# Copyright (c) Facebook, Inc. and its affiliates.

include(FBCMakeParseArgs)

# Generate a C++ library from a thrift file
#
# Parameters: - SERVICES <svc1> [<svc2> ...] The names of the services defined
# in the thrift file. - DEPENDS <dep1> [<dep2> ...] A list of other thrift C++
# libraries that this library depends on. - OPTIONS <opt1> [<opt2> ...] A list
# of options to pass to the thrift compiler. - INCLUDE_DIR <path> The
# sub-directory where generated headers will be installed. Defaults to "include"
# if not specified.  The caller must still call install() to install the thrift
# library if desired. - THRIFT_INCLUDE_DIR <path> The sub-directory where
# generated headers will be installed. Defaults to "${INCLUDE_DIR}/thrift-files"
# if not specified. The caller must still call install() to install the thrift
# library if desired.
function(add_fbthrift_cpp_library LIB_NAME THRIFT_FILE)
  # Parse the arguments
  set(one_value_args INCLUDE_DIR THRIFT_INCLUDE_DIR)
  set(multi_value_args SERVICES DEPENDS OPTIONS)
  fb_cmake_parse_args(ARG "" "${one_value_args}" "${multi_value_args}"
                      "${ARGN}")
  if(NOT DEFINED ARG_INCLUDE_DIR)
    set(ARG_INCLUDE_DIR "include")
  endif()
  if(NOT DEFINED ARG_THRIFT_INCLUDE_DIR)
    set(ARG_THRIFT_INCLUDE_DIR "${ARG_INCLUDE_DIR}/thrift-files")
  endif()

  get_filename_component(base ${THRIFT_FILE} NAME_WE)
  get_filename_component(output_dir ${CMAKE_CURRENT_BINARY_DIR}/${THRIFT_FILE}
                         DIRECTORY)

  # Generate relative paths in #includes
  file(RELATIVE_PATH include_prefix "${CMAKE_SOURCE_DIR}"
       "${CMAKE_CURRENT_SOURCE_DIR}/${THRIFT_FILE}")
  get_filename_component(include_prefix ${include_prefix} DIRECTORY)

  if(NOT "${include_prefix}" STREQUAL "")
    list(APPEND ARG_OPTIONS "include_prefix=${include_prefix}")
  endif()
  # CMake 3.12 is finally getting a list(JOIN) function, but until then treating
  # the list as a string and replacing the semicolons is good enough.
  string(REPLACE ";" "," GEN_ARG_STR "${ARG_OPTIONS}")

  # Compute the list of generated files
  list(
    APPEND
    generated_headers
    "${output_dir}/gen-cpp2/${base}_constants.h"
    "${output_dir}/gen-cpp2/${base}_types.h"
    "${output_dir}/gen-cpp2/${base}_types.tcc"
    "${output_dir}/gen-cpp2/${base}_types_custom_protocol.h"
    "${output_dir}/gen-cpp2/${base}_metadata.h")
  list(
    APPEND
    generated_sources
    "${output_dir}/gen-cpp2/${base}_constants.cpp"
    "${output_dir}/gen-cpp2/${base}_data.h"
    "${output_dir}/gen-cpp2/${base}_data.cpp"
    "${output_dir}/gen-cpp2/${base}_types.cpp"
    "${output_dir}/gen-cpp2/${base}_metadata.cpp")
  foreach(service IN LISTS ARG_SERVICES)
    list(
      APPEND
      generated_headers
      "${output_dir}/gen-cpp2/${service}.h"
      "${output_dir}/gen-cpp2/${service}.tcc"
      "${output_dir}/gen-cpp2/${service}AsyncClient.h"
      "${output_dir}/gen-cpp2/${service}_custom_protocol.h")
    list(
      APPEND
      generated_sources
      "${output_dir}/gen-cpp2/${service}.cpp"
      "${output_dir}/gen-cpp2/${service}AsyncClient.cpp"
      "${output_dir}/gen-cpp2/${service}_processmap_binary.cpp"
      "${output_dir}/gen-cpp2/${service}_processmap_compact.cpp")
  endforeach()

