Allow installer to run multiple times

lib/generators/web_git/install_generator.rb

@@ -2,32 +2,46 @@ module WebGit
   class InstallGenerator < Rails::Generators::Base
     def generate_server
 
+      filename = Rails.root.join("config.ru")
+
       log :insert, "Updating config.ru to run apps in parallel."
-
-      contents = <<-RUBY.gsub(/^      /, "")
+      if File.exists?(filename) && already_installed?
+        log :identical, "Skipping overrides."
+      else
+        contents = <<~RUBY
 
-      if Rails.env.development?
-        map '/git' do
-          run WebGit::Server
+        if Rails.env.development?
+          map '/git' do
+            run WebGit::Server
+          end
         end
+
+        map '/' do
+        RUBY
+
+        filename = "config.ru"
+        match_text = "run Rails.application"
+
+        insert_into_file filename, contents, before: match_text
+        insert_into_file filename, "\nend", after: match_text, force: true
+        gsub_file filename, match_text, "\t#{match_text}"
       end
 
-      map '/' do
-      RUBY
-
-      filename = "config.ru"
-      match_text = "run Rails.application"
-
-      insert_into_file filename, contents, before: match_text
-      insert_into_file filename, "\nend", after: match_text, force: true
-      gsub_file filename, match_text, "\t#{match_text}"
-
       expect_installed = run("which expect")
 
       unless expect_installed
         log :insert, "Installing expect."
         run "sudo apt install -y expect"
+      else
+        log :identical, "expect already installed."
       end
     end
+
+    def already_installed?
+      filename = Rails.root.join("config.ru")
+      contents = open(filename).read
+
+      contents.match?(/if\s*Rails.env.development\?\s*map\s*'\/git'\s*do\s*run\s*WebGit::Server\s*end\s*end/)
+    end
   end
 end