"use client";

import { useEffect, useState } from "react";
import { X, Download, Share } from "lucide-react";
import { Button } from "@/components/ui/button";

const DISMISSED_KEY = "epicure:install-prompt-dismissed";
const IOS_DISMISSED_KEY = "epicure:ios-install-hint-dismissed";

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

function isStandalone(): boolean {
  return window.matchMedia("(display-mode: standalone)").matches || (navigator as { standalone?: boolean }).standalone === true;
}

/** iOS Safari has no beforeinstallprompt and no programmatic install API at
 * all (Apple restriction, not a capability gap we can code around) — the
 * only path is the user manually using the Share sheet, so the best we can
 * do is tell them that. */
function isIosSafari(): boolean {
  const ua = navigator.userAgent;
  const isIos = /iPad|iPhone|iPod/.test(ua) || (ua.includes("Macintosh") && navigator.maxTouchPoints > 1);
  const isSafari = /^((?!chrome|android|crios|fxios).)*safari/i.test(ua);
  return isIos && isSafari;
}

/** Chromium (Chrome/Edge/Android) shows an "Install" button driven by the
 * real beforeinstallprompt event; iOS Safari — which never fires it — gets
 * a static instructional banner instead. Both are no-ops once the app is
 * already installed (standalone display mode). */
export function InstallPrompt() {
  const [deferredEvent, setDeferredEvent] = useState<BeforeInstallPromptEvent | null>(null);
  const [dismissed, setDismissed] = useState(() => typeof localStorage !== "undefined" && localStorage.getItem(DISMISSED_KEY) === "true");
  const [showIosHint, setShowIosHint] = useState(
    () => typeof window !== "undefined" && isIosSafari() && !isStandalone() && localStorage.getItem(IOS_DISMISSED_KEY) !== "true"
  );

  useEffect(() => {
    function handler(e: Event) {
      e.preventDefault();
      setDeferredEvent(e as BeforeInstallPromptEvent);
    }
    window.addEventListener("beforeinstallprompt", handler);
    return () => window.removeEventListener("beforeinstallprompt", handler);
  }, []);

  function dismiss() {
    localStorage.setItem(DISMISSED_KEY, "true");
    setDismissed(true);
  }

  function dismissIosHint() {
    localStorage.setItem(IOS_DISMISSED_KEY, "true");
    setShowIosHint(false);
  }

  async function install() {
    if (!deferredEvent) return;
    await deferredEvent.prompt();
    await deferredEvent.userChoice;
    setDeferredEvent(null);
  }

  if (showIosHint) {
    return (
      <div className="fixed bottom-4 left-1/2 z-50 flex w-[calc(100%-2rem)] max-w-sm -translate-x-1/2 items-center gap-3 rounded-lg border bg-background p-3 shadow-lg">
        <Share className="h-5 w-5 shrink-0 text-muted-foreground" />
        <div className="min-w-0 flex-1">
          <p className="text-sm font-medium">Install Epicure</p>
          <p className="text-xs text-muted-foreground">Tap Share, then &quot;Add to Home Screen&quot;.</p>
        </div>
        <button type="button" onClick={dismissIosHint} aria-label="Dismiss" className="text-muted-foreground hover:text-foreground">
          <X className="h-4 w-4" />
        </button>
      </div>
    );
  }

  if (!deferredEvent || dismissed) return null;

  return (
    <div className="fixed bottom-4 left-1/2 z-50 flex w-[calc(100%-2rem)] max-w-sm -translate-x-1/2 items-center gap-3 rounded-lg border bg-background p-3 shadow-lg">
      <Download className="h-5 w-5 shrink-0 text-muted-foreground" />
      <div className="min-w-0 flex-1">
        <p className="text-sm font-medium">Install Epicure</p>
        <p className="text-xs text-muted-foreground">Add to your home screen for quick access.</p>
      </div>
      <Button type="button" size="sm" onClick={() => { void install(); }}>
        Install
      </Button>
      <button type="button" onClick={dismiss} aria-label="Dismiss" className="text-muted-foreground hover:text-foreground">
        <X className="h-4 w-4" />
      </button>
    </div>
  );
}