packages/file_selector/file_selector_platform_interface/lib/src/platform_interface/file_selector_interface.dart

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';

import 'package:cross_file/cross_file.dart';
import 'package:file_selector_platform_interface/file_selector_platform_interface.dart';
import 'package:plugin_platform_interface/plugin_platform_interface.dart';

import '../method_channel/method_channel_file_selector.dart';

/// The interface that implementations of file_selector must implement.
///
/// Platform implementations should extend this class rather than implement it as `file_selector`
/// does not consider newly added methods to be breaking changes. Extending this class
/// (using `extends`) ensures that the subclass will get the default implementation, while
/// platform implementations that `implements` this interface will be broken by newly added
/// [FileSelectorPlatform] methods.
abstract class FileSelectorPlatform extends PlatformInterface {
  /// Constructs a FileSelectorPlatform.
  FileSelectorPlatform() : super(token: _token);

  static final Object _token = Object();

  static FileSelectorPlatform _instance = MethodChannelFileSelector();

  /// The default instance of [FileSelectorPlatform] to use.
  ///
  /// Defaults to [MethodChannelFileSelector].
  static FileSelectorPlatform get instance => _instance;

  /// Platform-specific plugins should set this with their own platform-specific
  /// class that extends [FileSelectorPlatform] when they register themselves.
  static set instance(FileSelectorPlatform instance) {
    PlatformInterface.verify(instance, _token);
    _instance = instance;
  }

  /// Open file dialog for loading files and return a file path
  /// Returns `null` if user cancels the operation.
  Future<XFile?> openFile({
    List<XTypeGroup>? acceptedTypeGroups,
    String? initialDirectory,
    String? confirmButtonText,
  }) {
    throw UnimplementedError('openFile() has not been implemented.');
  }

  /// Open file dialog for loading files and return a list of file paths
  Future<List<XFile>> openFiles({
    List<XTypeGroup>? acceptedTypeGroups,
    String? initialDirectory,
    String? confirmButtonText,
  }) {
    throw UnimplementedError('openFiles() has not been implemented.');
  }

  /// Open file dialog for saving files and return a file path at which to save
  /// Returns `null` if user cancels the operation.
  Future<String?> getSavePath({
    List<XTypeGroup>? acceptedTypeGroups,
    String? initialDirectory,
    String? suggestedName,
    String? confirmButtonText,
  }) {
    throw UnimplementedError('getSavePath() has not been implemented.');
  }

  /// Open file dialog for loading directories and return a directory path
  /// Returns `null` if user cancels the operation.
  Future<String?> getDirectoryPath({
    String? initialDirectory,
    String? confirmButtonText,
  }) {
    throw UnimplementedError('getDirectoryPath() has not been implemented.');
  }
}