'use strict';

const Pager = (() => {
  const SCREEN_WIDTH = 480;
  const SCREEN_HEIGHT = 222;
  const FB_STRIDE = SCREEN_WIDTH * 4;
  const PAGER_WIDTH = 745;
  const MAX_QUEUED_KEYS = 24;

  const KEY_MAP = {
    'LEFT.png': 'ArrowLeft',
    'UP.png': 'ArrowUp',
    'RIGHT.png': 'ArrowRight',
    'DOWN.png': 'ArrowDown',
    'A_Button.png': 'Enter',
    'B_Button.png': 'Escape'
  };

  let panel = null;
  let bodyEl = null;
  let table = null;
  let pager = null;
  let canvas = null;
  let screenerr = null;
  let keyws = null;
  let screenws = null;
  let wantOpen = false;
  let retryTimer = null;
  let retryMs = 400;
  const pendingKeys = [];

  function ensure() {
    if (table) return;
    panel = document.getElementById('pager-panel');
    bodyEl = document.getElementById('pager-body');
    table = document.getElementById('pager_ui');
    pager = document.getElementById('pager');
    canvas = document.getElementById('pager_canvas');
    screenerr = document.getElementById('pager_error');
    table.querySelectorAll('img.pager-btn').forEach((img) => {
      const src = img.getAttribute('src').split('/').pop();
      const key = KEY_MAP[src];
      if (!key) return;
      img.setAttribute('alt', key.replace('Arrow', ''));
      img.addEventListener('pointerdown', (event) => {
        event.preventDefault();
        press(img, key);
      });
    });
    const retry = document.getElementById('screen_retry');
    if (retry) retry.addEventListener('click', () => {
      retryMs = 400;
      connect();
    });
  }

  function press(el, key) {
    el.classList.add('pressed');
    setTimeout(() => el.classList.remove('pressed'), 80);
    sendKey(key);
  }

  function queueKey(k) {
    pendingKeys.push(k);
    while (pendingKeys.length > MAX_QUEUED_KEYS) pendingKeys.shift();
  }

  function flushKeys() {
    while (pendingKeys.length && keyws && keyws.readyState === WebSocket.OPEN) {
      try { keyws.send(pendingKeys.shift()); }
      catch (e) { break; }
    }
  }

  function sendKey(k) {
    if (keyws && keyws.readyState === WebSocket.OPEN) {
      try { keyws.send(k); return true; }
      catch (e) {}
    }
    queueKey(k);
    if (wantOpen) connectKeys();
    return false;
  }

  function renderRGBAFrame(bytes) {
    if (bytes.length < FB_STRIDE * SCREEN_HEIGHT) {
      console.warn('pager frame too small for 480x222', bytes.length);
      return;
    }
    const ctx = canvas.getContext('2d');
    const imageData = ctx.createImageData(SCREEN_WIDTH, SCREEN_HEIGHT);
    const dst = imageData.data;
    let di = 0;
    for (let y = 0; y < SCREEN_HEIGHT; y++) {
      const rowStart = y * FB_STRIDE;
      for (let x = 0; x < SCREEN_WIDTH; x++) {
        const si = rowStart + x * 4;
        dst[di] = bytes[si];
        dst[di + 1] = bytes[si + 1];
        dst[di + 2] = bytes[si + 2];
        dst[di + 3] = bytes[si + 3];
        di += 4;
      }
    }
    ctx.putImageData(imageData, 0, 0);
    pager.src = canvas.toDataURL('image/png');
  }

  function showError(show) {
    if (screenerr) screenerr.hidden = !show;
  }

  function scheduleReconnect() {
    if (!wantOpen) return;
    clearTimeout(retryTimer);
    retryTimer = setTimeout(() => {
      if (!wantOpen) return;
      connectScreen();
      connectKeys();
    }, retryMs);
    retryMs = Math.min(5000, Math.max(400, retryMs * 2));
  }

