// Copyright (c) 2012, 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.

library pub.pubspec;

import 'package:path/path.dart' as path;
import 'package:source_span/source_span.dart';
import 'package:yaml/yaml.dart';

import 'barback/transformer_config.dart';
import 'exceptions.dart';
import 'io.dart';
import 'package.dart';
import 'source_registry.dart';
import 'utils.dart';
import 'version.dart';

/// The parsed contents of a pubspec file.
///
/// The fields of a pubspec are, for the most part, validated when they're first
/// accessed. This allows a partially-invalid pubspec to be used if only the
/// valid portions are relevant. To get a list of all errors in the pubspec, use
/// [allErrors].
class Pubspec {
  // If a new lazily-initialized field is added to this class and the
  // initialization can throw a [PubspecException], that error should also be
  // exposed through [allErrors].

  /// The registry of sources to use when parsing [dependencies] and
  /// [devDependencies].
  ///
  /// This will be null if this was created using [new Pubspec] or [new
  /// Pubspec.empty].
  final SourceRegistry _sources;

  /// The location from which the pubspec was loaded.
  ///
  /// This can be null if the pubspec was created in-memory or if its location
  /// is unknown.
  Uri get _location => fields.span.sourceUrl;

  /// All pubspec fields.
  ///
  /// This includes the fields from which other properties are derived.
  final YamlMap fields;

  /// The package's name.
  String get name {
    if (_name != null) return _name;

    var name = fields['name'];
    if (name == null) {
      throw new PubspecException(
          'Missing the required "name" field.', fields.span);
    } else if (name is! String) {
      throw new PubspecException(
          '"name" field must be a string.', fields.nodes['name'].span);
    }

    _name = name;
    return _name;
  }
  String _name;

  /// The package's version.
  Version get version {
    if (_version != null) return _version;

    var version = fields['version'];
    if (version == null) {
      _version = Version.none;
      return _version;
    }

    var span = fields.nodes['version'].span;
    if (version is! String) {
      _error('"version" field must be a string.', span);
    }

    _version = _wrapFormatException('version number', span,
        () => new Version.parse(version));
    return _version;
  }
  Version _version;

  /// The additional packages this package depends on.
  List<PackageDep> get dependencies {
    if (_dependencies != null) return _dependencies;
    _dependencies = _parseDependencies('dependencies');
    if (_devDependencies == null) {
      _checkDependencyOverlap(_dependencies, devDependencies);
    }
    return _dependencies;
  }
  List<PackageDep> _dependencies;

  /// The packages this package depends on when it is the root package.
  List<PackageDep> get devDependencies {
    if (_devDependencies != null) return _devDependencies;
    _devDependencies = _parseDependencies('dev_dependencies');
    if (_dependencies == null) {
      _checkDependencyOverlap(dependencies, _devDependencies);
    }
    return _devDependencies;
  }
  List<PackageDep> _devDependencies;

  /// The dependency constraints that this package overrides when it is the
  /// root package.
  ///
  /// Dependencies here will replace any dependency on a package with the same
  /// name anywhere in the dependency graph.
  List<PackageDep> get dependencyOverrides {
    if (_dependencyOverrides != null) return _dependencyOverrides;
    _dependencyOverrides = _parseDependencies('dependency_overrides');
    return _dependencyOverrides;
  }
  List<PackageDep> _dependencyOverrides;

  /// The configurations of the transformers to use for this package.
  List<Set<TransformerConfig>> get transformers {
    if (_transformers != null) return _transformers;

    var transformers = fields['transformers'];
    if (transformers == null) {
      _transformers = [];
      return _transformers;
    }

    if (transformers is! List) {
      _error('"transformers" field must be a list.',
          fields.nodes['transformers'].span);
    }

    var i = 0;
    _transformers = transformers.nodes.map((phase) {
      var phaseNodes = phase is YamlList ? phase.nodes : [phase];
      return phaseNodes.map((transformerNode) {
        var transformer = transformerNode.value;
        if (transformer is! String && transformer is! Map) {
          _error('A transformer must be a string or map.',
                 transformerNode.span);
        }

