Introduce a LicenseTemplate model and LicenseTemplateFinder helper

app/finders/license_template_finder.rb

+# LicenseTemplateFinder
+#
+# Used to find license templates, which may come from a variety of external
+# sources
+#
+# Arguments:
+#   popular: boolean. When set to true, only "popular" licenses are shown. When
+#            false, all licenses except popular ones are shown. When nil (the
+#            default), *all* licenses will be shown.
+class LicenseTemplateFinder
+  attr_reader :params
+
+  def initialize(params = {})
+    @params = params
+  end
+
+  def execute
+    Licensee::License.all(featured: popular_only?).map do |license|
+      LicenseTemplate.new(
+        id: license.key,
+        name: license.name,
+        nickname: license.nickname,
+        category: (license.featured? ? :Popular : :Other),
+        content: license.content,
+        url: license.url,
+        meta: license.meta
+      )
+    end
+  end
+
+  private
+
+  def popular_only?
+    params.fetch(:popular, nil)
+  end
+end

app/models/license_template.rb

+class LicenseTemplate
+  PROJECT_TEMPLATE_REGEX =
+    %r{[\<\{\[]
+      (project|description|
+      one\sline\s.+\swhat\sit\sdoes\.) # matching the start and end is enough here
+    [\>\}\]]}xi.freeze
+  YEAR_TEMPLATE_REGEX = /[<{\[](year|yyyy)[>}\]]/i.freeze
+  FULLNAME_TEMPLATE_REGEX =
+    %r{[\<\{\[]
+      (fullname|name\sof\s(author|copyright\sowner))
+    [\>\}\]]}xi.freeze
+
+  attr_reader :id, :name, :category, :nickname, :url, :meta
+
+  alias_method :key, :id
+
+  def initialize(id:, name:, category:, content:, nickname: nil, url: nil, meta: {})
+    @id = id
+    @name = name
+    @category = category
+    @content = content
+    @nickname = nickname
+    @url = url
+    @meta = meta
+  end
+
+  def popular?
+    category == :Popular
+  end
+  alias_method :featured?, :popular?
+
+  # Returns the text of the license
+  def content
+    if @content.respond_to?(:call)
+      @content = @content.call
+    else
+      @content
+    end
+  end
+
+  # Populate placeholders in the LicenseTemplate content
+  def resolve!(project_name: nil, fullname: nil, year: Time.now.year.to_s)
+    # Ensure the string isn't shared with any other instance of LicenseTemplate
+    new_content = content.dup
+    new_content.gsub!(YEAR_TEMPLATE_REGEX, year) if year.present?
+    new_content.gsub!(PROJECT_TEMPLATE_REGEX, project_name) if project_name.present?
+    new_content.gsub!(FULLNAME_TEMPLATE_REGEX, fullname) if fullname.present?
+
+    @content = new_content
+
+    self
+  end
+end

spec/finders/license_template_finder_spec.rb

+require 'spec_helper'
+
+describe LicenseTemplateFinder do
+  describe '#execute' do
+    subject(:result) { described_class.new(params).execute }
+
+    let(:categories) { categorised_licenses.keys }
+    let(:categorised_licenses) { result.group_by(&:category) }
+
+    context 'popular: true' do
+      let(:params) { { popular: true } }
+
+      it 'only returns popular licenses' do
+        expect(categories).to contain_exactly(:Popular)
+        expect(categorised_licenses[:Popular]).to be_present
+      end
+    end
+
+    context 'popular: false' do
+      let(:params) { { popular: false } }
+
+      it 'only returns unpopular licenses' do
+        expect(categories).to contain_exactly(:Other)
+        expect(categorised_licenses[:Other]).to be_present
+      end
+    end
+
+    context 'popular: nil' do
+      let(:params) { { popular: nil } }
+
+      it 'returns all licenses known by the Licensee gem' do
+        from_licensee = Licensee::License.all.map { |l| l.key }
+
+        expect(result.map(&:id)).to match_array(from_licensee)
+      end
+
+      it 'correctly copies all attributes' do
+        licensee = Licensee::License.all.first
+        found = result.find { |r| r.key == licensee.key }
+
+        aggregate_failures do
+          %i[key name content nickname url meta featured?].each do |k|
+            expect(found.public_send(k)).to eq(licensee.public_send(k))
+          end
+        end
+      end
+    end
+  end
+end

spec/models/license_template_spec.rb

+require 'spec_helper'
+
+describe LicenseTemplate do
+  describe '#content' do
+    it 'calls a proc exactly once if provided' do
+      lazy = build_template(-> { 'bar' })
+      content = lazy.content
+
+      expect(content).to eq('bar')
+      expect(content.object_id).to eq(lazy.content.object_id)
+
+      content.replace('foo')
+      expect(lazy.content).to eq('foo')
+    end
+
+    it 'returns a string if provided' do
+      lazy = build_template('bar')
+
+      expect(lazy.content).to eq('bar')
+    end
+  end
+
+  describe '#resolve!' do
+    let(:content) do
+      <<~TEXT
+      Pretend License
+
+      [project]
+
+      Copyright (c) [year] [fullname]
+      TEXT
+    end
+
+    let(:expected) do
+      <<~TEXT
+      Pretend License
+
+      Foo Project
+
+      Copyright (c) 1985 Nick Thomas
+      TEXT
+    end
+
+    let(:template) { build_template(content) }
+
+    it 'updates placeholders in a copy of the template content' do
+      expect(template.content.object_id).to eq(content.object_id)
+
+      template.resolve!(project_name: "Foo Project", fullname: "Nick Thomas", year: "1985")
+
+      expect(template.content).to eq(expected)
+      expect(template.content.object_id).not_to eq(content.object_id)
+    end
+  end
+
+  def build_template(content)
+    described_class.new(id: 'foo', name: 'foo', category: :Other, content: content)
+  end
+end