#!/usr/bin/env sh
progname="$(basename "$0")"
data="$(dirname "$(readlink -f "$0")")"
export data # path to directory containing reload.d, switch.d, etc.

run_switch=1
run_reload=1
no_cfg=0
theme="" # absolute path to theme

# print error message and exit with error
stupid() {
	echo "$@" >&2
	echo "run \`$progname --help\` for options" >&2
	exit 1
}

usage() {
	cat << EOF
$progname -- switch system themes

usage:
	$progname [-chr] action|theme

options:
	-s, --no-switch    disable running switch.d hooks
	-c, --no-cfggen    disable generation of templated configuration files
	-h, --help         display this help text
	-r, --no-reload    disable reloading of applications after applying theme

actions:
	restore    switch to last set theme ($XDG_CACHE_HOME/mode/state/theme)
	reload     do not update configuration files, only reload applications
	help       same as --help option
	list       list all themes

examples:
	mode dark                   switch to dark mode and reload applications
	mode restore --no-reload    make sure all configuration files are up-to-date
	mode reload                 only reload applications

EOF
}

# run a module file
run_mod() {
	mod_name="$1"

	# modules must be executable
	! [ -x "$mod_name" ] && return

	# parse interpreter from shebang
	interpreter="$(basename "$(command -v $(head -n1 "$mod_name" | sed -n 's/^#!\(.*\)/\1/p'))")"
	if [ "$interpreter" = "sh" ] ; then
		# source module if interpreter is POSIX sh (makes plugin functions available)
		( . "$mod_name" )
	else
		# else, just run them
		"$mod_name"
	fi
}

# generate config files from theme file using scripts in switch.d
switch() {
	[ -z "$theme" ] && stupid "error: no theme selected"
	[ ! -e "$theme" ] && stupid "error: theme not found"
	export theme

	theme_name="$(basename "$theme")"
	echo "setting theme to $theme_name..."

	# clean up environment
	unset accent accent_text
	unset mode

	# load theme colors + aux variables
	. "$theme"

	# load plugins (TODO: plugins aren't loaded when only reloading)
	for plugin in "$data"/plug.d/* ; do . "$plugin" ; done

	# generate new config files / snippets (in parallel)
	for switch_function in "$data"/switch.d/* ; do
		run_mod "$switch_function" &
	done

	# join all processes started above
	wait $(jobs -p)
}

# reload programs using scripts in reload.d
reload() {
	echo "reloading programs..."

	for reload_function in "$data"/reload.d/* ; do
		run_mod "$reload_function" &
	done

	wait $(jobs -p)
}

# main program argument parser (later argument always take priority)
for arg in "$@" ; do
	case "$arg" in
		# stop parsing arguments after --
		--) break ;;
		# help
		-h|--help|help) usage && exit 0 ;;
		# only run reload scripts
		reload) run_reload=1 run_switch=0 ;;
		# prevent reload.d scripts from running
		-r|--no-reload) run_reload=0 ;;
		# prevent switch.d scripts from running
		-s|--no-switch) run_switch=0 ;;
		# prevent switch.d scripts from running
		-c|--no-cfggen) no_cfg=1 ;;
		# restore previous theme stored as symlink (see switch.d/mode)
		restore)
			theme="$(readlink -f "$XDG_CACHE_HOME/mode/state/theme")"
			[ ! -e "$theme" ] && stupid "error: could not locate previous theme"
			;;
		# list themes in themes folder
		list)
			find "$data/themes" -type f,l | while read -r theme ; do
				printf '%s' "$(basename "$theme")"
				link="$(readlink "$theme")" && printf ' (%s)' "$link"
				printf '\n'
			done
			exit 0
			;;
		*)
			# check if unknown argument is a theme name
			if [ -e "$data/themes/$arg" ] ; then
				theme="$(readlink -f "$data/themes/$arg")"
				continue
			fi
			# else throw error
			stupid "error: unknown argument or theme: $arg"
			;;
	esac
done

export no_cfg

# main
[ $run_switch -eq 1 ] && switch
[ $run_reload -eq 1 ] && reload