import {
  useCallback,
  useEffect,
  useRef,
  useState,
  type MutableRefObject,
  type RefObject,
  type WheelEvent as ReactWheelEvent,
} from "react";
import type { QueryClient } from "@tanstack/react-query";
import Hls from "hls.js";
import {
  exitFullscreen,
  fullscreenElement,
  onFullscreenChange,
  requestFullscreen,
} from "./fullscreen";
import { api, type PlexItemDetail, type PlexMarker } from "./api";
import { qk } from "./queryKeys";
import { clamp01, type PlexPlayerPrefs } from "./plexPlayerPrefs";

// A live wall clock for the top bar, re-rendered every 15s (minute resolution is enough for the
// HH:MM display, and a coarse tick keeps the whole player from re-rendering each second).
export function useWallClock(): Date {
  const [now, setNow] = useState(() => new Date());
  useEffect(() => {
    const iv = window.setInterval(() => setNow(new Date()), 15000);
    return () => window.clearInterval(iv);
  }, []);
  return now;
}

// Fullscreen toggle for `el` (the player wrapper) + a reactive `fs` flag.
// Via lib/fullscreen, not the raw API: WebKit (Safari/iPadOS) ships only the prefixed spelling, so
// reading `document.fullscreenElement` alone made this player believe it is never fullscreen — the
// button did nothing, `fs` never flipped, and Escape read "not fullscreen" as permission to close the
// whole player instead of just leaving fullscreen.
export function useFullscreen(wrapRef: RefObject<HTMLElement | null>): {
  fs: boolean;
  toggleFs: () => void;
} {
  const [fs, setFs] = useState(false);
  const toggleFs = useCallback(() => {
    const el = wrapRef.current;
    if (!el) return;
    if (fullscreenElement()) exitFullscreen();
    else requestFullscreen(el);
  }, [wrapRef]);
  useEffect(() => onFullscreenChange(() => setFs(!!fullscreenElement())), []);
  return { fs, toggleFs };
}

// Auto-hiding control bar: `uiVisible` drives the chrome opacity; `wake` reveals it and (re)arms the
// 3s hide timer. Reads the caller's live refs so the timer callback sees fresh state without a
// closure rebuild: barAutoHide (per-user "never auto-hide" setting), whether a menu is open (keep the
// bar up so it can't vanish mid-choice), and the <video> paused state (a paused video keeps the bar).
export function useControlsVisibility(opts: {
  barAutoHideRef: RefObject<boolean>;
  menuOpenRef: RefObject<boolean>;
  videoRef: RefObject<HTMLVideoElement | null>;
}): { uiVisible: boolean; wake: () => void } {
  const { barAutoHideRef, menuOpenRef, videoRef } = opts;
  const [uiVisible, setUiVisible] = useState(true);
  const hideTimer = useRef<number | null>(null);
  const wake = useCallback(() => {
    setUiVisible(true);
    if (hideTimer.current) window.clearTimeout(hideTimer.current);
    if (!barAutoHideRef.current) return; // per-user setting: never auto-hide the control bar
    hideTimer.current = window.setTimeout(() => {
      // Keep the controls up while the audio/subtitle menu is open, else it would vanish mid-choice.
      if (!videoRef.current?.paused && !menuOpenRef.current) setUiVisible(false);
    }, 3000);
  }, [barAutoHideRef, menuOpenRef, videoRef]);
  return { uiVisible, wake };
}

