/*
    FFmpeg convert - the job half

    Converts one video on whichever node the scheduler picked. The launcher
    asks for the "ffmpeg" capability, so this only ever runs on a node that
    has ffmpeg installed, and lists the input file, so a node that already
    holds a copy of it is preferred and the video does not cross the network
    twice.

    The ffmpeg library reads the input and writes the output through the
    cluster drive, so cluster:/ paths work here exactly like user:/ paths.

    args:
        input   default "cluster:/demo.mp4"
        output  default "cluster:/demo.webm" (the extension picks the format)
*/

requirelib("filelib");

function run(job) {
    var args = job.args || {};
    var input = args.input || "cluster:/demo.mp4";
    var output = args.output || "cluster:/demo.webm";

    //The scheduler already checked for ffmpeg, but a node can lose it
    if (!requirelib("ffmpeg")) {
        throw new Error("ffmpeg is not available on this node");
    }
    if (!filelib.fileExists(input)) {
        throw new Error("input file not found: " + input);
    }

    job.log("Converting " + input + " to " + output + " on node " + job.node);
    job.progress(0.05);

    var started = Date.now();
    var ok = ffmpeg.convert(input, output);
    if (!ok) {
        throw new Error("ffmpeg could not convert " + input);
    }

    job.progress(1);
    job.log("Done");

    return {
        input: input,
        inputBytes: filelib.filesize(input),
        output: output,
        outputBytes: filelib.filesize(output),
        convertedOn: job.node,
        seconds: Math.round((Date.now() - started) / 100) / 10
    };
}