#!/bin/sh
awk=awk
me() { basename "$0"; }

printhelp() {
cat << HELPDOC
Usage:
  $(me): [-gh] [COMMAND] [COMMAND ARGS]...

Args:
  -g, --gen-cache : Force generate cache
  -h, --help      : show this help message

Config Syntax:
  +host [HOSTNAME]
    Add a new host. Hosts can be referenced using their number starting with 1.
  [COMMAND]
    launch [COMMAND] will start the process specified for the specific hostname. Aliases are separated by |.
  [TAB][SHELL]
    Run this shell command when the above [COMMAND] is specified. In order of hostnames. Can be a number to reference to a hostname, a '-' to disregard this command for the specific host, or a '^' to reference the previous command.
HELPDOC
}

# Make sure user is using GNU Awk (gawk)
checkawk() {
	if ! ($awk -V >/dev/null 2>/dev/null && $awk -V | grep "GNU Awk" >/dev/null); then
		if command -v gawk > /dev/null; then
			awk=gawk
		else
			echo "$(me) requires GNU Awk (gawk) to function properly. Please install GNU Awk and try again."
			exit 0
		fi
	fi
}

gencache() {
$awk '
BEGIN {
	print "run=\"$1\"; shift"
	print "case \"$run\" in"
}
{
	sub(/#.*/, "") # Remove comments
	if (!/^\s*$/) {
		if (/^\+host/) {
			sub(/\s*\+host\s*/, "")
			h++
			hosts[h] = $0
		}
		else {
			if (!/^\t/) {
				hostnum = 1
				o++
				opts[o] = $0
			}
			else {
				sub(/^\t/, "")
				if ($0 == "^")
					$0 = cache
				else if ($0 ~ /^[0-9]*$/)
					$0 = cmds[hosts[$0]":"opts[o]]
				cmds[hosts[hostnum]":"opts[o]] = cache = $0
				hostnum++
			}
		}
	}
}
END {
	for (host in hosts) {
		if (hosts[host] != "'`hostname`'")
			continue
		for (cmd in cmds) {
			if (cmd ~ hosts[host] && cmds[cmd] && cmds[cmd] != "-") {
				i = cmd
				sub(/.*:/, "", cmd)
				print "\t"cmd") "cmds[i]" \"$@\" & ;;"
			}
		}
	}
	print "\t*) command -v \"$run\" >/dev/null && exec \"$run\" \"$@\" || echo \"\\`$run${@:+ $@}\\` Does not exist or exited with an error\" ;;"
	print "esac"
}
' $conf > $cache
chmod +x $cache
}

# Config file setup
confdir=${XDG_CONFIG_HOME:-~/.config}/launch
conf=$confdir/config
if [ ! -e $conf ]; then
	mkdir -p $confdir
	echo "#HOSTS\n+host $(hostname)\n\n#OPTS\ntest\n\techo \"Tested!\"" > $conf
	echo "No config file exists! new config file created at $conf! Exiting\n"
	printhelp
	exit 1
fi

# Cache file setup
cachedir=${XDG_CACHE_HOME:-~/.cache}/launch
cache=$cachedir/cache
[ ! -e $cache ] && mkdir -p $cachedir && gencache
[ $conf -nt $cache ] && gencache

# Command line options
checkawk
case "$1" in
	-g|--gen-cache) echo "Generating new cache: $cache"; gencache && cat $cache ;;
	-h|--help|'') printhelp ;;
	*) exec $cache "$@" ;; # Run
esac