module Jsus
  class SourceFile
    attr_accessor :header
    attr_accessor :relative_filename
    attr_accessor :filename
    # constructors

    def self.from_file(filename)
      if File.exists?(filename)
        source = File.read(filename) # TODO: read only first several lines of file
        yaml_data = source.match(%r(^/\*\s*(---.*?)\*/)m)
        if (yaml_data && yaml_data[1] && header = YAML.load(yaml_data[1]))
          result = new
          result.header = header
          result.relative_filename = filename
          result.filename = File.expand_path(filename)
          result
        else
          # puts "WARNING: file #{filename} has invalid format (should be YAML)"
          nil
        end
      else
        # puts "WARNING: file #{filename} does not exist"
        nil
      end
    end

    # Public API
    def dependencies
      header["requires"] ||= []
    end

    def provides
      header["provides"] ||= []
    end

    def description
      header["description"] ||= ""
    end

  end
end