1// Copyright 2014 The Flutter Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5import 'package:process/process.dart';
6
7import '../base/common.dart';
8import '../base/file_system.dart';
9import '../base/io.dart';
10import '../base/logger.dart';
11import '../base/process.dart';
12import '../base/terminal.dart';
13import '../cache.dart';
14import '../globals.dart' as globals;
15import '../persistent_tool_state.dart';
16import '../runner/flutter_command.dart';
17import '../version.dart';
18
19/// The flutter downgrade command returns the SDK to the last recorded version
20/// for a particular branch.
21///
22/// For example, suppose a user on the beta channel upgrades from 1.2.3 to 1.4.6.
23/// The tool will record that sha "abcdefg" was the last active beta channel in the
24/// persistent tool state. If the user is still on the beta channel and runs
25/// flutter downgrade, this will take the user back to "abcdefg". They will not be
26/// able to downgrade again, since the tool only records one prior version.
27/// Additionally, if they had switched channels to stable before trying to downgrade,
28/// the command would fail since there was no previously recorded stable version.
29class DowngradeCommand extends FlutterCommand {
30 DowngradeCommand({
31 bool verboseHelp = false,
32 PersistentToolState? persistentToolState,
33 required Logger logger,
34 ProcessManager? processManager,
35 FlutterVersion? flutterVersion,
36 Terminal? terminal,
37 Stdio? stdio,
38 FileSystem? fileSystem,
39 }) : _terminal = terminal,
40 _flutterVersion = flutterVersion,
41 _persistentToolState = persistentToolState,
42 _processManager = processManager,
43 _stdio = stdio,
44 _logger = logger,
45 _fileSystem = fileSystem {
46 argParser.addOption(
47 'working-directory',
48 hide: !verboseHelp,
49 help:
50 'Override the downgrade working directory. '
51 'This is only intended to enable integration testing of the tool itself. '
52 'It allows one to use the flutter tool from one checkout to downgrade a '
53 'different checkout.',
54 );
55 argParser.addFlag(
56 'prompt',
57 defaultsTo: true,
58 hide: !verboseHelp,
59 help: 'Show the downgrade prompt.',
60 );
61 }
62
63 Terminal? _terminal;
64 FlutterVersion? _flutterVersion;
65 PersistentToolState? _persistentToolState;
66 ProcessUtils? _processUtils;
67 ProcessManager? _processManager;
68 final Logger _logger;
69 Stdio? _stdio;
70 FileSystem? _fileSystem;
71
72 @override
73 String get description => 'Downgrade Flutter to the last active version for the current channel.';
74
75 @override
76 String get name => 'downgrade';
77
78 @override
79 final String category = FlutterCommandCategory.sdk;
80
81 @override
82 Future<FlutterCommandResult> runCommand() async {
83 // Commands do not necessarily have access to the correct zone injected
84 // values when being created. Fields must be lazily instantiated in runCommand,
85 // at least until the zone injection is refactored.
86 _terminal ??= globals.terminal;
87 _flutterVersion ??= globals.flutterVersion;
88 _persistentToolState ??= globals.persistentToolState;
89 _processManager ??= globals.processManager;
90 _processUtils ??= ProcessUtils(processManager: _processManager!, logger: _logger);
91 _stdio ??= globals.stdio;
92 _fileSystem ??= globals.fs;
93 String workingDirectory = Cache.flutterRoot!;
94 if (argResults!.wasParsed('working-directory')) {
95 workingDirectory = stringArg('working-directory')!;
96 _flutterVersion = FlutterVersion(fs: _fileSystem!, flutterRoot: workingDirectory);
97 }
98
99 final String currentChannel = _flutterVersion!.channel;
100 final Channel? channel = getChannelForName(currentChannel);
101 if (channel == null) {
102 throwToolExit(
103 'Flutter is not currently on a known channel. '
104 'Use "flutter channel" to switch to an official channel. ',
105 );
106 }
107 final PersistentToolState persistentToolState = _persistentToolState!;
108 final String? lastFlutterVersion = persistentToolState.lastActiveVersion(channel);
109 final String? currentFlutterVersion = _flutterVersion?.frameworkRevision;
110 if (lastFlutterVersion == null || currentFlutterVersion == lastFlutterVersion) {
111 final String trailing = await _createErrorMessage(workingDirectory, channel);
112 throwToolExit(
113 "It looks like you haven't run "
114 '"flutter upgrade" on channel "$currentChannel".\n'
115 '\n'
116 '"flutter downgrade" undoes the last "flutter upgrade".\n'
117 '\n'
118 'To switch to a specific Flutter version, see: '
119 'https://flutter.dev/to/switch-flutter-version'
120 '$trailing',
121 );
122 }
123
124 // Detect unknown versions.
