#!/bin/bash

# Install a specific gcc version in user space

PROD='gcc'

# Show usage of this script
function usage {
    echo "Usage: ${BASH_SOURCE[0]}  [--gcc-version=<version>] [--prefix=<directory>] [--build-dir=<directory>]"
    echo '  --gcc-version=<version>  Supply the gcc version to build'
    echo '  --prefix=<directory>     The installation directory'
    echo '  --build-dir=<directory>  The build directory'
    echo '  --help                   Display this usage information'
    echo
    echo 'For every unset option a default is used'
    echo 'All options (set or defaults) are shown at build start.'
    echo
    echo 'This script was tested with the following versions of gcc:'
    echo '12.2.0, 12.1.0, 11.3.0, 11.2.0, 10.3.0, 9.4.0, 8.5.0, 7.5.0, 6.5.0'
}

# Returns true, if version of $1 is greater than $2
function version_gt() {
    test "$(printf '%s\n' "$@" |
        sort -V |
        head -n 1)" != "${1}"
}

# Iterate over options and set them
shopt -s extglob
while (($#)); do
    case "${1}" in
    --gcc-version=*)
        VERSION="${1##*=}"
        shift
        ;;
    --prefix=*)
        PREFIX="${1##*=}"
        shift
        ;;
    --build-dir=*)
        BUILDDIR="${1##*=}"
        shift
        ;;
    --help)
        usage
        shift
        exit 0
        ;;
    *)
        echo "Unknown argument '${1}' ignored"
        echo
        usage
        shift
        exit 1
        ;;
    esac
done

# Set default if no option was given
if [[ -z ${VERSION} ]]; then
    VERSION="7.5.0"
fi

if [[ ${VERSION} =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
    # The option matches a version string
    WORKDIR="/scratch/${USER}/${PROD}-${VERSION}"
    # Set defaults if no options were given
    if [[ -z ${PREFIX} ]]; then
        PREFIX="${WORKDIR}/install"
    fi
    if [[ -z ${BUILDDIR} ]]; then
        BUILDDIR="${WORKDIR}/build"
    fi
    # Summarize options
    echo 'Using options:'
    echo "- gcc version:       ${VERSION}"
    echo "- prefix directory:  ${PREFIX}"
    echo "- build directory:   ${BUILDDIR}"

    # Create paths used for building and installation
    mkdir -v -p "${WORKDIR}" "${BUILDDIR}" "${PREFIX}" &&
        cd "${WORKDIR}" &&
        # Download gcc
        wget -c "https://ftpmirror.gnu.org/${PROD}/${PROD}-${VERSION}/${PROD}-${VERSION}.tar.gz" &&
        # Extract gcc archive
        tar --overwrite -vxzf "${PROD}-${VERSION}.tar.gz" &&
        cd "${WORKDIR}/${PROD}-${VERSION}" &&
        # Download prerequisites
        contrib/download_prerequisites &&
        cd "${WORKDIR}/build" &&
        # Configure build
        ../${PROD}-"${VERSION}"/configure \
            --build=x86_64-linux-gnu \
            --host=x86_64-linux-gnu \
            --target=x86_64-linux-gnu \
            --prefix="${PREFIX}" \
            --enable-checking=release \
            --enable-languages=c,c++ \
            --disable-nls \
            --disable-multilib \
            --program-suffix="-${VERSION}" &&
        # Start build
        make -s -j "$(nproc)" &&
        # Install
        make install-strip &&
        echo &&
        echo "${PROD}-${VERSION} was successfully built and installed in ${PREFIX}" &&
        exit 0
else
    echo "Version '${VERSION}' does not match a version string of the form n.m.p"
    exit 1
fi

alias showgccs='{ echo "PATH;VERSION" && which -a gcc |while read -r GCC; do echo $GCC && $GCC --version |head -n1; done |paste -d";" - - ;} |column -t -s";"'