// Periodic + on-unmount progress checkpoint. Reads live position/duration through refs (owned by the
// component, since seeking/skip/ended all mutate absRef too) so the interval and unload beacon see the
// current spot without rebuilding the effect.
export function usePlexProgress(opts: {
  id: string;
  qc: QueryClient;
  videoRef: RefObject<HTMLVideoElement | null>;
  absRef: MutableRefObject<number>;
  durationRef: MutableRefObject<number>;
}): void {
  const { id, qc, videoRef, absRef, durationRef } = opts;
  useEffect(() => {
    // `final` = a settled checkpoint (pause / page-hide / leaving the player) vs. the periodic tick.
    // Only final checkpoints get mirrored to a linked Plex account (backend-side debounce), so Plex
    // sees the resume position when the user actually stops — not a timeline call every 10 seconds.
    const flush = (final = false) => {
      if (absRef.current > 0 && durationRef.current > 0)
        api
          .plexProgress(id, Math.floor(absRef.current), durationRef.current, final)
          .catch(() => {});
    };
    const iv = window.setInterval(flush, 10000);
    // Pausing is a settled position — push it to Plex now rather than waiting for unmount/unload.
    const onPauseFlush = () => flush(true);
    const video = videoRef.current;
    video?.addEventListener("pause", onPauseFlush);
    // Save on page unload too (F5/close/navigate): React effect cleanup does NOT run on a full reload,
    // so without this the resume point lags up to 10s — e.g. a seek right before F5 was lost. Uses a
    // keepalive beacon so the POST survives the unload (a final checkpoint — the user is leaving).
    const onHide = () => {
      if (absRef.current > 0 && durationRef.current > 0)
        api.plexProgressBeacon(id, Math.floor(absRef.current), durationRef.current, true);
    };
    window.addEventListener("pagehide", onHide);
    return () => {
      window.clearInterval(iv);
      window.removeEventListener("pagehide", onHide);
      video?.removeEventListener("pause", onPauseFlush);
      flush(true);
      // Back (unmount) persists the position server-side via flush(), but reopening the same item in
      // the SAME session read react-query's CACHED detail — whose position_seconds predated this
      // watch — so the resume landed at the old spot (the progress GET could also race the POST).
      // Patch the cached detail here so a reopen resumes from where we left off. (F5 was always fine:
      // a reload starts with an empty cache and fetches the fresh position.) Safe to do only on
      // unmount — patching while mounted would retrigger the loadSession effect and reseek mid-play.
      // Reading the LATEST abs/duration at cleanup is the whole point of the checkpoint (the resume
      // point when leaving), not a stale snapshot — the "ref value may have changed" hint is a false
      // positive here. Scoped disable so the deps array below is still checked.
      /* eslint-disable react-hooks/exhaustive-deps */
      if (absRef.current > 0 && durationRef.current > 0) {
        const pos = Math.floor(absRef.current);
        qc.setQueryData(qk.plexItem(id), (old) => (old ? { ...old, position_seconds: pos } : old));
      }
      /* eslint-enable react-hooks/exhaustive-deps */
      qc.invalidateQueries({ queryKey: qk.plexLibrary() });
      qc.invalidateQueries({ queryKey: qk.plexShow() });
    };
    // absRef/durationRef/videoRef are stable ref objects — listed to satisfy exhaustive-deps without
    // changing when the effect re-runs (id/qc only), matching the original in-component effect.
  }, [id, qc, absRef, durationRef, videoRef]);
}

// Volume/mute for the Plex player's HTML5 <video> (0..1 float, independent .muted flag). Persists to
// the per-account prefs (survives F5) and re-applies on each fresh session (the element resets to its
// default volume after a load/seek-restart). NOTE: this is the Plex-side model; the YouTube player has
// its own 0-100 / no-mute-flag arithmetic in playerVolume.ts. Sharing the tested pure core across both
// is a separate R12 consolidation sprint — this hook is the seam it will rework internally.
export function usePlayerVolume(opts: {
  videoRef: RefObject<HTMLVideoElement | null>;
  volume: number;
  muted: boolean;
  ready: boolean;
  patchPrefs: (patch: Partial<PlexPlayerPrefs>) => void;
  infoOpenRef: RefObject<boolean>;
  helpOpenRef: RefObject<boolean>;
}): {
  setVol: (vol: number, mute: boolean) => void;
  nudgeVolume: (d: number) => void;
  toggleMute: () => void;
  onWheel: (e: ReactWheelEvent) => void;
} {
  const { videoRef, volume, muted, ready, patchPrefs, infoOpenRef, helpOpenRef } = opts;
  const applyVolume = useCallback(
    (vol: number, mute: boolean) => {
      const v = videoRef.current;
      if (!v) return;
      v.volume = clamp01(vol);
      v.muted = mute;
    },
    [videoRef],
  );
  // Set volume/mute on the <video> AND persist (survives F5).
  const setVol = useCallback(
    (vol: number, mute: boolean) => {
      applyVolume(vol, mute);
      patchPrefs({ volume: clamp01(vol), muted: mute });
    },
    [applyVolume, patchPrefs],
  );
  const nudgeVolume = useCallback(
    (d: number) => setVol(clamp01(volume + d), clamp01(volume + d) === 0),
    [volume, setVol],
  );
  const toggleMute = useCallback(() => setVol(volume, !muted), [volume, muted, setVol]);
  // Re-apply the persisted volume/mute to the <video> each time a session becomes ready (the element
  // is fresh after a load/seek-restart, and starts at its default volume otherwise).
  useEffect(() => {
    if (ready) applyVolume(volume, muted);
  }, [ready, applyVolume, volume, muted]);
  // Mouse-wheel over the player adjusts volume (5 units per notch); overlays scroll normally.
  const onWheel = useCallback(
    (e: ReactWheelEvent) => {
      if (infoOpenRef.current || helpOpenRef.current) return;
      nudgeVolume(e.deltaY < 0 ? 0.05 : -0.05);
    },
    [nudgeVolume, infoOpenRef, helpOpenRef],
  );
  return { setVol, nudgeVolume, toggleMute, onWheel };
}

