// Copyright (c) 2018, 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.
import 'dart:io';

// READ ME! If you add a new field to this, make sure to add it to
// [parse()], [optionsEqual()], [hashCode], and [toString()]. A good check is to
// comment out an existing field and see what breaks. Every error is a place
// where you will need to add code for your new field.

/// A set of options that affects how a Dart SDK test is run in a way that may
/// affect its outcome.
///
/// This includes options like "compiler" and "runtime" which fundamentally
/// decide how a test is executed. Options are tracked because a single test
/// may have different outcomes for different configurations. For example, it
/// may currently pass on the VM but not dart2js or vice versa.
///
/// Options that affect how a test can be run but don't affect its outcome are
/// *not* stored here. Things like how test results are displayed, where logs
/// are written, etc. live outside of this.
class Configuration {
  /// Expands a configuration name "[template]" all using [optionsJson] to a
  /// list of configurations.
  ///
  /// A template is a configuration name that contains zero or more
  /// parenthesized sections. Within the parentheses are a series of options
  /// separated by pipes. For example:
  ///
  ///     strong-fasta-(linux|mac|win)-(debug|release)
  ///
  /// Text outside of parenthesized groups is treated literally. Each
  /// parenthesized section expands to a configuration for each of the options
  /// separated by pipes. If a template contains multiple parenthesized
  /// sections, configurations are created for all combinations of them. The
  /// above template expands to:
  ///
  ///     strong-fasta-linux-debug
  ///     strong-fasta-linux-release
  ///     strong-fasta-mac-debug
  ///     strong-fasta-mac-release
  ///     strong-fasta-win-debug
  ///     strong-fasta-win-release
  ///
  /// After expansion, the resulting strings (and [optionsJson]) are passed to
  /// [parse()] to convert each one to a full configuration.
  static List<Configuration> expandTemplate(
      String template, Map<String, dynamic> optionsJson) {
    if (template.isEmpty) throw FormatException("Template must not be empty.");

    var sections = <List<String>>[];
    var start = 0;
    while (start < template.length) {
      var openParen = template.indexOf("(", start);

      if (openParen == -1) {
        // Add the last literal section.
        sections.add([template.substring(start, template.length)]);
        break;
      }

      var closeParen = template.indexOf(")", openParen);
      if (closeParen == -1) {
        throw FormatException('Missing ")" in name template "$template".');
      }

      // Add the literal part before the next "(".
      sections.add([template.substring(start, openParen)]);

      // Add the options within the parentheses.
      sections.add(template.substring(openParen + 1, closeParen).split("|"));

      // Continue past the ")".
      start = closeParen + 1;
    }

    var result = <Configuration>[];

    // Walk through every combination of every section.
    iterateSection(String prefix, int section) {
      // If we pinned all the sections, parse it.
      if (section >= sections.length) {
        try {
          result.add(Configuration.parse(prefix, optionsJson));
        } on FormatException catch (ex) {
          throw FormatException(
              'Could not parse expanded configuration "$prefix" from template '
              '"$template":\n${ex.message}');
        }
        return;
      }

      for (var i = 0; i < sections[section].length; i++) {
        iterateSection(prefix + sections[section][i], section + 1);
      }
    }

    iterateSection("", 0);

    return result;
  }

  /// Parse a single configuration with [name] with additional options defined
  /// in [optionsJson].
  ///
  /// The name should be a series of words separated by hyphens. Any word that
  /// matches the name of an [Architecture], [Compiler], [Mode], [Runtime], or
  /// [System] sets that option in the resulting configuration. Those options
  /// may also be specified in the JSON map.
  ///
  /// Additional Boolean and string options are defined in the map. The key
  /// names match the corresponding command-line option names, using kebab-case.
  static Configuration parse(String name, Map<String, dynamic> optionsJson) {
    if (name.isEmpty) throw FormatException("Name must not be empty.");

    // Infer option values from the words in the configuration name.
    var words = name.split("-").toSet();
    var optionsCopy = Map.of(optionsJson);

    T enumOption<T extends NamedEnum>(
        String option, List<String> allowed, T Function(String) parse) {
      // Look up the value from the words in the name.
      T fromName;
      for (var value in allowed) {
        // Don't treat "none" as matchable since it's ambiguous as to whether
        // it refers to compiler or runtime.
        if (value == "none") continue;

        if (words.contains(value)) {
          if (fromName != null) {
            throw FormatException(
                'Found multiple values for $option ("$fromName" and "$value"), '
                'in configuration name.');
          }
          fromName = parse(value);
        }
      }

