import * as BackgroundTask from 'expo-background-task';
import * as TaskManager from 'expo-task-manager';
import { getUploadTaskStatus, initUploadTable, insertUploadTask } from '../db';
import { getMediaByDateRange } from './media';
import { processAndUploadMedia } from './uploader';

const BACKGROUND_UPLOAD_TASK = 'background-upload-task';

// 注册后台任务
export const registerBackgroundUploadTask = async () => {
    try {
        // 初始化数据库表
        await initUploadTable();

        const isRegistered = await TaskManager.isTaskRegisteredAsync(BACKGROUND_UPLOAD_TASK);
        if (isRegistered) {
            console.log('Background task already registered.');
        } else {
            await BackgroundTask.registerTaskAsync(BACKGROUND_UPLOAD_TASK, {
                minimumInterval: 15 * 60, // 15 分钟
            });
            console.log('Background task registered successfully.');
        }
        return true;
    } catch (error) {
        console.error('Error registering background task:', error);
        return false;
    }
};

// 定义后台任务
TaskManager.defineTask(BACKGROUND_UPLOAD_TASK, async () => {
    try {
        console.log('Running background upload task...');
        const now = new Date();
        const oneDayAgo = new Date(now.getTime() - 24 * 60 * 60 * 1000);

        // 获取最近24小时的媒体文件
        const media = await getMediaByDateRange(oneDayAgo, now);

        if (media.length === 0) {
            console.log('No new media files to upload in the last 24 hours.');
            return BackgroundTask.BackgroundTaskResult.Success;
        }

        console.log(`Found ${media.length} media files to potentially upload.`);

        // 串行上传文件
        let successCount = 0;
        let skippedCount = 0;
        let failedCount = 0;

        for (const file of media) {
            try {
                const existingTask = await getUploadTaskStatus(file.uri);
                if (!existingTask) {
                    // If not in DB, insert as pending
                    await insertUploadTask(file.uri, file.filename);
                } else if (existingTask.status === 'success' || existingTask.status === 'skipped') {
                    console.log(`File ${file.uri} already ${existingTask.status}, skipping processing.`);
                    skippedCount++;
                    continue; // Skip processing if already successful or skipped
                }

                const result = await processAndUploadMedia(file);
                if (result === null) {
                    // Skipped by processAndUploadMedia (e.g., already uploaded)
                    skippedCount++;
                } else if (result.originalSuccess) {
                    successCount++;
                } else {
                    // Failed
                    failedCount++;
                }
            } catch (e) {
                console.error('Upload failed for', file.uri, e);
                failedCount++;
            }
        }

        console.log(`Background upload task finished. Successful: ${successCount}, Skipped: ${skippedCount}, Failed: ${failedCount}, Total: ${media.length}`);

        return BackgroundTask.BackgroundTaskResult.Success;
    } catch (error) {
        console.error('Background task error:', error);
        return BackgroundTask.BackgroundTaskResult.Failed;
    }
});