/**
 * The site's audio and video player.
 *
 * @module
 */

import { useEffect, useRef, useState } from "react";
import { fmt } from "../../utils/player/duration.ts";
import { t } from "@lingui/core/macro";
import {
  IconFullscreen,
  IconPause,
  IconPlay,
  IconVolume,
} from "./PlayerIcons.tsx";
import { SeekBar } from "./SeekBar.tsx";
import { Waveform } from "./Waveform.tsx";
import { rememberVolume, storedVolume } from "../../utils/player/volume.ts";

/** How long a playing video's controls stay after the pointer stops, in ms. */
const HIDE_DELAY = 2500;

/** The props of {@link MediaPlayer}. */
export interface MediaPlayerProps {
  /** The media's URL. */
  src: string;
  /** Whether it is audio or video. */
  kind: "audio" | "video";
  /** The media's type. */
  mime?: string;
  /** A video's still before it plays. */
  poster?: string;
  /** Whether it starts playing on mount. */
  autoplay?: boolean;
  /** Where it starts, in seconds. */
  startTime?: number;
  /** Called when it starts or stops playing. */
  onPlayStateChange?: (playing: boolean) => void;
  /** Called as it plays, with the playhead and the duration. */
  onTimeUpdate?: (time: number, duration: number) => void;
  /** Fired when the media reaches its end — the queue's advance hook. */
  onEnded?: () => void;
  /** Fired when the element fails to load or decode. For expiring stream URLs
   *  this is the signal to re-resolve. */
  onError?: () => void;
  /** "waveform" (default) decodes peaks from the source; "progress" draws a
   *  slim seek bar and never fetches the media a second time. */
  trackStyle?: "waveform" | "progress";
  /** Receives its seek handle, for the global player's controls. */
  seekRef?: { current: ((t: number) => void) | null };
  /** Receives its play/pause handle, for the global player's controls. */
  toggleRef?: { current: (() => void) | null };
}

/**
 * Renders a media element with the site's own controls: play/pause, a waveform
 * or seek bar, time, volume (remembered across players) and, for video,
 * fullscreen.
 */
export function MediaPlayer(
  {
    src,
    kind,
    mime,
    poster,
    autoplay,
    startTime,
    onPlayStateChange,
    onTimeUpdate,
    onEnded,
    onError,
    trackStyle = "waveform",
    seekRef,
    toggleRef,
  }: MediaPlayerProps,
): React.JSX.Element {
  const mediaRef = useRef<HTMLMediaElement>(null);
  const [playing, setPlaying] = useState(false);
  const [current, setCurrent] = useState(0);
  const [duration, setDuration] = useState(0);
  const [dragging, setDragging] = useState(false);
  const [volume, setVolume] = useState(() => storedVolume().volume);
  const [muted, setMuted] = useState(() => storedVolume().muted);
  const [controlsVisible, setControlsVisible] = useState(true);
  const hideTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  // ── Callback refs ─────────────────────────────────────────────────────────────
  // Updated via effects (after render) so the linter doesn't flag render-phase ref
  // mutation. No cleanup → no null window. Negligible stale-window between commit
  // and effect, acceptable since these are only called from async event handlers.
  const onPlayStateChangeRef = useRef(onPlayStateChange);
  const onTimeUpdateRef = useRef(onTimeUpdate);
  const onEndedRef = useRef(onEnded);
  const onErrorRef = useRef(onError);

  // Sync prop callbacks after every render
  useEffect(() => {
    onPlayStateChangeRef.current = onPlayStateChange;
    onTimeUpdateRef.current = onTimeUpdate;
    onEndedRef.current = onEnded;
    onErrorRef.current = onError;
  });

  // Stable function refs — updated via effects, indirected by the registration
  // effect below so external seekRef/toggleRef never see a null window.
  const seekToFnRef = useRef((_t: number) => {});
  const toggleFnRef = useRef(() => {});

  // seekTo: all captured values are stable (setCurrent from useState, mediaRef DOM ref)
  useEffect(() => {
    seekToFnRef.current = (time: number) => {
      setCurrent(time);
      mediaRef.current!.currentTime = time;
    };
  }, []);