  function connectScreen() {
    if (!wantOpen) return;
    if (screenws && (screenws.readyState === WebSocket.OPEN || screenws.readyState === WebSocket.CONNECTING)) return;
    try {
      const sock = new WebSocket(App.pagerScreenWs);
      sock.binaryType = 'arraybuffer';
      screenws = sock;
      sock.onopen = () => {
        retryMs = 400;
        if (keyws && keyws.readyState === WebSocket.OPEN) showError(false);
      };
      sock.onmessage = (ev) => {
        showError(false);
        if (ev.data instanceof ArrayBuffer) renderRGBAFrame(new Uint8Array(ev.data));
        else if (ev.data && ev.data.arrayBuffer) ev.data.arrayBuffer().then((b) => renderRGBAFrame(new Uint8Array(b)));
      };
      sock.onerror = () => { showError(true); };
      sock.onclose = () => {
        if (screenws === sock) screenws = null;
        showError(true);
        scheduleReconnect();
      };
    } catch (e) {
      showError(true);
      scheduleReconnect();
    }
  }

  function connectKeys() {
    if (!wantOpen) return;
    if (keyws && (keyws.readyState === WebSocket.OPEN || keyws.readyState === WebSocket.CONNECTING)) return;
    try {
      const sock = new WebSocket(App.pagerKeysWs);
      keyws = sock;
      sock.onopen = () => {
        retryMs = 400;
        flushKeys();
        if (screenws && screenws.readyState === WebSocket.OPEN) showError(false);
      };
      sock.onclose = () => {
        if (keyws === sock) keyws = null;
        scheduleReconnect();
      };
      sock.onerror = () => { try { sock.close(); } catch (e2) {} };
    } catch (e) {
      keyws = null;
      scheduleReconnect();
    }
  }

  function connect() {
    connectScreen();
    connectKeys();
  }

  function disconnect() {
    wantOpen = false;
    clearTimeout(retryTimer);
    retryTimer = null;
    pendingKeys.length = 0;
    if (screenws) { try { screenws.close(); } catch (e) {} screenws = null; }
    if (keyws) { try { keyws.close(); } catch (e) {} keyws = null; }
  }

  function applyScale() {
    if (!bodyEl || !table) return;
    const availableWidth = bodyEl.clientWidth - 20;
    const scale = Math.min(1, availableWidth / PAGER_WIDTH);
    table.style.zoom = String(scale);
    table.style.marginBottom = '';
  }

  function toggle() {
    ensure();
    if (panel.classList.contains('hidden')) {
      panel.classList.remove('hidden');
      document.getElementById('pager-btn').classList.add('active');
      applyScale();
      wantOpen = true;
      retryMs = 400;
      connect();
      try { pager.focus(); } catch (e) {}
    } else {
      panel.classList.add('hidden');
      document.getElementById('pager-btn').classList.remove('active');
      disconnect();
    }
  }

  function isOpen() {
    return !!panel && !panel.classList.contains('hidden');
  }

  function close() {
    if (isOpen()) toggle();
  }

  window.addEventListener('resize', () => {
    if (table && panel && !panel.classList.contains('hidden')) applyScale();
  });

  document.addEventListener('keydown', (e) => {
    if (!isOpen()) return;
    const t = e.target;
    if (t && (t.tagName === 'INPUT' || t.tagName === 'TEXTAREA' || t.tagName === 'SELECT'
              || t.tagName === 'BUTTON' || t.tagName === 'A' || t.isContentEditable)) return;
    if (e.ctrlKey || e.metaKey || e.altKey) return;
    const keys = ['ArrowLeft', 'ArrowUp', 'ArrowRight', 'ArrowDown', 'Enter', 'Escape'];
    if (keys.indexOf(e.key) === -1) return;
    if (e.key.indexOf('Arrow') === 0) e.preventDefault();
    if (!e.repeat) sendKey(e.key);
  });

  return { toggle, close, isOpen };
})();