'use client';

import { ExternalLink, Play, Volume2, VolumeX } from 'lucide-react';
import { useCallback, useEffect, useRef, useState } from 'react';

/**
 * Hero video player tuned for the stubborn-autoplay cases we hit in
 * the field (Chrome with prefers-reduced-motion, data saver, etc.).
 *
 * Three failure modes we defend against:
 *
 *   1. Browser allows muted autoplay — the happy path. Element loads,
 *      starts playing, the `play` event flips `playing` to true and
 *      hides the overlay.
 *
 *   2. Browser blocks autoplay but allows playback on user gesture —
 *      the play overlay sits over the poster, the user clicks, we
 *      call `.load()` first to reset the resource-selection state
 *      (some Chrome builds park the element at networkState=2/
 *      readyState=0 forever if the original autoplay was blocked
 *      before the source ever fetched) and then `.play()` with the
 *      user gesture in scope. Plays.
 *
 *   3. Browser refuses to play even after the gesture — extension-
 *      sandboxed contexts, hardware-decoder failures, etc. We catch
 *      the promise rejection, surface a small "open video in a new
 *      tab" link so the visitor isn't completely stuck.
 *
 * Source order: MP4 only. We previously offered WebM (VP9) first as a
 * size win, but Chrome will pick WebM if listed first, and if that
 * decode fails it does NOT fall back to MP4 — it just sits in an
 * unloaded state. Single MP4 source (Main profile / yuv420p / TV-
 * range / faststart) plays everywhere and the file is 2.6 MB which is
 * close enough to the WebM that the extra HTTP source-juggling isn't
 * worth the failure surface.
 */
export function HeroVideo() {
  const videoRef = useRef<HTMLVideoElement>(null);
  const [muted, setMuted] = useState(true);
  const [playing, setPlaying] = useState(false);
  const [playFailed, setPlayFailed] = useState(false);

  useEffect(() => {
    const v = videoRef.current;
    if (!v) return;
    const onPlay = () => {
      setPlaying(true);
      setPlayFailed(false);
    };
    const onPause = () => setPlaying(false);
    v.addEventListener('play', onPlay);
    v.addEventListener('pause', onPause);
    // Best-effort autoplay attempt — silently fail on browsers that
    // block it; the overlay is the user's escape hatch.
    v.play().catch(() => undefined);
    return () => {
      v.removeEventListener('play', onPlay);
      v.removeEventListener('pause', onPause);
    };
  }, []);

  const togglePlay = useCallback(async () => {
    const v = videoRef.current;
    if (!v) return;
    if (v.paused) {
      setPlayFailed(false);
      try {
        // .load() resets the media element's resource selection — required
        // when an earlier autoplay attempt was blocked before the source
        // ever fetched. Without it, .play() on a stuck element no-ops.
        v.load();
        await v.play();
      } catch {
        setPlayFailed(true);
      }
    } else {
      v.pause();
    }
  }, []);

  const toggleMute = useCallback((e: React.MouseEvent) => {
    e.stopPropagation();
    const v = videoRef.current;
    if (!v) return;
    const next = !v.muted;
    v.muted = next;
    setMuted(next);
    // Restart from frame 0 whenever the audio state toggles. Visitors who
    // unmute want to hear the opening, not whatever moment the video was
    // already at; visitors who re-mute also expect a clean restart so the
    // animation lines up with the silent loop again.
    v.currentTime = 0;
    if (v.paused) {
      v.play().catch(() => undefined);
    }
  }, []);

  return (
    <>
      <video
        ref={videoRef}
        autoPlay
        muted
        loop
        playsInline
        preload="auto"
        poster="/videos/hero-poster.jpg"
        onClick={togglePlay}
        className="size-full cursor-pointer object-cover"
        aria-label="Animation: a prompt becomes a live MCP server, with secrets staying isolated from the AI pipeline"
      >
        {/* MP4 only — see file-header note on dropping the WebM source. */}
        <source src="/videos/hero.mp4" type="video/mp4" />
      </video>

      {/* PLAY overlay — visible while paused. Full-frame so clicking
          anywhere starts playback (YouTube / Vimeo pattern). */}
      {!playing && (
        <button
          type="button"
          onClick={togglePlay}
          aria-label="Play video"
          className="group absolute inset-0 z-10 flex items-center justify-center"
          style={{
            backgroundColor:
              'color-mix(in oklab, var(--color-bg) 30%, transparent)',
          }}
        >
          <div
            className="flex size-20 items-center justify-center rounded-full border backdrop-blur transition-transform duration-200 ease-out group-hover:scale-110"
            style={{
              backgroundColor:
                'color-mix(in oklab, var(--color-bg-elevated) 80%, transparent)',
              borderColor: 'var(--color-accent)',
              boxShadow:
                '0 0 32px rgba(99, 102, 241, 0.45), 0 12px 40px rgba(0,0,0,0.55)',
              color: 'var(--color-accent)',
            }}
          >
            {/* translate-x-0.5 optically centres the triangle */}
            <Play size={32} fill="currentColor" className="translate-x-0.5" />
          </div>
        </button>
      )}

      {/* Fallback escape hatch — surfaces only if .play() rejects even
          after a user gesture (extension sandbox, hardware-decoder
          failures, etc.). One-line link to the raw MP4 so the visitor
          isn't trapped staring at a poster forever. */}
      {playFailed && !playing && (
        <a
          href="/videos/hero.mp4"
          target="_blank"
          rel="noopener noreferrer"
          className="absolute inset-x-0 bottom-20 z-20 mx-auto flex w-fit items-center gap-2 rounded-md border px-3 py-2 text-[12px] backdrop-blur hover:text-[--color-fg]"
          style={{
            backgroundColor:
              'color-mix(in oklab, var(--color-bg-elevated) 85%, transparent)',
            borderColor: 'var(--color-border-strong)',
            color: 'var(--color-fg-muted)',
          }}
        >
          your browser blocked playback. open the video directly
          <ExternalLink size={12} />
        </a>
      )}

      {/* Mute toggle — always visible, top of z-stack. */}
      <button
        type="button"
        onClick={toggleMute}
        aria-label={muted ? 'Unmute video' : 'Mute video'}
        aria-pressed={!muted}
        className="absolute bottom-4 right-4 z-30 inline-flex size-10 items-center justify-center rounded-full border backdrop-blur transition-colors duration-150 hover:text-[--color-fg] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[--color-accent]"
        style={{
          backgroundColor:
            'color-mix(in oklab, var(--color-bg-elevated) 75%, transparent)',
          borderColor: 'var(--color-border)',
          color: muted ? 'var(--color-fg-muted)' : 'var(--color-accent)',
        }}
      >
        {muted ? <VolumeX size={18} /> : <Volume2 size={18} />}
      </button>
    </>
  );
}
