"use client";

import { useEffect, useRef, useState } from "react";

/* Frutiger Aero soundtrack: a random track from the "Frutiger Aero" playlist on
   SoundCloud. A hidden SoundCloud iframe is driven through their Widget API so
   the playlist autoplays, jumps to a random track and re-randomises whenever
   playback moves on; a small glass chip shows what's playing and gives the
   visitor a play/pause control. The iframe is only mounted by `WebLayout` while
   aero mode is active, so unmounting it stops the music. */

const PLAYLIST_URL = "https://soundcloud.com/rustie-gamer/sets/frutiger-aero";
const API_SRC = "https://w.soundcloud.com/player/api.js";
const VOLUME = 35;
/* Ignore PLAY events for this long after we pick a track: a `skip()` can still
   report the previous index for a moment, which would otherwise bounce us into
   an endless re-pick. */
const PICK_GUARD_MS = 3000;

type SoundCloudSound = {
  title?: string;
  user?: { username?: string };
};

type SoundCloudWidget = {
  play: () => void;
  pause: () => void;
  skip: (index: number) => void;
  setVolume: (volume: number) => void;
  getSounds: (callback: (sounds: SoundCloudSound[]) => void) => void;
  getCurrentSound: (callback: (sound: SoundCloudSound | null) => void) => void;
  getCurrentSoundIndex: (callback: (index: number) => void) => void;
  bind: (event: string, listener: () => void) => void;
};

type SoundCloudGlobal = {
  Widget: ((element: HTMLIFrameElement) => SoundCloudWidget) & {
    Events: { READY: string; PLAY: string; FINISH: string };
  };
};

type Track = { title: string; artist: string };

const PLACEHOLDER: Track = { title: "Frutiger Aero", artist: "SoundCloud playlist" };

declare global {
  interface Window {
    SC?: SoundCloudGlobal;
  }
}

const WIDGET_SRC =
  "https://w.soundcloud.com/player/?url=" +
  encodeURIComponent(PLAYLIST_URL) +
  "&color=%2364e3ff&auto_play=true&hide_related=true&show_comments=false" +
  "&show_user=false&show_reposts=false&show_teaser=false&visual=false";

let apiPromise: Promise<SoundCloudGlobal> | null = null;

/** Loads SoundCloud's Widget API once; later mounts reuse the same promise. */
function loadWidgetApi(): Promise<SoundCloudGlobal> {
  if (window.SC) return Promise.resolve(window.SC);
  apiPromise ??= new Promise<SoundCloudGlobal>((resolve, reject) => {
    const script = document.createElement("script");
    script.dataset.soundcloudApi = "";
    script.src = API_SRC;
    script.async = true;
    script.addEventListener("load", () => {
      if (window.SC) resolve(window.SC);
      else reject(new Error("SoundCloud widget API did not initialise"));
    });
    script.addEventListener("error", () =>
      reject(new Error("SoundCloud widget API failed to load")),
    );
    document.head.appendChild(script);
  });
  return apiPromise;
}

function toTrack(sound: SoundCloudSound | null | undefined): Track {
  if (!sound) return PLACEHOLDER;
  return {
    title: sound.title || PLACEHOLDER.title,
    artist: sound.user?.username || "SoundCloud",
  };
}

export default function AeroMusic() {
  const frameRef = useRef<HTMLIFrameElement>(null);
  const widgetRef = useRef<SoundCloudWidget | null>(null);
  const [track, setTrack] = useState<Track>(PLACEHOLDER);
  const [playing, setPlaying] = useState(true);

  useEffect(() => {
    let cancelled = false;
    /* The index we deliberately jumped to, and when — see PICK_GUARD_MS. */
    let chosen = -1;
    let pickedAt = 0;
    let syncTimer = 0;

    loadWidgetApi()
      .then((SC) => {
        const frame = frameRef.current;
        if (cancelled || !frame) return;
        const widget = SC.Widget(frame);
        widgetRef.current = widget;

        /* The chip mirrors what the player is actually on, so a skip that gets
           ignored can't leave it lying. Partial reads are ignored rather than
           blanking the label. */
        const syncTrack = () => {
          widget.getCurrentSound((sound) => {
            if (cancelled || !sound || !sound.title) return;
            setTrack({ title: sound.title, artist: sound.user?.username || "SoundCloud" });
          });
        };

        const playRandomTrack = () => {
          widget.getSounds((sounds) => {
            if (cancelled || !sounds || sounds.length === 0) return;
            let index = Math.floor(Math.random() * sounds.length);
            /* Don't just replay whatever is already on. */
            if (sounds.length > 1 && index === chosen) index = (index + 1) % sounds.length;
            chosen = index;
            pickedAt = Date.now();
            widget.skip(index);
            widget.play();
            /* Show it straight away, then settle on the truth once the player
               has caught up. */
            setTrack(toTrack(sounds[index]));
            window.clearTimeout(syncTimer);
            syncTimer = window.setTimeout(syncTrack, 900);
          });
        };

        widget.bind(SC.Widget.Events.READY, () => {
          widget.setVolume(VOLUME);
          playRandomTrack();
        });

        /* The set plays on in its own order — grab every chance to re-randomise
           instead of following the playlist track by track. */
        widget.bind(SC.Widget.Events.PLAY, () => {
          setPlaying(true);
          syncTrack();
          if (Date.now() - pickedAt < PICK_GUARD_MS) return;
          widget.getCurrentSoundIndex((index) => {
            if (cancelled || index === chosen) return;
            playRandomTrack();
          });
        });

        /* Fires at the end of the set (or of the single selected track). */
        widget.bind(SC.Widget.Events.FINISH, playRandomTrack);

        /* Cover the case where READY already fired before we bound it. */
        widget.setVolume(VOLUME);
        playRandomTrack();
      })
      .catch(() => {
        /* Offline, blocked or SoundCloud is down — the theme just stays silent. */
      });

    return () => {
      cancelled = true;
      window.clearTimeout(syncTimer);
      widgetRef.current?.pause();
      widgetRef.current = null;
    };
  }, []);

  const toggle = () => {
    const widget = widgetRef.current;
    if (!widget) return;
    if (playing) {
      widget.pause();
      setPlaying(false);
    } else {
      widget.play();
      setPlaying(true);
    }
  };

  return (
    <>
      <iframe
        ref={frameRef}
        className="web-aero-music-frame"
        src={WIDGET_SRC}
        title={`Frutiger Aero playlist on SoundCloud — ${track.title} by ${track.artist}`}
        allow="autoplay"
        loading="eager"
      />
      <button
        type="button"
        className="web-aero-music"
        onClick={toggle}
        aria-pressed={playing}
        title={playing ? "Pause the Frutiger Aero soundtrack" : "Play the Frutiger Aero soundtrack"}
      >
        <span className="web-aero-music-icon" aria-hidden="true">
          {playing ? "❚❚" : "▶"}
        </span>
        <span className="web-aero-music-text">
          <span className="web-aero-music-title">{track.title}</span>
          <span className="web-aero-music-artist">{track.artist} · SoundCloud</span>
        </span>
      </button>
    </>
  );
}