#!/bin/bash

# Runs this compiler in the current directory every time something changes in the specified directory,
# and if successful, runs the resulting program.
#
# Without arguments, run monitors the parent directory and compiles all *cpp, *cc, *cxx.
COMPILE="clang++ -std=c++20"

shopt -s nullglob

usage() {
	>&2 echo "run [monitored directory] [compiler arguments]"
	exit 1
}

if [ "$1" == "--runrunrun" ]; then
	prog="$2"
	[ -f "$prog" ] || usage
	shift 2

	time_prog=$(which time)
	>&2 echo -e "\n\e[1;33m==> compiling <==\e[0m"
	$time_prog -f "%E" $COMPILE ${@:-*cpp *cc *cxx} -o $prog &&
	$time_prog -f "%Es (%Mkb)" $prog
else
	[ -x "$(command -v entr)" ] || { >&2 echo "Please install entr (https://github.com/eradman/entr)."; exit; }

	MONITOR="${1:-..}"
	[ -d "$MONITOR" ] || usage
	shift 1

	TMP=$(mktemp)
	trap "rm -f $TMP; exit" INT

	>&2 echo "monitoring $(cd $MONITOR; pwd)"
	>&2 echo "$COMPILE " ${@:-*cpp *cc *cxx}
	while true; do
		find $MONITOR | entr -nd ./run --runrunrun $TMP $@
	done
fi