      // Look up the value from the options.
      T fromOption;
      if (optionsCopy.containsKey(option)) {
        fromOption = parse(optionsCopy[option] as String);
        optionsCopy.remove(option);
      }

      if (fromName != null && fromOption != null) {
        if (fromName == fromOption) {
          throw FormatException(
              'Redundant $option in configuration name "$fromName" and options.');
        } else {
          throw FormatException(
              'Found $option "$fromOption" in options and "$fromName" in '
              'configuration name.');
        }
      }

      return fromName ?? fromOption;
    }

    bool boolOption(String option) {
      if (!optionsCopy.containsKey(option)) return null;

      var value = optionsCopy.remove(option);
      if (value == null) throw FormatException('Option "$option" was null.');
      if (value is! bool) {
        throw FormatException('Option "$option" had value "$value", which is '
            'not a bool.');
      }
      return value as bool;
    }

    int intOption(String option) {
      if (!optionsCopy.containsKey(option)) return null;

      var value = optionsCopy.remove(option);
      if (value == null) throw FormatException('Option "$option" was null.');
      if (value is! int) {
        throw FormatException('Option "$option" had value "$value", which is '
            'not an int.');
      }
      return value as int;
    }

    String stringOption(String option) {
      if (!optionsCopy.containsKey(option)) return null;

      var value = optionsCopy.remove(option);
      if (value == null) throw FormatException('Option "$option" was null.');
      if (value is! String) {
        throw FormatException('Option "$option" had value "$value", which is '
            'not a string.');
      }
      return value as String;
    }

    List<String> stringListOption(String option) {
      if (!optionsCopy.containsKey(option)) return null;

      var value = optionsCopy.remove(option);
      if (value == null) throw FormatException('Option "$option" was null.');
      if (value is! List) {
        throw FormatException('Option "$option" had value "$value", which is '
            'not a List.');
      }
      return List<String>.from(value as List);
    }

    // Extract options from the name and map.
    var architecture =
        enumOption("architecture", Architecture.names, Architecture.find);
    var compiler = enumOption("compiler", Compiler.names, Compiler.find);
    var mode = enumOption("mode", Mode.names, Mode.find);
    var runtime = enumOption("runtime", Runtime.names, Runtime.find);
    var system = enumOption("system", System.names, System.find);
    var nnbdMode = enumOption("nnbd", NnbdMode.names, NnbdMode.find);
    var sanitizer = enumOption("sanitizer", Sanitizer.names, Sanitizer.find);

    // Fill in any missing values using defaults when possible.
    architecture ??= Architecture.x64;
    system ??= System.host;
    nnbdMode ??= NnbdMode.legacy;
    sanitizer ??= Sanitizer.none;

    // Infer from compiler from runtime or vice versa.
    if (compiler == null) {
      if (runtime == null) {
        throw FormatException(
            'Must specify at least one of compiler or runtime in options or '
            'configuration name.');
      } else {
        compiler = runtime.defaultCompiler;
      }
    } else {
      if (runtime == null) {
        runtime = compiler.defaultRuntime;
      } else {
        // Do nothing, specified both.
      }
    }

    // Infer the mode from the compiler.
    mode ??= compiler.defaultMode;

    var configuration = Configuration(
        name, architecture, compiler, mode, runtime, system,
        nnbdMode: nnbdMode,
        sanitizer: sanitizer,
        babel: stringOption("babel"),
        builderTag: stringOption("builder-tag"),
        genKernelOptions: stringListOption("gen-kernel-options"),
        vmOptions: stringListOption("vm-options"),
        dart2jsOptions: stringListOption("dart2js-options"),
        experiments: stringListOption("enable-experiment"),
        timeout: intOption("timeout"),
        enableAsserts: boolOption("enable-asserts"),
        isChecked: boolOption("checked"),
        isCsp: boolOption("csp"),
        isHostChecked: boolOption("host-checked"),
        isMinified: boolOption("minified"),
        useAnalyzerCfe: boolOption("use-cfe"),
        useAnalyzerFastaParser: boolOption("analyzer-use-fasta-parser"),
        useElf: boolOption("use-elf"),
        useHotReload: boolOption("hot-reload"),
        useHotReloadRollback: boolOption("hot-reload-rollback"),
        useSdk: boolOption("use-sdk"),
        useQemu: boolOption("use-qemu"));

