# Copyright 1999-2013 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Id$

# @ECLASS: fortran-2.eclass
# @MAINTAINER:
# jlec@gentoo.org
# sci@gentoo.org
# @AUTHOR:
# Author Justin Lecher <jlec@gentoo.org>
# Test functions provided by Sebastien Fabbro and Kacper Kowalik
# @BLURB: Simplify fortran compiler management
# @DESCRIPTION:
# If you need a fortran compiler, then you should be inheriting this eclass.
# In case you only need optional support, please export FORTRAN_NEEDED before
# inheriting the eclass.
#
# The eclass tests for working fortran compilers
# and exports the variables FC and F77.
# Optionally, it checks for extended capabilities based on
# the variable options selected in the ebuild
# The only phase function exported is fortran-2_pkg_setup.
# @EXAMPLE:
# FORTRAN_NEEDED="lapack fortran"
#
# inherit fortran-2
#
# FORTRAN_NEED_OPENMP=1

# @ECLASS-VARIABLE: FORTRAN_NEED_OPENMP
# @DESCRIPTION:
# Set to "1" in order to automatically have the eclass abort if the fortran
# compiler lacks openmp support.
: ${FORTRAN_NEED_OPENMP:=0}

# @ECLASS-VARIABLE: FORTRAN_STANDARD
# @DESCRIPTION:
# Set this, if a special dialect needs to be supported.
# Generally not needed as default is sufficient.
#
# Valid settings are any combination of: 77 90 95 2003
: ${FORTRAN_STANDARD:=77}

# @ECLASS-VARIABLE: FORTRAN_NEEDED
# @DESCRIPTION:
# If your package has an optional fortran support, set this variable
# to the space separated list of USE triggering the fortran
# dependency.
#
# e.g. FORTRAN_NEEDED=lapack would result in
#
# DEPEND="lapack? ( virtual/fortran )"
#
# If unset, we always depend on virtual/fortran.
: ${FORTRAN_NEEDED:=always}

inherit eutils toolchain-funcs

for _f_use in ${FORTRAN_NEEDED}; do
	case ${_f_use} in
		always)
			DEPEND+=" virtual/fortran"
			break
			;;
		no)
			break
			;;
		*)
			DEPEND+=" ${_f_use}? ( virtual/fortran )"
			;;
	esac
done
RDEPEND="${DEPEND}"

# @FUNCTION: _fortran_write_testsuite
# @INTERNAL
# @DESCRIPTION:
# writes fortran test code
_fortran_write_testsuite() {
	local filebase=${T}/test-fortran

	# f77 code
	cat <<- EOF > "${filebase}.f"
	       end
	EOF

	# f90/95 code
	cat <<- EOF > "${filebase}.f90"
	end
	EOF

	# f2003 code
	cat <<- EOF > "${filebase}.f03"
	       procedure(), pointer :: p
	       end
	EOF
}

# @FUNCTION: _fortran_compile_test
# @USAGE: <compiler> [dialect]
# @INTERNAL
# @DESCRIPTION:
# Takes fortran compiler as first argument and dialect as second.
# Checks whether the passed fortran compiler speaks the fortran dialect
_fortran_compile_test() {
	local filebase=${T}/test-fortran
	local fcomp=${1}
	local fdia=${2}
	local fcode=${filebase}.f${fdia}
	local ret

	[[ $# -lt 1 ]] && \
		die "_fortran_compile_test() needs at least one argument"

	[[ -f ${fcode} ]] || _fortran_write_testsuite

	${fcomp} "${fcode}" -o "${fcode}.x" \
		>> "${T}"/_fortran_compile_test.log 2>&1
	ret=$?

