# Copyright 1999-2012 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: /var/cvsroot/gentoo-x86/eclass/python-r1.eclass,v 1.14 2012/10/31 14:18:41 mgorny Exp $

# @ECLASS: python-r1
# @MAINTAINER:
# Michał Górny <mgorny@gentoo.org>
# Python herd <python@gentoo.org>
# @AUTHOR:
# Author: Michał Górny <mgorny@gentoo.org>
# Based on work of: Krzysztof Pawlik <nelchael@gentoo.org>
# @BLURB: A common, simple eclass for Python packages.
# @DESCRIPTION:
# A common eclass providing helper functions to build and install
# packages supporting being installed for multiple Python
# implementations.
#
# This eclass sets correct IUSE and REQUIRED_USE. It exports PYTHON_DEPS
# and PYTHON_USEDEP so you can create correct dependencies for your
# package easily. It also provides methods to easily run a command for
# each enabled Python implementation and duplicate the sources for them.
#
# Please note that this eclass is mostly intended to be extended
# on-request. If you find something you used in other eclasses missing,
# please don't hack it around and request an enhancement instead.

case "${EAPI}" in
	0|1|2|3)
		die "Unsupported EAPI=${EAPI} (too old) for ${ECLASS}"
		;;
	4|5)
		# EAPI=4 needed for REQUIRED_USE
		;;
	*)
		die "Unsupported EAPI=${EAPI} (unknown) for ${ECLASS}"
		;;
esac

inherit multilib

# @ECLASS-VARIABLE: _PYTHON_ALL_IMPLS
# @INTERNAL
# @DESCRIPTION:
# All supported Python implementations, most preferred last.
_PYTHON_ALL_IMPLS=(
	jython2_5
	pypy1_8 pypy1_9
	python3_1 python3_2 python3_3
	python2_5 python2_6 python2_7
)

# @ECLASS-VARIABLE: PYTHON_COMPAT
# @DESCRIPTION:
# This variable contains a list of Python implementations the package
# supports. It must be set before the `inherit' call. It has to be
# an array.
#
# The default is to enable all supported implementations. However, it is
# discouraged to use that default unless in very special cases and test
# the package with each added implementation instead.
#
# Example:
# @CODE
# PYTHON_COMPAT=( python2_5 python2_6 python2_7 )
# @CODE
#
# Please note that you can also use bash brace expansion if you like:
# @CODE
# PYTHON_COMPAT=( python{2_5,2_6,2_7} )
# @CODE
if ! declare -p PYTHON_COMPAT &>/dev/null; then
	PYTHON_COMPAT=( "${_PYTHON_ALL_IMPLS[@]}" )
fi

# @ECLASS-VARIABLE: PYTHON_REQ_USE
# @DEFAULT_UNSET
# @DESCRIPTION:
# The list of USEflags required to be enabled on the chosen Python
# implementations, formed as a USE-dependency string. It should be valid
# for all implementations in PYTHON_COMPAT, so it may be necessary to
# use USE defaults.
#
# Example:
# @CODE
# PYTHON_REQ_USE="gdbm,ncurses(-)?"
# @CODE
#
# It will cause the Python dependencies to look like:
# @CODE
# python_targets_pythonX_Y? (
#   dev-lang/python:X_Y[gdbm,ncurses(-)?] )
# @CODE

# @ECLASS-VARIABLE: PYTHON_DEPS
# @DESCRIPTION:
# This is an eclass-generated Python dependency string for all
# implementations listed in PYTHON_COMPAT.
#
# Example use:
# @CODE
# RDEPEND="${PYTHON_DEPS}
#   dev-foo/mydep"
# DEPEND="${RDEPEND}"
# @CODE
#
# Example value:
# @CODE
# python_targets2_6? ( dev-lang/python:2.6[gdbm] )
# python_targets2_7? ( dev-lang/python:2.7[gdbm] )
# @CODE

# @ECLASS-VARIABLE: PYTHON_USEDEP
# @DESCRIPTION:
# This is an eclass-generated USE-dependency string which can be used to
# depend on another Python package being built for the same Python
# implementations.
#
# The generate USE-flag list is compatible with packages using python-r1
# and python-distutils-ng eclasses. It must not be used on packages
# using python.eclass.
#
# Example use:
# @CODE
# RDEPEND="dev-python/foo[${PYTHON_USEDEP}]"
# @CODE
#
# Example value:
# @CODE
# python_targets_python2_6?,python_targets_python2_7?
# @CODE