125 final ProcessUtils processUtils = _processUtils!;
126 final RunResult parseResult = await processUtils.run(<String>[
127 'git',
128 'describe',
129 '--tags',
130 lastFlutterVersion,
131 ], workingDirectory: workingDirectory);
132 if (parseResult.exitCode != 0) {
133 throwToolExit('Failed to parse version for downgrade:\n${parseResult.stderr}');
134 }
135 final String humanReadableVersion = parseResult.stdout;
136
137 // If there is a terminal attached, prompt the user to confirm the downgrade.
138 final Stdio stdio = _stdio!;
139 final Terminal terminal = _terminal!;
140 if (stdio.hasTerminal && boolArg('prompt')) {
141 terminal.usesTerminalUi = true;
142 final String result = await terminal.promptForCharInput(
143 const <String>['y', 'n'],
144 prompt: 'Downgrade flutter to version $humanReadableVersion?',
145 logger: _logger,
146 );
147 if (result == 'n') {
148 return FlutterCommandResult.success();
149 }
150 } else {
151 _logger.printStatus('Downgrading Flutter to version $humanReadableVersion');
152 }
153
154 // To downgrade the tool, we perform a git checkout --hard, and then
155 // switch channels. The version recorded must have existed on that branch
156 // so this operation is safe.
157 try {
158 await processUtils.run(
159 <String>['git', 'reset', '--hard', lastFlutterVersion],
160 throwOnError: true,
161 workingDirectory: workingDirectory,
162 );
163 } on ProcessException catch (error) {
164 throwToolExit(
165 'Unable to downgrade Flutter: The tool could not update to the version '
166 '$humanReadableVersion.\n'
167 'Error: $error',
168 );
169 }
170 try {
171 await processUtils.run(
172 // The `--` bit (because it's followed by nothing) means that we don't actually change
173 // anything in the working tree, which avoids the need to first go into detached HEAD mode.
174 <String>['git', 'checkout', currentChannel, '--'],
175 throwOnError: true,
176 workingDirectory: workingDirectory,
177 );
178 } on ProcessException catch (error) {
179 throwToolExit(
180 'Unable to downgrade Flutter: The tool could not switch to the channel '
181 '$currentChannel.\n'
182 'Error: $error',
183 );
184 }
185 await FlutterVersion.resetFlutterVersionFreshnessCheck();
186 _logger.printStatus('Success');
187 return FlutterCommandResult.success();
188 }
189
190 // Formats an error message that lists the currently stored versions.
191 Future<String> _createErrorMessage(String workingDirectory, Channel currentChannel) async {
192 final buffer = StringBuffer();
193 for (final Channel channel in Channel.values) {
194 if (channel == currentChannel) {
195 continue;
196 }
197 final String? sha = _persistentToolState?.lastActiveVersion(channel);
198 if (sha == null) {
199 continue;
200 }
201 final RunResult parseResult = await _processUtils!.run(<String>[
202 'git',
203 'describe',
204 '--tags',
205 sha,
206 ], workingDirectory: workingDirectory);
207 if (parseResult.exitCode == 0) {
208 if (buffer.isEmpty) {
209 buffer.writeln();
210 }
211 buffer.writeln();
212 buffer.writeln(
213 'Channel "${getNameForChannel(channel)}" was previously on: '
214 '${parseResult.stdout}.',
215 );
216 }
217 }
218 return buffer.toString();
219 }
220}
221