# Copyright 2022 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

# @ECLASS: virtualwl.eclass
# @MAINTAINER:
# amit.prakash.ambasta@gmail.com
# @AUTHOR:
# Amit Prakash Ambasta
# @SUPPORTED_EAPIS: 8
# @BLURB: This eclass can be used for packages that need a working wayland environment to build.

case ${EAPI} in
	8) ;;
	*) die "${ECLASS}: EAPI ${EAPI} unsupported."
esac

if [[ ! ${_VIRTUALWL_ECLASS} ]]; then
_VIRTUALWL_ECLASS=1

# @ECLASS-VARIABLE: VIRTUALWL_REQUIRED
# @PRE_INHERIT
# @DESCRIPTION:
# Variable specifying the dependency on wayland.
# Possible special values are "always" and "manual", which specify
# the dependency to be set unconditionally or not at all.
# Any other value is taken as useflag desired to be in control of
# the dependency (eg. VIRTUALWL_REQUIRED="kde" will add the dependency
# into "kde? ( )" and add kde into IUSE.
: ${VIRTUALWL_REQUIRED:=test}

# @ECLASS-VARIABLE: VIRTUALWL_DEPEND
# @OUTPUT_VARIABLE
# @DESCRIPTION:
# Standard dependencies string that is automatically added to BDEPEND
# unless VIRTUALWL_REQUIRED is set to "manual".
readonly VIRTUALWL_DEPEND="
	gui-wm/sway
	sys-auth/seatd
"

case ${VIRTUALWL_REQUIRED} in
	manual)
		;;
	always)
		BDEPEND="${VIRTUALWL_DEPEND}"
		;;
	*)
		BDEPEND="${VIRTUALWL_REQUIRED}? ( ${VIRTUALWL_DEPEND} )"
		IUSE="${VIRTUALWL_REQUIRED}"
		[[ ${VIRTUALWL_REQUIRED} == "test" ]] &&
			RESTRICT+=" !test? ( test )"
		;;
esac

# @FUNCTION: virtwl
# @USAGE: <command> [command arguments]
# @DESCRIPTION:
# Start a new wayland session and run commands in it.
#
# IMPORTANT: This command is run nonfatal !!!
#
# This means we are checking for the return code and raise an exception if it
# isn't 0. So you need to make sure that all commands return a proper
# code and not just die. All eclass function used should support nonfatal
# calls properly.
#
# The rationale behind this is the tear down of the started wayland session. A
# straight die would leave a running session behind.
#
# Example:
#
# @CODE
# src_test() {
#     virtwl default
# }
# @CODE
#
# @CODE
# python_test() {
#     virtwl py.test --verbose
# }
# @CODE
#
# @CODE
# my_test() {
#   some_command
#   return $?
# }
#
# src_test() {
#	  virtwl my_test
# }
# @CODE
virtwl() {
	debug-print-function ${FUNCNAME} "$@"

	[[ $# -lt 1 ]] && die "${FUNCNAME} needs at least one argument. Missing command to run"

	local retval=0
	local SWAY DBUS WL_DISPLAY
	local swayargs="-d"

	SWAY=$(type -p sway) || die
	DBUS=$(type -p dbus-launch) || die

	debug-print "${FUNCNAME}: running headless sway"

	export WLR_BACKEND=drm
	export XDG_RUNTIME_DIR=${T}
	export XDG_SESSION_TYPE=wayland
	export WLR_RENDERER=vulkan

	einfo "Starting wayland..."

	debug-print "${FUNCNAME}: ${DBUS} ${SWAY} ${swayargs}"
	${DBUS} ${SWAY} ${swayargs} &>/dev/null &
	sleep 5

	echo "Started wayland on socket ${WAYLAND_DISPLAY}"

	# Do not break on error, but setup $retval, as we need
	# to kill the started wayland session.
	debug-print "${FUNCNAME}: $@"
	nonfatal "$@"
	retval=$?

	# Now kill sway
	fuser -k -TERM ${T}/${WAYLAND_DISPLAY}.lock

	# die if our command failed
	[[ ${retval} -ne 0 ]] && die "Command '$@' failed with return code ${retval}"

	return 0 # always return 0, it can be altered by failed kill for sway
}

fi