src/render.ts

/**
 * Render Module
 * 
 * Handles Remotion video rendering with optimized settings.
 * After render completes, uploads to Firebase Storage.
 */

import { bundle } from '@remotion/bundler';
import { renderMedia, selectComposition, getCompositions } from '@remotion/renderer';
import path from 'path';
import fs from 'fs';
import { uploadToFirebase } from './firebase-admin';

const REMOTION_ENTRY = path.resolve(process.cwd(), 'remotion/index.tsx');
const VIDEOS_DIR = path.join(process.cwd(), 'videos');
const JOBS_DIR = path.join(process.cwd(), 'jobs');
const COMPOSITION_ID = 'VEditor';

// Configuration
const CONFIG = {
    // Set concurrency to 1 to ensure stability in container environments
    // os.cpus() can report host cores which are not accessible
    concurrency: 1,
    verbose: false,
    timeoutMs: 300000, // 5 minutes
};

interface RenderOptions {
    fps?: number;
    width?: number;
    height?: number;
    format?: 'mp4' | 'webm';
}

// Helper to update job status file
function updateJobStatus(jobId: string, status: object): void {
    const statusFile = path.join(JOBS_DIR, `${jobId}.status.json`);
    fs.writeFileSync(statusFile, JSON.stringify(status));
}

export async function renderVideo(
    jobId: string,
    design: unknown,
    options: RenderOptions
): Promise<string> {
    console.log(`[Render] Job ${jobId}: Starting`);
    console.log(`[Render] Concurrency: ${CONFIG.concurrency}`);

    // Update status to bundling
    updateJobStatus(jobId, { status: 'bundling', progress: 0 });

    // Ensure output directory exists
    if (!fs.existsSync(VIDEOS_DIR)) {
        fs.mkdirSync(VIDEOS_DIR, { recursive: true });
    }

    // Bundle
    console.log(`[Render] Bundling from: ${REMOTION_ENTRY}`);
    const bundlePath = await bundle({
        entryPoint: REMOTION_ENTRY,
    });
    console.log(`[Render] Bundle created: ${bundlePath}`);

    // Select composition
    const inputProps = { design };
    const compositions = await getCompositions(bundlePath, { inputProps });
    console.log(`[Render] Compositions: ${compositions.map(c => c.id).join(', ')}`);

    const composition = await selectComposition({
        serveUrl: bundlePath,
        id: COMPOSITION_ID,
        inputProps,
    });

    console.log(`[Render] Selected: ${composition.id} - ${composition.durationInFrames} frames`);

    // Update status to rendering
    updateJobStatus(jobId, { status: 'rendering', progress: 5 });

    // Render
    const format = options.format || 'mp4';
    const outputPath = path.join(VIDEOS_DIR, `${jobId}.${format}`);

    let lastReportedProgress = 0;

    await renderMedia({
        composition,
        serveUrl: bundlePath,
        codec: format === 'webm' ? 'vp8' : 'h264',
        outputLocation: outputPath,
        inputProps,
        verbose: CONFIG.verbose,
        concurrency: CONFIG.concurrency,
        timeoutInMilliseconds: CONFIG.timeoutMs,
        chromiumOptions: {
            disableWebSecurity: true,
            gl: 'angle',
        },
        onProgress: ({ progress, renderedFrames }) => {
            const pct = Math.round(progress * 100);

            // Only update if progress changed by at least 5%
            if (pct >= lastReportedProgress + 5 || pct === 100) {
                lastReportedProgress = pct;
                console.log(`[Render] Progress: ${pct}% (${renderedFrames}/${composition.durationInFrames})`);

                // Update status file with current progress (max 90% for render, 10% for upload)
                updateJobStatus(jobId, {
                    status: 'rendering',
                    progress: Math.min(pct * 0.9, 90),
                    renderedFrames,
                    totalFrames: composition.durationInFrames
                });
            }
        },
    });

    console.log(`[Render] Render completed: ${outputPath}`);

    // Upload to Firebase Storage
    updateJobStatus(jobId, { status: 'uploading', progress: 92 });
    console.log(`[Render] Uploading to Firebase...`);

    const firebaseUrl = await uploadToFirebase(outputPath, `exports/${jobId}.${format}`);

    console.log(`[Render] Upload completed: ${firebaseUrl}`);

    // Clean up local file to save space
    try {
        fs.unlinkSync(outputPath);
        console.log(`[Render] Cleaned up local file: ${outputPath}`);
    } catch (e) {
        console.warn(`[Render] Failed to clean up local file: ${outputPath}`);
    }

    return firebaseUrl;
}