        var libraryNode;
        var configurationNode;
        if (transformer is String) {
          libraryNode = transformerNode;
        } else {
          if (transformer.length != 1) {
            _error('A transformer map must have a single key: the transformer '
                'identifier.', transformerNode.span);
          } else if (transformer.keys.single is! String) {
            _error('A transformer identifier must be a string.',
                transformer.nodes.keys.single.span);
          }

          libraryNode = transformer.nodes.keys.single;
          configurationNode = transformer.nodes.values.single;
          if (configurationNode is! YamlMap) {
            _error("A transformer's configuration must be a map.",
                configurationNode.span);
          }
        }

        var config = _wrapSpanFormatException('transformer config', () {
          return new TransformerConfig.parse(
            libraryNode.value, libraryNode.span,
            configurationNode);
        });

        var package = config.id.package;
        if (package != name &&
            !config.id.isBuiltInTransformer &&
            !dependencies.any((ref) => ref.name == package) &&
            !devDependencies.any((ref) => ref.name == package) &&
            !dependencyOverrides.any((ref) => ref.name == package)) {
          _error('"$package" is not a dependency.',
              libraryNode.span);
        }

        return config;
      }).toSet();
    }).toList();

    return _transformers;
  }
  List<Set<TransformerConfig>> _transformers;

  /// The environment-related metadata.
  PubspecEnvironment get environment {
    if (_environment != null) return _environment;

    var yaml = fields['environment'];
    if (yaml == null) {
      _environment = new PubspecEnvironment(VersionConstraint.any);
      return _environment;
    }

    if (yaml is! Map) {
      _error('"environment" field must be a map.',
             fields.nodes['environment'].span);
    }

    _environment = new PubspecEnvironment(
        _parseVersionConstraint(yaml.nodes['sdk']));
    return _environment;
  }
  PubspecEnvironment _environment;

  /// The URL of the server that the package should default to being published
  /// to, "none" if the package should not be published, or `null` if it should
  /// be published to the default server.
  ///
  /// If this does return a URL string, it will be a valid parseable URL.
  String get publishTo {
    if (_parsedPublishTo) return _publishTo;

    var publishTo = fields['publishTo'];
    if (publishTo != null) {
      var span = fields.nodes['publishTo'].span;

      if (publishTo is! String) {
        _error('"publishTo" field must be a string.', span);
      }

      // It must be "none" or a valid URL.
      if (publishTo != "none") {
        _wrapFormatException('"publishTo" field', span,
            () => Uri.parse(publishTo));
      }
    }

    _parsedPublishTo = true;
    _publishTo = publishTo;
    return _publishTo;
  }
  bool _parsedPublishTo = false;
  String _publishTo;

  /// Whether the package is private and cannot be published.
  ///
  /// This is specified in the pubspec by setting "publishTo" to "none".
  bool get isPrivate => publishTo == "none";

  /// Whether or not the pubspec has no contents.
  bool get isEmpty =>
    name == null && version == Version.none && dependencies.isEmpty;

  /// Loads the pubspec for a package located in [packageDir].
  ///
  /// If [expectedName] is passed and the pubspec doesn't have a matching name
  /// field, this will throw a [PubspecError].
  factory Pubspec.load(String packageDir, SourceRegistry sources,
      {String expectedName}) {
    var pubspecPath = path.join(packageDir, 'pubspec.yaml');
    var pubspecUri = path.toUri(pubspecPath);
    if (!fileExists(pubspecPath)) {
      throw new FileException(
          'Could not find a file named "pubspec.yaml" in "$packageDir".',
          pubspecPath);
    }

    return new Pubspec.parse(readTextFile(pubspecPath), sources,
        expectedName: expectedName, location: pubspecUri);
  }

  Pubspec(this._name, this._version, this._dependencies, this._devDependencies,
          this._dependencyOverrides, this._environment, this._transformers,
          [Map fields])
    : this.fields = fields == null ? new YamlMap() : fields,
      _sources = null;