// Auto-skip intro/credits. Entering a marker whose auto-skip is on runs a countdown (skipProgress
// 0→1 over autoSkipDelay s, shown on the Skip button); on completion it skips — intro → jump to the
// marker end, credits → next item (binge). The returned refs (skipProgressRef / cancelAutoSkipRef)
// are the forward-declaration bridge the earlier-defined keyboard/back handlers read to cancel a
// running countdown (Esc/Backspace during the countdown cancels it and must NOT navigate back).
export function useAutoSkip(opts: {
  id: string;
  abs: number;
  markers: PlexMarker[] | undefined;
  autoSkipIntro: boolean;
  autoSkipCredits: boolean;
  autoSkipDelay: number;
  nextId: string | null | undefined;
  go: (id: string | null | undefined) => void;
  seekTo: (t: number) => void;
  videoRef: RefObject<HTMLVideoElement | null>;
}): {
  activeMarker: PlexMarker | undefined;
  skipProgress: number | null;
  skipProgressRef: MutableRefObject<number | null>;
  cancelAutoSkipRef: MutableRefObject<() => void>;
  doSkip: (m: PlexMarker) => void;
} {
  const {
    id,
    abs,
    markers,
    autoSkipIntro,
    autoSkipCredits,
    autoSkipDelay,
    nextId,
    go,
    seekTo,
    videoRef,
  } = opts;
  const skipProgressRef = useRef<number | null>(null);
  const cancelAutoSkipRef = useRef<() => void>(() => {});

  const activeMarker: PlexMarker | undefined = markers?.find(
    (m) => abs >= m.start_s && abs < m.end_s - 1,
  );
  const activeMarkerRef = useRef(activeMarker);
  activeMarkerRef.current = activeMarker;

  const [skipProgress, setSkipProgress] = useState<number | null>(null);
  skipProgressRef.current = skipProgress;
  const cancelledMarkerRef = useRef<string | null>(null);
  // Forget a cancelled-skip when the item changes: the ref holds a `${type}-${start_s}` key, and a
  // marker at the same offset on the NEXT episode would otherwise be suppressed by a cancel made on
  // the previous one (auto-skip silently dead for the rest of a binge).
  useEffect(() => {
    cancelledMarkerRef.current = null;
  }, [id]);
  // The running countdown interval, so cancelAutoSkip can actually STOP it — clearing skipProgress
  // alone left the interval ticking, which re-set the progress ~100ms later and skipped anyway.
  const skipTimerRef = useRef<number | null>(null);
  const doSkip = useCallback(
    (m: PlexMarker) => {
      setSkipProgress(null);
      if (m.type === "credits" && nextId) {
        // Binge auto-advance: the episode we're leaving was watched through the credits, so mark IT
        // (the current id, captured here — not the reactive id, which go() is about to change).
        api.plexSetState(id, "watched").catch(() => {});
        go(nextId);
      } else seekTo(m.end_s);
    },
    [id, go, nextId, seekTo],
  );
  const cancelAutoSkip = useCallback(() => {
    const m = activeMarkerRef.current;
    if (m) cancelledMarkerRef.current = `${m.type}-${m.start_s}`; // don't re-arm this same marker
    if (skipTimerRef.current) {
      window.clearInterval(skipTimerRef.current); // actually stop the countdown, not just blank it
      skipTimerRef.current = null;
    }
    setSkipProgress(null);
  }, []);
  cancelAutoSkipRef.current = cancelAutoSkip;
  useEffect(() => {
    const m = activeMarker;
    if (!m) return setSkipProgress(null);
    const key = `${m.type}-${m.start_s}`;
    const enabled = m.type === "intro" ? autoSkipIntro : autoSkipCredits;
    if (!enabled || cancelledMarkerRef.current === key) return setSkipProgress(null);
    if (autoSkipDelay <= 0) return doSkip(m); // immediate
    let elapsed = 0;
    setSkipProgress(0);
    const iv = window.setInterval(() => {
      // Freeze the countdown while the video is paused — otherwise it would fire and auto-seek a
      // deliberately-paused video. It resumes from where it stopped when playback resumes.
      if (videoRef.current?.paused) return;
      elapsed += 0.1;
      const p = Math.min(1, elapsed / autoSkipDelay);
      setSkipProgress(p);
      if (p >= 1) {
        window.clearInterval(iv);
        skipTimerRef.current = null;
        doSkip(m);
      }
    }, 100);
    skipTimerRef.current = iv;
    return () => {
      window.clearInterval(iv);
      skipTimerRef.current = null;
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [
    activeMarker?.type,
    activeMarker?.start_s,
    autoSkipIntro,
    autoSkipCredits,
    autoSkipDelay,
    doSkip,
  ]);

