import { type RefObject, useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import type Hls from "hls.js";
import { X } from "lucide-react";
import { buildStatRows, type HlsLevelInfo, type StatRow } from "../lib/plexStats";

// "Stats for nerds" debug overlay (E6 S2). Samples the live HTML5 <video> + hls.js state once a second
// and renders the active mode, resolution, codec/bitrate, dropped frames, buffer, hls level and session
// offset. No data layer — the refs are already in hand. Doubles as the S1 verification surface (it shows
// the transcode mode + that the re-encode is engaged). Toggled with "d" / the gauge button / its X.
export function PlexStatsOverlay({
  videoRef,
  hlsRef,
  playable,
  hwRef,
  tonemapRef,
  sessionStartRef,
  absRef,
  durationRef,
  onClose,
}: {
  videoRef: RefObject<HTMLVideoElement | null>;
  hlsRef: RefObject<Hls | null>;
  playable: string;
  hwRef: RefObject<boolean | null>; // active transcode encoder: true=GPU, false=CPU, null=not transcode
  tonemapRef: RefObject<boolean | null>; // HW HDR→SDR tonemap engaged (adds a "· HDR→SDR" mode tag)
  sessionStartRef: RefObject<number>;
  absRef: RefObject<number>;
  durationRef: RefObject<number>;
  onClose: () => void;
}) {
  const { t } = useTranslation();
  const [rows, setRows] = useState<StatRow[]>([]);

  useEffect(() => {
    const sample = () => {
      const v = videoRef.current;
      const hls = hlsRef.current;

      let dropped = 0;
      let total = 0;
      try {
        const q = v?.getVideoPlaybackQuality?.();
        if (q) {
          dropped = q.droppedVideoFrames;
          total = q.totalVideoFrames;
        }
      } catch {
        /* getVideoPlaybackQuality unsupported — leave 0/0 (renders as a dash) */
      }

      let bufferAhead = 0;
      if (v) {
        const now = v.currentTime;
        for (let i = 0; i < v.buffered.length; i++) {
          if (now >= v.buffered.start(i) && now <= v.buffered.end(i)) {
            bufferAhead = v.buffered.end(i) - now;
            break;
          }
        }
      }

      let level: HlsLevelInfo | null = null;
      if (hls) {
        // currentLevel is -1 while auto-ABR hasn't settled; fall back to loadLevel for the res/bitrate.
        const idx = hls.currentLevel >= 0 ? hls.currentLevel : hls.loadLevel;
        const lv = idx >= 0 ? hls.levels?.[idx] : undefined;
        level = {
          index: hls.currentLevel,
          total: hls.levels?.length ?? 0,
          width: lv?.width,
          height: lv?.height,
          bitrate: lv?.bitrate,
          videoCodec: lv?.videoCodec,
          audioCodec: lv?.audioCodec,
        };
      }

      setRows(
        buildStatRows({
          playable,
          hwEncoder: hwRef.current,
          tonemap: tonemapRef.current,
          transport: hls ? "hls" : "direct",
          videoWidth: v?.videoWidth ?? 0,
          videoHeight: v?.videoHeight ?? 0,
          droppedFrames: dropped,
          totalFrames: total,
          bufferAheadS: bufferAhead,
          hlsLevel: level,
          sessionStartS: sessionStartRef.current ?? 0,
          abs: absRef.current ?? 0,
          duration: durationRef.current ?? 0,
        }),
      );
    };
    sample();
    const iv = setInterval(sample, 1000);
    return () => clearInterval(iv);
  }, [videoRef, hlsRef, playable, hwRef, tonemapRef, sessionStartRef, absRef, durationRef]);

  return (
    <div
      role="region"
      aria-label={t("plex.player.stats.title")}
      onClick={(e) => e.stopPropagation()}
      className="absolute left-4 top-16 z-menu w-64 rounded-xl border border-white/15 bg-black/80 p-3 text-white shadow-2xl backdrop-blur-sm"
    >
      <div className="mb-2 flex items-center justify-between">
        <span className="text-xs font-semibold uppercase tracking-wide text-white/70">
          {t("plex.player.stats.title")}
        </span>
        <button
          onClick={onClose}
          aria-label={t("plex.player.close")}
          className="rounded p-0.5 text-white/60 hover:bg-white/10 hover:text-white"
        >
          <X className="h-4 w-4" />
        </button>
      </div>
      {/* No aria-live here: the rows re-sample every second, so a live region would make a screen
          reader announce the changing values continuously and drown out real player announcements.
          The overlay is a role="region" (labelled above) a user reads on demand, not a status feed. */}
      <dl className="grid grid-cols-[auto_1fr] gap-x-3 gap-y-1 text-2xs">
        {rows.map((r) => (
          <div key={r.key} className="contents">
            <dt className="text-white/55">{t(r.labelKey)}</dt>
            <dd className="text-right font-mono tabular-nums text-white/90">{r.value}</dd>
          </div>
        ))}
      </dl>
    </div>
  );
}