    // Should have consumed the whole map.
    if (optionsCopy.isNotEmpty) {
      throw FormatException('Unknown option "${optionsCopy.keys.first}".');
    }

    return configuration;
  }

  final String name;

  final Architecture architecture;

  final Compiler compiler;

  final Mode mode;

  final Runtime runtime;

  final System system;

  /// Which NNBD mode to run the test files under.
  final NnbdMode nnbdMode;

  final Sanitizer sanitizer;

  final String babel;

  final String builderTag;

  final List<String> genKernelOptions;

  final List<String> vmOptions;

  final List<String> dart2jsOptions;

  /// The names of the experiments to enable while running tests.
  ///
  /// A test may *require* an experiment to always be enabled by containing a
  /// comment like:
  ///
  ///     // SharedOptions=--enable-experiment=extension-methods
  ///
  /// Enabling an experiment here in the configuration allows running the same
  /// test both with an experiment on and off.
  final List<String> experiments;

  final int timeout;

  final bool enableAsserts;

  // TODO(rnystrom): Remove this when Dart 1.0 is no longer supported.
  final bool isChecked;

  final bool isCsp;

  /// Enables asserts in the dart2js compiler.
  final bool isHostChecked;

  final bool isMinified;

  // TODO(whesse): Remove these when only fasta front end is in analyzer.
  final bool useAnalyzerCfe;
  final bool useAnalyzerFastaParser;

  final bool useElf;

  final bool useHotReload;
  final bool useHotReloadRollback;

  final bool useSdk;

  final bool useQemu;

  Configuration(this.name, this.architecture, this.compiler, this.mode,
      this.runtime, this.system,
      {NnbdMode nnbdMode,
      Sanitizer sanitizer,
      String babel,
      String builderTag,
      List<String> genKernelOptions,
      List<String> vmOptions,
      List<String> dart2jsOptions,
      List<String> experiments,
      int timeout,
      bool enableAsserts,
      bool isChecked,
      bool isCsp,
      bool isHostChecked,
      bool isMinified,
      bool useAnalyzerCfe,
      bool useAnalyzerFastaParser,
      bool useElf,
      bool useHotReload,
      bool useHotReloadRollback,
      bool useSdk,
      bool useQemu})
      : nnbdMode = nnbdMode ?? NnbdMode.legacy,
        sanitizer = sanitizer ?? Sanitizer.none,
        babel = babel ?? "",
        builderTag = builderTag ?? "",
        genKernelOptions = genKernelOptions ?? <String>[],
        vmOptions = vmOptions ?? <String>[],
        dart2jsOptions = dart2jsOptions ?? <String>[],
        experiments = experiments ?? <String>[],
        timeout = timeout ?? -1,
        enableAsserts = enableAsserts ?? false,
        isChecked = isChecked ?? false,
        isCsp = isCsp ?? false,
        isHostChecked = isHostChecked ?? false,
        isMinified = isMinified ?? false,
        useAnalyzerCfe = useAnalyzerCfe ?? false,
        useAnalyzerFastaParser = useAnalyzerFastaParser ?? false,
        useElf = useElf ?? false,
        useHotReload = useHotReload ?? false,
        useHotReloadRollback = useHotReloadRollback ?? false,
        useSdk = useSdk ?? false,
        useQemu = useQemu ?? false;

  /// Returns `true` if this configuration's options all have the same values
  /// as [other].
  bool optionsEqual(Configuration other) =>
      architecture == other.architecture &&
      compiler == other.compiler &&
      mode == other.mode &&
      runtime == other.runtime &&
      system == other.system &&
      nnbdMode == other.nnbdMode &&
      sanitizer == other.sanitizer &&
      babel == other.babel &&
      builderTag == other.builderTag &&
      _listsEqual(genKernelOptions, other.genKernelOptions) &&
      _listsEqual(vmOptions, other.vmOptions) &&
      _listsEqual(dart2jsOptions, other.dart2jsOptions) &&
      _listsEqual(experiments, other.experiments) &&
      timeout == other.timeout &&
      enableAsserts == other.enableAsserts &&
      isChecked == other.isChecked &&
      isCsp == other.isCsp &&
      isHostChecked == other.isHostChecked &&
      isMinified == other.isMinified &&
      useAnalyzerCfe == other.useAnalyzerCfe &&
      useAnalyzerFastaParser == other.useAnalyzerFastaParser &&
      useElf == other.useElf &&
      useHotReload == other.useHotReload &&
      useHotReloadRollback == other.useHotReloadRollback &&
      useSdk == other.useSdk &&
      useQemu == other.useQemu;

