injector class to handle gem injection

1 files changed, 55 insertions, 0 deletions

diff --git a/lib/bundler/injector.rb b/lib/bundler/injector.rb
new file mode 100644
index 0000000000..5c1603fa9c
--- /dev/null
+++ b/lib/bundler/injector.rb
@@ -0,0 +1,55 @@
+module Bundler
+  class Injector
+    def self.inject(new_deps)
+      injector = new(new_deps)
+      injector.inject(Bundler.default_gemfile, Bundler.default_lockfile)
+    end
+
+    def initialize(new_deps)
+      @new_deps = new_deps
+    end
+
+    def inject(gemfile_path, lockfile_path)
+      # evaluate the Gemfile we have now
+      builder = Dsl.new
+      builder.eval_gemfile(gemfile_path)
+
+      # don't inject any gems that are already in the Gemfile
+      @new_deps -= builder.dependencies
+
+      # add new deps to the end of the in-memory Gemfile
+      builder.eval_gemfile("injected gems", new_gem_lines) if @new_deps.any?
+
+      # resolve to see if the new deps broke anything
+      definition = builder.to_definition(lockfile_path, {})
+      definition.resolve_remotely!
+
+      # since nothing broke, we can add those gems to the gemfile
+      append_to(gemfile_path) if @new_deps.any?
+
+      # since we resolved successfully, write out the lockfile
+      definition.lock(Bundler.default_lockfile)
+
+      # return an array of the deps that we added
+      return @new_deps
+    end
+
+  private
+
+    def new_gem_lines
+      @new_deps.map do |d|
+        %|gem '#{d.name}', '#{d.requirement}'|
+      end.join("\n")
+    end
+
+    def append_to(gemfile_path)
+      gemfile_path.open("a") do |f|
+        f.puts
+        f.puts "# Added at #{Time.now} by #{`whoami`.chomp}:"
+        f.puts new_gem_lines
+      end
+    end
+
+
+  end
+end
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