import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:worldhopper/l10n/app_localizations.dart';
import 'package:worldhopper/config/constants.dart';
import 'package:worldhopper/models/opds_entry.dart';
import 'package:worldhopper/providers/connectivity_provider.dart';
import 'package:worldhopper/providers/series_navigation_provider.dart';

/// Overlay widget shown when reading is complete.
///
/// - If a next entry exists in the series feed, shows "Next: [title]".
/// - If there is no next entry (last in series or no feed context),
///   shows "Finished" with a link back to the OPDS entry (online)
///   or the library (offline).
///
/// Can be dismissed by swiping down or tapping the close button.
class NextInSeriesOverlay extends ConsumerStatefulWidget {
  final String serverId;
  final String? feedUrl;
  final OPDSEntry entry;
  final bool isVisible;
  final bool einkMode;
  final Future<void> Function()? onBeforeNavigate;

  const NextInSeriesOverlay({
    super.key,
    required this.serverId,
    this.feedUrl,
    required this.entry,
    required this.isVisible,
    this.einkMode = false,
    this.onBeforeNavigate,
  });

  @override
  ConsumerState<NextInSeriesOverlay> createState() =>
      _NextInSeriesOverlayState();
}

class _NextInSeriesOverlayState extends ConsumerState<NextInSeriesOverlay> {
  bool _dismissed = false;

  @override
  Widget build(BuildContext context) {
    if (_dismissed || !widget.isVisible) {
      return const SizedBox.shrink();
    }

    // If we have a feed URL, try to resolve the next entry
    if (widget.feedUrl != null) {
      final request = NextInSeriesRequest(
        serverId: widget.serverId,
        feedUrl: widget.feedUrl!,
        currentEntryId: widget.entry.id,
      );

      final nextEntryAsync = ref.watch(nextInSeriesProvider(request));

      return nextEntryAsync.when(
        data: (nextEntry) {
          if (nextEntry != null) {
            return _buildNextOverlay(context, nextEntry);
          }
          return _buildFinishedOverlay(context);
        },
        loading: () => const SizedBox.shrink(),
        error: (_, __) => _buildFinishedOverlay(context),
      );
    }

    // No feed context — just show "Finished"
    return _buildFinishedOverlay(context);
  }

  // ---------------------------------------------------------------------------
  // "Next in series" bar
  // ---------------------------------------------------------------------------

  Widget _buildNextOverlay(BuildContext context, OPDSEntry nextEntry) {
    return _buildDismissibleBar(
      key: 'next-in-series-${nextEntry.id}',
      color: Theme.of(context).colorScheme.primaryContainer,
      onColor: Theme.of(context).colorScheme.onPrimaryContainer,
      onTap: () => _navigateToNext(context, nextEntry),
      icon: Icons.skip_next,
      label: AppLocalizations.of(context).nextInSeriesNext,
      title: nextEntry.title,
      trailingIcon: Icons.arrow_forward,
    );
  }

  // ---------------------------------------------------------------------------
  // "Finished reading" bar
  // ---------------------------------------------------------------------------

  Widget _buildFinishedOverlay(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final connectivityState = ref.watch(connectivityStateProvider);
    final isOnline = connectivityState.whenOrNull(
          data: (online) => online,
        ) ??
        true;

    return _buildDismissibleBar(
      key: 'finished-reading-${widget.entry.id}',
      color: Theme.of(context).colorScheme.secondaryContainer,
      onColor: Theme.of(context).colorScheme.onSecondaryContainer,
      onTap: () => _navigateBack(context, isOnline),
      icon: Icons.check_circle_outline,
      label: l10n.nextInSeriesFinished,
      title: isOnline
          ? l10n.nextInSeriesBackToDetails
          : l10n.nextInSeriesBackToLibrary,
      trailingIcon: Icons.arrow_back,
    );
  }

  // ---------------------------------------------------------------------------
  // Shared bar builder
  // ---------------------------------------------------------------------------

  Widget _buildDismissibleBar({
    required String key,
    required Color color,
    required Color onColor,
    required VoidCallback onTap,
    required IconData icon,
    required String label,
    required String title,
    required IconData trailingIcon,
  }) {
    final barContent = Material(
      elevation: 8,
      borderRadius: BorderRadius.circular(12),
      color: color,
      child: InkWell(
        borderRadius: BorderRadius.circular(12),
        onTap: onTap,
        child: Padding(
          padding:
              const EdgeInsets.only(left: 16, top: 12, bottom: 12, right: 4),
          child: Row(
            children: [
              Icon(icon, color: onColor),
              const SizedBox(width: 12),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Text(
                      label,
                      style: Theme.of(context).textTheme.labelSmall?.copyWith(
                            color: onColor.withValues(alpha: 0.7),
                          ),
                    ),
                    Text(
                      title,
                      style: Theme.of(context).textTheme.titleSmall?.copyWith(
                            color: onColor,
                            fontWeight: FontWeight.bold,
                          ),
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis,
                    ),
                  ],
                ),
              ),
              const SizedBox(width: 4),
              Icon(trailingIcon, color: onColor),
              SizedBox(
                width: 36,
                height: 36,
                child: IconButton(
                  padding: EdgeInsets.zero,
                  iconSize: 20,
                  icon: Icon(
                    Icons.close,
                    color: onColor.withValues(alpha: 0.7),
                  ),
                  onPressed: () {
                    setState(() {
                      _dismissed = true;
                    });
                  },
                ),
              ),
            ],
          ),
        ),
      ),
    );

    return Positioned(
      bottom: MediaQuery.of(context).padding.bottom + 16,
      left: 16,
      right: 16,
      child: widget.einkMode
          ? barContent
          : Dismissible(
              key: ValueKey(key),
              direction: DismissDirection.down,
              onDismissed: (_) {
                setState(() {
                  _dismissed = true;
                });
              },
              child: barContent,
            ),
    );
  }

  // ---------------------------------------------------------------------------
  // Navigation helpers
  // ---------------------------------------------------------------------------

  void _navigateToNext(BuildContext context, OPDSEntry nextEntry) async {
    await widget.onBeforeNavigate?.call();
    if (!context.mounted) return;
    if (nextEntry.isEpub) {
      context.pushReplacement(
        AppConstants.routeEpubReader,
        extra: {
          'entry': nextEntry,
          'serverId': widget.serverId,
          'feedUrl': widget.feedUrl,
        },
      );
    } else if (nextEntry.hasStreamLink) {
      context.pushReplacement(
        AppConstants.routeReader,
        extra: {
          'entry': nextEntry,
          'serverId': widget.serverId,
          'initialPage': 0,
          'feedUrl': widget.feedUrl,
        },
      );
    } else {
      context.pushReplacement(
        AppConstants.routePublicationDetail,
        extra: {
          'entry': nextEntry,
          'serverId': widget.serverId,
          'feedUrl': widget.feedUrl,
        },
      );
    }
  }

  void _navigateBack(BuildContext context, bool isOnline) async {
    await widget.onBeforeNavigate?.call();
    if (!context.mounted) return;
    if (isOnline) {
      // Go to the publication detail screen for the current entry
      context.pushReplacement(
        AppConstants.routePublicationDetail,
        extra: {
          'entry': widget.entry,
          'serverId': widget.serverId,
          'feedUrl': widget.feedUrl,
        },
      );
    } else {
      // Go to the library
      context.go(AppConstants.routeLibrary);
    }
  }
}