Autolink package names in Gemfile

7 files changed, 263 insertions, 10 deletions

diff --git a/lib/gitlab/dependency_linker.rb b/lib/gitlab/dependency_linker.rb
new file mode 100644
index 00000000000..5e884c4bea1
--- /dev/null
+++ b/lib/gitlab/dependency_linker.rb
@@ -0,0 +1,18 @@
+module Gitlab
+  module DependencyLinker
+    LINKERS = [
+      GemfileLinker,
+    ].freeze
+
+    def self.linker(blob_name)
+      LINKERS.find { |linker| linker.support?(blob_name) }
+    end
+
+    def self.link(blob_name, plain_text, highlighted_text)
+      linker = linker(blob_name)
+      return highlighted_text unless linker
+
+      linker.link(plain_text, highlighted_text)
+    end
+  end
+end
diff --git a/lib/gitlab/dependency_linker/base_linker.rb b/lib/gitlab/dependency_linker/base_linker.rb
new file mode 100644
index 00000000000..40a4ad11372
--- /dev/null
+++ b/lib/gitlab/dependency_linker/base_linker.rb
@@ -0,0 +1,103 @@
+module Gitlab
+  module DependencyLinker
+    class BaseLinker
+      def self.link(plain_text, highlighted_text)
+        new(plain_text, highlighted_text).link
+      end
+
+      attr_accessor :plain_text, :highlighted_text
+
+      def initialize(plain_text, highlighted_text)
+        @plain_text = plain_text
+        @highlighted_text = highlighted_text
+      end
+
+      def link
+        link_dependencies
+
+        highlighted_lines.join.html_safe
+      end
+
+      private
+
+      def package_url(name)
+        raise NotImplementedError
+      end
+
+      def link_dependencies
+        raise NotImplementedError
+      end
+
+      def package_link(name, url = package_url(name))
+        return name unless url
+
+        %{<a href="#{ERB::Util.html_escape_once(url)}" rel="noopener noreferrer" target="_blank">#{ERB::Util.html_escape_once(name)}</a>}
+      end
+
+      # Links package names in a method call or assignment string argument.
+      #
+      # Example:
+      #   link_method_call("gem")
+      #   # Will link `package` in `gem "package"`, `gem("package")` and `gem = "package"`
+      #
+      #   link_method_call("gem", "specific_package")
+      #   # Will link `specific_package` in `gem "specific_package"`
+      #
+      #   link_method_call("github", /[^\/]+\/[^\/]+/)
+      #   # Will link `user/repo` in `github "user/repo"`, but not `github "package"`
+      #
+      #   link_method_call(%w[add_dependency add_development_dependency])
+      #   # Will link `spec.add_dependency "package"` and `spec.add_development_dependency "package"`
+      #
+      #   link_method_call("name")
+      #   # Will link `package` in `self.name = "package"`
+      def link_method_call(method_names, value = nil, &url_proc)
+        value =
+          case value
+          when String
+            Regexp.escape(value)
+          when nil
+            /[^'"]+/
+          else
+            value
+          end
+
+        method_names = Array(method_names).map { |name| Regexp.escape(name) }
+
+        regex = %r{
+          #{Regexp.union(method_names)} # Method name
+          \s*                           # Whitespace
+          [(=]?                         # Opening brace or equals sign
+          \s*                           # Whitespace
+          ['"](?<name>#{value})['"]     # Package name in quotes
+        }x
+
+        link_regex(regex, &url_proc)
+      end
+
+      # Links package names based on regex.
+      #
+      # Example:
+      #   link_regex(/(github:|:github =>)\s*['"](?<name>[^'"]+)['"]/)
+      #   # Will link `user/repo` in `github: "user/repo"` or `:github => "user/repo"`
+      def link_regex(regex)
+        highlighted_lines.map!.with_index do |rich_line, i|
+          marker = StringRegexMarker.new(plain_lines[i], rich_line.html_safe)
+
+          marker.mark(regex, group: :name) do |text, left:, right:|
+            url = block_given? ? yield(text) : package_url(text)
+            package_link(text, url)
+          end
+        end
+      end
+
+      def plain_lines
+        @plain_lines ||= plain_text.lines
+      end
+
+      def highlighted_lines
+        @highlighted_lines ||= highlighted_text.lines
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/dependency_linker/gemfile_linker.rb b/lib/gitlab/dependency_linker/gemfile_linker.rb
new file mode 100644
index 00000000000..e36b88d357d
--- /dev/null
+++ b/lib/gitlab/dependency_linker/gemfile_linker.rb
@@ -0,0 +1,28 @@
+module Gitlab
+  module DependencyLinker
+    class GemfileLinker < BaseLinker
+      def self.support?(blob_name)
+        blob_name == 'Gemfile' || blob_name == 'gems.rb'
+      end
+
+      private
+
+      def link_dependencies
+        # Link `gem "package_name"` to https://rubygems.org/gems/package_name
+        link_method_call("gem")
+
+        # Link `github: "user/repo"` to https://github.com/user/repo
+        link_regex(/(github:|:github\s*=>)\s*['"](?<name>[^'"]+)['"]/) do |name|
+          "https://github.com/#{name}"
+        end
+
+        # Link `source "https://rubygems.org"` to https://rubygems.org
+        link_method_call("source", %r{https?://[^'"]+}) { |url| url }
+      end
+
+      def package_url(name)
+        "https://rubygems.org/gems/#{name}"
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/highlight.rb b/lib/gitlab/highlight.rb
index d787d5db4a0..83bc230df3e 100644
--- a/lib/gitlab/highlight.rb
+++ b/lib/gitlab/highlight.rb
@@ -13,6 +13,8 @@ module Gitlab
       highlight(file_name, blob.data, repository: repository).lines.map!(&:html_safe)
     end
 
