import 'dart:io';

import 'package:flutter/material.dart';

import '../../../routing/app_routes.dart';
import '../../../share_intent/pending_share.dart';
import '../../../share_intent/share_intent_listener.dart';

class ShareTargetPage extends StatelessWidget {
  final PendingShare share;

  const ShareTargetPage({super.key, required this.share});

  static const _imageExtensions = {
    '.jpg',
    '.jpeg',
    '.png',
    '.gif',
    '.webp',
    '.heic',
    '.heif',
    '.bmp',
  };

  bool _isImagePath(String path) {
    final lower = path.toLowerCase();
    return _imageExtensions.any(lower.endsWith);
  }

  String _appBarTitle() {
    if (share.hasFiles && share.hasText) return 'Inhalte teilen';
    if (share.hasFiles) {
      return share.filePaths.length == 1
          ? '1 Datei teilen'
          : '${share.filePaths.length} Dateien teilen';
    }
    return 'Inhalt teilen';
  }

  @override
  Widget build(BuildContext context) => PopScope(
    onPopInvokedWithResult: (didPop, _) {
      if (didPop) ShareIntentListener.instance.clear();
    },
    child: Scaffold(
      appBar: AppBar(title: Text(_appBarTitle())),
      body: Column(
        children: [
          Expanded(
            child: SingleChildScrollView(
              padding: const EdgeInsets.fromLTRB(16, 16, 16, 8),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  if (share.hasFiles) _buildFilePreview(context),
                  if (share.hasFiles && share.hasText)
                    const SizedBox(height: 12),
                  if (share.hasText) _buildTextPreview(context),
                ],
              ),
            ),
          ),
          const Divider(height: 1),
          SafeArea(
            top: false,
            child: Padding(
              padding: const EdgeInsets.only(top: 12, bottom: 8),
              child: Column(
                children: [
                  Padding(
                    padding: const EdgeInsets.fromLTRB(16, 4, 16, 12),
                    child: Column(
                      children: [
                        Icon(
                          Icons.ios_share,
                          size: 44,
                          color: Theme.of(context).colorScheme.primary,
                        ),
                        const SizedBox(height: 8),
                        Text(
                          'Wo möchtest du teilen?',
                          textAlign: TextAlign.center,
                          style: Theme.of(context).textTheme.titleLarge
                              ?.copyWith(fontWeight: FontWeight.w600),
                        ),
                      ],
                    ),
                  ),
                  ListTile(
                    leading: const Icon(Icons.chat_bubble_outline),
                    title: const Text('An Chat senden'),
                    subtitle: const Text(
                      'Datei oder Text in einem Talk-Chat teilen',
                    ),
                    trailing: const Icon(Icons.chevron_right),
                    onTap: () =>
                        AppRoutes.openShareChatPicker(context, share),
                  ),
                  ListTile(
                    enabled: share.hasFiles,
                    leading: const Icon(Icons.folder_outlined),
                    title: const Text('In Dateien speichern'),
                    subtitle: Text(
                      share.hasFiles
                          ? 'In einen Nextcloud-Ordner hochladen'
                          : 'Nur für Dateien verfügbar',
                    ),
                    trailing: const Icon(Icons.chevron_right),
                    onTap: share.hasFiles
                        ? () => AppRoutes.openShareFolderPicker(context, share)
                        : null,
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    ),
  );

  Widget _buildFilePreview(BuildContext context) {
    if (share.filePaths.length == 1) {
      final path = share.filePaths.first;
      final name = path.split(Platform.pathSeparator).last;
      return ConstrainedBox(
        constraints: const BoxConstraints(maxHeight: 320),
        child: Container(
          decoration: BoxDecoration(
            color: Theme.of(context).colorScheme.surfaceContainer,
            borderRadius: BorderRadius.circular(12),
          ),
          clipBehavior: Clip.antiAlias,
          child: _isImagePath(path)
              ? Image.file(
                  File(path),
                  fit: BoxFit.contain,
                  // Decode at most ~1080px so 50-MP gallery photos don't
                  // balloon the decode buffer just to render at <320px high.
                  cacheWidth: 1080,
                  errorBuilder: (_, _, _) => _fileFallbackLarge(name),
                )
              : _fileFallbackLarge(name),
        ),
      );
    }
    return GridView.builder(
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 2,
        crossAxisSpacing: 10,
        mainAxisSpacing: 10,
      ),
      itemCount: share.filePaths.length,
      itemBuilder: (context, i) {
        final path = share.filePaths[i];
        final name = path.split(Platform.pathSeparator).last;
        return Container(
          decoration: BoxDecoration(
            color: Theme.of(context).colorScheme.surfaceContainer,
            borderRadius: BorderRadius.circular(12),
          ),
          clipBehavior: Clip.antiAlias,
          child: _isImagePath(path)
              ? Image.file(
                  File(path),
                  fit: BoxFit.cover,
                  // Grid tiles are ~half-screen wide; 480px decode is
                  // sharp on 3x displays without blowing up memory when
                  // many files are shared at once.
                  cacheWidth: 480,
                  errorBuilder: (_, _, _) => _fileFallbackLarge(name),
                )
              : _fileFallbackLarge(name),
        );
      },
    );
  }

  Widget _buildTextPreview(BuildContext context) => Card(
    margin: EdgeInsets.zero,
    child: Padding(
      padding: const EdgeInsets.all(12),
      child: Text(
        share.text!,
        maxLines: 6,
        overflow: TextOverflow.ellipsis,
      ),
    ),
  );

  Widget _fileFallbackLarge(String name) => Padding(
    padding: const EdgeInsets.all(16),
    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        const Icon(Icons.insert_drive_file_outlined, size: 64),
        const SizedBox(height: 8),
        Text(
          name,
          maxLines: 3,
          overflow: TextOverflow.ellipsis,
          textAlign: TextAlign.center,
          style: const TextStyle(fontSize: 12),
        ),
      ],
    ),
  );
}