function runMake () {
    run gmake -w -j $(detectNumCPUs) $@
}

function configure () {
    if [[ ! -f configure.ac && ! -f configure.in ]]; then
        echo "ERROR: Neither configure.ac nor configure.in exists in the current directory." >&2
        return 1
    fi

    if [[ ! -f configure ]]; then
        run autoreconf -v -i -f
    fi

    if [[ ! -f "_build/Makefile" ]]; then
        run mkdir -p _build
        run pushd _build
        run ../configure "${configArgs[@]}"
        run popd
    fi
}

function build () {
    configure
    runMake -C "_build" $buildTarget
}

function doc () {
    configure
    runMake -C "_build/$docDirectory" $docTarget
}

function check () {
    build
    runMake -C "_build" check "$@"
}

function clean () {
    run rm -rf "_build"
}

function dist () {
    configure
    runMake -C "_build" dist
}

function install () {
    build
    runMake -C "_build" install "$0"
}

function usage () {
    cat <<EOF >&2
Usage: $0 [COMMAND]

This is an automation script designed to work with autotools. It creates a
directory "./_build" and builds any files inside it.

If no COMMAND is given, it defaults to "build".

Commands:
    build          run "$0 configure" then make(1).
    check [ARG]    run "$0 build" then "make check [ARG]".
    configure      run autoreconf(1) and "./configure" if necessary.
    clean          run "rm -rf _build"
    dist           run "make dist"
    doc            similar to "$0 build" but only build the documentation.
    install [ARG]  run "$0 build" then "make install [ARG]".

Please report any bugs, feature requests, and pull requests (the most
preferred!) to the maintainer presented in the preamble of the "$0" itself.
EOF
    return 1
}

function main () {
    local cmd
    case "$1" in
        ""|"build" ) cmd="build"    ;;
        "configure") cmd="configure";;
        "doc"      ) cmd="doc"      ;;
        "check"    ) cmd="check"    ;;
        "clean"    ) cmd="clean"    ;;
        "dist"     ) cmd="dist"     ;;
        "install"  ) cmd="install"  ;;
        *)           cmd="usage"    ;;
    esac
    if (( $# > 0 )); then
        shift
    fi
    "$cmd" "$@"
}

main "$@"