import { Capacitor } from "@capacitor/core";
import { useEffect, useState } from "react";
import { apiClient } from "../../api/client";
import { isNewerVersion } from "./version-compare";

/** How often a background check is allowed to actually hit the network — cold start and every resume-from-background otherwise re-checks needlessly. */
const CHECK_INTERVAL_MS = 6 * 60 * 60 * 1000; // 6h

const LAST_CHECKED_KEY = "appUpdate_lastCheckedAt";
const DISMISSED_VERSION_KEY = "appUpdate_dismissedVersion";

/**
 * Detects whether a newer version of the Android app has been tagged than
 * the one currently installed, and offers a way to dismiss the notice for
 * that specific version.
 *
 * **Native only** — on the web, "the app" is just whatever the server is
 * currently serving; there is no "installed version" to compare against,
 * and reloading the page always gets the latest build. `Capacitor`/
 * `@capacitor/app`/`@capacitor/preferences` stay dynamically imported so
 * none of them enter the web bundle (same pattern as `main.tsx`'s own
 * `capacitor-token-store` bootstrap) — this hook is safe to call
 * unconditionally from `AppLayout`, which renders on both platforms.
 *
 * No Play Store integration exists (this app isn't distributed there) —
 * Google's In-App Update API has no purchase here at all, so this is a
 * from-scratch check, not a wrapper around it.
 *
 * Fails silently on any network/parsing error — a background version check
 * must never surface an error banner or block anything, same posture as
 * `ThemeContext`'s own preferences fetch.
 */
export function useAppUpdateCheck(): {
  /** The newer version's tag (e.g. `"v1.4.2"`), or `null` when none is available (or none has been checked/parsed yet). */
  availableVersion: string | null;
  /** Hides the banner for `availableVersion` specifically — it reappears only once an even newer version ships, never just on the next app start. */
  dismiss: () => void;
} {
  const [availableVersion, setAvailableVersion] = useState<string | null>(null);

  useEffect(() => {
    if (!Capacitor.isNativePlatform()) return;

    let cancelled = false;

    async function checkForUpdate() {
      try {
        const [{ App }, { Preferences }] = await Promise.all([
          import("@capacitor/app"),
          import("@capacitor/preferences"),
        ]);

        const { value: lastCheckedRaw } = await Preferences.get({ key: LAST_CHECKED_KEY });
        const lastCheckedAt = lastCheckedRaw ? Number(lastCheckedRaw) : 0;
        if (Date.now() - lastCheckedAt < CHECK_INTERVAL_MS) return;

        const [{ version: installedVersion }, { version: latestTag }] = await Promise.all([
          App.getInfo(),
          apiClient.getLatestMobileVersion(),
        ]);
        await Preferences.set({ key: LAST_CHECKED_KEY, value: String(Date.now()) });
        if (!latestTag || !isNewerVersion(installedVersion, latestTag)) return;

        const { value: dismissedVersion } = await Preferences.get({ key: DISMISSED_VERSION_KEY });
        if (dismissedVersion === latestTag) return;

        if (!cancelled) setAvailableVersion(latestTag);
      } catch {
        // Silent — see this hook's own doc comment. Nothing to log to
        // (apps/web has no client-side LoggerService equivalent yet), and a
        // failed version check is never actionable for the visitor anyway.
      }
    }

    void checkForUpdate();

    // Re-check whenever the app comes back to the foreground — the listener
    // itself is cheap to keep registered, `checkForUpdate`'s own throttle
    // above is what actually keeps this from hitting the network every time.
    let removeListener: (() => void) | undefined;
    void import("@capacitor/app").then(({ App }) => {
      if (cancelled) return;
      App.addListener("appStateChange", ({ isActive }) => {
        if (isActive) void checkForUpdate();
      }).then((handle) => {
        removeListener = () => void handle.remove();
      });
    });

    return () => {
      cancelled = true;
      removeListener?.();
    };
  }, []);

  function dismiss() {
    if (!availableVersion) return;
    const dismissed = availableVersion;
    setAvailableVersion(null);
    void import("@capacitor/preferences").then(({ Preferences }) =>
      Preferences.set({ key: DISMISSED_VERSION_KEY, value: dismissed }),
    );
  }

  return { availableVersion, dismiss };
}