import 'package:app_settings/app_settings.dart';
import 'package:file_picker/file_picker.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:image_picker/image_picker.dart';

import '../api/errors/permission_exception.dart';
import 'confirm_dialog.dart';
import 'info_dialog.dart';

/// Thin wrapper around the platform pickers. Every method resolves to `null`
/// when the user cancels **or** when picking failed; failures are reported to
/// the user right here (permission denial with a shortcut to the system
/// settings, everything else as a plain error dialog) so call sites can treat
/// the result like a cancel.
class FilePick {
  static final _picker = ImagePicker();

  static Future<List<XFile>?> multipleGalleryPick(BuildContext context) =>
      _guarded(context, () async {
        final pickedImages = await _picker.pickMultiImage();
        return pickedImages.isNotEmpty ? pickedImages : null;
      });

  static Future<XFile?> singleGalleryPick(
    BuildContext context, {
    bool forCrop = false,
  }) => _pickImage(context, ImageSource.gallery, forCrop: forCrop);

  static Future<XFile?> cameraPick(
    BuildContext context, {
    bool forCrop = false,
  }) => _pickImage(context, ImageSource.camera, forCrop: forCrop);

  /// [forCrop] makes the picker re-encode to a bounded JPEG: the Dart cropper
  /// can't decode HEIC (iOS gallery default) and is slow on full-size photos.
  static Future<XFile?> _pickImage(
    BuildContext context,
    ImageSource source, {
    required bool forCrop,
  }) => _guarded(
    context,
    () => _picker.pickImage(
      source: source,
      maxWidth: forCrop ? 2048 : null,
      maxHeight: forCrop ? 2048 : null,
      imageQuality: forCrop ? 90 : null,
    ),
  );

  static Future<List<String>?> documentPick() async {
    final result = await FilePicker.pickFiles(allowMultiple: true);
    return result?.files.map((e) => e.path).nonNulls.toList();
  }

  static Future<T?> _guarded<T>(
    BuildContext context,
    Future<T?> Function() pick,
  ) async {
    try {
      return await pick();
    } on PlatformException catch (e) {
      final denied = PermissionException.fromPlatform(e);
      if (!context.mounted) return null;
      if (denied != null) {
        _showPermissionDialog(context, denied);
      } else {
        _showErrorDialog(context, e);
      }
      return null;
    } catch (e) {
      if (context.mounted) _showErrorDialog(context, e);
      return null;
    }
  }

  static void _showPermissionDialog(
    BuildContext context,
    PermissionException denied,
  ) => ConfirmDialog(
    icon: Icons.block_outlined,
    title: 'Zugriff verweigert',
    content: denied.userMessage,
    confirmButton: 'Einstellungen öffnen',
    onConfirm: AppSettings.openAppSettings,
  ).asDialog(context);

  static void _showErrorDialog(BuildContext context, Object error) =>
      InfoDialog.showError(context, error);
}

/// "Aus Galerie wählen" / "Foto aufnehmen" tiles for an image-source sheet.
/// The optional [transform] (e.g. a cropper) runs with the sheet still
/// mounted; the sheet pops only once [onPicked] received the final bytes.
List<Widget> imageSourceTiles(
  BuildContext sheetContext, {
  required void Function(Uint8List bytes) onPicked,
  Future<Uint8List?> Function(Uint8List bytes)? transform,
}) {
  Widget tile(IconData icon, String title, Future<XFile?> Function() pick) =>
      ListTile(
        leading: Icon(icon),
        title: Text(title),
        onTap: () async {
          final picked = await pick();
          if (picked == null) return;
          Uint8List? bytes = await picked.readAsBytes();
          if (transform != null) {
            if (!sheetContext.mounted) return;
            bytes = await transform(bytes);
          }
          if (bytes == null || !sheetContext.mounted) return;
          onPicked(bytes);
          Navigator.of(sheetContext).pop();
        },
      );
  return [
    tile(
      Icons.photo_library_outlined,
      'Aus Galerie wählen',
      () => FilePick.singleGalleryPick(sheetContext, forCrop: true),
    ),
    tile(
      Icons.photo_camera_outlined,
      'Foto aufnehmen',
      () => FilePick.cameraPick(sheetContext, forCrop: true),
    ),
  ];
}