import 'dart:io';
import 'dart:typed_data';

import 'package:dartssh2/dartssh2.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:gallery/data_provider/data_provider.dart';

import 'dart:ui' as ui show Codec, ImmutableBuffer;

class SSHDataProvider extends DataProvider {
  final String host;
  final int port;
  final String username;
  final String password;
  final String initialPath;

  SftpClient? sftpClient;
  SSHClient? sshClient;

  SSHDataProvider(
      {required this.host,
      required this.port,
      required this.initialPath,
      required this.password,
      required this.username});

  @override
  Future<void> connect() async {
    if (sshClient != null && !sshClient!.isClosed) return;

    sshClient = SSHClient(
      await SSHSocket.connect(host, port),
      username: username,
      onPasswordRequest: () => password,
    );

    sftpClient = await sshClient?.sftp();
  }

  @override
  Future<Folder> listOfFiles({Uri? uri}) async {
    await connect();
    if (sftpClient == null) throw const FormatException("");

    final dir = uri != null ? Directory.fromUri(uri) : Directory(initialPath);

    final items = await sftpClient!.listdir(dir.path);
    List<Item> res = [];
    for (final val in items) {
      if (validSuffix.any((suff) => val.filename.endsWith(suff))) {
        res.add(Item(false, Uri.file(dir.path + val.filename), val.filename));
      } else if (val.attr.isDirectory) {
        res.add(
            Item(true, Uri.directory(dir.path + val.filename), val.filename));
      }
    }

    return Folder(res, dir.uri, dir.parent.uri);
  }

  @override
  ImageProvider getImageProvider(Uri uri) {
    return _SSHImageProvider(uri, sftpClient!);
  }
}

class _SSHImageProvider extends ImageProvider<_SSHImageProvider> {
  /// Creates an object that decodes a [File] as an image.
  ///
  /// The arguments must not be null.
  const _SSHImageProvider(this.uri, this.sftpClient, {this.scale = 1.0})
      : assert(scale != null);

  /// The file to decode into an image.
  final Uri uri;
  final SftpClient sftpClient;

  /// The scale to place in the [ImageInfo] object of the image.
  final double scale;

  @override
  Future<_SSHImageProvider> obtainKey(ImageConfiguration configuration) {
    return SynchronousFuture<_SSHImageProvider>(this);
  }

  @override
  ImageStreamCompleter load(_SSHImageProvider key, DecoderCallback decode) {
    return MultiFrameImageStreamCompleter(
      codec: _loadAsync(key, null, decode),
      scale: key.scale,
      debugLabel: key.uri.path,
      informationCollector: () => <DiagnosticsNode>[
        ErrorDescription('Path: ${uri.path}'),
      ],
    );
  }

  @override
  ImageStreamCompleter loadBuffer(
      _SSHImageProvider key, DecoderBufferCallback decode) {
    return MultiFrameImageStreamCompleter(
      codec: _loadAsync(key, decode, null),
      scale: key.scale,
      debugLabel: key.uri.path,
      informationCollector: () => <DiagnosticsNode>[
        ErrorDescription('Path: ${uri.path}'),
      ],
    );
  }

  Future<ui.Codec> _loadAsync(_SSHImageProvider key,
      DecoderBufferCallback? decode, DecoderCallback? decodeDeprecated) async {
    assert(key == this);

    final file = await sftpClient.open(uri.toFilePath());
    // todo do not load whole image in ram, create tempfile instead.
    final Uint8List bytes = await file.readBytes();

    if (bytes.lengthInBytes == 0) {
      // The file may become available later.
      PaintingBinding.instance.imageCache.evict(key);
      throw StateError('$file is empty and cannot be loaded as an image.');
    }

    if (decode != null) {
      return decode(await ui.ImmutableBuffer.fromUint8List(bytes));
    }
    return decodeDeprecated!(bytes);
  }

  @override
  bool operator ==(Object other) {
    if (other.runtimeType != runtimeType) {
      return false;
    }
    return other is _SSHImageProvider &&
        other.uri.path == uri.path &&
        other.scale == scale;
  }

  @override
  int get hashCode => Object.hash(uri.path, scale);

  @override
  String toString() =>
      '${objectRuntimeType(this, 'FileImage')}("${uri.path}", scale: $scale)';
}