# Copyright 1999-2023 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

EAPI=8

inherit toolchain-funcs

MV=$(ver_cut 1)$(ver_cut 2)
MY_P="${PN}${PV//./}"
LHA_VER="6.1"

DESCRIPTION="Lund Monte Carlo high-energy physics event generator"
HOMEPAGE="https://pythia.org/"
SRC_URI="https://pythia.org/download/${PN}${MV}/${MY_P}.tgz
	test? ( lhapdf? (
		https://www.hepforge.org/archive/lhapdf/pdfsets/${LHA_VER}/CT10.tar.gz
		https://www.hepforge.org/archive/lhapdf/pdfsets/${LHA_VER}/MRST2007lomod.tar.gz
		https://www.hepforge.org/archive/lhapdf/pdfsets/${LHA_VER}/NNPDF23_nlo_as_0119_qed_mc.tar.gz
		https://www.hepforge.org/archive/lhapdf/pdfsets/${LHA_VER}/NNPDF23_nnlo_as_0119_qed_mc.tar.gz
		https://www.hepforge.org/archive/lhapdf/pdfsets/${LHA_VER}/cteq66.tar.gz
		https://www.hepforge.org/archive/lhapdf/pdfsets/${LHA_VER}/cteq6l1.tar.gz
		https://www.hepforge.org/archive/lhapdf/pdfsets/${LHA_VER}/unvalidated/MRST2004qed.tar.gz
	) )"

SLOT="8"
LICENSE="GPL-2"
KEYWORDS="~amd64 ~x86 ~amd64-linux ~x86-linux"
IUSE="doc examples fastjet +hepmc lhapdf root test zlib"
RESTRICT="!test? ( test )"

RDEPEND="
	fastjet? ( sci-physics/fastjet )
	hepmc? ( sci-physics/hepmc:2= )
	lhapdf? ( sci-physics/lhapdf:= )
	zlib? ( sys-libs/zlib )"
# ROOT is used only when building related tests
DEPEND="${RDEPEND}
	test? (
		root? ( sci-physics/root:= )
	)"

PATCHES=(
	"${FILESDIR}"/${PN}8209-root-noninteractive.patch
)

S="${WORKDIR}/${MY_P}"

pkg_pretend() {
	if use root && ! use test; then
		ewarn "ROOT support will only affect examples code build during test stage."
		ewarn "Since you have tests disabled, this is a no-op."
	fi
}

src_prepare() {
	PYTHIADIR="/usr/share/pythia8"
	EPYTHIADIR="${EPREFIX}${PYTHIADIR}"

	default
	# set datadir for xmldor in include file
	sed -i \
		-e "s|../share/Pythia8/xmldoc|${EPYTHIADIR}/xmldoc|" \
		include/Pythia8/Pythia.h || die
	# respect libdir, prefix, flags
	sed -i \
		-e "s|/lib|/$(get_libdir)|g" \
		-e "s|/usr|${EPREFIX}/usr|g" \
		-e "s|-O2|${CXXFLAGS}|g" \
		-e "s|Cint|Core|g" \
		configure || die
	sed -i 's|$(CXX) $^ -o $@ $(CXX_COMMON) $(CXX_SHARED)|$(CXX) $(LDFLAGS) $^ -o $@ $(CXX_COMMON) $(CXX_SHARED)|g' \
		Makefile || die
	sed -i 's|$(CXX)|$(CXX) $(LDFLAGS)|' examples/Makefile || die
	# we use lhapdf6 instead of lhapdf5
	# some PDFs changed, use something similar
	sed -i \
		-e "s|LHAPDF5|LHAPDF6|g" \
		-e "s|\.LHgrid||g" \
		-e "s|\.LHpdf||g" \
		-e "s|MRST2001lo|MRST2007lomod|g" \
		-e "s|cteq6ll|cteq6l1|g" \
		-e "s|cteq6m|cteq66|g" \
		examples/*.{cc,cmnd} || die
	# After lhapdf5->6 migration PDFs are identical within ~1/1000
	# https|//www.hepforge.org/archive/lhapdf/pdfsets/6.1/README
	sed -i \
		-e "s|1e-8|3e-1|g" \
		-e "s|nlo_as_0119_qed|nlo_as_0119_qed_mc|g" \
		-e "s|xmldoc|share/Pythia8/xmldoc|g" \
		examples/main54.cc || die
	# ask cflags from root
	sed -i "s|root-config|root-config --cflags|g" examples/Makefile || die

	sed -i \
		-e '/TARGETS=$(LOCAL_LIB)\/libpythia8\.a/d' \
		-e 's|libpythia8\.a$|libpythia8$(LIB_SUFFIX)|g' \
		Makefile || die
	sed -i 's|libpythia8\.a|libpythia8$(LIB_SUFFIX)|g' \
		examples/Makefile || die
}