+    attr_reader :blob_name
+
     def initialize(blob_name, blob_content, repository: nil)
       @formatter = Rouge::Formatters::HTMLGitlab
       @repository = repository
@@ -21,16 +23,9 @@ module Gitlab
     end
 
     def highlight(text, continue: true, plain: false)
-      if plain
-        hl_lexer = Rouge::Lexers::PlainText
-        continue = false
-      else
-        hl_lexer = self.lexer
-      end
-
-      @formatter.format(hl_lexer.lex(text, continue: continue), tag: hl_lexer.tag).html_safe
-    rescue
-      @formatter.format(Rouge::Lexers::PlainText.lex(text)).html_safe
+      highlighted_text = highlight_text(text, continue: continue, plain: plain)
+      highlighted_text = link_dependencies(text, highlighted_text) if blob_name
+      highlighted_text
     end
 
     def lexer
@@ -50,5 +45,27 @@ module Gitlab
 
       Rouge::Lexer.find_fancy(language_name)
     end
+
+    def highlight_text(text, continue: true, plain: false)
+      if plain
+        highlight_plain(text)
+      else
+        highlight_rich(text, continue: continue)
+      end
+    end
+
+    def highlight_plain(text)
+      @formatter.format(Rouge::Lexers::PlainText.lex(text)).html_safe
+    end
+
+    def highlight_rich(text, continue: true)
+      @formatter.format(lexer.lex(text, continue: continue), tag: lexer.tag).html_safe
+    rescue
+      highlight_plain(text)
+    end
+
+    def link_dependencies(text, highlighted_text)
+      Gitlab::DependencyLinker.link(blob_name, text, highlighted_text)
+    end
   end
 end
diff --git a/spec/lib/gitlab/dependency_linker/gemfile_linker_spec.rb b/spec/lib/gitlab/dependency_linker/gemfile_linker_spec.rb
new file mode 100644
index 00000000000..62e477e1de0
--- /dev/null
+++ b/spec/lib/gitlab/dependency_linker/gemfile_linker_spec.rb
@@ -0,0 +1,63 @@
+require 'rails_helper'
+
+describe Gitlab::DependencyLinker::GemfileLinker, lib: true do
+  describe '.support?' do
+    it 'supports Gemfile' do
+      expect(described_class.support?('Gemfile')).to be_truthy
+    end
+
+    it 'supports gems.rb' do
+      expect(described_class.support?('gems.rb')).to be_truthy
+    end
+
+    it 'does not support other files' do
+      expect(described_class.support?('Gemfile.lock')).to be_falsey
+    end
+  end
+
+  describe '#link' do
+    let(:file_name) { 'Gemfile' }
+
+    let(:file_content) do
+      <<-CONTENT.strip_heredoc
+        source 'https://rubygems.org'
+
+        gem "rails", '4.2.6', github: "rails/rails"
+        gem 'rails-deprecated_sanitizer', '~> 1.0.3'
+
+        # Responders respond_to and respond_with
+        gem 'responders', '~> 2.0', :github => 'rails/responders'