  /// Whether [a] and [b] contain the same strings, regardless of order.
  bool _listsEqual(List<String> a, List<String> b) {
    if (a.length != b.length) return false;

    // Using sorted lists instead of sets in case there are duplicate strings
    // in the lists. ["a"] should not be considered equal to ["a", "a"].
    var aSorted = a.toList()..sort();
    var bSorted = b.toList()..sort();
    for (var i = 0; i < aSorted.length; i++) {
      if (aSorted[i] != bSorted[i]) return false;
    }
    return true;
  }

  bool operator ==(Object other) =>
      other is Configuration && name == other.name && optionsEqual(other);

  int _toBinary(List<bool> bits) =>
      bits.fold(0, (sum, bit) => (sum << 1) ^ (bit ? 1 : 0));

  int get hashCode =>
      name.hashCode ^
      architecture.hashCode ^
      compiler.hashCode ^
      mode.hashCode ^
      runtime.hashCode ^
      system.hashCode ^
      nnbdMode.hashCode ^
      babel.hashCode ^
      builderTag.hashCode ^
      genKernelOptions.join(" & ").hashCode ^
      vmOptions.join(" & ").hashCode ^
      dart2jsOptions.join(" & ").hashCode ^
      experiments.join(" & ").hashCode ^
      timeout.hashCode ^
      _toBinary([
        enableAsserts,
        isChecked,
        isCsp,
        isHostChecked,
        isMinified,
        useAnalyzerCfe,
        useAnalyzerFastaParser,
        useElf,
        useHotReload,
        useHotReloadRollback,
        useSdk,
        useQemu
      ]);

  String toString() {
    var buffer = StringBuffer();
    buffer.write(name);
    buffer.write("(");

    var fields = <String>[];
    fields.add("architecture: $architecture");
    fields.add("compiler: $compiler");
    fields.add("mode: $mode");
    fields.add("runtime: $runtime");
    fields.add("system: $system");

    if (nnbdMode != NnbdMode.legacy) fields.add("nnbd: $nnbdMode");

    stringListField(String name, List<String> field) {
      if (field.isEmpty) return;
      fields.add("$name: [${field.join(", ")}]");
    }

    if (babel.isNotEmpty) fields.add("babel: $babel");
    if (builderTag.isNotEmpty) fields.add("builder-tag: $builderTag");
    stringListField("gen-kernel-options", genKernelOptions);
    stringListField("vm-options", vmOptions);
    stringListField("dart2js-options", dart2jsOptions);
    stringListField("enable-experiment", experiments);
    if (timeout > 0) fields.add("timeout: $timeout");
    if (enableAsserts) fields.add("enable-asserts");
    if (isChecked) fields.add("checked");
    if (isCsp) fields.add("csp");
    if (isHostChecked) fields.add("host-checked");
    if (isMinified) fields.add("minified");
    if (useAnalyzerCfe) fields.add("use-cfe");
    if (useAnalyzerFastaParser) fields.add("analyzer-use-fasta-parser");
    if (useHotReload) fields.add("hot-reload");
    if (useHotReloadRollback) fields.add("hot-reload-rollback");
    if (useSdk) fields.add("use-sdk");
    if (useQemu) fields.add("use-qemu");

    buffer.write(fields.join(", "));
    buffer.write(")");
    return buffer.toString();
  }

