#!/bin/bash
# mg2d configure script
# partially inspired by/based on the FFmpeg configure script

die() {
    echo "$@" >&2
    exit 1
}

bootstrap() {
    local source_dir

    [ -e configure ] && die "Cannot build from the source dir, create a separate build directory"

    source_dir=$(realpath $(dirname "$0"))
    [ -d "$source_dir" ] || die "Cannot locate source directory"

    [ -h src ] || ln -s "$source_dir" src

    [ -h Makefile ] || ln -s "$source_dir/Makefile"

    echo $source_dir
}

toupper() {
    echo "$@" | tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ
}

is_in() {
    value=$1
    shift
    for var in $*; do
        [ $var = $value ] && return 0
    done
    return 1
}

probe_arch() {
    arch=$(cc -dumpmachine | sed 's/-.*//')
}

check_mpi() {
    pkg-config --exists mpi || return 1
    mpi_cflags=$(pkg-config --cflags mpi)
    mpi_libs=$(pkg-config --libs mpi)
}

check_nasm() {
    if ! command -v nasm &> /dev/null; then
        echo "nasm not found, assembly code will not be built"
        return 1
    fi
}

check_component() {
    name=$1
    shift
    eval "check_$name" $@ && eval "have_$name=yes"
}

source_dir=$(bootstrap)


CMDLINE_SET="
    cc
"

cc=cc

for arg; do
    name="${arg%%=*}"
    name="${name#--}"
    name=$(echo "$name" | sed 's/-/_/g')

    val="${arg#*=}"

	if is_in $name $CMDLINE_SET; then
        eval $name='$val'
        continue
	fi

    case "$name" in
        extra_cflags)
            extra_cflags=$val $extra_cflags
            ;;
        extra_ldflags)
            extra_ldflags=$val $extra_ldflags
            ;;
        *)
            die "Unknown commandline argument: $arg"
            ;;
    esac
done

probe_arch

COMPONENTS_REQUIRED="
    mpi
"

COMPONENTS_OPTIONAL="
    nasm
"

COMPONENTS="
    $COMPONENTS_REQUIRED
    $COMPONENTS_OPTIONAL
"

for c in $COMPONENTS_REQUIRED; do
    check_component $c || die "Required component $c not found"
done

for c in $COMPONENTS_OPTIONAL; do
    check_component $c
done

cat > config.mak <<EOF
SOURCE_DIR = $source_dir
CC = $cc
CFLAGS_DEP = $mpi_cflags
CFLAGS_EXTRA = $extra_cflags
LDFLAGS_DEP = $mpi_libs
LDFLAGS_EXTRA = $extra_ldflags
EOF

cat > config.h <<EOF
#ifndef MG2D_CONFIG_H
#define MG2D_CONFIG_H

EOF

cat > config.asm << EOF
EOF

case "$arch" in
    x86_64)
        echo "ARCH_X86_64 = 1" >> config.mak
        echo "#define ARCH_X86_64 1" >> config.h
        echo "%define ARCH_X86_64 1" >> config.asm
        ;;
    *)
        echo "ARCH_X86_64 = 0" >> config.mak
        echo "#define ARCH_X86_64 0" >> config.h
        echo "%define ARCH_X86_64 0" >> config.asm
        ;;
esac

for c in $COMPONENTS; do
    C=$(toupper $c)
    have_ref=have_$c

    if [ -n "${!have_ref}" ]; then
        val_mak=yes
        val_c=1
    else
        val_mak=no
        val_c=0
    fi

    echo "HAVE_$C = $val_mak" >> config.mak
    echo "#define HAVE_$C $val_c" >> config.h

done

echo "#endif // MG2D_CONFIG_H" >> config.h