import { spawn } from 'child_process';

const ENCTOOL = process.env['ENCTOOL'] || 'ffmpeg';

function ffmpeg(args: string[], files: number): Promise<void> {
    return new Promise((resolve, reject) => {
        console.log(`${ENCTOOL} ${args.join(' ')}`);
        const process = spawn(ENCTOOL, args);
        const to = setTimeout(async () => {
            process.kill();
            reject(new Error('timed out'));
        }, 5000 * files);
        process.on('exit', async (code) => {
            clearTimeout(to);
            if (code !== 0) {
                reject(new Error(`exited with ${code}`));
            }
            else {
                resolve();
            }
        });
    });
}

async function Stitcher(files: string[]) {
    const args: string[] = [];
    files.forEach(f => args.push('-i', f));
    args.push('-filter_complex', `[0:a][1:a][2:a]concat=n=${files.length}:v=0:a=1[out]`);
    args.push('-map', '[out]', '-ar', '44100', '-ac', '2', '-c:a', 'pcm_s16le', 'output.wav', '-y');
    await ffmpeg(args, files.length);
}

export default Stitcher;
export { Stitcher };