cmake_minimum_required(VERSION 3.4.1)
include(ExternalProject)

set(CC_OPTIMISATION_FLAGS "-ffunction-sections -fdata-sections")
set(LD_OPTIMISATION_FLAGS "-Wl,--gc-sections")

set(xCONFIG
  "CC=${CMAKE_C_COMPILER} \
    ${CMAKE_C_COMPILE_OPTIONS_EXTERNAL_TOOLCHAIN}${CMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN} \
    ${CMAKE_C_COMPILE_OPTIONS_TARGET}${CMAKE_C_COMPILER_TARGET} \
    ${CMAKE_C_COMPILE_OPTIONS_SYSROOT}${CMAKE_SYSROOT}"
  "LD=${CMAKE_LINKER}"
  "AR=${CMAKE_AR}"
  "RANLIB=${CMAKE_RANLIB}"
  "CFLAGS=${CMAKE_C_FLAGS} ${CC_OPTIMISATION_FLAGS}"
  "LDFLAGS=${CMAKE_SHARED_LINKER_FLAGS} ${LD_OPTIMISATION_FLAGS}"
  "--host=${CMAKE_C_COMPILER_TARGET}"
)

ExternalProject_Add(lzo
  URL               http://www.oberhumer.com/opensource/lzo/download/lzo-2.10.tar.gz
  URL_HASH          SHA1=4924676a9bae5db58ef129dc1cebce3baa3c4b5d
  CONFIGURE_COMMAND <SOURCE_DIR>/configure ${xCONFIG} --disable-shared
  BUILD_COMMAND     make -j8
  INSTALL_COMMAND   make install DESTDIR=${CMAKE_CURRENT_BINARY_DIR} &&
                    rm -r <BINARY_DIR>
)

ExternalProject_Add(libressl
  URL               https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.7.4.tar.gz
  URL_HASH          SHA256=1e3a9fada06c1c060011470ad0ff960de28f9a0515277d7336f7e09362517da6
  CONFIGURE_COMMAND <SOURCE_DIR>/configure ${xCONFIG} --disable-shared
  BUILD_COMMAND     make -j8 -C crypto
  INSTALL_COMMAND   make -C crypto install DESTDIR=${CMAKE_CURRENT_BINARY_DIR} &&
                    make -C include install DESTDIR=${CMAKE_CURRENT_BINARY_DIR} &&
                    rm -r <BINARY_DIR>
)

ExternalProject_Add(tinc
  DEPENDS           lzo libressl
  URL               https://tinc-vpn.org/packages/tinc-1.1pre15.tar.gz
  URL_HASH          SHA256=41dc3e40c5f8be497b779acd6f59ef4572e1430d0d0f0436f2de5cb21a59ef18
  CONFIGURE_COMMAND autoreconf -fsi <SOURCE_DIR> &&
                    <SOURCE_DIR>/configure ${xCONFIG}
                      --with-openssl=${CMAKE_CURRENT_BINARY_DIR}/usr/local
                      --with-lzo=${CMAKE_CURRENT_BINARY_DIR}/usr/local
                      --disable-curses
                      --disable-readline
  BUILD_COMMAND     make -j8 -C src
  INSTALL_COMMAND   make -C src install DESTDIR=${CMAKE_CURRENT_BINARY_DIR} &&
                    ${CMAKE_COMMAND} -E copy
                      ${CMAKE_CURRENT_BINARY_DIR}/usr/local/sbin/tinc ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libtinc.so &&
                    ${CMAKE_COMMAND} -E copy
                      ${CMAKE_CURRENT_BINARY_DIR}/usr/local/sbin/tincd ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/libtincd.so &&
                    rm -r <BINARY_DIR>
)

add_library(exec SHARED src/main/c/exec.c)
add_dependencies(exec tinc)