package usecase

import (
	"chat/internal/domain/entity"
	"chat/internal/domain/repository"
	"chat/internal/domain/usecase"
	"chat/internal/library/centrifugo"
	"chat/internal/utils"
	"context"
	"fmt"
	"time"

	"github.com/zeromicro/go-zero/core/logx"
)

type messageUseCase struct {
	messageRepo      repository.MessageRepository
	matchmakingRepo  repository.MatchmakingRepository
	centrifugoClient *centrifugo.Client
}

// NewMessageUseCase 創建新的訊息 UseCase
func NewMessageUseCase(
	messageRepo repository.MessageRepository,
	matchmakingRepo repository.MatchmakingRepository,
	centrifugoClient *centrifugo.Client,
) usecase.MessageUseCase {
	return &messageUseCase{
		messageRepo:      messageRepo,
		matchmakingRepo:  matchmakingRepo,
		centrifugoClient: centrifugoClient,
	}
}

// SendMessage 發送訊息
func (u *messageUseCase) SendMessage(ctx context.Context, roomID string, uid string, content string, clientMsgID string) error {
	// 驗證訊息內容不為空
	if content == "" {
		return fmt.Errorf("message content cannot be empty")
	}

	// 驗證使用者是否在房間中
	isMember, err := u.matchmakingRepo.IsRoomMember(ctx, roomID, uid)
	if err != nil {
		logx.Errorf("Failed to check room membership: roomID=%s, uid=%s, error=%v", roomID, uid, err)
		return fmt.Errorf("failed to check room membership: %w", err)
	}
	if !isMember {
		logx.Errorf("User is not a member of the room: roomID=%s, uid=%s", roomID, uid)
		return fmt.Errorf("user is not a member of the room")
	}

	// 生成訊息 ID
	messageID := utils.GenerateMessageID()
	if clientMsgID != "" {
		messageID = clientMsgID
	}

	// 建立訊息實體
	now := time.Now()
	msg := &entity.Message{
		RoomID:    roomID,
		BucketDay: utils.GetBucketDay(now),
		TS:        now.UnixNano() / 1e6, // milliseconds
		MessageID: messageID,
		UID:       uid,
		Content:   content,
	}

	// 儲存到 Cassandra
	if err := u.messageRepo.Insert(ctx, msg); err != nil {
		return fmt.Errorf("failed to save message: %w", err)
	}

	// 發布到 Centrifugo
	channel := fmt.Sprintf("room:%s", roomID)
	messageData := map[string]interface{}{
		"message_id": msg.MessageID,
		"uid":        msg.UID,
		"content":    msg.Content,
		"timestamp":   msg.TS,
		"room_id":    msg.RoomID,
	}

	if err := u.centrifugoClient.PublishJSON(channel, messageData); err != nil {
		logx.Errorf("failed to publish message to Centrifugo: %v", err)
		// 不返回錯誤，因為訊息已經儲存
	}

	return nil
}

// ListMessages 查詢訊息列表（分頁）
func (u *messageUseCase) ListMessages(ctx context.Context, roomID string, uid string, pageSize int, pageIndex int) ([]entity.Message, int64, error) {
	// 驗證使用者是否在房間中
	isMember, err := u.matchmakingRepo.IsRoomMember(ctx, roomID, uid)
	if err != nil {
		return nil, 0, fmt.Errorf("failed to check room membership: %w", err)
	}
	if !isMember {
		return nil, 0, fmt.Errorf("user is not a member of the room")
	}

	// 取得今天的 bucket_day
	bucketDay := utils.GetTodayBucketDay()

	// 查詢訊息
	messages, totalPages, err := u.messageRepo.ListByRoom(ctx, roomID, bucketDay, pageSize, pageIndex)
	if err != nil {
		return nil, 0, fmt.Errorf("failed to list messages: %w", err)
	}

	return messages, totalPages, nil
}