import { useCallback, useEffect, useRef, useState } from 'react';
import { Bomb, Loader2, Play, RefreshCw } from 'lucide-react';
import { useClient } from 'hooks/useClient';
import type { RfbError } from './rfb';
import { RfbClient } from './rfb';

type SessionStatus = {
  installed: boolean;
  running: boolean;
  window: { width: number; height: number; x: number; y: number } | null;
};

// The framebuffer is bigger than the board — the board sits at 0,0 and the rest is empty desktop.
// Rendering into an offscreen canvas the size of the framebuffer and showing only the board's corner
// of it is what makes this look like a window rather than a small game adrift in grey.
const VISIBLE = { width: 164, height: 226 };

const BUTTON_MASK: Record<number, number> = { 0: 1, 1: 2, 2: 4 };

// Plugin panels have no localisation mechanism yet — `officerdev`'s `useTranslation`/`panelCatalogs`
// (merged by `I18nBridge`) is platform-internal and not exported from the barrel, and
// `scripts/i18n/scan-hardcoded.ts` explicitly does not scan `plugins/`. So these stay plain English
// sentences rather than catalog keys, same as every other plugin's user-facing strings.
const describeRfbError = (error: RfbError): string => {
  switch (error.code) {
    case 'connectionFailed':
      return 'The connection to the Minesweeper session failed.';
    case 'refused':
      return 'The VNC server refused the connection.';
    case 'authUnsupported':
      return 'The VNC server wants authentication, which this client does not implement.';
    case 'handshakeRejected':
      return 'The VNC server rejected the handshake.';
    case 'unknownMessage':
      return `The VNC server sent an unknown message type (${error.type}).`;
    case 'unknownEncoding':
      return `The VNC server used encoding ${error.encoding}, which this client did not ask for.`;
  }
};

export const MinesweeperPanel = () => {
  // useClient() rebuilds its verbs on EVERY render, so putting one in a dependency list gives that
  // list a new identity every render. Held in a ref instead — the same fix the Jellyfin player needed
  // after its playback reports silently stopped for days. Getting this wrong here meant `refresh` was
  // unstable, its mount effect re-ran every render, and each run set state and caused another render:
  // an endless fetch loop that starved the socket and left the panel saying "connecting…" forever.
  const client = useClient();
  const clientRef = useRef(client);
  clientRef.current = client;
  const canvasRef = useRef<HTMLCanvasElement | null>(null);
  const offscreenRef = useRef<HTMLCanvasElement | null>(null);
  const rfbRef = useRef<RfbClient | null>(null);
  const buttonsRef = useRef(0);
  const geometryRef = useRef(VISIBLE);

  const [status, setStatus] = useState<SessionStatus | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [connected, setConnected] = useState(false);
  const [busy, setBusy] = useState(false);

  const adopt = useCallback((next: SessionStatus) => {
    // The board is 152x214 on beginner and wider on the other difficulties. Taking the size from
    // status means the canvas is right on the first paint instead of after the first poll.
    if (next.window) geometryRef.current = { width: next.window.width, height: next.window.height };
    setStatus(next);
  }, []);

  const refresh = useCallback(async () => {
    try {
      adopt(await clientRef.current.get<SessionStatus>('/minesweeper/status'));
    } catch {
      setError('Could not reach the server.');
    }
  }, [adopt]);

  useEffect(() => {
    void refresh();
  }, [refresh]);

  const start = async () => {
    setBusy(true);
    setError(null);
    try {
      adopt(await clientRef.current.post<SessionStatus>('/minesweeper/start', {}));
    } catch {
      setError('The session would not start. Is wine-minesweeper installed on the server?');
    } finally {
      setBusy(false);
    }
  };

  // Paint the visible canvas from the offscreen one. Only the board's rectangle is copied, so the
  // surrounding desktop never reaches the screen.
  const present = useCallback(() => {
    const canvas = canvasRef.current;
    const offscreen = offscreenRef.current;
    if (!canvas || !offscreen) return;
    const context = canvas.getContext('2d');
    if (!context) return;
    const { width, height } = geometryRef.current;
    if (canvas.width !== width || canvas.height !== height) {
      canvas.width = width;
      canvas.height = height;
    }
    context.drawImage(offscreen, 0, 0, width, height, 0, 0, width, height);
  }, []);

  useEffect(() => {
    if (!status?.running) return;

    const scheme = window.location.protocol === 'https:' ? 'wss' : 'ws';
    // 'BEARER_TOKEN' is the key the rest of the app uses (Terminal.tsx, useAudioRecording). Reading
    // 'token' here sent an empty string, and upgradeWs answered 401 before any RFB byte was exchanged.
    const token = localStorage.getItem('BEARER_TOKEN') ?? sessionStorage.getItem('BEARER_TOKEN') ?? '';
    // Plugin relay, not a platform websocket provider: `/api/plugin-ws/minesweeper` rather than the old
    // `/api/minesweeper/ws`. Same byte relay onto x11vnc, mounted by the plugin instead of the shell.
    const url = `${scheme}://${window.location.host}/api/plugin-ws/minesweeper?token=${encodeURIComponent(token)}`;

