lib/cli_logging.dart

// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/// This library contains functionality to help command-line utilities to easily
/// create aesthetic output.
library cli_logging;

import 'dart:async';
import 'dart:io' as io;

/// A small utility class to make it easier to work with common ANSI escape
/// sequences.
class Ansi {
  /// Return whether the current stdout terminal supports ANSI escape sequences.
  static bool get terminalSupportsAnsi =>
      io.stdout.supportsAnsiEscapes &&
      io.stdioType(io.stdout) == io.StdioType.terminal;

  final bool useAnsi;

  Ansi(this.useAnsi);

  String get cyan => _code('\u001b[36m');

  String get green => _code('\u001b[32m');

  String get magenta => _code('\u001b[35m');

  String get red => _code('\u001b[31m');

  String get yellow => _code('\u001b[33m');

  String get blue => _code('\u001b[34m');

  String get gray => _code('\u001b[1;30m');

  String get noColor => _code('\u001b[39m');

  String get none => _code('\u001b[0m');

  String get bold => _code('\u001b[1m');

  String get reversed => _code('\u001b[7m');

  String get backspace => '\b';

  String get bullet => io.stdout.supportsAnsiEscapes ? '•' : '-';

  /// Display [message] in an emphasized format.
  String emphasized(String message) => '$bold$message$none';

  /// Display [message] in an subtle (gray) format.
  String subtle(String message) => '$gray$message$none';

  /// Display [message] in an error (red) format.
  String error(String message) => '$red$message$none';

  String _code(String ansiCode) => useAnsi ? ansiCode : '';
}

/// An abstract representation of a [Logger] - used to pretty print errors,
/// standard status messages, trace level output, and indeterminate progress.
abstract class Logger {
  /// Create a normal [Logger]; this logger will not display trace level output.
  factory Logger.standard({Ansi? ansi}) => StandardLogger(ansi: ansi);

  /// Create a [Logger] that will display trace level output.
  ///
  /// If [logTime] is `true`, this logger will display the time of the message.
  factory Logger.verbose({Ansi? ansi, bool logTime = true}) {
    return VerboseLogger(ansi: ansi, logTime: logTime);
  }

  Ansi get ansi;

  bool get isVerbose;

  /// Print an error message.
  void stderr(String message);

  /// Print a standard status message.
  void stdout(String message);

  /// Print trace output.
  void trace(String message);

  /// Print text to stdout, without a trailing newline.
  void write(String message);

  /// Print a character code to stdout, without a trailing newline.
  void writeCharCode(int charCode);

  /// Start an indeterminate progress display.
  Progress progress(String message);

  /// Flush any un-written output.
  @Deprecated('This method will be removed in the future')
  void flush();
}

/// A handle to an indeterminate progress display.
abstract class Progress {
  final String message;
  final Stopwatch _stopwatch;

  Progress(this.message) : _stopwatch = Stopwatch()..start();

  Duration get elapsed => _stopwatch.elapsed;

  /// Finish the indeterminate progress display.
  void finish({String? message, bool showTiming = false});

  /// Cancel the indeterminate progress display.
  void cancel();
}

class StandardLogger implements Logger {
  @override
  Ansi ansi;

  StandardLogger({Ansi? ansi}) : ansi = ansi ?? Ansi(Ansi.terminalSupportsAnsi);

  @override
  bool get isVerbose => false;

  Progress? _currentProgress;

  @override
  void stderr(String message) {
    _cancelProgress();

    io.stderr.writeln(message);
  }

  @override
  void stdout(String message) {
    _cancelProgress();

    print(message);
  }

  @override
  void trace(String message) {}

  @override
  void write(String message) {
    _cancelProgress();

    io.stdout.write(message);
  }

  @override
  void writeCharCode(int charCode) {
    _cancelProgress();

    io.stdout.writeCharCode(charCode);
  }

  void _cancelProgress() {
    var progress = _currentProgress;
    if (progress != null) {
      _currentProgress = null;
      progress.cancel();
    }
  }

  @override
  Progress progress(String message) {
    _cancelProgress();

    var progress = ansi.useAnsi
        ? AnsiProgress(ansi, message)
        : SimpleProgress(this, message);
    _currentProgress = progress;
    return progress;
  }

  @override
  @Deprecated('This method will be removed in the future')
  void flush() {}
}

class SimpleProgress extends Progress {
  final Logger logger;

  SimpleProgress(this.logger, String message) : super(message) {
    logger.stdout('$message...');
  }

  @override
  void cancel() {}

  @override
  void finish({String? message, bool showTiming = false}) {}
}

class AnsiProgress extends Progress {
  static const List<String> kAnimationItems = ['/', '-', '\\', '|'];

  final Ansi ansi;

  int _index = 0;
  late final _timer = Timer.periodic(Duration(milliseconds: 80), (t) {
    _index++;
    _updateDisplay();
  });

  AnsiProgress(this.ansi, String message) : super(message) {
    io.stdout.write('$message...  '.padRight(40));
    _updateDisplay();
  }

  @override
  void cancel() {
    if (_timer.isActive) {
      _timer.cancel();
      _updateDisplay(cancelled: true);
    }
  }

  @override
  void finish({String? message, bool showTiming = false}) {
    if (_timer.isActive) {
      _timer.cancel();
      _updateDisplay(isFinal: true, message: message, showTiming: showTiming);
    }
  }

  void _updateDisplay(
      {bool isFinal = false,
      bool cancelled = false,
      String? message,
      bool showTiming = false}) {
    var char = kAnimationItems[_index % kAnimationItems.length];
    if (isFinal || cancelled) {
      char = '';
    }
    io.stdout.write('${ansi.backspace}$char');
    if (isFinal || cancelled) {
      if (message != null) {
        io.stdout.write(message.isEmpty ? ' ' : message);
      } else if (showTiming) {
        var time = (elapsed.inMilliseconds / 1000.0).toStringAsFixed(1);
        io.stdout.write('${time}s');
      } else {
        io.stdout.write(' ');
      }
      io.stdout.writeln();
    }
  }
}

class VerboseLogger implements Logger {
  @override
  Ansi ansi;
  bool logTime;
  final _timer = Stopwatch()..start();

  VerboseLogger({Ansi? ansi, this.logTime = false})
      : ansi = ansi ?? Ansi(Ansi.terminalSupportsAnsi);

  @override
  bool get isVerbose => true;

  @override
  void stdout(String message) {
    io.stdout.writeln('${_createPrefix()}$message');
  }

  @override
  void stderr(String message) {
    io.stderr.writeln('${_createPrefix()}${ansi.red}$message${ansi.none}');
  }

  @override
  void trace(String message) {
    io.stdout.writeln('${_createPrefix()}${ansi.gray}$message${ansi.none}');
  }

  @override
  void write(String message) {
    io.stdout.write(message);
  }

  @override
  void writeCharCode(int charCode) {
    io.stdout.writeCharCode(charCode);
  }

  @override
  Progress progress(String message) => SimpleProgress(this, message);

  @override
  @Deprecated('This method will be removed in the future')
  void flush() {}

  String _createPrefix() {
    if (!logTime) {
      return '';
    }

    var seconds = _timer.elapsedMilliseconds / 1000.0;
    var minutes = seconds ~/ 60;
    seconds -= minutes * 60.0;

    var buf = StringBuffer();
    if (minutes > 0) {
      buf.write((minutes % 60));
      buf.write('m ');
    }

    buf.write(seconds.toStringAsFixed(3).padLeft(minutes > 0 ? 6 : 1, '0'));
    buf.write('s');

    return '[${buf.toString().padLeft(11)}] ';
  }
}