#!/bin/sh
### Automatic build configuration script for Dinit.
### This script generates an "mconfig" file suitable for building on the current system.

## Initial preparation
set -eu
cd "$(dirname "$0")"

## Helper functions
# According to POSIX, echo has some unspecified behavior in some cases, for example
# when its first argument is "-n" or backslash ("\"). We prefer to rely on
# POSIX documented things.
# So we replace shell built-in echo with a printf based function.
# For more info see http://www.etalabs.net/sh_tricks.html
echo()
{
    IFS=" " printf %s\\n "$*"
}

info()
{
    echo "$*"
}

sub_info()
{
    echo "  ... $*"
}

error()
{
    >&2 echo "Error: $*"
    exit 1
}

sub_error()
{
    >&2 echo "  ... Error: $*"
    exit 1
}

warning()
{
    echo
    echo "Warning: $*"
}

sub_warning()
{
    echo "  ... $*"
    echo
}

cxx_works()
{
    info Checking whether \""$1"\" is a working C++ compiler...
    if ! $CXX -o testfile.o testfile.cc; then
        rm -f testfile*
        sub_error It seems like \""$CXX"\" is not working a working C++ compiler. Please specify compiler.
    else
        rm -f testfile
        sub_info Yes.
    fi
}

try_cxx_argument()
{
    info Checking whether the compiler accepts "$2"...
    if $CXX $CXXFLAGS $2 $CXXFLAGS_EXTRA $LDFLAGS $LDFLAGS_EXTRA testfile.cc -o testfile > /dev/null 2>&1; then
        rm testfile
        sub_info Yes.
        eval "$1=\"\${$1} \$2\""
        eval "$1=\${$1# }"
    else
        if [ "$2" = "-std=c++11" ]; then
            sub_error "It seems like the C++ compiler don't support the (required) \"$2\" option!"
        else
            sub_info No.
        fi
    fi
}

try_ld_argument()
{
    info Checking whether "$2" is accepted as a link-time option...
    if $CXX $CXXFLAGS $CXXFLAGS_EXTRA $LDFLAGS $LDFLAGS_EXTRA $2 testfile.cc -o testfile > /dev/null 2>&1; then
        sub_info Yes.
        eval "$1=\"\${$1} \$2\""
        eval "$1=\${$1# }"
    else
        sub_info No.
    fi
}

try_both_argument()
{
    info Checking whether the compiler/linker accept "$3"...
    if $CXX $CXXFLAGS $CXXFLAGS_EXTRA $LDFLAGS $LDFLAGS_EXTRA $3 testfile.cc -o testfile > /dev/null 2>&1; then
        sub_info Yes.
        eval "$1=\"\${$1} \$3\""
        eval "$1=\${$1# }"
        eval "$2=\"\${$2} \$3\""
        eval "$2=\${$2# }"
    else
        sub_info No.
    fi
}

usage()
{
    cat << _EOF
Usage: $0 [OPTION]...

Generates build configuration for Dinit.

Defaults for the options are specified in brackets.

  --help                        This help message.
  --quiet                       Don't print normal messages, just errors.
  --clean                       Clear mconfig and configure's temporary files.

Target options:
  --platform=PLATFORM           Set the platform manually (Just for cross-platform cross-compile!) [autodetected]
                                  Note: for all cross-compiles please specify correct CXX and CXX_FOR_BUILD!

Installation directories:
  --prefix=PREFIX               Main installation prefix [/usr]
  --exec-prefix=EPREFIX         Main executables prefix  [/]
  --sbindir=SBINDIR             Dinit executables        [EPREFIX/sbin]
  --mandir=MANDIR               Dinit man-pages location [PREFIX/share/man]
  --syscontrolsocket=SOCKETPATH Dinitctl socket location [/run/dinitctl] on Linux systems
                                                         [/var/run/dinitctl] on other systems