    const rfb = new RfbClient(url, {
      onReady: (width, height) => {
        const offscreen = document.createElement('canvas');
        offscreen.width = width;
        offscreen.height = height;
        offscreenRef.current = offscreen;
        setConnected(true);
        setError(null);
      },
      onFrame: (image, x, y) => {
        offscreenRef.current?.getContext('2d')?.putImageData(image, x, y);
        present();
      },
      onCopyRect: (from, to) => {
        const offscreen = offscreenRef.current;
        const context = offscreen?.getContext('2d');
        if (!offscreen || !context) return;
        context.drawImage(offscreen, from.x, from.y, to.w, to.h, to.x, to.y, to.w, to.h);
        present();
      },
      onResize: (width, height) => {
        const offscreen = offscreenRef.current;
        if (offscreen) {
          offscreen.width = width;
          offscreen.height = height;
        }
        rfb.requestUpdate(false);
      },
      onError: (rfbError) => setError(describeRfbError(rfbError)),
      onClose: () => setConnected(false),
    });

    rfbRef.current = rfb;
    return () => {
      rfb.close();
      rfbRef.current = null;
      setConnected(false);
    };
  }, [status?.running, present]);

  // The board resizes when the difficulty changes, and nothing in RFB announces that — the framebuffer
  // stays the same size. Polling the window geometry is what keeps the visible canvas matched to it.
  useEffect(() => {
    if (!connected) return;
    const timer = setInterval(async () => {
      try {
        const next = await clientRef.current.get<SessionStatus>('/minesweeper/status');
        if (!next.window) return;
        const { width, height } = next.window;
        if (width !== geometryRef.current.width || height !== geometryRef.current.height) {
          geometryRef.current = { width, height };
          present();
        }
      } catch {
        /* a failed poll is not worth surfacing; the next one will do */
      }
    }, 4000);
    return () => clearInterval(timer);
  }, [connected, present]);

  const toFramebuffer = (ev: React.MouseEvent<HTMLCanvasElement>) => {
    const rect = ev.currentTarget.getBoundingClientRect();
    const scaleX = ev.currentTarget.width / rect.width;
    const scaleY = ev.currentTarget.height / rect.height;
    return { x: (ev.clientX - rect.left) * scaleX, y: (ev.clientY - rect.top) * scaleY };
  };

  const onPointer = (ev: React.MouseEvent<HTMLCanvasElement>, kind: 'down' | 'up' | 'move') => {
    const rfb = rfbRef.current;
    if (!rfb) return;
    ev.preventDefault();

    if (kind !== 'move') {
      const bit = BUTTON_MASK[ev.button] ?? 0;
      buttonsRef.current = kind === 'down' ? buttonsRef.current | bit : buttonsRef.current & ~bit;
    }
    const { x, y } = toFramebuffer(ev);
    rfb.pointer(x, y, buttonsRef.current);
  };

  if (status && !status.installed) {
    return (
      <Centred>
        <Bomb className="size-8 text-muted-foreground" />
        <p className="text-sm text-muted-foreground">Minesweeper is not installed on this server.</p>
        {/* The package name sits at the end so the sentence is one key rather than two around an
            inline element — see docs/localization.md on the fragmentation that produces. */}
        <p className="max-w-sm text-center text-xs text-muted-foreground">
          It needs wine, a 32-bit prefix, and this package beside the platform: <code>wine-minesweeper</code>
        </p>
      </Centred>
    );
  }

  if (status && !status.running) {
    return (
      <Centred>
        <Bomb className="size-8 text-muted-foreground" />
        <p className="text-sm text-muted-foreground">The Minesweeper session is not running.</p>
        {error ? <p className="text-xs text-destructive">{error}</p> : null}
        <button
          type="button"
          onClick={start}
          disabled={busy}
          className="flex items-center gap-2 rounded-md bg-primary px-3 py-1.5 text-sm text-primary-foreground disabled:opacity-60"
        >
          {busy ? <Loader2 className="size-4 animate-spin" /> : <Play className="size-4" />}
          {busy ? 'Starting' : 'Start it'}
        </button>
      </Centred>
    );
  }

  return (
    <div className="flex size-full flex-col items-center justify-center gap-3 bg-muted/30 p-4">
      <canvas
        ref={canvasRef}
        width={VISIBLE.width}
        height={VISIBLE.height}
        onMouseDown={(ev) => onPointer(ev, 'down')}
        onMouseUp={(ev) => onPointer(ev, 'up')}
        onMouseMove={(ev) => onPointer(ev, 'move')}
        onContextMenu={(ev) => ev.preventDefault()}
        // Nearest-neighbour: this is a 16px-per-cell bitmap from 1995 and smoothing it looks like a
        // photograph of a screen rather than the screen.
        className="rounded-sm shadow-lg [image-rendering:pixelated]"
        style={{ cursor: connected ? 'default' : 'progress' }}
      />
      <div className="flex items-center gap-3 text-xs text-muted-foreground">
        <span>{connected ? 'connected' : 'connecting…'}</span>
        <button type="button" onClick={() => void refresh()} className="flex items-center gap-1 hover:text-foreground">
          <RefreshCw className="size-3" /> refresh
        </button>
      </div>
      {error ? <p className="text-xs text-destructive">{error}</p> : null}
    </div>
  );
};

const Centred = ({ children }: { children: React.ReactNode }) => (
  <div className="flex size-full flex-col items-center justify-center gap-3 p-6">{children}</div>
);