  return { activeMarker, skipProgress, skipProgressRef, cancelAutoSkipRef, doSkip };
}

// Audio/subtitle track selection + subtitle rendering. Owns the selected-ordinal state and the
// audio/subtitle change/cycle handlers; audio switches re-map server-side via loadSession (single
// stream) or client-side via hls.js (multi-rendition), while subtitle switches just flip the single
// mounted <track>. The shared media refs (video/hls/audio/aoff/abs/multiAudio) are owned by the
// component and passed in so this hook and the media session read/write the same substrate.
export function usePlexTracks(opts: {
  id: string;
  detail: PlexItemDetail | undefined;
  sessionK: number;
  subOffset: number;
  subPos: number;
  loadSession: (startAt: number, resumePlay?: boolean) => Promise<void>;
  patchPrefs: (patch: Partial<PlexPlayerPrefs>) => void;
  videoRef: RefObject<HTMLVideoElement | null>;
  hlsRef: RefObject<Hls | null>;
  multiAudioRef: RefObject<boolean>;
  audioRef: MutableRefObject<number | null>;
  aoffRef: MutableRefObject<number>;
  absRef: MutableRefObject<number>;
}): {
  audioOrd: number | null;
  setAudioOrd: (ord: number | null) => void;
  subOrd: number | null;
  setSubOrd: (ord: number | null) => void;
  changeAudio: (ord: number | null) => void;
  changeSubtitle: (ord: number | null) => void;
  cycleAudio: () => void;
  cycleSubtitle: () => void;
  changeAudioOffset: (v: number) => void;
  textSubs: PlexItemDetail["subtitle_streams"];
  selectedSub: PlexItemDetail["subtitle_streams"][number] | null;
  subTrackOffset: number;
} {
  const { id, detail, sessionK, subOffset, subPos, loadSession, patchPrefs } = opts;
  const { videoRef, hlsRef, multiAudioRef, audioRef, aoffRef, absRef } = opts;
  // Selected audio / subtitle stream ordinals (null audio = default first; null subtitle = off).
  const [audioOrd, setAudioOrd] = useState<number | null>(null);
  const [subOrd, setSubOrd] = useState<number | null>(null);
  // Debounced user subtitle offset: avoids re-fetching the VTT on every slider step while dragging.
  const [subOffApplied, setSubOffApplied] = useState(subOffset);
  useEffect(() => {
    const tmr = window.setTimeout(() => setSubOffApplied(subOffset), 250);
    return () => window.clearTimeout(tmr);
  }, [subOffset]);

