#!/bin/bash

error() {
	echo $* >&2
	exit 1
}

check_requisite() {
	case "$2" in
		program)
			[ -x "$(which $1 2>/dev/null)" ]
			;;
		lib)
			ldconfig -p | grep -q "^[[:space:]]*$1 "
			;;
		header)
			[ -n "$(find /usr/include/ /usr/local/include/ -path "*/$1" 2>/dev/null)" ]
			;;
		*)
			error "Unknown requisite type: $2"
			;;
	esac
}

failed_requisite() {
	local required
	if $3; then
		required="WARNING"
	else
		required="ERROR"
	fi
	case "$2" in
		program)
			echo "$required: The program $1 was not found in path."
			;;
		lib)
			echo "$required: The library $1 was not found in /etc/ld.so.cache."
			;;
		header)
			echo "$required: The header file $1 was not found in /usr/(local/)include."
			;;
		*)
			error "Unknown requisite type: $2"
			;;
	esac
}

declare -a req
parser=
warn=false

while [ $# -gt 0 ]; do
	case "$1" in
		-h|--header)
			parser=header
			warn=false
			;;
		-l|--lib)
			parser=lib
			warn=false
			;;
		-p|--program)
			parser=program
			warn=false
			;;
		-w|--warn)
			[ -n "$parser" ] && warn=true
			;;
		*)
			[ -z "$parser" ] && error "Invalid argument: $1"
			req[${#req[*]}]="$1"
			req[${#req[*]}]=$parser
			req[${#req[*]}]=$warn
			warn=false
	esac
	shift
done

err=0
i=0
while [ $i -lt ${#req[*]} ]; do
	if ! check_requisite "${req[$i]}" ${req[$((i+1))]} ${req[$((i+2))]}; then
		failed_requisite "${req[$i]}" ${req[$((i+1))]} ${req[$((i+2))]}
		${req[$((i+2))]} || err=1
	fi
	i=$((i+3))
done

exit $err