_python_set_globals() {
	local flags=( "${PYTHON_COMPAT[@]/#/python_targets_}" )
	local optflags=${flags[@]/%/?}

	IUSE=${flags[*]}
	REQUIRED_USE="|| ( ${flags[*]} )"
	PYTHON_USEDEP=${optflags// /,}

	local usestr
	[[ ${PYTHON_REQ_USE} ]] && usestr="[${PYTHON_REQ_USE}]"

	# 1) well, python-exec would suffice as an RDEP
	# but no point in making this overcomplex, BDEP doesn't hurt anyone
	# 2) python-exec should be built with all targets forced anyway
	# but if new targets were added, we may need to force a rebuild
	PYTHON_DEPS="dev-python/python-exec[${PYTHON_USEDEP}]"
	local i
	for i in "${PYTHON_COMPAT[@]}"; do
		local d
		case ${i} in
			python*)
				d='dev-lang/python';;
			jython*)
				d='dev-java/jython';;
			pypy*)
				d='dev-python/pypy';;
			*)
				die "Invalid implementation: ${i}"
		esac

		local v=${i##*[a-z]}
		PYTHON_DEPS+=" python_targets_${i}? ( ${d}:${v/_/.}${usestr} )"
	done
}
_python_set_globals

# @ECLASS-VARIABLE: BUILD_DIR
# @DESCRIPTION:
# The current build directory. In global scope, it is supposed to
# contain an initial build directory; if unset, it defaults to ${S}.
#
# In functions run by python_foreach_impl(), the BUILD_DIR is locally
# set to an implementation-specific build directory. That path is
# created through appending a hyphen and the implementation name
# to the final component of the initial BUILD_DIR.
#
# Example value:
# @CODE
# ${WORKDIR}/foo-1.3-python2_6
# @CODE

# @ECLASS-VARIABLE: PYTHON
# @DESCRIPTION:
# The absolute path to the current Python interpreter.
#
# Set and exported only in commands run by python_foreach_impl().
#
# Example value:
# @CODE
# /usr/bin/python2.6
# @CODE

# @ECLASS-VARIABLE: EPYTHON
# @DESCRIPTION:
# The executable name of the current Python interpreter.
#
# This variable is used consistently with python.eclass.
#
# Set and exported only in commands run by python_foreach_impl().
#
# Example value:
# @CODE
# python2.6
# @CODE

# @ECLASS-VARIABLE: PYTHON_SITEDIR
# @DESCRIPTION:
# The path to Python site-packages directory.
#
# Set and exported on request using python_export().
#
# Example value:
# @CODE
# @CODE

# @FUNCTION: python_export
# @USAGE: [<impl>] <variables>...
# @DESCRIPTION:
# Set and export the Python implementation-relevant variables passed
# as parameters.
#
# The optional first parameter may specify the requested Python
# implementation (either as PYTHON_TARGETS value, e.g. python2_7,
# or an EPYTHON one, e.g. python2.7). If no implementation passed,
# the current one will be obtained from ${EPYTHON}.
#
# The variables which can be exported are: PYTHON, EPYTHON,
# PYTHON_SITEDIR. They are described more completely in the eclass
# variable documentation.
python_export() {
	debug-print-function ${FUNCNAME} "${@}"

	local impl var

	case "${1}" in
		python*|jython*)
			impl=${1/_/.}
			shift
			;;
		pypy-c*)
			impl=${1}
			shift
			;;
		pypy*)
			local v=${1#pypy}
			impl=pypy-c${v/_/.}
			shift
			;;
		*)
			impl=${EPYTHON}
			[[ ${impl} ]] || die "python_export: no impl nor EPYTHON"
			;;
	esac
	debug-print "${FUNCNAME}: implementation: ${impl}"

	for var; do
		case "${var}" in
			EPYTHON)
				export EPYTHON=${impl}
				debug-print "${FUNCNAME}: EPYTHON = ${EPYTHON}"
				;;
			PYTHON)
				export PYTHON=${EPREFIX}/usr/bin/${impl}
				debug-print "${FUNCNAME}: PYTHON = ${PYTHON}"
				;;
			PYTHON_SITEDIR)
				local dir
				case "${impl}" in
					python*)
						dir=/usr/$(get_libdir)/${impl}
						;;
					jython*)
						dir=/usr/share/${impl}/Lib
						;;
					pypy*)
						dir=/usr/$(get_libdir)/${impl/-c/}
						;;
				esac

				export PYTHON_SITEDIR=${EPREFIX}${dir}/site-packages
				debug-print "${FUNCNAME}: PYTHON_SITEDIR = ${PYTHON_SITEDIR}"
				;;
			*)
				die "python_export: unknown variable ${var}"
		esac
	done
}

