require "take/project/requirement/base"
require "take/project/requirement/library"
require "take/project/requirement/header"
require "take/project/requirement/program"

module Take
  class Project
    module Requirement

      def self.convert(hash, project, &blk)
        if hash.size > 1
          raise ArgumentError, "Cannot use a block for a " \
            "multi-requirement!" if block_given?
        end

        requirements = []

        hash.each do |key, value|
          requirement_class = lookup(key)
          requirement = requirement_class.new(key, value, project,
            &blk)
          requirements << requirement
        end

        requirements
      end

      def self.lookup(name)
        case name
        when :header
          Header
        when :library
          Library
        when :program
          Program
        when Class
          name
        else
          raise ArgumentError, "Unknown requirement #{name.inspect}!"
        end
      end
    end
  end
end