# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

include(BuildFlatBuffers)
include(CMakeParseArguments)

# flatbuffer_cc_library()
#
# CMake function to imitate Bazel's flatbuffer_cc_library rule.
#
# Parameters:
# NAME: name of target (see Note)
# SRCS: List of source files for the library
# DEPS: List of other libraries to be linked in to the binary targets
# COPTS: List of private compile options
# DEFINES: List of public defines
# LINKOPTS: List of link options
# FLATC_ARGS: List of flattbuffers arguments. Default:
#             "--keep-prefix"
#             "--scoped-enums"
#             "--reflect-names"
#             "--gen-object-api"
# PUBLIC: Add this so that this library will be exported under iree::
# Also in IDE, target will appear in IREE folder while non PUBLIC will be in IREE/internal.
# TESTONLY: When added, this target will only be built if user passes -DIREE_BUILD_TESTS=ON to CMake.
#
# Note:
# By default, flatbuffer_cc_library will always create a library named ${NAME},
# and alias target iree::${NAME}. The iree:: form should always be used.
# This is to reduce namespace pollution.
#
# flatbuffer_cc_library(
#   NAME
#     base_schema
#   SRCS
#     "a.cc"
# )
# flatbuffer_cc_library(
#   NAME
#     other_schemas
#   SRCS
#     "b.fbs"
#   DEPS
#     iree::schemas::base_schema # not "awesome" !
#   PUBLIC
# )
#
# flatbuffer_cc_library(
#   NAME
#     main_lib
#   ...
#   DEPS
#     iree::schemas::other_schemas
# )
function(flatbuffer_cc_library)
  cmake_parse_arguments(_RULE
    "PUBLIC;TESTONLY"
    "NAME"
    "SRCS;COPTS;DEFINES;LINKOPTS;DEPS;FLATC_ARGS"
    ${ARGN}
  )

  if(NOT _RULE_TESTONLY OR IREE_BUILD_TESTS)
    # Prefix the library with the package name, so we get: iree_package_name
    iree_package_name(_PACKAGE_NAME)
    set(_NAME "${_PACKAGE_NAME}_${_RULE_NAME}")

    if(NOT DEFINED _RULE_FLATC_ARGS)
      set(FLATBUFFERS_FLATC_SCHEMA_EXTRA_ARGS
        # Preserve root-relative include paths in generated code.
        "--keep-prefix"
        # Use C++11 'enum class' for enums.
        "--scoped-enums"
        # Include reflection tables used for dumping debug representations.
        "--reflect-names"
        # Generate FooT types for unpack/pack support. Note that this should only
        # be used in tooling as the code size/runtime overhead is non-trivial.
        "--gen-object-api"
      )
    else()
      set(FLATBUFFERS_FLATC_SCHEMA_EXTRA_ARGS ${_RULE_FLATC_ARGS})
    endif()

    build_flatbuffers(
      "${_RULE_SRCS}"
      "${IREE_ROOT_DIR}"
      "${_NAME}_gen"  # custom_target_name
      "${_RULE_DEPS}" # additional_dependencies
      "${CMAKE_CURRENT_BINARY_DIR}" # generated_include_dir
      "${CMAKE_CURRENT_BINARY_DIR}" # binary_schemas_dir
      "" # copy_text_schemas_dir
    )

    add_library(${_NAME} INTERFACE)
    add_dependencies(${_NAME} ${_NAME}_gen)
    target_include_directories(${_NAME}
      INTERFACE
        "$<BUILD_INTERFACE:${IREE_COMMON_INCLUDE_DIRS}>"
        ${CMAKE_CURRENT_BINARY_DIR}
      )
    target_link_libraries(${_NAME}
      INTERFACE
        flatbuffers
        ${_RULE_LINKOPTS}
        ${IREE_DEFAULT_LINKOPTS}
    )
    target_compile_definitions(${_NAME}
      INTERFACE
        ${_RULE_DEFINES}
    )

    # Alias the iree_package_name library to iree::package::name.
    # This lets us more clearly map to Bazel and makes it possible to
    # disambiguate the underscores in paths vs. the separators.
    iree_package_ns(_PACKAGE_NS)
    add_library(${_PACKAGE_NS}::${_RULE_NAME} ALIAS ${_NAME})
  endif()
endfunction()