import { Config } from "./config.ts";

const ws = new WebSocket(Deno.args[0])
let config: Config = {} as unknown as Config

export class TextLineStream extends TransformStream<string, string> {
    line = "";
    constructor() {
        super({
            transform: (chunk, controller) => {
                this.line += chunk;
                while (true) {
                    const newline = this.line.indexOf("\n");
                    if (newline === -1) break;
                    controller.enqueue(this.line.slice(0, newline));
                    this.line = this.line.slice(newline + 1);
                }
            },
            flush: (controller) => {
                if (this.line === "") return;
                controller.enqueue(this.line);
            },
        });
    }
}

const supported = [
    "youtube",
    "bilibili",
    "niconico",
]
function key_to_url(key: string): string {
    const [kind, id] = key.split(":", 2)
    if (kind == "youtube") return `https://www.youtube.com/watch?v=${id}`
    if (kind == "bilibili") return `https://www.bilibili.com/video/${id}`
    if (kind == "niconico") return `https://www.nicovideo.jp/watch/${id}`
    throw new Error("unknown kind");
}

async function do_download(key: string, data: { [key: string]: string }) {
    const url = key_to_url(key)

    if (!data.output) throw new Error("no output");
    const output = data.output as string;
    if (!data.profile) throw new Error("no profile");
    const args = config.ytdlp_download.profiles[data.profile as string]
    if (!args) throw new Error(`unknown profile ${data.profile}`);

    await Deno.mkdir(output, { recursive: true })
    const child = new Deno.Command("yt-dlp", {
        args: [
            "--quiet",
            "--progress",
            "--progress-template", "%(progress)j",
            "--newline",
            ...args,
            url
        ],
        stdout: "piped",
        stderr: "piped",
        cwd: output
    }).spawn()

    let fail_reason = "unknown"

    Promise.all([
        (async () => {
            const lines = child.stderr.pipeThrough(new TextDecoderStream()).pipeThrough(new TextLineStream())
            for await (const line of lines) {
                if (!line.length) continue
                if (line.includes("members-only content")) fail_reason = "members_only"
                if (line.includes("Sign in to confirm") && line.includes(" not a bot")) fail_reason = "bot"
                if (line.includes("Sign in to confirm your age")) fail_reason = "age_restricted"
                console.error("ytdlp: " + line);
            }
        })(),
        (async () => {
            const lines = child.stdout.pipeThrough(new TextDecoderStream()).pipeThrough(new TextLineStream())
            for await (const line of lines) {
                if (!line.length) continue
                const k = JSON.parse(line)
                ws.send(JSON.stringify({
                    t: "metadata", key, data: {
                        progress: (k._percent ?? 0) / 100,
                        status: k._default_template?.trim() ?? ""
                    }
                }))
            }
        })()
    ])

    const status = await child.status
    if (!status.success) ws.send(JSON.stringify({ t: "metadata", key, data: { failed: fail_reason } }))
    ws.send(JSON.stringify({ t: "metadata", key, data: { progress: null, status: null } }))
    ws.send(JSON.stringify({ t: "complete", key }))
    ws.send(JSON.stringify({ t: "save" }))
}

ws.onerror = () => console.error("ws error")
ws.onclose = () => {
    console.error("ws closed")
    Deno.exit(1)
}
ws.onopen = () => {
    console.log("ws open");
    ws.send(JSON.stringify({ t: "register", name: "yt-dlp video downloader", task_kinds: supported }))
    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 == "config") config = p.config
    if (p.t == "error") console.error(`error: ${p.message}`);
    if (p.t == "work") {
        console.log("work");
        await do_download(p.key, p.data)
        console.log("accept");
        ws.send(JSON.stringify({ t: "accept" }))
    }
}