import * as cp from "child_process";
import * as fs from "fs";
import { ILogger } from "./Logger";

export async function spawnFfmpeg(logger: ILogger, ffmpegPath: string, argss: string[]): Promise<void> {
    return new Promise((resolve, reject) => {
        logger.log("Spawning FFMPEG", ffmpegPath, argss.join(" "));

        const ffmpeg = cp.spawn(ffmpegPath, argss);
        ffmpeg.on("message", (msg) => logger.log("ffmpeg message:", msg));
        ffmpeg.on("error", (msg) => {
            logger.error("ffmpeg error:", msg);
            reject(msg);
        });
        ffmpeg.on("close", (status) => {
            if (status !== 0) {
                logger.error(`ffmpeg closed with status ${status}`);
                reject(`ffmpeg closed with status ${status}`);
            } else {
                resolve();
            }
        });

        ffmpeg.stdout.on("data", (data) => logger.log(`ffmpeg stdout: ${data}`));
        ffmpeg.stderr.on("data", (data) => logger.log(`ffmpeg stderr: ${data}`));
    });
}

export async function mergeChunks(logger: ILogger, ffmpegPath: string, segments: string[], outputFile: string): Promise<void> {
    // Temporary files
    const segmentsFile = "ffmpeg-input.txt";

    // Generate a FFMPEG input file
    const inputStr = segments.map((f) => `file '${f}'\n`).join("");
    fs.writeFileSync(segmentsFile, inputStr);

    // Merge chunks
    const mergeArgs = [
        "-y",
        "-loglevel", "warning",
        "-f", "concat",
        "-i", segmentsFile,
        "-c", "copy",
        outputFile,
    ];
    await spawnFfmpeg(logger, ffmpegPath, mergeArgs);

    // Clear temporary file
    fs.unlinkSync(segmentsFile);
}

export async function transmuxTsToMp4(logger: ILogger, ffmpegPath: string, inputFile: string, outputFile: string): Promise<void> {
    await spawnFfmpeg(logger, ffmpegPath, [
        "-y",
        "-loglevel", "warning",
        "-i", inputFile,
        "-c", "copy",
        "-bsf:a", "aac_adtstoasc",
        outputFile,
    ]);
}