusMatched, value, nil
}

// CreateRoom 建立房間並添加成員
func (r *matchmakingRepository) CreateRoom(ctx context.Context, roomID string, members []string) error {
	membersKey := redisKey.RoomMembersKey(roomID)
	if err := r.client.SAdd(ctx, membersKey, members).Err(); err != nil {
		return fmt.Errorf("failed to add room members: %w", err)
	}

	// 設置 TTL 1 小時
	if err := r.client.Expire(ctx, membersKey, 1*time.Hour).Err(); err != nil {
		return fmt.Errorf("failed to set room TTL: %w", err)
	}

	return nil
}

// IsRoomMember 檢查使用者是否為房間成員
func (r *matchmakingRepository) IsRoomMember(ctx context.Context, roomID string, uid string) (bool, error) {
	membersKey := redisKey.RoomMembersKey(roomID)
	isMember, err := r.client.SIsMember(ctx, membersKey, uid).Result()
	if err != nil {
		return false, fmt.Errorf("failed to check room membership: %w", err)
	}
	return isMember, nil
}