import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_pdfviewer/pdfviewer.dart';

import '../../../../api/errors/error_mapper.dart';
import '../../../../api/errors/ticker_content_unavailable_exception.dart';
import '../../../../api/marianumconnect/queries/get_ticker_page/get_ticker_page_response.dart';
import '../../../../routing/app_routes.dart';
import '../../../../state/app/modules/ticker/repository/ticker_repository.dart';
import '../../../../theming/app_theme.dart';
import '../../../../widget/placeholder_view.dart';
import '../../../../widget/prosemirror/pm_json_view.dart';
import 'ticker_content_card.dart';

/// Embeddable renderer for a single ticker page. Loads the page on demand and
/// renders it by kind: CONTENT via the native ProseMirror renderer,
/// PROXIED_FILE as a PDF. It carries no Scaffold/AppBar so it can live both
/// in-place inside [TickerView] and inside the standalone `TickerPageView`
/// (deep links from outside the ticker module).
///
/// Reaching a REDIRECT here (e.g. via an internal content link whose slug turns
/// out to be a redirect) opens the browser and, if given, invokes [onRedirect]
/// so the host can leave this page.
class TickerPageBody extends StatefulWidget {
  final String slug;
  final void Function(String href) onLinkTap;
  final VoidCallback? onRedirect;

  const TickerPageBody({
    super.key,
    required this.slug,
    required this.onLinkTap,
    this.onRedirect,
  });

  @override
  State<TickerPageBody> createState() => _TickerPageBodyState();
}

class _TickerPageBodyState extends State<TickerPageBody> {
  final TickerRepository _repo = TickerRepository();
  late Future<TickerPageResponse> _future;

  @override
  void initState() {
    super.initState();
    _future = _repo.getPage(widget.slug);
  }

  void _reload() {
    setState(() => _future = _repo.getPage(widget.slug));
  }

  @override
  Widget build(BuildContext context) => FutureBuilder<TickerPageResponse>(
    future: _future,
    builder: (context, snapshot) {
      if (snapshot.connectionState != ConnectionState.done) {
        return const Center(child: CircularProgressIndicator());
      }
      final error = snapshot.error;
      if (error != null) return _buildError(context, error);
      return _buildContent(context, snapshot.data!);
    },
  );

  Widget _buildError(BuildContext context, Object error) {
    if (error is TickerContentUnavailableException) {
      return PlaceholderView(
        icon: Icons.public_off_outlined,
        text: error.userMessage,
        button: error.webUrl == null
            ? null
            : ElevatedButton.icon(
                onPressed: () => AppRoutes.openWebUrl(error.webUrl!),
                icon: const Icon(Icons.open_in_new),
                label: const Text('Im Browser öffnen'),
              ),
      );
    }
    return PlaceholderView(
      icon: Icons.error_outline,
      text: errorToUserMessage(error),
      button: errorAllowsRetry(error)
          ? ElevatedButton.icon(
              onPressed: _reload,
              icon: const Icon(Icons.refresh),
              label: const Text('Erneut versuchen'),
            )
          : null,
    );
  }

  Widget _buildContent(BuildContext context, TickerPageResponse page) {
    switch (page.kind) {
      case TickerPageKind.redirect:
        final url = page.externalUrl;
        WidgetsBinding.instance.addPostFrameCallback((_) {
          if (!mounted) return;
          if (url != null && url.isNotEmpty) AppRoutes.openExternalUrl(url);
          widget.onRedirect?.call();
        });
        return const Center(child: CircularProgressIndicator());
      case TickerPageKind.proxiedFile:
        return _ProxiedFileView(repo: _repo, slug: widget.slug);
      default:
        final content = page.content;
        if (content == null) {
          return PlaceholderView(
            icon: Icons.public_off_outlined,
            text: 'Dieser Inhalt ist in der App nicht verfügbar.',
            button: page.webUrl == null
                ? null
                : ElevatedButton.icon(
                    onPressed: () => AppRoutes.openWebUrl(page.webUrl!),
                    icon: const Icon(Icons.open_in_new),
                    label: const Text('Im Browser öffnen'),
                  ),
          );
        }
        return SingleChildScrollView(
          padding: const EdgeInsets.only(bottom: AppSpacing.lg),
          child: TickerContentCard(
            child: PmJsonView(json: content, onLinkTap: widget.onLinkTap),
          ),
        );
    }
  }
}

class _ProxiedFileView extends StatefulWidget {
  final TickerRepository repo;
  final String slug;

  const _ProxiedFileView({required this.repo, required this.slug});

  @override
  State<_ProxiedFileView> createState() => _ProxiedFileViewState();
}

class _ProxiedFileViewState extends State<_ProxiedFileView> {
  late Future<Uint8List> _bytes;

  @override
  void initState() {
    super.initState();
    _bytes = widget.repo.getPageFile(widget.slug);
  }

  @override
  Widget build(BuildContext context) => FutureBuilder<Uint8List>(
    future: _bytes,
    builder: (context, snapshot) {
      if (snapshot.connectionState != ConnectionState.done) {
        return const Center(child: CircularProgressIndicator());
      }
      final error = snapshot.error;
      if (error != null) {
        return PlaceholderView(
          icon: Icons.error_outline,
          text: errorToUserMessage(error),
          button: errorAllowsRetry(error)
              ? ElevatedButton.icon(
                  onPressed: () => setState(
                    () => _bytes = widget.repo.getPageFile(widget.slug),
                  ),
                  icon: const Icon(Icons.refresh),
                  label: const Text('Erneut versuchen'),
                )
              : null,
        );
      }
      final bytes = snapshot.data!;
      if (bytes.isEmpty) {
        return const PlaceholderView(
          icon: Icons.picture_as_pdf_outlined,
          text: 'Das Dokument konnte nicht geladen werden.',
        );
      }
      return SfPdfViewer.memory(bytes);
    },
  );
}