  # This generator expression gets the list of include directories required for
  # all of our dependencies. It requires using COMMAND_EXPAND_LISTS in the
  # add_custom_command() call below.  COMMAND_EXPAND_LISTS is only available in
  # CMake 3.8+ If we really had to support older versions of CMake we would
  # probably need to use a wrapper script around the thrift compiler that could
  # take the include list as a single argument and split it up before invoking
  # the thrift compiler.
  if(NOT POLICY CMP0067)
    message(FATAL_ERROR "add_fbthrift_cpp_library() requires CMake 3.8+")
  endif()
  set(thrift_include_options
      "-I;$<JOIN:$<TARGET_PROPERTY:${LIB_NAME}.thrift_includes,INTERFACE_INCLUDE_DIRECTORIES>,;-I;>"
  )

  # Emit the rule to run the thrift compiler
  add_custom_command(
    OUTPUT ${generated_headers} ${generated_sources}
    COMMAND_EXPAND_LISTS
    COMMAND "${CMAKE_COMMAND}" -E make_directory "${output_dir}"
    COMMAND
      "${FBTHRIFT_COMPILER}"
      # TODO: this flag does not exist in all fbthrift versions. --legacy-strict
      --gen "mstch_cpp2:${GEN_ARG_STR}" "${thrift_include_options}" -I
      "${FBTHRIFT_INCLUDE_DIR}" -o "${output_dir}"
      "${CMAKE_CURRENT_SOURCE_DIR}/${THRIFT_FILE}"
    WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
    MAIN_DEPENDENCY "${THRIFT_FILE}"
    DEPENDS ${ARG_DEPENDS} "${FBTHRIFT_COMPILER}")

  # Now emit the library rule to compile the sources
  if(BUILD_SHARED_LIBS)
    set(LIB_TYPE SHARED)
  else()
    set(LIB_TYPE STATIC)
  endif()

  add_library("${LIB_NAME}" ${LIB_TYPE} ${generated_sources})

  target_include_directories(
    "${LIB_NAME}" PUBLIC "$<BUILD_INTERFACE:${CMAKE_BINARY_DIR}>"
                         "$<INSTALL_INTERFACE:${ARG_INCLUDE_DIR}>")
  target_link_libraries(
    "${LIB_NAME}"
    PUBLIC ${ARG_DEPENDS}
           Folly::folly
           FBThrift::thriftcpp2
           # TODO: these symbols require other dependencies that need to be
           # correctly handle by Velox's build system before they can be
           # enabled. mvfst::mvfst_server_async_tran mvfst::mvfst_server
  )

  # Add ${generated_headers} to the PUBLIC_HEADER property for ${LIB_NAME}
  #
  # This allows callers to install it using "install(TARGETS ${LIB_NAME}
  # PUBLIC_HEADER)" However, note that CMake's PUBLIC_HEADER behavior is rather
  # inflexible, and does have any way to preserve header directory structure.
  # Callers must be careful to use the correct PUBLIC_HEADER DESTINATION
  # parameter when doing this, to put the files the correct directory
  # themselves. We define a HEADER_INSTALL_DIR property with the include
  # directory prefix, so typically callers should specify the PUBLIC_HEADER
  # DESTINATION as "$<TARGET_PROPERTY:${LIB_NAME},HEADER_INSTALL_DIR>"
  set_property(TARGET "${LIB_NAME}" PROPERTY PUBLIC_HEADER ${generated_headers})

  # Define a dummy interface library to help propagate the thrift include
  # directories between dependencies.
  add_library("${LIB_NAME}.thrift_includes" INTERFACE)
  target_include_directories(
    "${LIB_NAME}.thrift_includes"
    INTERFACE "$<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}>"
              "$<INSTALL_INTERFACE:${ARG_THRIFT_INCLUDE_DIR}>")
  foreach(dep IN LISTS ARG_DEPENDS)
    target_link_libraries("${LIB_NAME}.thrift_includes"
                          INTERFACE "${dep}.thrift_includes")
  endforeach()

  set_target_properties(
    "${LIB_NAME}"
    PROPERTIES EXPORT_PROPERTIES "THRIFT_INSTALL_DIR"
               THRIFT_INSTALL_DIR "${ARG_THRIFT_INCLUDE_DIR}/${include_prefix}"
               HEADER_INSTALL_DIR
               "${ARG_INCLUDE_DIR}/${include_prefix}/gen-cpp2")
endfunction()