From 2d77f64ae1a5084fec78139af305918f429012d3 Mon Sep 17 00:00:00 2001
From: Trevor Vallender <trevor@tsvallender.co.uk>
Date: Thu, 25 Jan 2024 15:55:49 +0000
Subject: [PATCH] Initial commit

---
 MIT-LICENSE                                   | 20 ++++++
 README.md                                     | 68 +++++++++++++++++++
 flaggle_rock.gemspec                          | 11 +++
 lib/flaggle_rock.rb                           | 49 +++++++++++++
 .../flaggle_rock/install/install_generator.rb | 21 ++++++
 .../install/templates/create_feature_flags.rb | 10 +++
 6 files changed, 179 insertions(+)
 create mode 100644 MIT-LICENSE
 create mode 100644 README.md
 create mode 100644 flaggle_rock.gemspec
 create mode 100644 lib/flaggle_rock.rb
 create mode 100644 lib/generators/flaggle_rock/install/install_generator.rb
 create mode 100644 lib/generators/flaggle_rock/install/templates/create_feature_flags.rb

diff --git a/MIT-LICENSE b/MIT-LICENSE
new file mode 100644
index 0000000..a306f55
--- /dev/null
+++ b/MIT-LICENSE
@@ -0,0 +1,20 @@
+Copyright (c) 2023 David Heinemeier Hansson
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..d666db6
--- /dev/null
+++ b/README.md
@@ -0,0 +1,68 @@
+# Flaggle Rock
+
+[View on RubyGems](https://rubygems.org/gems/flaggle_rock)
+
+Flaggle Rock is a simple feature flagging gem for use with Ruby on Rails applications.
+
+It is designed for easily hiding features from end users to help enable a fast-moving
+CI workflow. It currently does not aim to support more advanced features such as A/B
+testing.
+
+## Installation
+
+Add Flaggle Rock to your Gemfile:
+
+```ruby
+gem "flaggle_rock"
+```
+
+And install
+
+```sh
+bundle install
+```
+
+Generate the migrations, and run them to add feature flags to your database:
+```sh
+bundle exec rails generate fflag:install
+bundle exec rails db:migrate
+```
+
+## Usage
+
+All flags are _off by default_. There is no need to explicitly create a new flag—turning
+it on will do this.
+
+To enable/disable a flag:
+```ruby
+Rock.on(:flag_name)
+Rock.off(:flag_name)
+```
+To check whether a flag is on:
+```ruby
+Rock.on?(:flag_name)
+Rock.off?(:flag_name)
+```
+
+To remove a flag which is no longer used:
+```ruby
+Rock.delete(:flag_name)
+```
+
+To remove all disabled flags:
+```ruby
+Rock.delete_all_disabled
+```
+
+## Future
+
+Goals with Flaggle Rock include the creation of a web UI for easily administering flags.
+
+## Compatibility
+
+Flaggle Rock has been tested with Rails 7 and PostgreSQL 11, but should work with older versions of
+Rails and other database engines.
+
+## License
+
+Flaggle Rock is released under the [MIT License](MIT-LICENSE.md).
diff --git a/flaggle_rock.gemspec b/flaggle_rock.gemspec
new file mode 100644
index 0000000..559f354
--- /dev/null
+++ b/flaggle_rock.gemspec
@@ -0,0 +1,11 @@
+Gem::Specification.new do |s|
+  s.name        = "flaggle_rock"
+  s.version     = "0.1.0"
+  s.summary     = "A simple feature flag gem"
+  s.authors     = ["T S Vallender"]
+  s.email       = "t@tsvallender.co.uk"
+  s.homepage    = "https://git.tsvallender.co.uk/tsv/flaggle_rock"
+  s.files       = Dir["lib/**/*", "MIT-LICENSE", "README.md"]
+  s.license     = "MIT"
+end
+
diff --git a/lib/flaggle_rock.rb b/lib/flaggle_rock.rb
new file mode 100644
index 0000000..03cb314
--- /dev/null
+++ b/lib/flaggle_rock.rb
@@ -0,0 +1,49 @@
+class Rock
+  def self.turn_on(flag_name)
+    enable(flag_name, true)
+  end
+
+  def self.turn_off(flag_name)
+    enable(flag_name, false)
+  end
+
+  def self.on?(flag_name)
+    result = sql <<-SQL
+        SELECT enabled FROM feature_flags
+        WHERE name = '#{flag_name}';
+    SQL
+    result&.first&.dig("enabled") || false
+  end
+
+  def self.off?(flag_name)
+    !on?(flag_name)
+  end
+
+  def self.delete(flag_name)
+    sql <<-SQL
+        DELETE FROM feature_flags
+        WHERE name = '#{flag_name}';
+    SQL
+  end
+
+  def self.delete_all_disabled
+    sql <<-SQL
+        DELETE FROM feature_flags
+        WHERE enabled = false;
+    SQL
+  end
+
+  private
+
+  def self.enable(flag_name, enabled)
+    sql <<-SQL
+        INSERT INTO feature_flags (name, enabled, created_at, updated_at)
+        VALUES ('#{flag_name}', #{enabled}, now(), now())
+        ON CONFLICT (name) DO UPDATE SET enabled = #{enabled};
+    SQL
+  end
+
+  def self.sql(query_string)
+    ActiveRecord::Base.connection.execute(query_string)
+  end
+end
diff --git a/lib/generators/flaggle_rock/install/install_generator.rb b/lib/generators/flaggle_rock/install/install_generator.rb
new file mode 100644
index 0000000..d776bb5
--- /dev/null
+++ b/lib/generators/flaggle_rock/install/install_generator.rb
@@ -0,0 +1,21 @@
+require "rails/generators"
+require "rails/generators/migration"
+
+module FlaggleRock
+  module Generators
+    class InstallGenerator < Rails::Generators::Base
+      include Rails::Generators::Migration
+      source_root File.expand_path("templates", __dir__)
+      desc "Generates a migration to create the feature flags table"
+
+      def self.next_migration_number(path)
+        next_migration_number = current_migration_number(path) + 1
+        ActiveRecord::Migration.next_migration_number(next_migration_number)
+      end
+
+      def copy_migrations
+        migration_template "create_feature_flags.rb", "db/migrate/create_feature_flags.rb"
+      end
+    end
+  end
+end
diff --git a/lib/generators/flaggle_rock/install/templates/create_feature_flags.rb b/lib/generators/flaggle_rock/install/templates/create_feature_flags.rb
new file mode 100644
index 0000000..8407880
--- /dev/null
+++ b/lib/generators/flaggle_rock/install/templates/create_feature_flags.rb
@@ -0,0 +1,10 @@
+class CreateFeatureFlags < ActiveRecord::Migration[7.0]
+  def change
+    create_table :feature_flags do |t|
+      t.string :name, null: false, index: { unique: true }
+      t.boolean :enabled, null: false, default: false
+
+      t.timestamps
+    end
+  end
+end