# Op.cmake should be included by a CMake script that will build a custom Scanner
# op. It sets a few default flags and exposes a function build_op for simplifying
# the build process. See examples/tutorial/04_custom_op.py for an example usage.

list(INSERT CMAKE_MODULE_PATH 0 "${CMAKE_CURRENT_LIST_DIR}/Modules")

include(CheckCXXCompilerFlag)
CHECK_CXX_COMPILER_FLAG("-std=c++1y" COMPILER_SUPPORTS_CXX1Y)
if(NOT COMPILER_SUPPORTS_CXX1Y)
  message(FATAL_ERROR
    "The compiler ${CMAKE_CXX_COMPILER} has no C++1y support.")
endif()

if (NOT CMAKE_BUILD_TYPE)
    message(STATUS "No build type selected, defaulting to Release")
    set(CMAKE_BUILD_TYPE "Release")
endif()

function(build_op)
  set(options)
  set(oneValueArgs LIB_NAME PROTO_SRC BUILD_CUDA NO_FLAGS)
  set(multiValueArgs CPP_SRCS)
  cmake_parse_arguments(args "" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})

  include_directories("${CMAKE_CURRENT_BINARY_DIR}")

  find_package(SaneProtobuf REQUIRED)

  # Build protobuf files if they exist
  if(NOT("${args_PROTO_SRC}" STREQUAL ""))
    set(PROTOBUF_IMPORT_DIRS "${SCANNER_PATH}")
    protobuf_generate_cpp(PROTO_SRCS PROTO_HDRS OFF ${args_PROTO_SRC})
    protobuf_generate_python(PROTO_PY OFF ${args_PROTO_SRC})
    add_custom_target(${args_LIB_NAME}_proto_files
      DEPENDS ${PROTO_HDRS} ${PROTO_PY})
    add_library(${args_LIB_NAME} SHARED ${args_CPP_SRCS} ${PROTO_SRCS})
    target_link_libraries(${args_LIB_NAME} PUBLIC "${PROTOBUF_LIBRARY}")
    add_dependencies(${args_LIB_NAME} ${args_LIB_NAME}_proto_files)
    install(FILES ${PROTO_HDRS} ${PROTO_PY} DESTINATION .)
  else()
    add_library(${args_LIB_NAME} SHARED ${args_CPP_SRCS})
  endif()

  # Note: this has to be done even if the library doesn't use protobuf, since when you include
  # Scanner, if you have multiple protobuf installations on your machine, you'll get pointed to
  # the wrong one and including Scanner's protobuf files will fail.
  target_include_directories(${args_LIB_NAME} PUBLIC "${PROTOBUF_INCLUDE_DIRS}")

  install(TARGETS ${args_LIB_NAME} DESTINATION .)

  if(("${args_NO_FLAGS}" STREQUAL ""))
    # Explictly link libscanner.so
    execute_process(
      OUTPUT_VARIABLE SCANNER_LIB_PATH
      COMMAND
      python3 -c "import scannerpy.build_flags as b; b.print_lib()")

    if(APPLE)
      target_link_libraries(${args_LIB_NAME} PUBLIC
        "${SCANNER_LIB_PATH}/libscanner.dylib")
    else()
      target_link_libraries(${args_LIB_NAME} PUBLIC
        "${SCANNER_LIB_PATH}/libscanner.so")
    endif()

    execute_process(
      OUTPUT_VARIABLE BUILD_FLAGS
      COMMAND
      python3 -c "import scannerpy.build_flags as b; b.print_compile_flags()")
    set_target_properties(
      ${args_LIB_NAME} PROPERTIES
      COMPILE_FLAGS "${BUILD_FLAGS}")

    execute_process(
      OUTPUT_VARIABLE LINK_FLAGS
      COMMAND
      python3 -c "import scannerpy.build_flags as b; b.print_link_flags()")
    set_target_properties(
      ${args_LIB_NAME} PROPERTIES
      LINK_FLAGS "${LINK_FLAGS}")

    if("${args_BUILD_CUDA}" STREQUAL "ON")
      find_package(CUDA REQUIRED)
      target_compile_definitions(${args_LIB_NAME} PUBLIC -DHAVE_CUDA)
      target_include_directories(${args_LIB_NAME} PUBLIC ${CUDA_INCLUDE_DIRS})
      target_link_libraries(${args_LIB_NAME} PUBLIC ${CUDA_LIBRARIES})

      if(COMPILER_SUPPORTS_CXX1Y)
        set(CUDA_NVCC_FLAGS "${CUDA_NVCC_FLAGS} -std=c++11")
      endif()
    endif()
  endif()
endfunction()