  String visualCompare(Configuration other) {
    var buffer = StringBuffer();
    buffer.writeln(name);
    buffer.writeln(other.name);

    var fields = <String>[];
    fields.add("architecture: $architecture ${other.architecture}");
    fields.add("compiler: $compiler ${other.compiler}");
    fields.add("mode: $mode ${other.mode}");
    fields.add("runtime: $runtime ${other.runtime}");
    fields.add("system: $system ${other.system}");

    stringField(String name, String value, String otherValue) {
      if (value.isEmpty && otherValue.isEmpty) return;
      var ours = value.isEmpty ? "(none)" : value;
      var theirs = otherValue.isEmpty ? "(none)" : otherValue;
      fields.add("$name: $ours $theirs");
    }

    stringListField(String name, List<String> value, List<String> otherValue) {
      if (value.isEmpty && otherValue.isEmpty) return;
      fields.add("$name: [${value.join(', ')}] [${otherValue.join(', ')}]");
    }

    boolField(String name, bool value, bool otherValue) {
      if (!value && !otherValue) return;
      fields.add("$name: $value $otherValue");
    }

    fields.add("nnbd: $nnbdMode ${other.nnbdMode}");
    fields.add("sanitizer: $sanitizer ${other.sanitizer}");
    stringField("babel", babel, other.babel);
    stringField("builder-tag", builderTag, other.builderTag);
    stringListField(
        "gen-kernel-options", genKernelOptions, other.genKernelOptions);
    stringListField("vm-options", vmOptions, other.vmOptions);
    stringListField("dart2js-options", dart2jsOptions, other.dart2jsOptions);
    stringListField("experiments", experiments, other.experiments);
    fields.add("timeout: $timeout ${other.timeout}");
    boolField("enable-asserts", enableAsserts, other.enableAsserts);
    boolField("checked", isChecked, other.isChecked);
    boolField("csp", isCsp, other.isCsp);
    boolField("host-checked", isHostChecked, other.isHostChecked);
    boolField("minified", isMinified, other.isMinified);
    boolField("use-cfe", useAnalyzerCfe, other.useAnalyzerCfe);
    boolField("analyzer-use-fasta-parser", useAnalyzerFastaParser,
        other.useAnalyzerFastaParser);
    boolField("host-checked", isHostChecked, other.isHostChecked);
    boolField("hot-reload", useHotReload, other.useHotReload);
    boolField("hot-reload-rollback", useHotReloadRollback,
        other.useHotReloadRollback);
    boolField("use-sdk", useSdk, other.useSdk);
    boolField("use-qemu", useQemu, other.useQemu);

    buffer.write(fields.join("\n   "));
    buffer.write("\n");
    return buffer.toString();
  }
}

class Architecture extends NamedEnum {
  static const ia32 = Architecture._('ia32');
  static const x64 = Architecture._('x64');
  static const arm = Architecture._('arm');
  static const arm_x64 = Architecture._('arm_x64');
  static const armv6 = Architecture._('armv6');
  static const arm64 = Architecture._('arm64');
  static const simarm = Architecture._('simarm');
  static const simarmv6 = Architecture._('simarmv6');
  static const simarm64 = Architecture._('simarm64');

  static final List<String> names = _all.keys.toList();

  static final _all = Map<String, Architecture>.fromIterable([
    ia32,
    x64,
    arm,
    armv6,
    arm_x64,
    arm64,
    simarm,
    simarmv6,
    simarm64,
  ], key: (architecture) => (architecture as Architecture).name);

  static Architecture find(String name) {
    var architecture = _all[name];
    if (architecture != null) return architecture;

    throw ArgumentError('Unknown architecture "$name".');
  }

  const Architecture._(String name) : super(name);
}

class Compiler extends NamedEnum {
  static const none = Compiler._('none');
  static const dart2js = Compiler._('dart2js');
  static const dart2analyzer = Compiler._('dart2analyzer');
  static const compareAnalyzerCfe = Compiler._('compare_analyzer_cfe');
  static const dartdevc = Compiler._('dartdevc');
  static const dartdevk = Compiler._('dartdevk');
  static const appJitk = Compiler._('app_jitk');
  static const dartk = Compiler._('dartk');
  static const dartkp = Compiler._('dartkp');
  static const specParser = Compiler._('spec_parser');
  static const fasta = Compiler._('fasta');

  static final List<String> names = _all.keys.toList();

  static final _all = Map<String, Compiler>.fromIterable([
    none,
    dart2js,
    dart2analyzer,
    compareAnalyzerCfe,
    dartdevc,
    dartdevk,
    appJitk,
    dartk,
    dartkp,
    specParser,
    fasta,
  ], key: (compiler) => (compiler as Compiler).name);

  static Compiler find(String name) {
    var compiler = _all[name];
    if (compiler != null) return compiler;

    throw ArgumentError('Unknown compiler "$name".');
  }

  const Compiler._(String name) : super(name);

