core: BoxMetadata can read the JSON description

lib/vagrant/box_metadata.rb

@@ -0,0 +1,124 @@
+require "json"
+
+module Vagrant
+  # BoxMetadata represents metadata about a box, including the name
+  # it should have, a description of it, the versions it has, and
+  # more.
+  class BoxMetadata
+    # The name that the box should be if it is added.
+    #
+    # @return [String]
+    attr_accessor :name
+
+    # The long-form human-readable description of a box.
+    #
+    # @return [String]
+    attr_accessor :description
+
+    # Loads the metadata associated with the box from the given
+    # IO.
+    #
+    # @param [IO] io An IO object to read the metadata from.
+    def initialize(io)
+      begin
+        @raw = JSON.load(io)
+      rescue JSON::ParserError => e
+        raise Errors::BoxMetadataMalformed,
+          error: e.to_s
+      end
+
+      @name = @raw["name"]
+      @description = @raw["description"]
+      @version_map = @raw["versions"].map do |v|
+        [Gem::Version.new(v["version"]), v]
+      end
+      @version_map = Hash[@version_map]
+
+      # TODO: check for corruption:
+      #   - malformed version
+    end
+
+    # Returns data about a single version that is included in this
+    # metadata.
+    #
+    # @param [String] version The version to return, this can also
+    #   be a constraint.
+    # @return [Version] The matching version or nil if a matching
+    #   version was not found.
+    def version(version)
+      requirements = version.split(",").map do |v|
+        Gem::Requirement.new(v.strip)
+      end
+
+      @version_map.keys.sort.reverse.each do |v|
+        if requirements.all? { |r| r.satisfied_by?(v) }
+          return Version.new(@version_map[v])
+        end
+      end
+
+      nil
+    end
+
+    # Returns all the versions supported by this metadata. These
+    # versions are sorted so the last element of the list is the
+    # latest version.
+    #
+    # @return[Array<String>]
+    def versions
+      @version_map.keys.sort.map(&:to_s)
+    end
+
+    # Represents a single version within the metadata.
+    class Version
+      # The version that this Version object represents.
+      #
+      # @return [String]
+      attr_accessor :version
+
+      def initialize(raw=nil)
+        return if !raw
+
+        @version = raw["version"]
+        @provider_map = (raw["providers"] || []).map do |p|
+          [p["name"], p]
+        end
+        @provider_map = Hash[@provider_map]
+      end
+
+      # Returns a [Provider] for the given name, or nil if it isn't
+      # supported by this version.
+      def provider(name)
+        p = @provider_map[name]
+        return nil if !p
+        Provider.new(p)
+      end
+
+      # Returns the providers that are available for this version
+      # of the box.
+      #
+      # @return [Provider]
+      def providers
+        @provider_map.keys
+      end
+    end
+
+    # Provider represents a single provider-specific box available
+    # for a version for a box.
+    class Provider
+      # The name of the provider.
+      #
+      # @return [String]
+      attr_accessor :name
+
+      # The URL of the box.
+      #
+      # @return [String]
+      attr_accessor :url
+
+      def initialize(raw)
+        @name = raw["name"]
+        @url  = raw["url"]
+      end
+    end
+  end
+end

lib/vagrant/errors.rb

@@ -144,6 +144,10 @@ module Vagrant
       error_key(:box_metadata_file_not_found)
     end
 
+    class BoxMetadataMalformed < VagrantError
+      error_key(:box_metadata_malformed)
+    end
+
     class BoxNotFound < VagrantError
       error_key(:box_not_found)
     end

templates/locales/en.yml

@@ -266,6 +266,12 @@ en:
         box file format can be found at the URL below:
 
         http://docs.vagrantup.com/v2/boxes/format.html
+      box_metadata_malformed: |-
+        The metadata for the box was malformed. The exact error
+        is shown below. Please contact the maintainer of the box so
+        that this issue can be fixed.
+
+        %{error}
       box_not_found: Box '%{name}' with '%{provider}' provider could not be found.
       box_provider_doesnt_match: |-
         The box you attempted to add doesn't match the provider you specified.

test/unit/vagrant/box_metadata_test.rb

@@ -0,0 +1,139 @@
+require File.expand_path("../../base", __FILE__)
+
+require "vagrant/box_metadata"
+
+describe Vagrant::BoxMetadata do
+  include_context "unit"
+
+  let(:raw) do
+    <<-RAW
+      {
+        "name": "foo",
+        "description": "bar",
+        "versions": [
+          {
+            "version": "1.0.0"
+          },
+          {
+            "version": "1.1.5"
+          },
+          {
+            "version": "1.1.0"
+          }
+        ]
+      }
+    RAW
+  end
+
+  subject { described_class.new(raw) }
+
+  its(:name) { should eq("foo") }
+  its(:description) { should eq("bar") }
+
+  context "with poorly formatted JSON" do
+    let(:raw) {
+      <<-RAW
+      { "name": "foo", }
+      RAW
+    }
+
+    it "raises an exception" do
+      expect { subject }.
+        to raise_error(Vagrant::Errors::BoxMetadataMalformed)
+    end
+  end
+
+  describe "#version" do
+    it "matches an exact version" do
+      result = subject.version("1.0.0")
+      expect(result).to_not be_nil
+      expect(result).to be_kind_of(Vagrant::BoxMetadata::Version)
+      expect(result.version).to eq("1.0.0")
+    end
+
+    it "matches a constraint with latest matching version" do
+      result = subject.version(">= 1.0")
+      expect(result).to_not be_nil
+      expect(result).to be_kind_of(Vagrant::BoxMetadata::Version)
+      expect(result.version).to eq("1.1.5")
+    end
+
+    it "matches complex constraints" do
+      result = subject.version(">= 0.9, ~> 1.0.0")
+      expect(result).to_not be_nil
+      expect(result).to be_kind_of(Vagrant::BoxMetadata::Version)
+      expect(result.version).to eq("1.0.0")
+    end
+  end
+
+  describe "#versions" do
+    it "returns the versions it contained" do
+      expect(subject.versions).to eq(
+        ["1.0.0", "1.1.0", "1.1.5"])
+    end
+  end
+end
+
+describe Vagrant::BoxMetadata::Version do
+  let(:raw) { {} }
+
+  subject { described_class.new(raw) }
+
+  before do
+    raw["providers"] = [
+      {
+        "name" => "virtualbox",
+      },
+      {
+        "name" => "vmware",
+      }
+    ]
+  end
+
+  describe "#version" do
+    it "is the version in the raw data" do
+      v = "1.0"
+      raw["version"] = v
+      expect(subject.version).to eq(v)
+    end
+  end
+
+  describe "#provider" do
+    it "returns nil if a provider isn't supported" do
+      expect(subject.provider("foo")).to be_nil
+    end
+
+    it "returns the provider specified" do
+      result = subject.provider("virtualbox")
+      expect(result).to_not be_nil
+      expect(result).to be_kind_of(Vagrant::BoxMetadata::Provider)
+    end
+  end
+
+  describe "#providers" do
+    it "returns the providers available" do
+      expect(subject.providers.sort).to eq(
+        ["virtualbox", "vmware"])
+    end
+  end
+end
+
+describe Vagrant::BoxMetadata::Provider do
+  let(:raw) { {} }
+
+  subject { described_class.new(raw) }
+
+  describe "#name" do
+    it "is the name specified" do
+      raw["name"] = "foo"
+      expect(subject.name).to eq("foo")
+    end
+  end
+
+  describe "#url" do
+    it "is the URL specified" do
+      raw["url"] = "bar"
+      expect(subject.url).to eq("bar")
+    end
+  end
+end