#!/bin/bash
# by David Watzke <david@watzke.cz> @ 2006
# http://www.watzke.cz/bash

if [[ -r /sbin/functions.sh ]]; then
	source /sbin/functions.sh
else
	echo "Could not find /sbin/functions.sh!"
	echo "You will need sys-apps/baselayout!"
	exit 1
fi

die() {
	eerror "$@"
	exit 1
}

ehelp() {
	einfo "echange by David Watzke <david@watzke.cz> http://www.watzke.cz/en/bash"
	einfo "Usage: echange [[number of lines] [category/]package]"
	[[ $# -eq 0 ]] && exit 0 || exit 1
}

check_lineno() {
	if [[ "$1" =~ ^[[:digit:]]*$ ]]; then
		if [[ $1 -lt 18446744073709551616 ]]; then
			line=$1
		else
			die "Digit has to be less than 2^64!"
		fi
	else
		die "Not a digit: '$1'!"
	fi
}

check_pkgname() {
	[[ $(wc -l <<< "$1") -ne 1 ]] && goodname=false
	a=[[:alnum:]]
	if $goodname && grep -qE "^$a+(|(\-|$a)*$a)(|/$a+(|(\-|$a)*$a))$" <<< "$1"; then
		pkg=$1
	else
		die "Not a valid package name: '$1'!"
	fi
}

if [[ -r /etc/make.globals ]]; then
	source /etc/make.conf /etc/make.globals >& /dev/null
else
	eerror "Could not find a /etc/make.globals config file!"
	die "Are you sure you have Portage installed?"
fi

if [[ -z "$PORTDIR" ]]; then
	eerror "You have not '\$PORTDIR' variable set!"
	die "Could not find Portage tree!"
fi

if [[ "$PORTDIR" != "${PORTDIR// }" ]]; then
	eerror "You cannot have spaces in the path to the Portage tree!"
	die "Please fix this error!"
fi

if [[ $# -eq 1 ]]; then
	line=20
	check_pkgname $1
elif [[ $# -eq 2 ]]; then
	check_lineno $1
	check_pkgname $2
else
	ehelp
fi

if [[ "$pkg" =~ ./. ]]; then
	array=false
	log=$PORTDIR/$pkg/ChangeLog
else
	array=true
	log=($PORTDIR/*/$pkg/ChangeLog)
fi

if $array; then
	if [[ ${#log[*]} -eq 1 ]]; then
		log=${log[0]}
	else
		ewarn "Package name '$pkg' is ambiguous!"
		ewarn "Please specify full name (with category):"
		for ((i=0; i<${#log[*]}; i++)); do
			pkgtmp=${log[$i]#$PORTDIR}
			pkgtmp=${pkgtmp%/*}
			ewarn "\t${pkgtmp#/}"
		done
		exit 1
	fi
fi

if [[ -r $log ]]; then
	head -n$line $log
else
	die "Package '$pkg' was not found!"
fi

# TODO:
# kontrolovat zda $line neni moc velky cislo
# konfigurak