matheusmoreira/jewel

module Jewel
  class Gem

    # Stores Ruby gem metadata.
    #
    # @author Matheus Afonso Martins Moreira
    # @since 0.0.1
    class Metadata

      # Creates a new, empty set of gem metadata.
      #
      # If given a block, it will be evaluated in the context of the new
      # instance.
      #
      # @param [Proc] block the initializer block
      def initialize(&block)
        instance_eval &block if block_given?
      end

      # Assigns or returns attributes from the associated
      # {#gem_specification gem specification}. If it doesn't respond to it, the
      # attribute will be stored in this object.
      def method_missing(method_name, *arguments, &block)
        method = method_name.to_s.gsub(/[=?!]+\z/ix, '').strip.intern
        count = arguments.count
        if count.zero?
          if spec.respond_to? method
            spec.send method
          else
            stored_attributes[method]
          end
        else
          writer_method = '='.prepend(method.to_s).intern
          if spec.respond_to? writer_method
            spec.send writer_method, *arguments
          else
            value = count == 1 ? arguments.first : arguments
            stored_attributes[method] = value
          end
        end
      end

      # The gem's runtime dependencies.
      #
      # @return [Hash{String=>Array<String>}] names of gems associated with
      #   their requirements
      def dependencies
        convert_to_hash specification.runtime_dependencies
      end

      alias runtime_dependencies dependencies

      # The gem's development dependencies.
      #
      # @return [Hash{String=>Array<String>}] names of gems associated with
      #   their requirements
      def development_dependencies
        convert_to_hash specification.development_dependencies
      end

      # Runtime and development dependencies. The former takes precedence in
      # case of conflict.
      #
      # @return [Hash{String=>Array<String>}] names of gems associated with
      #   their requirements
      # @since 0.0.2
      def all_dependencies
        development_dependencies.merge dependencies
      end

      # Yields dependencies to the given block, or returns an enumerator.
      #
      # @option options [true, false, :only] :development (false) whether
      #   runtime and development dependencies should be included
      # @yield [gem_name, *requirements]
      # @yieldparam [String] gem_name the name of the gem
      # @yieldparam [Array<String>] requirements the version requirements
      # @since 0.0.2
      def each_dependency(options = {}, &block)
        return enum_for :each_dependency, options unless block_given?
        development = options.fetch :development, false
        case development
          when :only then development_dependencies
          when  true then all_dependencies
          else dependencies
        end.each &block
      end

      # The +::Gem::Specification+.
      #
      # @overload gem_specification
      #   Returns the +::Gem::Specification+ instance.
      #
      # @overload gem_specification(instance)
      #   Stores the given +::Gem::Specification+ instance.
      #
      #   @param [::Gem::Specification] instance the instance
      #
      # @return [::Gem::Specification] the specification
      # @since 0.0.4
      def gem_specification(*arguments)
        @gem_specification = arguments.shift if arguments.first.is_a? ::Gem::Specification
        @gem_specification ||= ::Gem::Specification.new
      end

      alias spec          gem_specification
      alias gemspec       gem_specification
      alias to_spec       gem_specification
      alias specification gem_specification

      private

      # The stored gem attributes.
      #
      # @return [Hash] hash holding information about the gem
      def stored_attributes
        @stored_attributes ||= {}
      end

      # Converts an array of Gem::Dependency objects into an array of hashes in
      # the following form:
      #
      #   { 'gem_name' => ['= 0.0.0'], ... }
      #
      # @return [Hash{String=>Array<String>}] names of gems associated with
      #   their requirements
      # @since 0.0.4
      def convert_to_hash(dependencies)
        Hash.new.tap do |hash|
          dependencies.each do |dependency|
            hash[dependency.name] = dependency.requirements_list
          end
        end
      end

    end

  end
end