/**
 * InstallPrompt.tsx — X3: PWA install banner
 * Appare dopo 45s di uso cumulativo. Android: "Installa" button.
 * iOS Safari: istruzioni "Condividi → Aggiungi a schermata Home".
 * Dismissable permanente via localStorage.
 */
import { useState, useEffect, useRef } from "react";
import { Z_INDEX } from "@/lib/zindex";
import { getCapabilities } from "@/lib/capabilities";

const DISMISSED_KEY = "pwa_install_dismissed_v1";
const USAGE_KEY     = "pwa_usage_seconds";

export default function InstallPrompt() {
  const [show, setShow]   = useState(false);
  const [isIos, setIsIos] = useState(false);
  const deferredRef = useRef<any>(null);

  useEffect(() => {
    try {
      const caps = getCapabilities();
      if (caps.isStandalone) return;
      if (localStorage.getItem(DISMISSED_KEY)) return;

      setIsIos(!!(caps.isIos && caps.isSafari));

      const handler = (e: Event) => {
        e.preventDefault();
        deferredRef.current = e;
      };
      window.addEventListener("beforeinstallprompt", handler);

      const prev = parseInt(localStorage.getItem(USAGE_KEY) ?? "0", 10);
      const start = Date.now();
      const tick = setInterval(() => {
        const elapsed = Math.floor((Date.now() - start) / 1000) + prev;
        localStorage.setItem(USAGE_KEY, String(elapsed));
        if (elapsed >= 45) {
          setShow(true);
          clearInterval(tick);
        }
      }, 5000);

      return () => {
        window.removeEventListener("beforeinstallprompt", handler);
        clearInterval(tick);
      };
    } catch { /* non-blocking */ }
    return undefined;
  }, []);

  if (!show) return null;

  const dismiss = () => {
    setShow(false);
    try { localStorage.setItem(DISMISSED_KEY, "1"); } catch { /* */ }
  };

  const install = async () => {
    if (deferredRef.current) {
      try {
        await deferredRef.current.prompt();
        const { outcome } = await deferredRef.current.userChoice;
        if (outcome === "accepted") dismiss();
      } catch { /* user dismissed */ }
    }
  };

  return (
    <div style={{
      position: "fixed", bottom: 72, left: 12, right: 12,
      background: "rgba(8,8,22,0.96)",
      border: "1px solid rgba(99,102,241,0.30)",
      borderRadius: 14, padding: "14px 16px",
      zIndex: Z_INDEX.CRITICAL_TOAST, boxShadow: "0 8px 32px rgba(0,0,0,0.6)",
      display: "flex", flexDirection: "column", gap: 10,
    }}>
      <div style={{ display: "flex", justifyContent: "space-between", alignItems: "flex-start" }}>
        <div>
          <div style={{ fontSize: "0.85rem", fontWeight: 700, color: "#e2e8f0" }}>
            Installa l'app
          </div>
          <div style={{ fontSize: "0.72rem", color: "rgba(148,163,184,0.7)", marginTop: 3 }}>
            {isIos
              ? 'Tocca Condividi → "Aggiungi a schermata Home"'
              : "Accesso rapido, funziona offline"}
          </div>
        </div>
        <button onClick={dismiss} style={{
          all: "unset", cursor: "pointer",
          color: "rgba(148,163,184,0.4)", fontSize: "1.2rem", padding: "0 4px",
          lineHeight: 1,
        }}>×</button>
      </div>
      {!isIos && (
        <button onClick={install} style={{
          all: "unset", cursor: "pointer", textAlign: "center",
          background: "rgba(99,102,241,0.2)", border: "1px solid rgba(99,102,241,0.4)",
          color: "#a5b4fc", borderRadius: 8, padding: "8px 0",
          fontSize: "0.78rem", fontWeight: 600,
        }}>
          Installa
        </button>
      )}
    </div>
  );
}