const ws = new WebSocket(Deno.args[0])


function key_to_url(key: string): [string, string] {
    const [kind, id] = key.split(":", 2)
    if (kind == "youtube-channel") return ["youtube", `https://youtube.com/channel/${id}`]
    throw new Error("unknown kind");
}

async function flat_playlist(url: string, kind: string, output: string) {
    console.log(output, url);
    const o = await new Deno.Command("yt-dlp", {
        args: [
            "--flat-playlist",
            "--print-json",
            "--match-filter", "availability=public & live_status=not_live",
            url
        ],
        stdout: "piped",
        stderr: "inherit",
    }).output()
    const otext = new TextDecoder().decode(o.stdout)
    for (const line of otext.split("\n")) {
        if (!line.length) continue
        const ob = JSON.parse(line)
        const key = `${kind}:${ob.id}`;
        ws.send(JSON.stringify({
            t: "metadata",
            key,
            data: {
                title: ob.title,
                subtitle: `by ${ob.playlist_uploader}; duration ${ob.duration_string}`,
                description: ob.description,
                thumbnail: ob.thumbnails[0]?.url,
                output,
            }
        }))
        ws.send(JSON.stringify({ t: "enqueue", key }))
    }
    console.log("done");
}

ws.onerror = () => console.error("ws error")
ws.onclose = () => console.error("ws closed")
ws.onopen = () => {
    console.log("ws open");
    ws.send(JSON.stringify({ t: "register", name: "yt-dlp playlist flattener", task_kinds: ["youtube-channel"] }))
    ws.send(JSON.stringify({ t: "accept" }))
}
ws.onmessage = async ev => {
    if (typeof ev.data != "string") return
    const p = JSON.parse(ev.data)
    if (p.t == "error") console.error(`error: ${p.message}`);
    if (p.t == "work") {
        const [outkind, url] = key_to_url(p.key)
        if (!p.data.output) throw new Error("no output");
        await flat_playlist(url, outkind, p.data.output)
        ws.send(JSON.stringify({ t: "complete", key: p.key }))
        ws.send(JSON.stringify({ t: "save" }))
        ws.send(JSON.stringify({ t: "accept" }))
    }
}