  // Switching AUDIO re-maps the track server-side, so it restarts the session at the current
  // position (like a seek). The ref is updated synchronously so loadSession sees it.
  const changeAudio = useCallback(
    (ord: number | null) => {
      audioRef.current = ord;
      setAudioOrd(ord);
      // Remember the LANGUAGE (not the ord) so F5 / the next item restores this choice. Menu stays open.
      patchPrefs({
        audioLang:
          ord == null ? "" : (detail?.audio_streams.find((s) => s.ord === ord)?.language ?? ""),
      });
      if (multiAudioRef.current && hlsRef.current) {
        // Multi-rendition: switch the audio track CLIENT-SIDE — instant, same timeline, no restart.
        try {
          hlsRef.current.audioTrack = ord ?? 0;
        } catch {
          /* ignore */
        }
      } else {
        loadSession(absRef.current); // single-audio: re-map the track server-side (session restart)
      }
    },
    [loadSession, detail, patchPrefs, audioRef, multiAudioRef, hlsRef, absRef],
  );
  // Subtitles are native <track>s overlaid by the browser — switching one just flips TextTrack modes
  // (applied by the effect below), NO session restart. Off = null.
  const changeSubtitle = useCallback(
    (ord: number | null) => {
      setSubOrd(ord);
      patchPrefs({
        subLang:
          ord == null ? "" : (detail?.subtitle_streams.find((s) => s.ord === ord)?.language ?? ""),
      });
    },
    [detail, patchPrefs],
  );
  // 'A' cycles audio tracks; 'S' cycles subtitle (off → each text sub → off).
  const cycleAudio = useCallback(() => {
    const streams = detail?.audio_streams ?? [];
    if (streams.length < 2) return;
    const idx = streams.findIndex((s) => s.ord === (audioRef.current ?? 0));
    const next = streams[(idx + 1) % streams.length]!; // length >= 2 (guarded), so in-bounds
    changeAudio(next.ord === 0 ? null : next.ord);
  }, [detail, changeAudio, audioRef]);
  const cycleSubtitle = useCallback(() => {
    const subs = (detail?.subtitle_streams ?? []).filter((s) => s.text);
    const order: (number | null)[] = [null, ...subs.map((s) => s.ord)];
    const i = order.findIndex((o) => o === subOrd);
    changeSubtitle(order[(i + 1) % order.length]!); // order always has [null, ...] → non-empty
  }, [detail, subOrd, changeSubtitle]);
  // Audio A/V-sync offset: persist immediately (for the slider) but debounce the session restart so
  // dragging doesn't respawn ffmpeg on every step.
  const aoffTimer = useRef<number | null>(null);
  const changeAudioOffset = useCallback(
    (v: number) => {
      patchPrefs({ audioOffset: v });
      aoffRef.current = v;
      if (aoffTimer.current) window.clearTimeout(aoffTimer.current);
      aoffTimer.current = window.setTimeout(() => loadSession(absRef.current), 500);
    },
    [patchPrefs, loadSession, aoffRef, absRef],
  );

  // Text subtitles offered in the picker; image subs (PGS/VobSub) can't be shown as text.
  const textSubs = (detail?.subtitle_streams ?? []).filter((s) => s.text);
  // Render ONLY the selected sub as a single <track> (below) — rendering all of them and flipping
  // modes raced (multiple "showing" at once → overlapping HU+EN) especially across a session restart.
  const selectedSub = textSubs.find((s) => s.ord === subOrd) ?? null;
  // The backend shifts the absolute-time VTT by (sessionK − userSubOffset): sessionK aligns it to the
  // HLS session's zero-based clock; subtracting the user offset makes +offset show the sub LATER. Uses
  // the DEBOUNCED user offset so slider drags don't refetch the whole VTT per step.
  // sessionK is already lag-compensated (see loadSession), so it is the true content-zero the VTT
  // must be shifted by; the user offset nudges on top.
  const subTrackOffset = sessionK - subOffApplied;
  // Force the single mounted track to "showing" (its VTT loads on mount; `default` alone can be flaky
  // after a remount). Re-runs when the selection or the shifted-track identity changes (fresh <track>).
  useEffect(() => {
    const video = videoRef.current;
    if (!video) return;
    for (const tr of Array.from(video.textTracks)) tr.mode = "showing";
  }, [subOrd, id, subTrackOffset, videoRef]);

  // Position subtitle cues per the user's vertical setting (subPos). The video fills the viewport
  // height, so a default (line "auto") cue renders at the extreme bottom and clips — line% lifts it.
  // Re-applied on each cue change (hls.js streams cues in as subtitle segments load; no per-cue event).
  useEffect(() => {
    const video = videoRef.current;
    if (!video) return;
    const placeAll = () => {
      for (const tr of Array.from(video.textTracks)) {
        for (const c of Array.from(tr.cues || [])) {
          try {
            (c as VTTCue).snapToLines = false;
            (c as VTTCue).line = subPos;
          } catch {
            /* not a positionable cue */
          }
        }
      }
    };
    const bind = (tr: TextTrack) => tr.addEventListener("cuechange", placeAll);
    for (const tr of Array.from(video.textTracks)) bind(tr);
    const onAddTrack = (e: TrackEvent) => {
      if (e.track) {
        bind(e.track as TextTrack);
        placeAll();
      }
    };
    video.textTracks.addEventListener("addtrack", onAddTrack as EventListener);
    placeAll();
    return () => {
      video.textTracks.removeEventListener("addtrack", onAddTrack as EventListener);
      for (const tr of Array.from(video.textTracks)) tr.removeEventListener("cuechange", placeAll);
    };
  }, [id, subPos, videoRef]);

  return {
    audioOrd,
    setAudioOrd,
    subOrd,
    setSubOrd,
    changeAudio,
    changeSubtitle,
    cycleAudio,
    cycleSubtitle,
    changeAudioOffset,
    textSubs,
    selectedSub,
    subTrackOffset,
  };
}