  /// Gets the runtimes this compiler can target.
  List<Runtime> get supportedRuntimes {
    switch (this) {
      case Compiler.dart2js:
        // Note: by adding 'none' as a configuration, if the user
        // runs test.py -c dart2js -r drt,none the dart2js_none and
        // dart2js_drt will be duplicating work. If later we don't need 'none'
        // with dart2js, we should remove it from here.
        return const [
          Runtime.d8,
          Runtime.jsshell,
          Runtime.none,
          Runtime.firefox,
          Runtime.chrome,
          Runtime.safari,
          Runtime.ie9,
          Runtime.ie10,
          Runtime.ie11,
          Runtime.edge,
          Runtime.chromeOnAndroid,
        ];

      case Compiler.dartdevc:
      case Compiler.dartdevk:
        // TODO(rnystrom): Expand to support other JS execution environments
        // (other browsers, d8) when tested and working.
        return const [
          Runtime.none,
          Runtime.chrome,
          Runtime.edge,
          Runtime.firefox,
          Runtime.safari,
        ];

      case Compiler.dart2analyzer:
      case Compiler.compareAnalyzerCfe:
        return const [Runtime.none];
      case Compiler.appJitk:
      case Compiler.dartk:
        return const [Runtime.vm, Runtime.selfCheck];
      case Compiler.dartkp:
        return const [Runtime.dartPrecompiled];
      case Compiler.specParser:
        return const [Runtime.none];
      case Compiler.fasta:
        return const [Runtime.none];
      case Compiler.none:
        return const [Runtime.vm, Runtime.flutter];
    }

    throw "unreachable";
  }

  /// The preferred runtime to use with this compiler if no other runtime is
  /// specified.
  Runtime get defaultRuntime {
    switch (this) {
      case Compiler.dart2js:
        return Runtime.d8;
      case Compiler.dartdevc:
      case Compiler.dartdevk:
        return Runtime.chrome;
      case Compiler.dart2analyzer:
      case Compiler.compareAnalyzerCfe:
        return Runtime.none;
      case Compiler.appJitk:
      case Compiler.dartk:
        return Runtime.vm;
      case Compiler.dartkp:
        return Runtime.dartPrecompiled;
      case Compiler.specParser:
      case Compiler.fasta:
        return Runtime.none;
      case Compiler.none:
        return Runtime.vm;
    }

    throw "unreachable";
  }

  Mode get defaultMode {
    switch (this) {
      case Compiler.dart2analyzer:
      case Compiler.compareAnalyzerCfe:
      case Compiler.dart2js:
      case Compiler.dartdevc:
      case Compiler.dartdevk:
      case Compiler.fasta:
        return Mode.release;

      default:
        return Mode.debug;
    }
  }
}

class Mode extends NamedEnum {
  static const debug = Mode._('debug');
  static const product = Mode._('product');
  static const release = Mode._('release');

  static final List<String> names = _all.keys.toList();

  static final _all = Map<String, Mode>.fromIterable([debug, product, release],
      key: (mode) => (mode as Mode).name);

  static Mode find(String name) {
    var mode = _all[name];
    if (mode != null) return mode;

    throw ArgumentError('Unknown mode "$name".');
  }

  const Mode._(String name) : super(name);

  bool get isDebug => this == debug;
}

class Sanitizer extends NamedEnum {
  static const none = Sanitizer._('none');
  static const asan = Sanitizer._('asan');
  static const lsan = Sanitizer._('lsan');
  static const msan = Sanitizer._('msan');
  static const tsan = Sanitizer._('tsan');
  static const ubsan = Sanitizer._('ubsan');

  static final List<String> names = _all.keys.toList();

  static final _all = Map<String, Sanitizer>.fromIterable(
      [none, asan, lsan, msan, tsan, ubsan],
      key: (mode) => (mode as Sanitizer).name);

  static Sanitizer find(String name) {
    var mode = _all[name];
    if (mode != null) return mode;

    throw ArgumentError('Unknown sanitizer "$name".');
  }

  const Sanitizer._(String name) : super(name);
}

class Runtime extends NamedEnum {
  static const vm = Runtime._('vm');
  static const flutter = Runtime._('flutter');
  static const dartPrecompiled = Runtime._('dart_precompiled');
  static const d8 = Runtime._('d8');
  static const jsshell = Runtime._('jsshell');
  static const firefox = Runtime._('firefox');
  static const chrome = Runtime._('chrome');
  static const safari = Runtime._('safari');
  static const ie9 = Runtime._('ie9');
  static const ie10 = Runtime._('ie10');
  static const ie11 = Runtime._('ie11');
  static const edge = Runtime._('edge');
  static const chromeOnAndroid = Runtime._('chromeOnAndroid');
  static const selfCheck = Runtime._('self_check');
  static const none = Runtime._('none');

