let baseTitle = "ihasmail";
let faviconCanvas: HTMLCanvasElement | null = null;
let baseFavicon: HTMLImageElement | null = null;

export function setBaseTitle(t: string) {
  baseTitle = t;
}

/** Update document title and favicon badge with unread count. */
export function setUnreadBadge(count: number): void {
  document.title = count > 0 ? `(${count > 999 ? "999+" : count}) ${baseTitle}` : baseTitle;
  try {
    const link = document.querySelector<HTMLLinkElement>('link[rel="icon"][type="image/png"]');
    if (!link) return;
    if (!baseFavicon) {
      baseFavicon = new Image();
      baseFavicon.src = "/img/favicon-64.png";
      baseFavicon.onload = () => setUnreadBadge(count);
      return;
    }
    if (!baseFavicon.complete) return;
    if (count <= 0) {
      link.href = "/img/favicon-64.png";
      return;
    }
    faviconCanvas ??= document.createElement("canvas");
    const c = faviconCanvas;
    c.width = 64;
    c.height = 64;
    const ctx = c.getContext("2d");
    if (!ctx) return;
    ctx.clearRect(0, 0, 64, 64);
    ctx.drawImage(baseFavicon, 0, 0, 64, 64);
    ctx.fillStyle = "#dc2626";
    ctx.beginPath();
    ctx.arc(46, 18, 16, 0, Math.PI * 2);
    ctx.fill();
    ctx.fillStyle = "#fff";
    ctx.font = "bold 22px system-ui, sans-serif";
    ctx.textAlign = "center";
    ctx.textBaseline = "middle";
    ctx.fillText(count > 99 ? "99" : String(count), 46, 19);
    link.href = c.toDataURL("image/png");
  } catch {
    /* ignore */
  }
}

export async function requestNotificationPermission(): Promise<NotificationPermission> {
  if (!("Notification" in window)) return "denied";
  if (Notification.permission !== "default") return Notification.permission;
  try {
    return await Notification.requestPermission();
  } catch {
    return "denied";
  }
}

export function showNotification(title: string, opts: NotificationOptions & { onClick?: () => void } = {}): void {
  if (!("Notification" in window) || Notification.permission !== "granted") return;
  if (document.visibilityState === "visible" && document.hasFocus()) return;
  try {
    const n = new Notification(title, { icon: "/img/icon-192.png", badge: "/img/favicon-64.png", ...opts });
    n.onclick = () => {
      window.focus();
      opts.onClick?.();
      n.close();
    };
    setTimeout(() => n.close(), 8000);
  } catch {
    /* ignore */
  }
}

let audioCtx: AudioContext | null = null;
/** Short, soft "ding" using WebAudio (no asset needed). */
export function playNewMailSound(): void {
  try {
    audioCtx ??= new AudioContext();
    const ctx = audioCtx;
    const o = ctx.createOscillator();
    const g = ctx.createGain();
    o.type = "sine";
    o.frequency.setValueAtTime(880, ctx.currentTime);
    o.frequency.exponentialRampToValueAtTime(1320, ctx.currentTime + 0.08);
    g.gain.setValueAtTime(0.0001, ctx.currentTime);
    g.gain.exponentialRampToValueAtTime(0.15, ctx.currentTime + 0.02);
    g.gain.exponentialRampToValueAtTime(0.0001, ctx.currentTime + 0.4);
    o.connect(g).connect(ctx.destination);
    o.start();
    o.stop(ctx.currentTime + 0.45);
  } catch {
    /* ignore */
  }
}