# Copyright 1999-2016 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Id$

# Description: eblit.eclass contains the core functions for creating "eblits".
#              eblits are a place to store common code shared among multiple
#              ebuilds for a specific package.
#
# Original Eblit Author: Mike Frysinger <vapier@gentoo.org>
# Original Eclass Author: Joshua Kinard <kumba@gentoo.org>
# Maintainer: base-system@gentoo.org

# Implementation Note: Since code in an eblit is used by multiple ebuilds,
# PLEASE revbump the eblit files when changes are made.  Then update each
# ebuild to use the new eblit version.  Remove old eblit versions when there
# are no more consumers.  This makes it a lot easier to debug problems with
# the shared code within an eblit, as well as the affected ebuilds.

# To create an eblit:
#  1. Create an "eblits" subdirectory under ${FILESDIR}, if one does not
#     already exist.
#  2. Create a new file name using the following formula:
#     [a-z0-9_]-v[0-9]+.eblit
#  3. Add the shared code, save, and close the file.
#
# Try to keep eblits specific to the functions they implement.  E.g., if a
# number of ebuilds have a large, but common src_unpack() function, and it
# is not already provided by an eclass, then add that code to an eblit named
# "src_unpack-vX.eblit".

# To load and use eblits:
#  1. Inherit the "eblit" eclass (this class).
#  2. Define a new function called "load_eblit_funcs" in the ebuild immediately
#     after the global ebuild variables


# eblit-core
# Usage: <function> [version]
# Main eblit engine
eblit-core() {
	local e v func=$1 ver=$2
	for v in ${ver:+-}${ver} -${PVR} -${PV} "" ; do
		e="${FILESDIR}/eblits/${func}${v}.eblit"
		if [[ -e ${e} ]] ; then
			. "${e}"
			[[ ${func} == pkg_* ]] && eval "${func}() { eblit-run ${func} ${ver} ; }"
			return 0
		fi
	done
	return 1
}

# eblit-include
# Usage: [--skip] <function> [version]
# Includes an "eblit" -- a chunk of common code among ebuilds in a given
# package so that its functions can be sourced and utilized within the
# ebuild.
eblit-include() {
	local skipable=false r=0
	[[ $1 == "--skip" ]] && skipable=true && shift
	[[ $1 == pkg_* ]] && skipable=true

	[[ -z $1 ]] && die "Usage: eblit-include <function> [version]"
	eblit-core $1 $2
	r="$?"
	${skipable} && return 0
	[[ "$r" -gt "0" ]] && die "Could not locate requested eblit '$1' in ${FILESDIR}/eblits/"
}

# eblit-run-maybe
# Usage: <function>
# Runs a function if it is defined in an eblit
eblit-run-maybe() {
	[[ $(type -t "$@") == "function" ]] && "$@"
}

# eblit-run
# Usage: <function> [version]
# Runs a function defined in an eblit
eblit-run() {
	eblit-include --skip common "${*:2}"
	eblit-include "$@"
	eblit-run-maybe eblit-$1-pre
	eblit-${PN}-$1
	eblit-run-maybe eblit-$1-post
}

# eblit-pkg
# Usage: <phase> [version]
# Runs the pkg_* functions AND evals them so they're included in the binpkgs
eblit-pkg() {
	[[ -z $1 ]] && die "Usage: eblit-pkg <phase> [version]"
	eblit-core pkg_$1 $2
}