A gem action

lib/suspenders/actions.rb

@@ -1,3 +1,5 @@
+require "strscan"
+
 module Suspenders
   module Actions
     def replace_in_file(relative_path, find, replace)
@@ -31,6 +33,10 @@ def expand_json(file, data)
       action ExpandJson.new(destination_root, file, data)
     end
 
+    def gem(name, version = nil, **options)
+      action Gem.new(destination_root, name, version, **options)
+    end
+
     class ExpandJson
       def initialize(destination_root, file, data)
         @destination_root = destination_root
@@ -81,5 +87,179 @@ def hash_unmerge(hash, subhash)
         end
       end
     end
+
+    class Gem
+      def initialize(destination_root, name, version, **options)
+        @destination_root = destination_root
+        @name = name
+        @version = version
+        @groups = Array(options.delete(:group))
+        @options = options
+      end
+
+      def invoke!
+        existing_gemfile = IO.read(gemfile_path)
+
+        if groups.present?
+          positioning = gem_group(existing_gemfile)
+
+          if positioning
+            insert_gemline(existing_gemfile, indentation: 2, positioning: positioning)
+          else
+            positioning = final_group(existing_gemfile)
+
+            if positioning
+              insert_gemline(existing_gemfile, indentation: 2, positioning: positioning)
+            else
+              insert_gemline(existing_gemfile, indentation: 2, positioning: [0, existing_gemfile.bytes.size])
+            end
+          end
+        else
+          insert_gemline(existing_gemfile, indentation: 0, positioning: [0, existing_gemfile.bytes.size])
+        end
+      end
+
+      def revoke!
+        existing_gemfile = IO.read(gemfile_path)
+
+        if groups.present?
+          positioning = gem_group(existing_gemfile)
+
+          if positioning
+            remove_gemline(existing_gemfile, indentation: 2, positioning: positioning)
+          end
+        else
+          remove_gemline(existing_gemfile, indentation: 0, positioning: [0, existing_gemfile.bytes.size])
+        end
+      end
+
+      private
+
+      attr_reader :destination_root, :name, :version, :groups, :options
+
+      def gemfile_path
+        File.join(destination_root, "Gemfile")
+      end
+
+      def gem_group(gemfile)
+        groups_re = groups.map {|group| ":#{group}" }.join("[, ]+")
+        data = /^group[ (]+#{groups_re}[ )]+do.+?^end/mo.match(gemfile)
+
+        if data
+          [data.begin(0), data[0].bytes.size]
+        end
+      end
+
+      def final_group(gemfile)
+        scanner = StringScanner.new(gemfile)
+        result = nil
+
+        while scanner.scan_until(/^group.+?do.+?^end+/m)
+          if scanner.matched?
+            result = [scanner.pos, scanner.matched.bytes.size]
+          end
+        end
+
+        result
+      end
+
+      def insert_gemline(gemfile, indentation:, positioning:)
+        position = subsequent_gemline(gemfile, indentation: indentation, positioning: positioning)
+
+        if position
+          insert_gemline_at(gemfile, positioning[0] + position, indentation: indentation)
+        else
+          final_positioning = final_line(gemfile, indentation: indentation, positioning: positioning)
+
+          if final_positioning
+            insert_gemline_at(gemfile, positioning[0] + final_positioning[1], indentation: indentation)
+          else
+            insert_gemline_at(gemfile, positioning[0] + positioning[1], indentation: indentation)
+          end
+        end
+      end
+
+      def remove_gemline(old_content, indentation:, positioning:)
+        group_without_gem = old_content.byteslice(positioning[0], positioning[1]).
+          sub(/^#{" " * indentation}gem[ (]+['"]#{name}.*\n/, "")
+        new_content = old_content.byteslice(0, positioning[0]) +
+          group_without_gem +
+          old_content.byteslice((positioning[0] + positioning[1])..)
+
+        announce
+        IO.write(gemfile_path, new_content)
+      end
+
+      def subsequent_gemline(gemfile, indentation:, positioning:)
+        scanner = StringScanner.new(
+          gemfile.byteslice(positioning[0], positioning[1]),
+        )
+
+        while scanner.scan_until(/^#{" " * indentation}gem[ (]+['"]([^'"]+)/)
+          if name < scanner.captures[0]
+            return scanner.pos - scanner.matched.bytes.size
+          end
+        end
+
+        nil
+      end
+
+      def insert_gemline_at(old_content, position, indentation:)
+        announce
+        IO.write(
+          gemfile_path,
+          new_content(old_content, position: position, indentation: indentation),
+        )
+      end
+
+      def new_content(old_content, position:, indentation:)
+        ensure_newline((old_content.byteslice(0, position) || "")) +
+          (" " *indentation) +
+          gemline +
+          ensure_newline((old_content.byteslice(position..) || ""))
+      end
+
+      def final_line(gemfile, indentation:, positioning:)
+        scanner = StringScanner.new(
+          gemfile.byteslice(positioning[0], positioning[1]),
+        )
+        result = nil
+
+        while scanner.scan_until(/#{" " *indentation}gem[ (]+['"][^'"]+['"]/)
+          result = [scanner.pos, scanner.matched.bytes.size]
+        end
+
+        result
+      end
+
+      def ensure_newline(str)
+        "#{str.chomp}\n"
+      end
+
+      def gemline
+        parts = [%{"#{name}"}, version]
+
+        options&.each_pair do |k,v|
+          parts << %{#{k}: "#{v}"}
+        end
+
+        "gem #{parts.compact.join(", ")}\n"
+      end
+
+      def announce
+        message = "#{name}"
+
+        if version
+          message << " (#{version})"
+        end
+
+        if options[:git]
+          message = options[:git]
+        end
+
+        Thor::Base.shell.new.say_status :gemfile, message
+      end
+
+    end
   end
 end

spec/features/ci_spec.rb

@@ -11,7 +11,10 @@
   end
 
   it "removes Circle and SimpleCov" do
-    with_app { destroy("suspenders:ci") }
+    with_app do
+      generate("suspenders:ci")
+      destroy("suspenders:ci")
+    end
 
     expect("circle.yml").not_to exist_as_a_file
     expect("test/test_helper.rb").not_to match_contents(/SimpleCov/)

spec/features/static_spec.rb

@@ -9,7 +9,10 @@
   end
 
   it "removes the gem and pages directory" do
-    with_app { destroy("suspenders:static") }
+    with_app do
+      generate("suspenders:static")
+      destroy("suspenders:static")
+    end
 
     expect("app/views/pages/.keep").not_to exist_as_a_file
     expect("Gemfile").not_to match_contents(/high_voltage/)