+
+        # Specify a sprockets version due to increased performance
+        # See https://gitlab.com/gitlab-org/gitlab-ce/issues/6069
+        gem 'sprockets', '~> 3.6.0'
+
+        # Default values for AR models
+        gem 'default_value_for', '~> 3.0.0'
+      CONTENT
+    end
+
+    subject { Gitlab::Highlight.highlight(file_name, file_content) }
+
+    def link(name, url)
+      %{<a href="#{url}" rel="noopener noreferrer" target="_blank">#{name}</a>}
+    end
+
+    it 'links sources' do
+      expect(subject).to include(link('https://rubygems.org', 'https://rubygems.org'))
+    end
+
+    it 'links dependencies' do
+      expect(subject).to include(link('rails', 'https://rubygems.org/gems/rails'))
+      expect(subject).to include(link('rails-deprecated_sanitizer', 'https://rubygems.org/gems/rails-deprecated_sanitizer'))
+      expect(subject).to include(link('responders', 'https://rubygems.org/gems/responders'))
+      expect(subject).to include(link('sprockets', 'https://rubygems.org/gems/sprockets'))
+      expect(subject).to include(link('default_value_for', 'https://rubygems.org/gems/default_value_for'))
+    end
+
+    it 'links GitHub repos' do
+      expect(subject).to include(link('rails/rails', 'https://github.com/rails/rails'))
+      expect(subject).to include(link('rails/responders', 'https://github.com/rails/responders'))
+    end
+  end
+end
diff --git a/spec/lib/gitlab/dependency_linker_spec.rb b/spec/lib/gitlab/dependency_linker_spec.rb
new file mode 100644
index 00000000000..03d5b61d70c
--- /dev/null
+++ b/spec/lib/gitlab/dependency_linker_spec.rb
@@ -0,0 +1,13 @@
+require 'rails_helper'
+
+describe Gitlab::DependencyLinker, lib: true do
+  describe '.link' do
+    it 'links using GemfileLinker' do
+      blob_name = 'Gemfile'
+
+      expect(described_class::GemfileLinker).to receive(:link)
+
+      described_class.link(blob_name, nil, nil)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/highlight_spec.rb b/spec/lib/gitlab/highlight_spec.rb
index e49799ad105..e57b3053871 100644
--- a/spec/lib/gitlab/highlight_spec.rb
+++ b/spec/lib/gitlab/highlight_spec.rb
@@ -57,4 +57,15 @@ describe Gitlab::Highlight, lib: true do
       end
     end
   end
+
+  describe '#highlight' do
+    subject { described_class.highlight(file_name, file_content, nowrap: false) }
+
+    it 'links dependencies via DependencyLinker' do
+      expect(Gitlab::DependencyLinker).to receive(:link).
+        with('file.name', 'Contents', anything).and_call_original
+
+      described_class.highlight('file.name', 'Contents')
+    end
+  end
 end