if [ -z "$SAGE_LOCAL" ]; then
    echo >&2 "Error: SAGE_LOCAL undefined - exiting..."
    echo >&2 "Maybe run 'sage -sh'?"
    exit 1
fi

# libpng needs to have no default options set for grep
unset GREP_OPTIONS

if [ "$SAGE64" = yes ]; then
    CFLAGS="$CFLAGS -m64 -fPIC -g"
    LDFLAGS="$LDFLAGS -m64"
else
    CFLAGS="$CFLAGS -fPIC -g"
fi

# Pick up Sage's zlib:
export CPPFLAGS="-I$SAGE_LOCAL/include $CPPFLAGS"

cd src

./configure --prefix="$SAGE_LOCAL" --libdir="$SAGE_LOCAL/lib" --enable-shared=yes
if [ $? -ne 0 ]; then
    echo >&2 "Error configuring libpng"
    exit 1
fi

# Needed to generate a correct import library
if [ "$UNAME" = "CYGWIN" ]; then
    MAKE="$MAKE SYMBOL_PREFIX= "
fi

echo "Building libpng..."
$MAKE
if [ $? -ne 0 ]; then
    echo >&2 "Error building libpng."
    exit 1
fi

echo "Installing libpng..."
$MAKE install
if [ $? -ne 0 ]; then
    echo >&2 "Error installing libpng."
    exit 1
fi


# Delete libpng.* symlinks, see SPKG.txt for details
rm -f "$SAGE_LOCAL"/lib/libpng.*
