SSH_CLIPBOARD_DIR="${SSH_CLIPBOARD_DIR:-$HOME/.cache}"
SSH_CLIPBOARD_SOCKET="${SSH_CLIPBOARD_SOCKET:-$SSH_CLIPBOARD_DIR/ssh-clipboard.sock}"
SSH_CLIPBOARD_PIDFILE="${SSH_CLIPBOARD_PIDFILE:-$SSH_CLIPBOARD_DIR/ssh-clipboard.pid}"
SSH_CLIPBOARD_LOG="${SSH_CLIPBOARD_LOG:-$SSH_CLIPBOARD_DIR/ssh-clipboard.log}"

# This path is created on the remote host.
# Override it when the remote username differs from the local username.
SSH_CLIPBOARD_REMOTE_SOCKET="/tmp/ssh-clipboard-client.sock"

function clipboard_server_running {
	local pid

	if [ -n "${SSH_CLIPBOARD_REMOTE_SOCKET:-}" ] &&
		[ -S "$SSH_CLIPBOARD_REMOTE_SOCKET" ]; then
		return 0
	fi

	[[ -f "$SSH_CLIPBOARD_PIDFILE" ]] || return 1

	read -r pid < "$SSH_CLIPBOARD_PIDFILE"

	[[ "$pid" =~ ^[0-9]+$ ]] || return 1
	kill -0 "$pid" 2>/dev/null
}

function init_clipboard_server {
	if clipboard_server_running; then
		return 0
	fi
	case "$OSTYPE" in
		darwin*)
			command -v socat >/dev/null 2>&1 || {
				echo "clipboard server: socat is not installed" >&2
				echo "Install it with: brew install socat" >&2
				return 1
			}

			[[ -x /usr/bin/pbcopy ]] || {
				echo "clipboard server: /usr/bin/pbcopy was not found" >&2
				return 1
			}

			mkdir -p "$SSH_CLIPBOARD_DIR"
			chmod 700 "$SSH_CLIPBOARD_DIR"

			rm -f "$SSH_CLIPBOARD_SOCKET" "$SSH_CLIPBOARD_PIDFILE"

			(
				umask 077

				socat \
					"UNIX-LISTEN:$SSH_CLIPBOARD_SOCKET,fork,mode=600" \
					EXEC:/usr/bin/pbcopy \
					>>"$SSH_CLIPBOARD_LOG" 2>&1 &

				echo "$!" > "$SSH_CLIPBOARD_PIDFILE"
			)
			;;

		cygwin*)
			echo "clipboard server: Cygwin support is not implemented" >&2
			return 1
			;;

		*)
			echo "clipboard server: $OSTYPE is not supported" >&2
			return 1
			;;
	esac
}

function stop_clipboard_server {
	local pid

	if clipboard_server_running; then
		read -r pid < "$SSH_CLIPBOARD_PIDFILE"
		kill "$pid" 2>/dev/null || true
	fi

	rm -f "$SSH_CLIPBOARD_SOCKET" "$SSH_CLIPBOARD_PIDFILE"
}

function clipboard_server_config {
	cat <<EOF
RemoteForward $SSH_CLIPBOARD_REMOTE_SOCKET $SSH_CLIPBOARD_SOCKET
StreamLocalBindUnlink yes
ExitOnForwardFailure yes
EOF
}

function sshc {
	init_clipboard_server || return

	echo "-- ssh with clipboard server"

	command ssh \
		-R "$SSH_CLIPBOARD_REMOTE_SOCKET:$SSH_CLIPBOARD_SOCKET" \
		"$@"
}

function pbcopy {
	if [ -n "${SSH_CLIPBOARD_REMOTE_SOCKET:-}" ] &&
		[ -S "$SSH_CLIPBOARD_REMOTE_SOCKET" ]; then

		command -v socat >/dev/null 2>&1 || {
			echo "pbcopy: socat is required for the remote clipboard" >&2
			return 1
		}

		socat - "UNIX-CONNECT:$SSH_CLIPBOARD_REMOTE_SOCKET"
		return $?
	fi

	case "$OSTYPE" in
		darwin*)
			if [ -x /usr/bin/pbcopy ]; then
				/usr/bin/pbcopy
			else
				echo "pbcopy: /usr/bin/pbcopy was not found" >&2
				return 1
			fi
			;;
		*)
			echo "pbcopy: no remote clipboard socket is available" >&2
			return 1
			;;
	esac
}

function cleanup_ssh_clipboard {
	[ -n "${SSH_CONNECTION:-}" ] || return
	[ -S "$SSH_CLIPBOARD_REMOTE_SOCKET" ] || return
	rm -f -- "$SSH_CLIPBOARD_REMOTE_SOCKET"
}

if [ -z "${SSH_CONNECTION:-}" ] && init_clipboard_server; then
	alias ssh='sshc'
fi

if [ -n "${SSH_CONNECTION:-}" ]; then
	trap cleanup_ssh_clipboard EXIT HUP TERM
fi