  // toggle: captures `playing` — re-synced whenever play state changes
  useEffect(() => {
    toggleFnRef.current = () => {
      const a = mediaRef.current!;
      if (playing) {
        a.pause();
        setPlaying(false);
        onPlayStateChangeRef.current?.(false);
      } else {
        a.play()
          .then(() => {
            setPlaying(true);
            onPlayStateChangeRef.current?.(true);
          })
          .catch(() => {});
      }
    };
  }, [playing]);

  // Stable wrappers used everywhere inside the component
  const seekTo = (time: number) => seekToFnRef.current(time);
  const toggle = () => toggleFnRef.current();

  // ── Effects ──────────────────────────────────────────────────────────────────

  // Resume to a restored offset once metadata (and thus seekability) is available.
  // Runs only on mount for the initial offset — later seeks go through seekTo.
  useEffect(() => {
    if (!startTime) return;
    const a = mediaRef.current!;
    const apply = () => {
      a.currentTime = startTime;
      setCurrent(startTime);
    };
    if (a.readyState >= 1) apply();
    else a.addEventListener("loadedmetadata", apply, { once: true });
    return () => a.removeEventListener("loadedmetadata", apply);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  // Apply the remembered volume to the freshly-mounted element, which always
  // starts at 1.0 regardless of what the last track was playing at.
  useEffect(() => {
    const a = mediaRef.current;
    if (!a) return;
    a.volume = volume;
    a.muted = muted;
    // Mount only: later changes go through changeVolume/toggleMute.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  // Autoplay on mount (e.g. triggered by play() in PlayerContext)
  useEffect(() => {
    if (!autoplay) return;
    mediaRef.current?.play()
      .then(() => {
        setPlaying(true);
        onPlayStateChangeRef.current?.(true);
      })
      .catch(() => {});
  }, [autoplay]);

  // On unmount: pause and cut callbacks so stale timeupdate/ended events that fire
  // between React's commit and the listener-removal effect can't reach the provider.
  useEffect(() => {
    const a = mediaRef.current!;
    return () => {
      a.pause();
      onPlayStateChangeRef.current = undefined;
      onTimeUpdateRef.current = undefined;
      onEndedRef.current = undefined;
      onErrorRef.current = undefined;
    };
  }, []);

  // Register imperative handles into provider refs. seekRef/toggleRef are stable
  // (created with useRef in PlayerProvider), so this effect runs exactly once.
  useEffect(() => {
    if (seekRef) seekRef.current = (t) => seekToFnRef.current(t);
    if (toggleRef) toggleRef.current = () => toggleFnRef.current();
    return () => {
      if (seekRef) seekRef.current = null;
      if (toggleRef) toggleRef.current = null;
    };
  }, [seekRef, toggleRef]);

  // Media element event listeners
  useEffect(() => {
    const a = mediaRef.current!;
    const onTime = () => {
      if (!dragging) {
        setCurrent(a.currentTime);
        onTimeUpdateRef.current?.(a.currentTime, a.duration);
      }
    };
    const onDuration = () => {
      setDuration(a.duration);
      onTimeUpdateRef.current?.(a.currentTime, a.duration);
    };
    const onEndedEvent = () => {
      setPlaying(false);
      onPlayStateChangeRef.current?.(false);
      onEndedRef.current?.();
    };
    const onErrorEvent = () => {
      setPlaying(false);
      onErrorRef.current?.();
    };
    // The element can also be started or stopped from outside the page — a
    // media key, a headset, the OS's media controls — so follow it rather
    // than only what our own button did.
    const onPlayEvent = () => {
      setPlaying(true);
      onPlayStateChangeRef.current?.(true);
    };
    const onPauseEvent = () => {
      setPlaying(false);
      onPlayStateChangeRef.current?.(false);
    };
    a.addEventListener("timeupdate", onTime);
    a.addEventListener("play", onPlayEvent);
    a.addEventListener("pause", onPauseEvent);
    a.addEventListener("durationchange", onDuration);
    a.addEventListener("ended", onEndedEvent);
    a.addEventListener("error", onErrorEvent);
    return () => {
      a.removeEventListener("timeupdate", onTime);
      a.removeEventListener("play", onPlayEvent);
      a.removeEventListener("pause", onPauseEvent);
      a.removeEventListener("durationchange", onDuration);
      a.removeEventListener("ended", onEndedEvent);
      a.removeEventListener("error", onErrorEvent);
    };
  }, [dragging]);