  static final List<String> names = _all.keys.toList();

  static final _all = Map<String, Runtime>.fromIterable([
    vm,
    flutter,
    dartPrecompiled,
    d8,
    jsshell,
    firefox,
    chrome,
    safari,
    ie9,
    ie10,
    ie11,
    edge,
    chromeOnAndroid,
    selfCheck,
    none
  ], key: (runtime) => (runtime as Runtime).name);

  static Runtime find(String name) {
    var runtime = _all[name];
    if (runtime != null) return runtime;

    throw ArgumentError('Unknown runtime "$name".');
  }

  const Runtime._(String name) : super(name);

  bool get isBrowser => const [
        ie9,
        ie10,
        ie11,
        edge,
        safari,
        chrome,
        firefox,
        chromeOnAndroid
      ].contains(this);

  bool get isIE => name.startsWith("ie");

  bool get isSafari => name.startsWith("safari");

  /// Whether this runtime is a command-line JavaScript environment.
  bool get isJSCommandLine => const [d8, jsshell].contains(this);

  /// If the runtime doesn't support `Window.open`, we use iframes instead.
  bool get requiresIFrame => !const [ie11, ie10].contains(this);

  /// The preferred compiler to use with this runtime if no other compiler is
  /// specified.
  Compiler get defaultCompiler {
    switch (this) {
      case vm:
      case flutter:
        return Compiler.none;

      case dartPrecompiled:
        return Compiler.dartkp;

      case d8:
      case jsshell:
      case firefox:
      case chrome:
      case safari:
      case ie9:
      case ie10:
      case ie11:
      case edge:
      case chromeOnAndroid:
        return Compiler.dart2js;

      case selfCheck:
        return Compiler.dartk;

      case none:
        // If we aren't running it, we probably just want to analyze it.
        return Compiler.dart2analyzer;
    }

    throw "unreachable";
  }
}

class System extends NamedEnum {
  static const android = System._('android');
  static const fuchsia = System._('fuchsia');
  static const linux = System._('linux');
  static const mac = System._('mac');
  static const win = System._('win');

  static final List<String> names = _all.keys.toList();

  static final _all = Map<String, System>.fromIterable(
      [android, fuchsia, linux, mac, win],
      key: (system) => (system as System).name);

  /// Gets the system of the current machine.
  static System get host => find(Platform.operatingSystem);

  static System find(String name) {
    var system = _all[name];
    if (system != null) return system;

    // Also allow dart:io's names for the operating systems.
    switch (Platform.operatingSystem) {
      case "macos":
        return mac;
      case "windows":
        return win;
    }
    // TODO(rnystrom): What about ios?

    throw ArgumentError('Unknown operating system "$name".');
  }

  const System._(String name) : super(name);

  /// The root directory name for build outputs on this system.
  String get outputDirectory {
    switch (this) {
      case android:
      case fuchsia:
      case linux:
      case win:
        return 'out/';

      case mac:
        return 'xcodebuild/';
    }

    throw "unreachable";
  }
}

/// What level of non-nullability support should be applied to the test files.
class NnbdMode extends NamedEnum {
  /// "Opted out" legacy mode with no NNBD features allowed.
  static const legacy = NnbdMode._('legacy');

  /// Opted in to NNBD features, but only static checking and weak runtime
  /// checks.
  static const weak = NnbdMode._('weak');

  /// Opted in to NNBD features and with full sound runtime checks.
  static const strong = NnbdMode._('strong');

  static final List<String> names = _all.keys.toList();

  static final _all = {
    for (var mode in [legacy, weak, strong]) mode.name: mode
  };

  static NnbdMode find(String name) {
    var mode = _all[name];
    if (mode != null) return mode;

    throw ArgumentError('Unknown NNBD mode "$name".');
  }

  const NnbdMode._(String name) : super(name);
}

/// Base class for an enum-like class whose values are identified by name.
abstract class NamedEnum {
  final String name;

  const NamedEnum(this.name);

  String toString() => name;
}