  Pubspec.empty()
    : _sources = null,
      _name = null,
      _version = Version.none,
      _dependencies = <PackageDep>[],
      _devDependencies = <PackageDep>[],
      _environment = new PubspecEnvironment(),
      _transformers = <Set<TransformerConfig>>[],
      fields = new YamlMap();

  /// Returns a Pubspec object for an already-parsed map representing its
  /// contents.
  ///
  /// If [expectedName] is passed and the pubspec doesn't have a matching name
  /// field, this will throw a [PubspecError].
  ///
  /// [location] is the location from which this pubspec was loaded.
  Pubspec.fromMap(Map fields, this._sources, {String expectedName,
      Uri location})
      : fields = fields is YamlMap ? fields :
            new YamlMap.wrap(fields, sourceUrl: location) {
    // If [expectedName] is passed, ensure that the actual 'name' field exists
    // and matches the expectation.
    if (expectedName == null) return;
    if (name == expectedName) return;

    throw new PubspecException('"name" field doesn\'t match expected name '
        '"$expectedName".', this.fields.nodes["name"].span);
  }

  /// Parses the pubspec stored at [filePath] whose text is [contents].
  ///
  /// If the pubspec doesn't define a version for itself, it defaults to
  /// [Version.none].
  factory Pubspec.parse(String contents, SourceRegistry sources,
      {String expectedName, Uri location}) {
    var pubspecNode = loadYamlNode(contents, sourceUrl: location);
    if (pubspecNode is YamlScalar && pubspecNode.value == null) {
      pubspecNode = new YamlMap(sourceUrl: location);
    } else if (pubspecNode is! YamlMap) {
      throw new PubspecException(
          'The pubspec must be a YAML mapping.', pubspecNode.span);
    }

    return new Pubspec.fromMap(pubspecNode, sources,
        expectedName: expectedName, location: location);
  }

  /// Returns a list of most errors in this pubspec.
  ///
  /// This will return at most one error for each field.
  List<PubspecException> get allErrors {
    var errors = <PubspecException>[];
    _getError(fn()) {
      try {
        fn();
      } on PubspecException catch (e) {
        errors.add(e);
      }
    }

    _getError(() => this.name);
    _getError(() => this.version);
    _getError(() => this.dependencies);
    _getError(() => this.devDependencies);
    _getError(() => this.transformers);
    _getError(() => this.environment);
    _getError(() => this.publishTo);
    return errors;
  }

  /// Parses the dependency field named [field], and returns the corresponding
  /// list of dependencies.
  List<PackageDep> _parseDependencies(String field) {
    var dependencies = <PackageDep>[];

    var yaml = fields[field];
    // Allow an empty dependencies key.
    if (yaml == null) return dependencies;

    if (yaml is! Map) {
      _error('"$field" field must be a map.', fields.nodes[field].span);
    }

    var nonStringNode = yaml.nodes.keys.firstWhere((e) => e.value is! String,
        orElse: () => null);
    if (nonStringNode != null) {
      _error('A dependency name must be a string.', nonStringNode.span);
    }

    yaml.nodes.forEach((nameNode, specNode) {
      var name = nameNode.value;
      var spec = specNode.value;
      if (fields['name'] != null && name == this.name) {
        _error('A package may not list itself as a dependency.',
            nameNode.span);
      }

      var descriptionNode;
      var sourceName;

      var versionConstraint = new VersionRange();
      if (spec == null) {
        descriptionNode = nameNode;
        sourceName = _sources.defaultSource.name;
      } else if (spec is String) {
        descriptionNode = nameNode;
        sourceName = _sources.defaultSource.name;
        versionConstraint = _parseVersionConstraint(specNode);
      } else if (spec is Map) {
        // Don't write to the immutable YAML map.
        spec = new Map.from(spec);

        if (spec.containsKey('version')) {
          spec.remove('version');
          versionConstraint = _parseVersionConstraint(
              specNode.nodes['version']);
        }

        var sourceNames = spec.keys.toList();
        if (sourceNames.length > 1) {
          _error('A dependency may only have one source.', specNode.span);
        }

        sourceName = sourceNames.single;
        if (sourceName is! String) {
          _error('A source name must be a string.',
              specNode.nodes.keys.single.span);
        }

        descriptionNode = specNode.nodes[sourceName];
      } else {
        _error('A dependency specification must be a string or a mapping.',
            specNode.span);
      }