Optional options:
  --shutdown-prefix=PREFIX      Name prefix for shutdown, poweroff, reboot, halt programs []
  --enable-shutdown             Build shutdown, poweroff, reboot, halt programs [Enabled only on Linux systems]
  --disable-shutdown            Don't build shutdown, poweroff, reboot, halt programs
  --enable-cgroups              Enable Cgroups support [Enabled only on Linux based systems]
  --disable-cgroups             Disable Cgroups support
  --enable-utmpx                Enable manipulating the utmp/utmpx database via the related POSIX functions [auto]
  --disable-utmpx               Disable manipulating the utmp/utmpx database via the related POSIX functions

Build variables:
  Note: build variables can be passed in the environment, or as $0 argument (as "var=VALUE").
  Note: CXXFLAGS, TEST_CXXFLAGS, LDFLAGS and TEST_LDFLAGS by default will be set to options considered suitable
  for the platform, filtered to remove any options not supported by the  compiler/linker. To disable this,
  specify the values explicitly (an empty string is accepted). To add options without removing the defaults,
  set the variable with _EXTRA appended to the name (eg CXXFLAGS_EXTRA).

  CXX                           C++ compiler
  CXX_FOR_BUILD                 C++ compiler generating code for the build system (for cross-compiles).
  CXXFLAGS_FOR_BUILD            Flags to use when generating code for the build system.
                                  Defaults to the value of CXXFLAGS.
  CPPFLAGS_FOR_BUILD            Preprocessor flags to use when generating code for the build system.
                                  Defaults to the value of CPPFLAGS.
  LDFLAGS_FOR_BUILD             Link flags to use when generating code for the build system.
                                  Defaults to the value of LDFLAGS.
  CXXFLAGS                      Flags to use when compiling C++ code.
  CXXFLAGS_EXTRA                Additional flags to use when compiling C++ code.
  TEST_CXXFLAGS                 Flags to use when compiling C++ code in tests.
  TEST_CXXFLAGS_EXTRA           Additional flags to use when compiling C++ code in tests.
  CPPFLAGS                      Preprocessor flags to use when compiling C++ code. 
  LDFLAGS                       Link flags.
  LDFLAGS_EXTRA                 Additional link flags.
  TEST_LDFLAGS                  Links flags when building test executables.
  TEST_LDFLAGS_EXTRA            Additional link flags when building test executables.

Note: paths specified via --prefix/--exec-prefix/--sbindir/--mandir, and build variable values, must be
escaped for use in a makefile and in shell commands. If there are spaces in paths it is recommended to
prepend a backslash (\) to them.
For example: ./configure --prefix="/home/my\ home"

See BUILD file for more information.
_EOF
    exit 0
}

## Don't take values from environment for these variables:
for var in PREFIX \
           EPREFIX \
           SBINDIR \
           MANDIR \
           NO_SANITIZE \
           SHUTDOWN_PREFIX \
           BUILD_SHUTDOWN \
           SUPPORT_CGROUPS \
           SYSCONTROLSOCKET
do
    unset $var
done

## Flag parser
for arg in "$@"; do
    case "$arg" in
        --help) usage ;;
        --quiet)
            info() { true; }
            sub_info() { true; }
            warning() { true; }
            sub_warning() { true; }
        ;;
        --clean) rm -f test* & rm -f mconfig && exit 0 ;;
        --platform=*) PLATFORM="${arg#*=}" && shift ;;
        --prefix=*) PREFIX="${arg#*=}" && shift ;;
        --exec-prefix=*) EPREFIX="${arg#*=}" && shift;;
        --sbindir=*) SBINDIR="${arg#*=}" && shift ;;
        --mandir=*) MANDIR="${arg#*=}" && shift ;;
        --syscontrolsocket=*) SYSCONTROLSOCKET="${arg#*=}" && shift ;;
        --shutdown-prefix=*) SHUTDOWN_PREFIX="${arg#*=}" && shift ;;
        --enable-shutdown|--enable-shutdown=yes) BUILD_SHUTDOWN=yes ;;
        --disable-shutdown|--enable-shutdown=no) BUILD_SHUTDOWN=no ;;
        --enable-cgroups|--enable-cgroups=yes) SUPPORT_CGROUPS=1 ;;
        --disable-cgroups|--enable-cgroups=no) SUPPORT_CGROUPS=0 ;;
        --enable-utmpx|--enable-utmpx=yes) USE_UTMPX=1 ;;
        --disable-utmpx|--enable-utmpx=no) USE_UTMPX=0 ;;
        CXX=*|CXX_FOR_BUILD=*|CXXFLAGS_FOR_BUILD=*|CPPFLAGS_FOR_BUILD=*\
        |LDFLAGS_FOR_BUILD=*|CXXFLAGS=*|CXXFLAGS_EXTRA=*|TEST_CXXFLAGS=*\
        |TEST_CXXFLAGS_EXTRA|LDFLAGS=*|LDFLAGS_EXTRA=*|TEST_LDFLAGS=*\
        |TEST_LDFLAGS_EXTRA=*|CPPFLAGS=*) eval "${arg%%=*}=\${arg#*=}" ;;
        *=*) warning Unknown variable: "${arg%%=*}" ;;
        *) warning Unknown argument: "$arg" ;;
    esac
done

