"use client";

import { useEffect, useState } from "react";
import type Hls from "hls.js";
import type { CurrentBroadcastResponse } from "@/lib/types";

interface StatsPanelProps {
  videoRef: React.RefObject<HTMLVideoElement | null>;
  hlsRef: React.RefObject<Hls | null>;
  streamingProtocol?: "hls" | "direct_file";
  broadcast?: CurrentBroadcastResponse | null;
}

interface Stats {
  protocol: string;
  resolution: string;
  bitrate: string;
  bandwidth: string;
  buffer: string;
  offset: string;
  slotEnds: string;
}

function fmtSecs(s: number) {
  const h = Math.floor(s / 3600);
  const m = Math.floor((s % 3600) / 60);
  const sec = Math.floor(s % 60);
  if (h > 0) return `${h}:${String(m).padStart(2, "0")}:${String(sec).padStart(2, "0")}`;
  return `${String(m).padStart(2, "0")}:${String(sec).padStart(2, "0")}`;
}

function fmtKbps(bps: number) {
  if (!bps) return "--";
  return `${Math.round(bps / 1000).toLocaleString()} kbps`;
}

function getBufferAhead(video: HTMLVideoElement) {
  const ct = video.currentTime;
  for (let i = 0; i < video.buffered.length; i++) {
    if (video.buffered.start(i) <= ct && ct <= video.buffered.end(i)) {
      return video.buffered.end(i) - ct;
    }
  }
  return 0;
}

export function StatsPanel({ videoRef, hlsRef, streamingProtocol, broadcast }: StatsPanelProps) {
  const [stats, setStats] = useState<Stats>({
    protocol: "--",
    resolution: "--",
    bitrate: "--",
    bandwidth: "--",
    buffer: "--",
    offset: "--",
    slotEnds: "--",
  });

  useEffect(() => {
    const update = () => {
      const video = videoRef.current;
      const hls = hlsRef.current;

      const protocol =
        streamingProtocol === "direct_file"
          ? "Direct file"
          : hls
            ? "HLS (hls.js)"
            : "HLS (native)";

      let resolution = "--";
      let bitrate = "--";
      let bandwidth = "--";

      if (hls) {
        const level = hls.currentLevel >= 0 ? hls.levels[hls.currentLevel] : null;
        if (level) {
          resolution = `${level.width}×${level.height}`;
          bitrate = fmtKbps(level.bitrate);
        }
        if (hls.bandwidthEstimate > 0) {
          bandwidth = fmtKbps(hls.bandwidthEstimate);
        }
      }

      const buffer = video ? `${getBufferAhead(video).toFixed(1)} s` : "--";
      const offset = video ? fmtSecs(video.currentTime) : "--";

      let slotEnds = "--";
      if (broadcast?.slot.end_at) {
        const secsLeft = (new Date(broadcast.slot.end_at).getTime() - Date.now()) / 1000;
        if (secsLeft > 0) {
          slotEnds = `in ${fmtSecs(secsLeft)}`;
        } else {
          slotEnds = "ending…";
        }
      }

      setStats({ protocol, resolution, bitrate, bandwidth, buffer, offset, slotEnds });
    };

    update();
    const id = setInterval(update, 1000);
    return () => clearInterval(id);
  }, [videoRef, hlsRef, streamingProtocol, broadcast]);

  return (
    <div className="pointer-events-none absolute bottom-20 left-4 z-30 min-w-56 rounded-lg border border-white/10 bg-black/75 px-4 py-3 backdrop-blur-sm">
      <div className="mb-2.5 flex items-center gap-2">
        <span className="text-[10px] font-bold uppercase tracking-widest text-violet-400">
          Stats for nerds
        </span>
        <span className="rounded bg-green-900/50 px-1.5 py-0.5 text-[9px] text-green-400">
          LIVE
        </span>
      </div>
      <table className="w-full border-collapse font-mono text-[11px]">
        <tbody>
          <tr>
            <td className="pr-4 text-zinc-500">Protocol</td>
            <td className="text-zinc-200">{stats.protocol}</td>
          </tr>
          <tr>
            <td className="pr-4 text-zinc-500">Resolution</td>
            <td className="text-zinc-200">{stats.resolution}</td>
          </tr>
          <tr>
            <td className="pr-4 text-zinc-500">Bitrate</td>
            <td className="text-zinc-200">{stats.bitrate}</td>
          </tr>
          <tr>
            <td className="pr-4 text-zinc-500">Bandwidth est.</td>
            <td className="text-green-400">{stats.bandwidth}</td>
          </tr>
          <tr>
            <td className="pr-4 text-zinc-500">Buffer</td>
            <td className="text-zinc-200">{stats.buffer}</td>
          </tr>
          <tr className="border-t border-white/10">
            <td className="pr-4 pt-2 text-zinc-500">Offset</td>
            <td className="pt-2 text-zinc-200">{stats.offset}</td>
          </tr>
          <tr>
            <td className="pr-4 text-zinc-500">Slot ends</td>
            <td className="text-zinc-200">{stats.slotEnds}</td>
          </tr>
        </tbody>
      </table>
    </div>
  );
}