// Copyright 2019 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 'dart:io' show Directory, Platform;

import 'package:flutter/foundation.dart' show kIsWeb, visibleForTesting;
import 'package:path_provider_linux/path_provider_linux.dart';
import 'package:path_provider_windows/path_provider_windows.dart';
import 'package:path_provider_platform_interface/path_provider_platform_interface.dart';
import 'package:path_provider_platform_interface/src/method_channel_path_provider.dart';

export 'package:path_provider_platform_interface/path_provider_platform_interface.dart'
    show StorageDirectory;

@visibleForTesting
@Deprecated('This is no longer necessary, and is now a no-op')
set disablePathProviderPlatformOverride(bool override) {}

bool _manualDartRegistrationNeeded = true;

/// An exception thrown when a directory that should always be available on
/// the current platform cannot be obtained.
class MissingPlatformDirectoryException implements Exception {
  /// Creates a new exception
  MissingPlatformDirectoryException(this.message, {this.details});

  /// The explanation of the exception.
  final String message;

  /// Added details, if any.
  ///
  /// E.g., an error object from the platform implementation.
  final Object? details;

  @override
  String toString() {
    String detailsAddition = details == null ? '' : ': $details';
    return 'MissingPlatformDirectoryException($message)$detailsAddition';
  }
}

PathProviderPlatform get _platform {
  // This is to manually endorse Dart implementations until automatic
  // registration of Dart plugins is implemented. For details see
  // https://github.com/flutter/flutter/issues/52267.
  if (_manualDartRegistrationNeeded) {
    // Only do the initial registration if it hasn't already been overridden
    // with a non-default instance.
    if (!kIsWeb && PathProviderPlatform.instance is MethodChannelPathProvider) {
      if (Platform.isLinux) {
        PathProviderPlatform.instance = PathProviderLinux();
      } else if (Platform.isWindows) {
        PathProviderPlatform.instance = PathProviderWindows();
      }
    }
    _manualDartRegistrationNeeded = false;
  }

  return PathProviderPlatform.instance;
}

/// Path to the temporary directory on the device that is not backed up and is
/// suitable for storing caches of downloaded files.
///
/// Files in this directory may be cleared at any time. This does *not* return
/// a new temporary directory. Instead, the caller is responsible for creating
/// (and cleaning up) files or directories within this directory. This
/// directory is scoped to the calling application.
///
/// On iOS, this uses the `NSCachesDirectory` API.
///
/// On Android, this uses the `getCacheDir` API on the context.
///
/// Throws a `MissingPlatformDirectoryException` if the system is unable to
/// provide the directory.
Future<Directory> getTemporaryDirectory() async {
  final String? path = await _platform.getTemporaryPath();
  if (path == null) {
    throw MissingPlatformDirectoryException(
        'Unable to get temporary directory');
  }
  return Directory(path);
}

/// Path to a directory where the application may place application support
/// files.
///
/// Use this for files you don’t want exposed to the user. Your app should not
/// use this directory for user data files.
///
/// On iOS, this uses the `NSApplicationSupportDirectory` API.
/// If this directory does not exist, it is created automatically.
///
/// On Android, this function uses the `getFilesDir` API on the context.
///
/// Throws a `MissingPlatformDirectoryException` if the system is unable to
/// provide the directory.
Future<Directory> getApplicationSupportDirectory() async {
  final String? path = await _platform.getApplicationSupportPath();
  if (path == null) {
    throw MissingPlatformDirectoryException(
        'Unable to get application support directory');
  }

  return Directory(path);
}

/// Path to the directory where application can store files that are persistent,
/// backed up, and not visible to the user, such as sqlite.db.
///
/// On Android, this function throws an [UnsupportedError] as no equivalent
/// path exists.
///
/// Throws a `MissingPlatformDirectoryException` if the system is unable to
/// provide the directory on a supported platform.
Future<Directory> getLibraryDirectory() async {
  final String? path = await _platform.getLibraryPath();
  if (path == null) {
    throw MissingPlatformDirectoryException('Unable to get library directory');
  }
  return Directory(path);
}

/// Path to a directory where the application may place data that is
/// user-generated, or that cannot otherwise be recreated by your application.
///
/// On iOS, this uses the `NSDocumentDirectory` API. Consider using
/// [getApplicationSupportDirectory] instead if the data is not user-generated.
///
/// On Android, this uses the `getDataDirectory` API on the context. Consider
/// using [getExternalStorageDirectory] instead if data is intended to be visible
/// to the user.
///
/// Throws a `MissingPlatformDirectoryException` if the system is unable to
/// provide the directory.
Future<Directory> getApplicationDocumentsDirectory() async {
  final String? path = await _platform.getApplicationDocumentsPath();
  if (path == null) {
    throw MissingPlatformDirectoryException(
        'Unable to get application documents directory');
  }
  return Directory(path);
}

/// Path to a directory where the application may access top level storage.
/// The current operating system should be determined before issuing this
/// function call, as this functionality is only available on Android.
///
/// On iOS, this function throws an [UnsupportedError] as it is not possible
/// to access outside the app's sandbox.
///
/// On Android this uses the `getExternalFilesDir(null)`.
Future<Directory?> getExternalStorageDirectory() async {
  final String? path = await _platform.getExternalStoragePath();
  if (path == null) {
    return null;
  }
  return Directory(path);
}

/// Paths to directories where application specific external cache data can be
/// stored. These paths typically reside on external storage like separate
/// partitions or SD cards. Phones may have multiple storage directories
/// available.
///
/// The current operating system should be determined before issuing this
/// function call, as this functionality is only available on Android.
///
/// On iOS, this function throws an UnsupportedError as it is not possible
/// to access outside the app's sandbox.
///
/// On Android this returns Context.getExternalCacheDirs() or
/// Context.getExternalCacheDir() on API levels below 19.
Future<List<Directory>?> getExternalCacheDirectories() async {
  final List<String>? paths = await _platform.getExternalCachePaths();
  if (paths == null) {
    return null;
  }

  return paths.map((String path) => Directory(path)).toList();
}

/// Paths to directories where application specific data can be stored.
/// These paths typically reside on external storage like separate partitions
/// or SD cards. Phones may have multiple storage directories available.
///
/// The current operating system should be determined before issuing this
/// function call, as this functionality is only available on Android.
///
/// On iOS, this function throws an UnsupportedError as it is not possible
/// to access outside the app's sandbox.
///
/// On Android this returns Context.getExternalFilesDirs(String type) or
/// Context.getExternalFilesDir(String type) on API levels below 19.
Future<List<Directory>?> getExternalStorageDirectories({
  /// Optional parameter. See [StorageDirectory] for more informations on
  /// how this type translates to Android storage directories.
  StorageDirectory? type,
}) async {
  final List<String>? paths =
      await _platform.getExternalStoragePaths(type: type);
  if (paths == null) {
    return null;
  }

  return paths.map((String path) => Directory(path)).toList();
}

/// Path to the directory where downloaded files can be stored.
/// This is typically only relevant on desktop operating systems.
///
/// On Android and on iOS, this function throws an [UnsupportedError] as no equivalent
/// path exists.
Future<Directory?> getDownloadsDirectory() async {
  final String? path = await _platform.getDownloadsPath();
  if (path == null) {
    return null;
  }
  return Directory(path);
}