  // Hide video controls after inactivity
  useEffect(() => {
    if (kind !== "video") return;
    if (hideTimer.current) clearTimeout(hideTimer.current);
    if (playing) {
      hideTimer.current = setTimeout(
        () => setControlsVisible(false),
        HIDE_DELAY,
      );
    }
    return () => {
      if (hideTimer.current) clearTimeout(hideTimer.current);
    };
  }, [playing, kind]);

  // ── Render helpers ────────────────────────────────────────────────────────────

  const showingControls = kind !== "video" || !playing || controlsVisible;

  const showControlsTemporarily = () => {
    if (kind !== "video") return;
    setControlsVisible(true);
    if (hideTimer.current) clearTimeout(hideTimer.current);
    if (playing) {
      hideTimer.current = setTimeout(
        () => setControlsVisible(false),
        HIDE_DELAY,
      );
    }
  };

  const changeVolume = (e: React.ChangeEvent<HTMLInputElement>) => {
    const v = Number(e.target.value);
    const nextMuted = v > 0 && muted ? false : muted;
    setVolume(v);
    mediaRef.current!.volume = v;
    if (nextMuted !== muted) {
      setMuted(nextMuted);
      mediaRef.current!.muted = nextMuted;
    }
    rememberVolume(v, nextMuted);
  };

  const toggleMute = () => {
    const next = !muted;
    setMuted(next);
    mediaRef.current!.muted = next;
    rememberVolume(volume, next);
  };

  const goFullscreen = () => {
    (mediaRef.current as HTMLVideoElement).requestFullscreen?.();
  };

  // A waveform needs the raw bytes, which cross-origin streams won't hand over.
  // Those get an honest progress bar rather than a permanent loading skeleton.
  const track = kind === "audio" && trackStyle === "waveform"
    ? (
      <Waveform
        src={src}
        current={current}
        duration={duration}
        onSeek={seekTo}
      />
    )
    : (
      <SeekBar
        current={current}
        duration={duration}
        onSeek={seekTo}
        onDragChange={setDragging}
        className={kind === "audio" ? "audio-player-track--stream" : undefined}
      />
    );

  const controls = (
    <>
      <button
        type="button"
        className="audio-player-btn"
        onClick={toggle}
        aria-label={playing ? t`Pause` : t`Play`}
      >
        {playing ? <IconPause /> : <IconPlay />}
      </button>

      <span className="audio-player-time">{fmt(current)}</span>

      {track}

      <span className="audio-player-time">{fmt(duration)}</span>

      <div className="audio-player-volume">
        <button
          type="button"
          className="audio-player-vol-btn"
          onClick={toggleMute}
          aria-label={muted ? t`Unmute` : t`Mute`}
        >
          <IconVolume muted={muted} />
        </button>
        <div className="audio-player-track audio-player-track--volume">
          <div
            className="audio-player-fill"
            style={{ width: `${(muted ? 0 : volume) * 100}%` }}
          />
          <input
            type="range"
            className="audio-player-range"
            min={0}
            max={1}
            step={0.01}
            value={muted ? 0 : volume}
            onChange={changeVolume}
            aria-label={t`Volume`}
          />
        </div>
      </div>

      {kind === "video" && (
        <button
          type="button"
          className="audio-player-vol-btn"
          onClick={goFullscreen}
          aria-label={t`Fullscreen`}
        >
          <IconFullscreen />
        </button>
      )}
    </>
  );

  if (kind === "video") {
    return (
      <div
        className={`video-player${
          showingControls ? " video-player--controls-visible" : ""
        }`}
        onMouseMove={showControlsTemporarily}
        onMouseLeave={() => playing && setControlsVisible(false)}
      >
        <video
          ref={mediaRef as React.RefObject<HTMLVideoElement>}
          src={src}
          poster={poster}
          preload="metadata"
          className="video-player-video"
          onClick={toggle}
        >
          {mime && <source src={src} type={mime} />}
        </video>
        <div className="video-player-controls audio-player">
          {controls}
        </div>
      </div>
    );
  }

  return (
    <div className="audio-player">
      <audio
        ref={mediaRef as React.RefObject<HTMLAudioElement>}
        src={src}
        preload="metadata"
      >
        {mime && <source src={src} type={mime} />}
      </audio>
      {controls}
    </div>
  );
}