# encoding: utf-8
require 'fedux_org_stdlib/plugins/no_plugin'
require 'fedux_org_stdlib/plugins/plugin'

require_library %w{ json active_support/core_ext/string/inflections }

module FeduxOrgStdlib
  module Plugins
    # Plugin Manager
    # 
    # Make sure you've got a class method `.plugin_prefix` on your main module
    #
    # @example
    #    # -- main.rb --
    #    # main module
    #    module YourApplication
    #      # The manager
    #      @plugin_manager = PluginManager.new
    #
    #      # This regex depends on your application's plugins file system structure
    #      @plugin_prefix  = Regexp.new("^#{self.name.underscore.gsub(/\//, '-')}-")
    #  
    #      class << self
    #        attr_reader :plugin_prefix, :plugin_manager
    #
    #        def load_plugins
    #          self.plugin_manager.locate_plugins
    #          self.plugin_manager.load_plugins
    #        end
    #      end
    #    end
    #
    # At some place you need to load your plugins.
    #
    # @example
    #
    #   # -- runner.rb --
    #
    #   YourApplication.load_plugins
    #
    class PluginManager
      private

      attr_reader :plugins

      public

      def initialize(plugins: [])
        @plugins = plugins
      end

      # Find all installed plugins and store them in an internal array.
      def locate_plugins
        Gem.refresh

        (Gem::Specification.respond_to?(:each) ? Gem::Specification : Gem.source_index.find_name('')).each do |gem|
          next if gem.name !~ plugin_prefix

          plugin_name = gem.name.split('-', 2).last
          @plugins << Plugin.new(plugin_name, gem.name, gem, true) if !gem_located?(gem.name)
        end

        @plugins
      end

      # @return [Hash] A hash with all plugin names (minus the '<prefix>-') as
      #   keys and Plugin objects as values.
      def plugins
        h = Hash.new { |_, key| NoPlugin.new(key) }

        @plugins.each do |plugin|
          h[plugin.name] = plugin
        end

        h
      end

      # Require all enabled plugins, disabled plugins are skipped.
      def load_plugins
        @plugins.each do |plugin|
          plugin.activate! if plugin.enabled?
        end
      end

      private

      def gem_located?(gem_name)
        @plugins.any? { |plugin| plugin.gem_name == gem_name }
      end

      def plugin_prefix
        module_name = if self.class.name.deconstantize.blank?
                        self.class.name
                      else
                        self.class.name.deconstantize
                      end

        module_name.constantize.plugin_prefix
      end
    end
  end
end