# @FUNCTION: python_get_PYTHON
# @USAGE: [<impl>]
# @DESCRIPTION:
# Obtain and print the path to the Python interpreter for the given
# implementation. If no implementation is provided, ${EPYTHON} will
# be used.
#
# If you just need to have PYTHON set (and exported), then it is better
# to use python_export() directly instead.
python_get_PYTHON() {
	debug-print-function ${FUNCNAME} "${@}"

	python_export "${@}" PYTHON
	echo "${PYTHON}"
}

# @FUNCTION: python_get_EPYTHON
# @USAGE: <impl>
# @DESCRIPTION:
# Obtain and print the EPYTHON value for the given implementation.
#
# If you just need to have EPYTHON set (and exported), then it is better
# to use python_export() directly instead.
python_get_EPYTHON() {
	debug-print-function ${FUNCNAME} "${@}"

	python_export "${@}" EPYTHON
	echo "${EPYTHON}"
}

# @FUNCTION: python_get_sitedir
# @USAGE: [<impl>]
# @DESCRIPTION:
# Obtain and print the 'site-packages' path for the given
# implementation. If no implementation is provided, ${EPYTHON} will
# be used.
#
# If you just need to have PYTHON_SITEDIR set (and exported), then it is
# better to use python_export() directly instead.
python_get_sitedir() {
	debug-print-function ${FUNCNAME} "${@}"

	python_export "${@}" PYTHON_SITEDIR
	echo "${PYTHON_SITEDIR}"
}

# @FUNCTION: python_copy_sources
# @DESCRIPTION:
# Create a single copy of the package sources (${S}) for each enabled
# Python implementation.
#
# The sources are always copied from S to implementation-specific build
# directories respecting BUILD_DIR.
python_copy_sources() {
	debug-print-function ${FUNCNAME} "${@}"

	local impl
	local bdir=${BUILD_DIR:-${S}}

	debug-print "${FUNCNAME}: bdir = ${bdir}"
	einfo "Will copy sources from ${S}"
	# the order is irrelevant here
	for impl in "${PYTHON_COMPAT[@]}"; do
		if use "python_targets_${impl}"
		then
			local BUILD_DIR=${bdir%%/}-${impl}

			einfo "${impl}: copying to ${BUILD_DIR}"
			debug-print "${FUNCNAME}: [${impl}] cp ${S} => ${BUILD_DIR}"
			cp -pr "${S}" "${BUILD_DIR}" || die
		fi
	done
}

# @FUNCTION: python_foreach_impl
# @USAGE: <command> [<args>...]
# @DESCRIPTION:
# Run the given command for each of the enabled Python implementations.
# If additional parameters are passed, they will be passed through
# to the command. If the command fails, python_foreach_impl dies.
# If necessary, use ':' to force a successful return.
#
# For each command being run, EPYTHON, PYTHON and BUILD_DIR are set
# locally, and the former two are exported to the command environment.
python_foreach_impl() {
	debug-print-function ${FUNCNAME} "${@}"

	local impl
	local bdir=${BUILD_DIR:-${S}}

	debug-print "${FUNCNAME}: bdir = ${bdir}"
	for impl in "${_PYTHON_ALL_IMPLS[@]}"; do
		if has "${impl}" "${PYTHON_COMPAT[@]}" && use "python_targets_${impl}"
		then
			local EPYTHON PYTHON
			python_export "${impl}" EPYTHON PYTHON
			local BUILD_DIR=${bdir%%/}-${impl}
			export EPYTHON PYTHON

			einfo "${EPYTHON}: running ${@}"
			"${@}" || die "${EPYTHON}: ${1} failed"
		fi
	done
}

# @FUNCTION: python_export_best
# @USAGE: [<variable>...]
# @DESCRIPTION:
# Find the best (most preferred) Python implementation enabled
# and export given variables for it. If no variables are provided,
# EPYTHON & PYTHON will be exported.
python_export_best() {
	debug-print-function ${FUNCNAME} "${@}"

