#!/bin/bash

# The purpose of this thing is to pick the parts out of a best_version.
# Working to add a way to make it skip a given part (package, version or
# revision).

# To add it to an ebuild/eclass, drop the 'portageq' call and the $ROOT mention
# in it ('/'). $1 is the package you want to match, $2 is the variable you want
# the revision set to at the end, $3 is the variable you want the version set
# to, $4 is the variable you want the package name set to, $5 is the variable
# you want the category name set to.
# It is currently NOT exported to the environment. As written, this depends on
# bash-2, portageq, cut, echo and seq.
# Author: Donnie Berkholz <spyderous@gentoo.org>

# In a format suitable for a DEPEND string
PACKAGE_ATOM="${1:-=sys-apps/coreutils-5*}"
# Pick the name of the variable you want the revision set to
REVISION_NAME="${2:-COREUTILS_REVISION}"
# Pick the name of the variable you want the version set to
VERSION_NAME="${3:-COREUTILS_VERSION}"
# Pick the name of the variable you want the name set to
PACKAGE_NAME="${4:-COREUTILS_PACKAGE}"
# Pick the name of the variable you want the category set to
CATEGORY_NAME="${5:-COREUTILS_CATEGORY}"

# For testing, to optimize times without calling portage
if [ -n "${SKIP_PORTAGEQ}" ]; then
	FULL_NAME="${1:-x11-libs/gtk+-1.2.10-r11}"
else
	FULL_NAME="$(portageq best_version / ${PACKAGE_ATOM})"
fi
# Initialize parts array
declare -a PARTS

# Grab everything after the / (in other words, the pkg-ver-rev)
PARTS=($(echo ${FULL_NAME} \
	| cut -d/ -f2 --output-delimiter=' ' \
	| cut -d- -f1- --output-delimiter=' '))

# Grab category
declare ${CATEGORY_NAME}="$(echo ${FULL_NAME} \
	| cut -d/ -f1 --output-delimiter=' ')"
echo "Confirmed category ${!CATEGORY_NAME}."

# Start countdown based on last part -- note arrays start at 0
PART_COUNTDOWN="$(( ${#PARTS[@]} - 1 ))"

# Make sure these isn't around before we start
unset ${VERSION_NAME} ${REVISION_NAME} ${PACKAGE_NAME}

# Initialize
declare LOOP_COUNT="0" REVISION_DONE="0" VERSION_DONE="0" PACKAGE_DONE="0"

# The ${!VAR} thing is called an indirect variable reference.
# a=b, b=c, ${a}=b, ${!a}=c
# This particular way of doing it requires bash 2 or greater.
# The other option involves eval echo \$$foo.

until [ -n "${!PACKAGE_NAME}" ]; do
	if [ ${VERSION_DONE} -eq 0 ]; then
		# Test whether it starts with 'r' (i.e., is a revision)
		if [ "${PARTS[${PART_COUNTDOWN}]:0:1}" = "r" ] \
			&& [ ${REVISION_DONE} -eq 0 ]; then
			declare ${REVISION_NAME}="${PARTS[${PART_COUNTDOWN}]}"
			echo "Confirmed revision ${!REVISION_NAME}."
		# Test whether it starts with a number (i.e., is a version)
		else
			for NUMBER in $(seq 0 9); do
				if [ "${PARTS[${PART_COUNTDOWN}]:0:1}" = "${NUMBER}" ]; then
					declare ${VERSION_NAME}="${PARTS[${PART_COUNTDOWN}]}"
					echo "Confirmed version ${!VERSION_NAME}."
				fi
			done
			VERSION_DONE="1"
		fi
		REVISION_DONE="1"
	elif [ ${PACKAGE_DONE} -eq 0 ]; then
		# Unhyphenated package names
		if [ ${PART_COUNTDOWN} -eq 0 ]; then
			declare ${PACKAGE_NAME}="${PARTS[${PART_COUNTDOWN}]}"
		# Hyphenated package names
		else
			for PACKAGE_COUNTDOWN in $(seq ${PART_COUNTDOWN} -1 0); do
				declare ${PACKAGE_NAME}="${PARTS[${PACKAGE_COUNTDOWN}]}${!PACKAGE_NAME:+-${!PACKAGE_NAME}}"
			done
		fi
		echo "Confirmed package ${!PACKAGE_NAME}."
		PACKAGE_DONE="1"
	else
		# If it didn't have anything left to make a name with, die
		if [ -z ${!PACKAGE_NAME} ]; then
			echo "Not enough data fields. Quitting."
			break
		fi

		break
	fi

	# Counter
	(( PART_COUNTDOWN -= 1 ))
	if (( PART_COUNTDOWN < 0 )); then
		echo "Countdown less than zero. Quitting."
		break
	fi
	echo "Looping..."
done

echo "R=${!REVISION_NAME:-(none)} V=${!VERSION_NAME:-(none)} P=${!PACKAGE_NAME:-(none)} C=${!CATEGORY_NAME:-(none)}"
echo "Reconstructed: ${!CATEGORY_NAME}/${!PACKAGE_NAME}-${!VERSION_NAME}${!REVISION_NAME:+-${!REVISION_NAME}}"