1 files changed, 97 insertions, 0 deletions
diff --git a/lib/bundler/cli/list.rb b/lib/bundler/cli/list.rb
new file mode 100644
index 0000000000..6a467f45a9
--- /dev/null
+++ b/lib/bundler/cli/list.rb
@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+require "json"
+
+module Bundler
+  class CLI::List
+    def initialize(options)
+      @options = options
+      @without_group = options["without-group"].map(&:to_sym)
+      @only_group = options["only-group"].map(&:to_sym)
+      @format = options["format"]
+    end
+
+    def run
+      raise InvalidOption, "The `--only-group` and `--without-group` options cannot be used together" if @only_group.any? && @without_group.any?
+
+      raise InvalidOption, "The `--name-only` and `--paths` options cannot be used together" if @options["name-only"] && @options[:paths]
+
+      specs = if @only_group.any? || @without_group.any?
+        filtered_specs_by_groups
+      else
+        begin
+          Bundler.load.specs
+        rescue GemNotFound => e
+          Bundler.ui.error e.message
+          Bundler.ui.warn "Install missing gems with `bundle install`."
+          exit 1
+        end
+      end.reject {|s| s.name == "bundler" }.sort_by(&:name)
+
+      case @format
+      when "json"
+        print_json(specs: specs)
+      when nil
+        print_human(specs: specs)
+      else
+        raise InvalidOption, "Unknown option`--format=#{@format}`. Supported formats: `json`"
+      end
+    end
+
+    private
+
+    def print_json(specs:)
+      gems = if @options["name-only"]
+        specs.map {|s| { name: s.name } }
+      else
+        specs.map do |s|
+          {
+            name: s.name,
+            version: s.version.to_s,
+            git_version: s.git_version&.strip,
+          }.tap do |h|
+            h[:path] = s.full_gem_path if @options["paths"]
+          end
+        end
+      end
+      Bundler.ui.info({ gems: gems }.to_json)
+    end
+
+    def print_human(specs:)
+      return Bundler.ui.info "No gems in the Gemfile" if specs.empty?
+
+      return specs.each {|s| Bundler.ui.info s.name } if @options["name-only"]
+      return specs.each {|s| Bundler.ui.info s.full_gem_path } if @options["paths"]
+
+      Bundler.ui.info "Gems included by the bundle:"
+
+      specs.each {|s| Bundler.ui.info "  * #{s.name} (#{s.version}#{s.git_version})" }
+
+      Bundler.ui.info "Use `bundle info` to print more detailed information about a gem"
+    end
+
+    def verify_group_exists(groups)
+      (@without_group + @only_group).each do |group|
+        raise InvalidOption, "`#{group}` group could not be found." unless groups.include?(group)
+      end
+    end
+
+    def filtered_specs_by_groups
+      definition = Bundler.definition
+      groups = definition.groups
+
+      verify_group_exists(groups)
+
+      show_groups =
+        if @without_group.any?
+          groups.reject {|g| @without_group.include?(g) }
+        elsif @only_group.any?
+          groups.select {|g| @only_group.include?(g) }
+        else
+          groups
+        end.map(&:to_sym)
+
+      definition.specs_for(show_groups)
+    end
+  end
+end