      // Let the source validate the description.
      var description = _wrapFormatException('description',
          descriptionNode.span, () {
        var pubspecPath;
        if (_location != null && _isFileUri(_location)) {
          pubspecPath = path.fromUri(_location);
        }

        return _sources[sourceName].parseDescription(
            pubspecPath, descriptionNode.value, fromLockFile: false);
      });

      dependencies.add(new PackageDep(
          name, sourceName, versionConstraint, description));
    });

    return dependencies;
  }

  /// Parses [node] to a [VersionConstraint].
  VersionConstraint _parseVersionConstraint(YamlNode node) {
    if (node.value == null) return VersionConstraint.any;
    if (node.value is! String) {
      _error('A version constraint must be a string.', node.span);
    }

    return _wrapFormatException('version constraint', node.span,
        () => new VersionConstraint.parse(node.value));
  }

  /// Makes sure the same package doesn't appear as both a regular and dev
  /// dependency.
  void _checkDependencyOverlap(List<PackageDep> dependencies,
      List<PackageDep> devDependencies) {
    var dependencyNames = dependencies.map((dep) => dep.name).toSet();
    var collisions = dependencyNames.intersection(
        devDependencies.map((dep) => dep.name).toSet());
    if (collisions.isEmpty) return;

    var span = fields["dependencies"].nodes.keys
        .firstWhere((key) => collisions.contains(key.value)).span;

    // TODO(nweiz): associate source range info with PackageDeps and use it
    // here.
    _error('${pluralize('Package', collisions.length)} '
        '${toSentence(collisions.map((package) => '"$package"'))} cannot '
        'appear in both "dependencies" and "dev_dependencies".',
        span);
  }

  /// Runs [fn] and wraps any [FormatException] it throws in a
  /// [PubspecException].
  ///
  /// [description] should be a noun phrase that describes whatever's being
  /// parsed or processed by [fn]. [span] should be the location of whatever's
  /// being processed within the pubspec.
  _wrapFormatException(String description, SourceSpan span, fn()) {
    try {
      return fn();
    } on FormatException catch (e) {
      _error('Invalid $description: ${e.message}', span);
    }
  }

  _wrapSpanFormatException(String description, fn()) {
    try {
      return fn();
    } on SourceSpanFormatException catch (e) {
      _error('Invalid $description: ${e.message}', e.span);
    }
  }

  /// Throws a [PubspecException] with the given message.
  void _error(String message, SourceSpan span) {
    var name;
    try {
      name = this.name;
    } on PubspecException catch (_) {
      // [name] is null.
    }

    throw new PubspecException(message, span);
  }
}

/// The environment-related metadata in the pubspec.
///
/// Corresponds to the data under the "environment:" key in the pubspec.
class PubspecEnvironment {
  /// The version constraint specifying which SDK versions this package works
  /// with.
  final VersionConstraint sdkVersion;

  PubspecEnvironment([VersionConstraint sdk])
      : sdkVersion = sdk != null ? sdk : VersionConstraint.any;
}

/// An exception thrown when parsing a pubspec.
///
/// These exceptions are often thrown lazily while accessing pubspec properties.
class PubspecException extends SourceSpanFormatException
    implements ApplicationException {
  PubspecException(String message, SourceSpan span)
      : super(message, span);
}

/// Returns whether [uri] is a file URI.
///
/// This is slightly more complicated than just checking if the scheme is
/// 'file', since relative URIs also refer to the filesystem on the VM.
bool _isFileUri(Uri uri) => uri.scheme == 'file' || uri.scheme == '';