configure

#!/bin/sh
set -eu

script_dir="$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)"
pwd_dir="$(pwd)"

prefix="/usr/local"
exec_prefix=""
bindir=""
libdir=""
build_dir=""
build_dir_set="0"
cabal="cabal"
cabal_update="0"
gcc_lib=""

usage() {
    cat <<'EOF'
Usage: ./configure [options]

Options:
  --prefix=PATH            install prefix (default: /usr/local)
  --exec-prefix=PATH       exec prefix (default: PREFIX)
  --bindir=PATH            user executables dir (default: EXEC_PREFIX/bin)
  --libdir=PATH            libraries dir (default: EXEC_PREFIX/lib)
  --build-dir=DIR          build output directory (default: build)
  --with-cabal=CMD         cabal command (default: cabal)
  --gcc-lib=PATH           gcc import/static lib directory (for syslib staging)
  --enable-cabal-update    set CABAL_UPDATE=1 in config.mk
  --disable-cabal-update   set CABAL_UPDATE=0 in config.mk (default)
  -h, --help               show help
EOF
}

need_value() {
    opt="$1"
    if [ "$#" -lt 2 ] || [ -z "${2:-}" ]; then
        echo "error: missing value for $opt" >&2
        exit 2
    fi
}

while [ "$#" -gt 0 ]; do
    case "$1" in
        --prefix=*)
            prefix="${1#*=}"
            shift
            ;;
        --prefix)
            need_value "$@"
            prefix="$2"
            shift 2
            ;;
        --exec-prefix=*)
            exec_prefix="${1#*=}"
            shift
            ;;
        --exec-prefix)
            need_value "$@"
            exec_prefix="$2"
            shift 2
            ;;
        --bindir=*)
            bindir="${1#*=}"
            shift
            ;;
        --bindir)
            need_value "$@"
            bindir="$2"
            shift 2
            ;;
        --libdir=*)
            libdir="${1#*=}"
            shift
            ;;
        --libdir)
            need_value "$@"
            libdir="$2"
            shift 2
            ;;
        --build-dir=*)
            build_dir="${1#*=}"
            build_dir_set="1"
            shift
            ;;
        --build-dir)
            need_value "$@"
            build_dir="$2"
            build_dir_set="1"
            shift 2
            ;;
        --with-cabal=*)
            cabal="${1#*=}"
            shift
            ;;
        --with-cabal)
            need_value "$@"
            cabal="$2"
            shift 2
            ;;
        --gcc-lib=*)
            gcc_lib="${1#*=}"
            shift
            ;;
        --gcc-lib)
            need_value "$@"
            gcc_lib="$2"
            shift 2
            ;;
        --enable-cabal-update)
            cabal_update="1"
            shift
            ;;
        --disable-cabal-update)
            cabal_update="0"
            shift
            ;;
        -h|--help)
            usage
            exit 0
            ;;
        *)
            echo "error: unknown option: $1" >&2
            usage
            exit 2
            ;;
    esac
done

if [ "$build_dir_set" = "0" ]; then
    if [ "$pwd_dir" = "$script_dir" ]; then
        build_dir="build"
    else
        build_dir="."
    fi
fi

if [ -z "$exec_prefix" ]; then
    exec_prefix="$prefix"
fi
if [ -z "$bindir" ]; then
    bindir="$exec_prefix/bin"
fi
if [ -z "$libdir" ]; then
    libdir="$exec_prefix/lib"
fi

xlang_libdir="$libdir/xlang"
config_file="config.mk"

cat > "$config_file" <<EOF
# Generated by ./configure
PREFIX := $prefix
EXEC_PREFIX := $exec_prefix
BINDIR := $bindir
LIBDIR := $libdir
XLANG_LIBDIR := $xlang_libdir
BUILD_DIR := $build_dir
CABAL := $cabal
CABAL_UPDATE := $cabal_update
GCC_LIB := $gcc_lib
EOF

cat <<EOF
Configuration written to $config_file
  PREFIX          = $prefix
  EXEC_PREFIX     = $exec_prefix
  BINDIR          = $bindir
  LIBDIR          = $libdir
  XLANG_LIBDIR    = $xlang_libdir
  BUILD_DIR       = $build_dir
  CABAL           = $cabal
  CABAL_UPDATE    = $cabal_update
  GCC_LIB         = $gcc_lib

Next steps:
  make -j24
  make install
EOF

# Out-of-tree convenience: allow plain `make` in the build directory.
if [ "$pwd_dir" != "$script_dir" ]; then
    cat > Makefile <<EOF
# Generated by $0
# Out-of-tree build wrapper.
include $script_dir/Makefile
EOF
fi