	[[ ${#} -gt 0 ]] || set -- EPYTHON PYTHON

	local impl best
	for impl in "${_PYTHON_ALL_IMPLS[@]}"; do
		if has "${impl}" "${PYTHON_COMPAT[@]}" && use "python_targets_${impl}"
		then
			best=${impl}
		fi
	done

	[[ ${best+1} ]] || die "python_export_best(): no implementation found!"

	debug-print "${FUNCNAME}: Best implementation is: ${impl}"
	python_export "${impl}" "${@}"
}

# @FUNCTION: _python_rewrite_shebang
# @INTERNAL
# @USAGE: [<EPYTHON>] <path>...
# @DESCRIPTION:
# Replaces 'python' executable in the shebang with the executable name
# of the specified interpreter. If no EPYTHON value (implementation) is
# used, the current ${EPYTHON} will be used.
#
# All specified files must start with a 'python' shebang. A file not
# having a matching shebang will be refused. The exact shebang style
# will be preserved in order not to break anything.
#
# Example conversions:
# @CODE
# From: #!/usr/bin/python -R
# To: #!/usr/bin/python2.7 -R
#
# From: #!/usr/bin/env FOO=bar python
# To: #!/usr/bin/env FOO=bar python2.7
# @CODE
_python_rewrite_shebang() {
	debug-print-function ${FUNCNAME} "${@}"

	local impl
	case "${1}" in
		python*|jython*|pypy-c*)
			impl=${1}
			shift
			;;
		*)
			impl=${EPYTHON}
			[[ ${impl} ]] || die "${FUNCNAME}: no impl nor EPYTHON"
			;;
	esac
	debug-print "${FUNCNAME}: implementation: ${impl}"

	local f
	for f; do
		local shebang=$(head -n 1 "${f}")
		debug-print "${FUNCNAME}: path = ${f}"
		debug-print "${FUNCNAME}: shebang = ${shebang}"

		if [[ "${shebang} " != *'python '* ]]; then
			eerror "A file does not seem to have a supported shebang:"
			eerror "  file: ${f}"
			eerror "  shebang: ${shebang}"
			die "${FUNCNAME}: ${f} does not seem to have a valid shebang"
		fi

		sed -i -e "1s:python:${impl}:" "${f}" || die
	done
}

# @FUNCTION: _python_ln_rel
# @USAGE: <from> <to>
# @DESCRIPTION:
# Create a relative symlink.
_python_ln_rel() {
	debug-print-function ${FUNCNAME} "${@}"

	local from=${1}
	local to=${2}

	local frpath=${from%/*}/
	local topath=${to%/*}/
	local rel_path=

	# remove double slashes
	frpath=${frpath/\/\///}
	topath=${topath/\/\///}

	while [[ ${topath} ]]; do
		local frseg=${frpath%%/*}
		local toseg=${topath%%/*}

		if [[ ${frseg} != ${toseg} ]]; then
			rel_path=../${rel_path}${frseg:+${frseg}/}
		fi

		frpath=${frpath#${frseg}/}
		topath=${topath#${toseg}/}
	done
	rel_path+=${frpath}${1##*/}

	debug-print "${FUNCNAME}: ${from} -> ${to}"
	debug-print "${FUNCNAME}: rel_path = ${rel_path}"

	ln -fs "${rel_path}" "${to}"
}

# @FUNCTION: python_replicate_script
# @USAGE: <path>...
# @DESCRIPTION:
# Copy the given script to variants for all enabled Python
# implementations, then replace it with a symlink to the wrapper.
#
# All specified files must start with a 'python' shebang. A file not
# having a matching shebang will be refused.
python_replicate_script() {
	debug-print-function ${FUNCNAME} "${@}"

	local suffixes=()

	_add_suffix() {
		suffixes+=( "${EPYTHON}" )
	}
	python_foreach_impl _add_suffix
	debug-print "${FUNCNAME}: suffixes = ( ${suffixes[@]} )"

	local f suffix
	for suffix in "${suffixes[@]}"; do
		for f; do
			local newf=${f}-${suffix}

			debug-print "${FUNCNAME}: ${f} -> ${newf}"
			cp "${f}" "${newf}" || die
		done

		_python_rewrite_shebang "${suffix}" "${@/%/-${suffix}}"
	done

	for f; do
		_python_ln_rel "${ED}"/usr/bin/python-exec "${f}" || die
	done
}