"use client";

import { useEffect, useState } from "react";

export interface BeforeInstallPromptEvent extends Event {
  prompt: () => Promise<void>;
  userChoice: Promise<{ outcome: "accepted" | "dismissed" }>;
}

function isStandalone(): boolean {
  if (typeof window === "undefined") return false;
  return (
    window.matchMedia("(display-mode: standalone)").matches ||
    // iOS Safari's own (non-standard, but the only signal it exposes).
    (window.navigator as Navigator & { standalone?: boolean }).standalone === true
  );
}

function isIos(): boolean {
  if (typeof navigator === "undefined") return false;
  return /iphone|ipad|ipod/i.test(navigator.userAgent);
}

/**
 * Shared `beforeinstallprompt` capture + standalone/iOS detection — the
 * one PWA install implementation both `InstallAppButton` (Settings, every
 * role) and `WelcomeInstallCard` (the unauthenticated Welcome page) use.
 * See the brief's explicit "do not create a competing second installer".
 * All detection lives in `useEffect`, never a `useState` lazy
 * initializer — reading `window`/`navigator` during the initializer would
 * run during SSR too and mismatch the client's first render (the same
 * hydration bug this app's push-subscribe-toggle.tsx fixed in Phase 7).
 */
export function useInstallPrompt() {
  const [deferredPrompt, setDeferredPrompt] = useState<BeforeInstallPromptEvent | null>(null);
  const [installed, setInstalled] = useState(false);
  const [ios, setIos] = useState(false);

  useEffect(() => {
    // Async chain, not a direct setState call in the effect body — same
    // pattern push-subscribe-toggle.tsx uses (see that file's own
    // comment) to satisfy react-hooks/set-state-in-effect while still
    // reading browser-only APIs that can't run during SSR.
    void Promise.resolve().then(() => {
      setInstalled(isStandalone());
      setIos(isIos());
    });

    const onBeforeInstallPrompt = (event: Event) => {
      event.preventDefault();
      setDeferredPrompt(event as BeforeInstallPromptEvent);
    };
    const onInstalled = () => {
      setInstalled(true);
      setDeferredPrompt(null);
    };
    window.addEventListener("beforeinstallprompt", onBeforeInstallPrompt);
    window.addEventListener("appinstalled", onInstalled);
    return () => {
      window.removeEventListener("beforeinstallprompt", onBeforeInstallPrompt);
      window.removeEventListener("appinstalled", onInstalled);
    };
  }, []);

  const promptInstall = async (): Promise<void> => {
    if (!deferredPrompt) return;
    await deferredPrompt.prompt();
    await deferredPrompt.userChoice;
    setDeferredPrompt(null);
  };

  return { installed, ios, canPromptNatively: !!deferredPrompt, promptInstall };
}