1 files changed, 51 insertions, 0 deletions
diff --git a/lib/bundler/cli/init.rb b/lib/bundler/cli/init.rb
new file mode 100644
index 0000000000..246b9d6460
--- /dev/null
+++ b/lib/bundler/cli/init.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Init
+    attr_reader :options
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      if File.exist?(gemfile)
+        Bundler.ui.error "#{gemfile} already exists at #{File.expand_path(gemfile)}"
+        exit 1
+      end
+
+      unless File.writable?(Dir.pwd)
+        Bundler.ui.error "Can not create #{gemfile} as the current directory is not writable."
+        exit 1
+      end
+
+      if options[:gemspec]
+        gemspec = File.expand_path(options[:gemspec])
+        unless File.exist?(gemspec)
+          Bundler.ui.error "Gem specification #{gemspec} doesn't exist"
+          exit 1
+        end
+
+        spec = Bundler.load_gemspec_uncached(gemspec)
+
+        File.open(gemfile, "wb") do |file|
+          file << "# Generated from #{gemspec}\n"
+          file << spec.to_gemfile
+        end
+      else
+        File.open(File.expand_path("../templates/Gemfile", __dir__), "r") do |template|
+          File.open(gemfile, "wb") do |destination|
+            IO.copy_stream(template, destination)
+          end
+        end
+      end
+
+      puts "Writing new #{gemfile} to #{SharedHelpers.pwd}/#{gemfile}"
+    end
+
+    private
+
+    def gemfile
+      @gemfile ||= options[:gemfile] || Bundler.preferred_gemfile_name
+    end
+  end
+end