/*
 * Copyright (c) 2024-2026 Fabian Freund.
 *
 * This file is part of WebLibre
 * (see https://weblibre.eu).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

/// A hook that manages visibility state based on scroll direction.
///
/// Returns a [ValueNotifier<bool>] that automatically updates based on scroll behavior:
/// - Hides when scrolling down beyond [hideThreshold]
/// - Shows when scrolling up beyond [showThreshold] or at the top of the scroll view
/// - Ignores scroll events during [initializationDelay] to prevent hiding during jumpTo/animateTo
///
/// Example:
/// ```dart
/// final scrollController = useScrollController();
/// final isVisible = useScrollVisibility(scrollController);
///
/// return AnimatedOpacity(
///   opacity: isVisible.value ? 1.0 : 0.0,
///   child: FloatingActionButton(...),
/// );
/// ```
ValueNotifier<bool> useScrollVisibility(
  ScrollController scrollController, {
  double hideThreshold = 5.0,
  double showThreshold = 5.0,
  Duration initializationDelay = const Duration(milliseconds: 1000),
  bool disableAnimations = false,
}) {
  final isVisible = useState(true);
  final lastScrollOffset = useRef(0.0);
  final isInitialized = useRef(false);

  useEffect(
    () {
      // Start timer to enable scroll listener after initialization delay
      final timer = Timer(
        disableAnimations ? Duration.zero : initializationDelay,
        () {
          if (scrollController.hasClients) {
            lastScrollOffset.value = scrollController.offset;
          }
          isInitialized.value = true;
        },
      );

      void scrollListener() {
        // Ignore scroll events until initialization is complete
        if (!isInitialized.value) return;

        final currentOffset = scrollController.offset;
        final difference = currentOffset - lastScrollOffset.value;

        // Hide when scrolling down beyond threshold
        if (difference > hideThreshold && isVisible.value) {
          isVisible.value = false;
        }
        // Show when scrolling up beyond threshold or at top
        else if ((difference < -showThreshold || currentOffset <= 0) &&
            !isVisible.value) {
          isVisible.value = true;
        }

        lastScrollOffset.value = currentOffset;
      }

      scrollController.addListener(scrollListener);
      return () {
        timer.cancel();
        scrollController.removeListener(scrollListener);
      };
    },
    [
      scrollController,
      hideThreshold,
      showThreshold,
      initializationDelay,
      disableAnimations,
    ],
  );

  return isVisible;
}