#!/bin/sh
# Copyright 2020 Oliver Smith
# SPDX-License-Identifier: GPL-3.0-or-later

setup_log() {
	logfile=${XDG_STATE_HOME:-~/.local/state}/tinydm.log
	mkdir -p "$(dirname "$logfile")"
	if [ -f "$logfile" ]; then
		# keep previous log file around
		mv "$logfile" "$logfile".old
	fi

	exec >"$logfile" 2>&1
}

source_profile() {
	for profile in /etc/profile "$HOME"/.profile; do
		if [ -f "$profile" ]; then
			# shellcheck disable=SC1090
			. "$profile"
		fi
	done
}

# $1: session type (i.e. 'wayland', or 'x11')
source_session_profiles() {
	session_type="$1"
	if [ "$session_type" != "wayland" ] && [ "$session_type" != "x11" ]; then
		echo "Unknown session type: $session_type"
		exit 1
	fi

	for file in "/usr/share/tinydm/env-${session_type}.d/"*; do
		if ! [ -e "$file" ]; then
			continue
		fi

		echo "tinydm: sourcing file: $file"
		# shellcheck disable=SC1090
		. "$file"
	done

	# Source /etc dirs after /usr/share to override options properly
	for file in "/etc/tinydm.d/env-${session_type}.d/"*; do
		if ! [ -e "$file" ]; then
			continue
		fi

		echo "tinydm: sourcing file: $file"
		# shellcheck disable=SC1090
		. "$file"
	done
}

# $1: file
# $2: key
parse_xdg_desktop() {
	grep "^$2=" "$1" | cut -d "=" -f 2- | tr ';' ':' | sed 's/:$//'
}

# $1: Exec line from .desktop file
run_session_wayland() {
	export XDG_SESSION_TYPE=wayland
	exec setpriv --ambient-caps '-all' "$@"
}

# $1: Exec line from .desktop file
run_session_x() {
	export XDG_SESSION_TYPE=X11

	cmd_startx="startx $(command -v "$1")"

	shift
	for arg in "$@"; do
		cmd_startx="$cmd_startx $arg"
	done

	cmd_startx="$cmd_startx -- -nocursor -nolisten tcp vt1 -keeptty"

	# shellcheck disable=SC2086
	exec setpriv --ambient-caps '-all' $cmd_startx
}

run_session() {
	target="/var/lib/tinydm/default-session.desktop"

	if ! [ -e "$target" ]; then
		echo "ERROR: no session configured!"
		exit 1
	fi

	resolved="$(realpath "$target")"
	desktop="$(basename "$resolved" | sed 's/\.desktop$//')"
	export XDG_SESSION_DESKTOP="$desktop"
	cmd="$(parse_xdg_desktop "$resolved" "Exec")"

	desktop_names="$(parse_xdg_desktop "$resolved" "DesktopNames")"
	if [ -n "$desktop_names" ]; then
		export XDG_CURRENT_DESKTOP="$desktop_names"
	fi

	if [ -z "$DBUS_SESSION_BUS_ADDRESS" ] &&
	   [ "$TINYDM_START_DBUS_SESSION" = "true" ] &&
	   [ "$(command -v dbus-launch)" ]; then
		cmd="$(command -v dbus-launch) --exit-with-x11 $cmd"
	fi

	echo "--- tinydm ---"
	echo "Date:    $(date)"
	echo "Session: $resolved"
	echo "Desktop: $desktop"
	echo "Exec:    $cmd"
	echo "---"

	case "$resolved" in
		/usr/share/wayland-sessions*)
			source_session_profiles wayland
			# shellcheck disable=SC2086
			run_session_wayland $cmd
			;;
		/usr/share/xsessions*)
			source_session_profiles x11
			# shellcheck disable=SC2086
			run_session_x $cmd
			;;
		*)
			echo "ERROR: could not detect session type!"
			exit 1
			;;
	esac
}

setup_log
source_profile
run_session