	rm -f "${fcode}.x"
	return ${ret}
}

# @FUNCTION: _fortran-has-openmp
# @RETURN: return code of the compiler
# @INTERNAL
# @DESCRIPTION:
# See if the fortran supports OpenMP.
_fortran-has-openmp() {
	local flag
	local filebase=${T}/test-fc-openmp
	local fcode=${filebase}.f
	local ret
	local _fc=$(tc-getFC)

	cat <<- EOF > "${fcode}"
	       call omp_get_num_threads
	       end
	EOF

	for flag in -fopenmp -xopenmp -openmp -mp -omp -qsmp=omp; do
		${_fc} ${flag} "${fcode}" -o "${fcode}.x" \
			&>> "${T}"/_fortran_compile_test.log
		ret=$?
		(( ${ret} )) || break
	done

	rm -f "${fcode}.x"
	return ${ret}
}

# @FUNCTION: _fortran_die_msg
# @INTERNAL
# @DESCRIPTION:
# Detailed description how to handle fortran support
_fortran_die_msg() {
	echo
	eerror "Please install currently selected gcc version with USE=fortran."
	eerror "If you intend to use a different compiler then gfortran, please"
	eerror "set FC variable accordingly and take care that the necessary"
	eerror "fortran dialects are supported."
	echo
	die "Currently no working fortran compiler is available"
}

# @FUNCTION: _fortran_test_function
# @INTERNAL
# @DESCRIPTION:
# Internal test function for working fortran compiler.
# It is called in fortran-2_pkg_setup.
_fortran_test_function() {
	local dialect

	: ${F77:=$(tc-getFC)}

	: ${FORTRAN_STANDARD:=77}
	for dialect in ${FORTRAN_STANDARD}; do
		case ${dialect} in
			77) _fortran_compile_test $(tc-getF77) || \
				_fortran_die_msg ;;
			90|95) _fortran_compile_test $(tc-getFC) 90 || \
				_fortran_die_msg ;;
			2003) _fortran_compile_test $(tc-getFC) 03 || \
				_fortran_die_msg ;;
			2008) die "Future" ;;
			*) die "${dialect} is not a Fortran dialect." ;;
		esac
	done

	tc-export F77 FC
	einfo "Using following Fortran compiler:"
	einfo "  F77: ${F77}"
	einfo "  FC:  ${FC}"

	if [[ ${FORTRAN_NEED_OPENMP} == 1 ]]; then
		if _fortran-has-openmp; then
			einfo "${FC} has OPENMP support"
		else
			die "Please install current gcc with USE=openmp or set the FC variable to a compiler that supports OpenMP"
		fi
	fi
}

# @FUNCTION: _fortran-2_pkg_setup
# @INTERNAL
# @DESCRIPTION:
# _The_ fortran-2_pkg_setup() code
_fortran-2_pkg_setup() {
	for _f_use in ${FORTRAN_NEEDED}; do
   	case ${_f_use} in
      	always)
				_fortran_test_function && break
	         ;;
   	   no)
				einfo "Forcing fortran support off"
				break
	         ;;
   	   *)
				if use ${_f_use}; then
					_fortran_test_function && break
				else
					unset FC
					unset F77
				fi
   	      ;;
	   esac
	done
}


# @FUNCTION: fortran-2_pkg_setup
# @DESCRIPTION:
# Setup functionality,
# checks for a valid fortran compiler and optionally for its openmp support.
fortran-2_pkg_setup() {
	case ${EAPI:-0} in
		0|1|2|3)
			eqawarn "Support for EAPI < 4 will be removed from the"
			eqawarn "fortran-2.eclass in until 2013-09-30."
			eqawarn "Please migrate your package to a higher EAPI"
			eqawarn "or file a bug at https://bugs.gentoo.org"
			_fortran-2_pkg_setup ;;
		4|5)
			if [[ ${MERGE_TYPE} != binary ]]; then
				_fortran-2_pkg_setup
			fi
			;;
	esac
}

case ${EAPI:-0} in
	0|1|2|3|4|5) EXPORT_FUNCTIONS pkg_setup ;;
	*) die "EAPI=${EAPI} is not supported" ;;
esac