/*
    FFmpeg convert - the launcher

    Converts cluster:/demo.mp4 into cluster:/demo.webm as a cluster job.
    You never choose the node: the job asks for the "ffmpeg" capability and
    names its input file, and the scheduler picks a node that has ffmpeg,
    preferring one that already stores demo.mp4.

    Optional parameters, in the URL query or a form body:
        input   default cluster:/demo.mp4
        output  default cluster:/demo.webm

    A conversion can take a while, so this waits up to 30 seconds and then
    returns the job id. Watch the rest on System Settings > Cluster Jobs, or
    call cluster.jobs.status(id) later.

    Keep ffmpeg_convert.job.agi in the same folder as this file.
*/

requirelib("cluster");

//Read a request parameter. A script run as a Serverless endpoint gets the
//request through getPara() (URL query) and postPara() (form body); a WebApp
//backend script gets its POST fields as global variables instead.
function requestParam(name) {
    var v = null;
    if (typeof getPara === "function") {
        v = getPara(name);
    }
    if ((v === null || v === "") && typeof postPara === "function") {
        v = postPara(name);
    }
    if (v === null || v === "") {
        var globalScope = (function () { return this; })();
        v = (typeof globalScope[name] === "string") ? globalScope[name] : "";
    }
    return v === null ? "" : String(v);
}

function main() {
    if (!cluster.inCluster()) {
        return { error: "This node is not part of a cluster. Create or join one in System Settings > Cluster Settings." };
    }

    var src = requestParam("input") || "cluster:/demo.mp4";
    var dst = requestParam("output") || "cluster:/demo.webm";

    var id = cluster.jobs.submit({
        name: "Convert " + src.split("/").pop() + " to " + dst.split(".").pop().toUpperCase(),
        script: "ffmpeg_convert.job.agi",
        args: { input: src, output: dst },
        inputs: [src],          //prefer a node that already holds the video
        features: ["ffmpeg"],   //only nodes with ffmpeg may take this job
        timeout: 3600
    });

    var rec;
    try {
        rec = cluster.jobs.wait(id, 30);
    } catch (e) {
        rec = cluster.jobs.status(id);
        return {
            job: id,
            status: rec.state.status,
            node: rec.state.node || "",
            //When nothing can take the job, reason says why (for example no node has ffmpeg)
            reason: rec.state.reason || "",
            note: "Still working. Follow it on System Settings > Cluster Jobs."
        };
    }

    if (rec.state.status !== "succeeded") {
        return { job: id, status: rec.state.status, error: rec.state.error || rec.state.reason || "" };
    }
    return rec.state.output;
}

sendJSONResp(JSON.stringify(main()));