function __agent_is_started -d "check if ssh agent is already started"
   if begin; test -f $SSH_ENV; and test -z "$SSH_AGENT_PID"; end
        source $SSH_ENV > /dev/null
   end

   if test -z "$SSH_AGENT_PID"
        return 1
   end

    ps -p $SSH_AGENT_PID > /dev/null
    return $status
end

function __agent_start -d "start a new ssh agent"
    secure-agent daemon > $SSH_ENV
    chmod 600 $SSH_ENV
    source $SSH_ENV > /dev/null
    true
end

function fish_ssh_agent --description "start ssh-agent if not started yet, or uses already started ssh-agent."
    if test -z "$SSH_ENV"
        set -xg SSH_ENV $HOME/.ssh/environment
    end

    if not __agent_is_started
        __agent_start
    end
end

fish_ssh_agent