import { join } from "node:path";
import { APP_NAME } from "./constants.ts";
import { notificationToDesktopText, type NotificationInput } from "./notify-protocol.ts";
import type { Runtime } from "./runtime.ts";
import { $which } from "./which.ts";

export type DesktopNotifierKind = "notify-send" | "gdbus";
export interface DesktopNotifier { kind: DesktopNotifierKind; path: string; }

const cache = new WeakMap<object, DesktopNotifier | null>();
const urgencyByte = { low: 0, normal: 1, critical: 2 } as const;

export function hasLinuxDesktopSession(runtime: Runtime): boolean {
  if (runtime.platform !== "linux" && runtime.platform !== "wsl") return false;
  if (runtime.env.DBUS_SESSION_BUS_ADDRESS) return true;
  const runtimeDir = runtime.env.XDG_RUNTIME_DIR;
  return Boolean(runtimeDir && runtime.existsSync(join(runtimeDir, "bus")));
}

export function resetDesktopNotifierCache(runtime?: Runtime): void {
  if (runtime) cache.delete(runtime);
}

export function resolveDesktopNotifier(runtime: Runtime): DesktopNotifier | null {
  const cached = cache.get(runtime);
  if (cached !== undefined) return cached;
  const notifySend = $which("notify-send", runtime);
  if (notifySend) {
    const notifier = { kind: "notify-send" as const, path: notifySend };
    cache.set(runtime, notifier);
    return notifier;
  }
  const gdbus = $which("gdbus", runtime);
  if (gdbus) {
    const notifier = { kind: "gdbus" as const, path: gdbus };
    cache.set(runtime, notifier);
    return notifier;
  }
  cache.set(runtime, null);
  return null;
}

export function buildDesktopNotifyCommand(notifier: DesktopNotifier, input: NotificationInput): string[] {
  const { title, body, urgency } = notificationToDesktopText(input);
  if (notifier.kind === "notify-send") {
    return [notifier.path, "--app-name", APP_NAME, `--urgency=${urgency}`, "--expire-time=5000", title, body];
  }
  return [
    notifier.path, "call", "--session", "--dest", "org.freedesktop.Notifications",
    "--object-path", "/org/freedesktop/Notifications", "--method",
    "org.freedesktop.Notifications.Notify", APP_NAME, "0", "", title, body, "[]",
    `{"urgency": <byte ${urgencyByte[urgency]}>}`, "5000",
  ];
}

export function resolveLinuxDesktopCommand(input: NotificationInput, runtime: Runtime): { command: string; args: string[] } | null {
  if (!hasLinuxDesktopSession(runtime)) return null;
  const notifier = resolveDesktopNotifier(runtime);
  if (!notifier) return null;
  const argv = buildDesktopNotifyCommand(notifier, input);
  return { command: argv[0]!, args: argv.slice(1) };
}

/** Fire-and-forget helper; returns whether a notifier was resolved and attempted. */
export function sendLinuxDesktopNotification(input: NotificationInput, runtime: Runtime): boolean {
  const resolved = resolveLinuxDesktopCommand(input, runtime);
  if (!resolved) return false;
  runtime.spawnDetached(resolved.command, resolved.args);
  return true;
}