## Defaults for variables not specified by user
: "${PLATFORM:=$(uname)}"
: "${PREFIX:="/usr"}"
: "${EPREFIX:="/"}"
: "${SBINDIR:="${EPREFIX%%/}/sbin"}"
: "${MANDIR:="${PREFIX%%/}/share/man"}"
: "${NO_SANITIZE:="auto"}"
: "${SHUTDOWN_PREFIX:=""}"
: "${CXXFLAGS_EXTRA:=""}"
: "${TEST_CXXFLAGS_EXTRA:=""}"
: "${CPPFLAGS:=""}"
: "${LDFLAGS_EXTRA:=""}"
: "${TEST_LDFLAGS_EXTRA:=""}"
if [ "$PLATFORM" = "Linux" ]; then
    : "${BUILD_SHUTDOWN:="yes"}"
    : "${SUPPORT_CGROUPS:="1"}"
    : "${SYSCONTROLSOCKET:="/run/dinitctl"}"
else
    : "${BUILD_SHUTDOWN:="no"}"
    : "${SUPPORT_CGROUPS:="0"}"
    : "${SYSCONTROLSOCKET:="/var/run/dinitctl"}"
fi

## Finalize $CXXFLAGS, $TEST_CXXFLAGS, $LDFLAGS, $TEST_LDFLAGS
if [ -z "${CXXFLAGS+IS_SET}" ]; then
    CXXFLAGS=""
    AUTO_CXXFLAGS="true"
else
    AUTO_CXXFLAGS="false"
fi
if [ -z "${TEST_CXXFLAGS+IS_SET}" ]; then
    TEST_CXXFLAGS=""
    AUTO_TEST_CXXFLAGS="true"
else
    AUTO_TEST_CXXFLAGS="false"
fi
if [ -z "${LDFLAGS+IS_SET}" ]; then
    LDFLAGS=""
    AUTO_LDFLAGS="true"
else
    AUTO_LDFLAGS="false"
fi
if [ -z "${TEST_LDFLAGS+IS_SET}" ]; then
    TEST_LDFLAGS=""
    AUTO_TEST_LDFLAGS="true"
else
    AUTO_TEST_LDFLAGS="false"
fi

## Verify PLATFORM value
if [ "$PLATFORM" != "Linux" ] && [ "$PLATFORM" != "FreeBSD" ] && \
[ "$PLATFORM" != "OpenBSD" ] && [ "$PLATFORM" != "Darwin" ]; then
    warning "$PLATFORM" platform is unknown!
    sub_warning Known Platforms are: Linux, FreeBSD, OpenBSD, Darwin
fi

## Create testfile.cc to test c++ compiler
echo "int main(int argc, char **argv) { return 0; }" > testfile.cc || error Can\'t create temporary file

## Find and test C++ compiler
if [ -z "${CXX:-}" ]; then
    info Checking C++ compiler...
    for guess in g++ clang++ c++; do
        if type "$guess" > /dev/null 2>&1; then
            CXX="$guess"
            sub_info "$CXX"
            break # Found
        fi
    done
    if [ -z "${CXX:-}" ]; then
       sub_error No C++ compiler found! # Not found
    fi
fi
cxx_works "$CXX"
if [ -n "${CXX_FOR_BUILD:-}" ]; then
    cxx_works "$CXX_FOR_BUILD"
fi

