#!/bin/bash

function assert_eq() {
	local expected="$1"
	local actual="$2"
	local message="$3"
	if [ "$1" -ne "$2" ] ; then
		if [ ! -z "$message" ]; then
			echo "$message"
		fi
		die_usage
	fi
}

function assert_le() {
	local expected="$1"
	local actual="$2"
	local message="$3"
	if [ "$1" -gt "$2" ] ; then
		if [ ! -z "$message" ]; then
			echo "$message"
		fi
		die_usage
	fi
}

function get_pkginfo() {
	local file="$1"
	# FIXME remove dep on GNU tar
	tar --to-stdout -xf "$file" .PKGINFO
}

function get_pkginfo_field() {
	local file="$1"
	local field="$2"
	get_pkginfo "$file" | grep '^'"$field"'' | awk -F' = ' '{print $2}'
}

function die_usage() {
	echo "Syntax: introspect.sh <action> [options]"
	echo ""
	echo "Valid actions:"
	echo "all   <package>"
	echo "field <package> <field_name>"
	echo "files <package>"
	exit 1
}

assert_le 2 $# "Not enough arguments"

case "$1" in
	"all")
		assert_eq 2 $#
		get_pkginfo $2
		;;
	"field")
		assert_eq 3 $#
		get_pkginfo_field $2 $3
		;;
	"files")
		assert_eq 2 $#
		echo Files not implemented
		exit 1
		;;
	*)
		echo "Unknown action \"$1\""
		die_usage
		;;
esac