# TODO: the following optional packages are out of Gentoo tree:
# - EvtGen http://atlas-computing.web.cern.ch/atlas-computing/links/externalDirectory/EvtGen/
# - PowHEG http://powhegbox.mib.infn.it/
# - ProMC  https://github.com/Argonne-National-Laboratory/ProMC/
src_configure() {
	# homemade configure script
	./configure \
		--arch=Linux \
		--cxx="$(tc-getCXX)" \
		--enable-shared \
		--prefix="${EPREFIX}/usr" \
		--prefix-lib="$(get_libdir)" \
		--prefix-share="${EPYTHIADIR}" \
		$(usex fastjet "--with-fastjet3" "") \
		$(usex zlib "--with-gzip" "") \
		$(usex hepmc "--with-hepmc2" "") \
		$(usex lhapdf "--with-lhapdf6
			--with-lhapdf6-plugin=LHAPDF6.h
			--with-lhapdf6-lib=${EPREFIX}/usr/$(get_libdir)" "") \
		$(usex root "--with-root
			--with-root-include=${EPREFIX}/usr/include/root
			--with-root-lib=${EPREFIX}/usr/$(get_libdir)/root" "") \
		|| die

	# fix pythia config script
	sed -i \
		-e 's|pythia8/examples/Makefile.inc|pythia8/Makefile.inc|' \
		-e 's|LINE%=|LINE%%=|' \
		bin/pythia8-config || die
}

src_test() {
	cd examples || die

	local tests="$(echo main{{01..32},37,38,61,62,73,80}.out)"
	use hepmc && tests+=" $(echo main{41,42,85,86}.out)"
	use hepmc && use lhapdf && tests+=" $(echo main{43,{87..89}}.out)"
	use lhapdf && tests+=" $(echo main{51..54}.out)"
	use fastjet && tests+=" $(echo main{71,72}.out)"
	use fastjet && use hepmc && use lhapdf && tests+=" $(echo main{81..84}).out"
	use root && tests+=" main91.out"
	# Disabled tests:
	# 33	needs PowHEG
	# 46	needs ProMC
	# 48	needs EvtGen
	# 92	generated ROOT dictionary is badly broken

	# use emake for parallel instead of long runmains
	LD_LIBRARY_PATH="${S}/$(get_libdir):${LD_LIBRARY_PATH}" \
	PYTHIA8DATA="../share/Pythia8/xmldoc/" \
	LHAPDF_DATA_PATH="${WORKDIR}" \
	emake ${tests}
	emake clean
}

src_install() {
	# make install is too broken, much easier to install manually
	dobin bin/pythia8-config
	doheader -r include/*
	dolib.so lib/libpythia8.so
	use lhapdf && dolib.so lib/libpythia8lhapdf6.so
	insinto "${PYTHIADIR}"
	doins -r share/Pythia8/xmldoc examples/Makefile.inc

	newenvd - 99pythia8 <<- _EOF_
		PYTHIA8DATA=${EPYTHIADIR}/xmldoc
	_EOF_

	dodoc AUTHORS GUIDELINES README
	if use doc; then
		dodoc -r share/Pythia8/pdfdoc/.
		dodoc -r share/Pythia8/htmldoc/.
	fi
	if use examples; then
		# reuse system Makefile.inc
		rm examples/Makefile.inc || die
		sed -i "s|include Makefile.inc|include ${EPYTHIADIR}|" \
			examples/Makefile || die

		insinto /usr/share/${PN}
		doins -r examples
		docompress -x /usr/share/doc/${PF}/examples
	fi

	# cleanup
	unset PYTHIADIR EPYTHIADIR
}