## Test compiler/linker supported arguments
if [ "$AUTO_CXXFLAGS" = "true" ]; then
    for argument in -std=c++11 \
                    -Wall \
                    -Os \
                    -fno-plt
    do
        try_cxx_argument CXXFLAGS $argument
    done
    if [ "$PLATFORM" != "Darwin" ]; then
        try_cxx_argument CXXFLAGS -fno-rtti
    fi
fi
if [ "$AUTO_LDFLAGS" = "true" ] && [ "$AUTO_CXXFLAGS" = "true" ]; then
    try_both_argument CXXFLAGS LDFLAGS -flto
fi
if [ "$AUTO_LDFLAGS" = "true" ] && [ "$PLATFORM" = "FreeBSD" ]; then
    try_ld_argument LDFLAGS -lrt
fi
# Add $CXXFLAGS and $LDFLAGS to $TEST_{LD,CXX}FLAGS when AUTO_TEST vars are true
if [ "$AUTO_TEST_CXXFLAGS" = "true" ]; then
    TEST_CXXFLAGS="$CXXFLAGS"
fi
if [ "$AUTO_TEST_LDFLAGS" = "true" ]; then
    TEST_LDFLAGS="$LDFLAGS"
fi
if [ "$AUTO_TEST_LDFLAGS" = "true" ] && [ "$AUTO_TEST_CXXFLAGS" = "true" ]; then
    try_both_argument TEST_CXXFLAGS TEST_LDFLAGS -fsanitize=address,undefined
fi

## Create mconfig
rm -f testfile*
info Creating mconfig...
cat << _EOF > mconfig
## Auto-generated by "$0" for "$PLATFORM"
# All changes will be lost if "$0" is re-run.

# See BUILD for help on all variables.

# Installation path options.

SBINDIR=$SBINDIR
MANDIR=$MANDIR
SYSCONTROLSOCKET=$SYSCONTROLSOCKET

# General build options.

CXX=$CXX
CXXFLAGS=$CXXFLAGS
CXXFLAGS_EXTRA=$CXXFLAGS_EXTRA
TEST_CXXFLAGS=$TEST_CXXFLAGS
TEST_CXXFLAGS_EXTRA=$TEST_CXXFLAGS_EXTRA
CPPFLAGS=$CPPFLAGS
LDFLAGS=$LDFLAGS
LDFLAGS_EXTRA=$LDFLAGS_EXTRA
TEST_LDFLAGS=$TEST_LDFLAGS
TEST_LDFLAGS_EXTRA=$TEST_LDFLAGS_EXTRA
BUILD_SHUTDOWN=$BUILD_SHUTDOWN

# Feature settings
SUPPORT_CGROUPS=$SUPPORT_CGROUPS

# Optional settings
SHUTDOWN_PREFIX=${SHUTDOWN_PREFIX:-}
_EOF
if [ -n "${USE_UTMPX:-}" ]; then
    echo "USE_UTMPX=$USE_UTMPX" >> mconfig
fi
if [ -n "${CXX_FOR_BUILD:-}" ]; then
    {
        echo ""
        echo "# For cross-compiling"
        echo "CXX_FOR_BUILD=$CXX_FOR_BUILD"
    } >> mconfig
fi
if [ -n "${CXXFLAGS_FOR_BUILD:-}" ]; then
    echo "CXXFLAGS_FOR_BUILD=$CXXFLAGS_FOR_BUILD" >> mconfig
fi
if [ -n "${CPPFLAGS_FOR_BUILD:-}" ]; then
    echo "CPPFLAGS_FOR_BUILD=$CPPFLAGS_FOR_BUILD" >> mconfig
fi
if [ -n "${LDFLAGS_FOR_BUILD:-}" ]; then
    echo "LDFLAGS_FOR_BUILD=$LDFLAGS_FOR_BUILD" >> mconfig
fi
sub_info done.
info Done!
exit 0