module Usage

    def usage_message message
        puts ''
        puts message
        puts ''
        exit 0
    end

    def check_for_env_vars(env_vars, example)
        missing = []
        env_vars.each do |env_var|
            unless ENV[env_var]
                missing << env_var
            end
        end
        if !missing.empty?
            usage = "Usage: This task requires #{env_vars.to_sentence} - missing #{missing.to_sentence}"
            if example
                usage += "\nExample: #{example}"
            end
            usage_message usage
        end
    end

end