1 files changed, 95 insertions, 0 deletions
diff --git a/lib/bundler/lockfile_generator.rb b/lib/bundler/lockfile_generator.rb
new file mode 100644
index 0000000000..585077d18d
--- /dev/null
+++ b/lib/bundler/lockfile_generator.rb
@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+module Bundler
+  class LockfileGenerator
+    attr_reader :definition
+    attr_reader :out
+
+    # @private
+    def initialize(definition)
+      @definition = definition
+      @out = String.new
+    end
+
+    def self.generate(definition)
+      new(definition).generate!
+    end
+
+    def generate!
+      add_sources
+      add_platforms
+      add_dependencies
+      add_locked_ruby_version
+      add_bundled_with
+
+      out
+    end
+
+  private
+
+    def add_sources
+      definition.send(:sources).lock_sources.each_with_index do |source, idx|
+        out << "\n" unless idx.zero?
+
+        # Add the source header
+        out << source.to_lock
+
+        # Find all specs for this source
+        specs = definition.resolve.select {|s| source.can_lock?(s) }
+        add_specs(specs)
+      end
+    end
+
+    def add_specs(specs)
+      # This needs to be sorted by full name so that
+      # gems with the same name, but different platform
+      # are ordered consistently
+      specs.sort_by(&:full_name).each do |spec|
+        next if spec.name == "bundler".freeze
+        out << spec.to_lock
+      end
+    end
+
+    def add_platforms
+      add_section("PLATFORMS", definition.platforms)
+    end
+
+    def add_dependencies
+      out << "\nDEPENDENCIES\n"
+
+      handled = []
+      definition.dependencies.sort_by(&:to_s).each do |dep|
+        next if handled.include?(dep.name)
+        out << dep.to_lock
+        handled << dep.name
+      end
+    end
+
+    def add_locked_ruby_version
+      return unless locked_ruby_version = definition.locked_ruby_version
+      add_section("RUBY VERSION", locked_ruby_version.to_s)
+    end
+
+    def add_bundled_with
+      add_section("BUNDLED WITH", definition.locked_bundler_version.to_s)
+    end
+
+    def add_section(name, value)
+      out << "\n#{name}\n"
+      case value
+      when Array
+        value.map(&:to_s).sort.each do |val|
+          out << "  #{val}\n"
+        end
+      when Hash
+        value.to_a.sort_by {|k, _| k.to_s }.each do |key, val|
+          out << "  #{key}: #{val}\n"
+        end
+      when String
+        out << "   #{value}\n"
+      else
+        raise ArgumentError, "#{value.inspect} can't be serialized in a lockfile"
+      end
+    end
+  end
+end