FindOcean.cmake

# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# 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
#
#     http://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.

# FindOcean.cmake — fetch, build, and install Facebook Ocean as static libraries
# Place this in a folder on CMAKE_MODULE_PATH (e.g. cmake/modules)

# Prevent multiple inclusion
if(Ocean_FOUND)
  return()
endif()

# Reuse the Ocean targets installed alongside VRS when this module is loaded
# from vrslibConfig.cmake. This avoids fetching and rebuilding Ocean in every
# downstream project.
set(_Ocean_INSTALLED_TARGETS "${CMAKE_CURRENT_LIST_DIR}/../../Ocean/FindOceanTargets.cmake")
if(EXISTS "${_Ocean_INSTALLED_TARGETS}")
  include("${_Ocean_INSTALLED_TARGETS}")
  if(TARGET Ocean::Ocean)
    set(Ocean_LIBRARIES Ocean::Ocean)
    set(Ocean_FOUND TRUE)
    unset(_Ocean_INSTALLED_TARGETS)
    return()
  endif()
endif()
unset(_Ocean_INSTALLED_TARGETS)

# --------------------------
# 0) Standard install dirs
include(GNUInstallDirs)

# Try to find Ocean in fbsource tree first
set(OCEAN_FBSOURCE_PATHS
  "${VRS_SOURCE_DIR}/../../../xplat/ocean"
  "${CMAKE_CURRENT_SOURCE_DIR}/../../../xplat/ocean"
  "${CMAKE_SOURCE_DIR}/../../../xplat/ocean"
)
foreach(ocean_path IN LISTS OCEAN_FBSOURCE_PATHS)
  if(EXISTS "${ocean_path}/CMakeLists.txt")
    set(OCEAN_SOURCE_DIR "${ocean_path}")
    break()
  endif()
endforeach()

if(OCEAN_SOURCE_DIR)
  message(STATUS "Found Ocean in fbsource at ${OCEAN_SOURCE_DIR}")
  set(OCEAN_BUILD_MINIMAL ON CACHE BOOL "" FORCE)
  set(OCEAN_BUILD_TEST OFF CACHE BOOL "" FORCE)
  # Ocean requires CMake 3.26, VRS requires 3.16 - allow higher version
  add_subdirectory("${OCEAN_SOURCE_DIR}" "${CMAKE_BINARY_DIR}/ocean")
  set(ocean_SOURCE_DIR "${OCEAN_SOURCE_DIR}")
else()
  # --------------------------
  # 1) Fetch & build Ocean
  include(FetchContent)
  FetchContent_Declare(
    ocean
    GIT_REPOSITORY https://github.com/facebookresearch/ocean.git
    GIT_TAG        5fca1d27a9f37e868738b6db09a6b1e00723d80f # master branch, 2025.11.07
  )
  set(OCEAN_BUILD_MINIMAL ON)
  set(OCEAN_BUILD_TEST    OFF)
  message(STATUS "⤷ FetchContent: pulling and building Facebook Ocean…")
  FetchContent_MakeAvailable(ocean)
endif()

# --------------------------
# 2) Normalize component include dirs to avoid build-tree paths
foreach(_lib IN ITEMS ocean_base ocean_cv ocean_math)
  # Clear any pre-existing include dirs
  set_target_properties(${_lib} PROPERTIES
    INTERFACE_INCLUDE_DIRECTORIES ""
  )
  # Add proper GENERATOR_EXPR-based includes
  target_include_directories(${_lib} INTERFACE
    $<BUILD_INTERFACE:${ocean_SOURCE_DIR}/impl>
    $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
  )
endforeach()

# --------------------------
# 3) Bundle into a single INTERFACE target
add_library(ocean INTERFACE)
target_link_libraries(ocean INTERFACE
  ocean_base
  ocean_cv
  ocean_math
)
add_library(Ocean::Ocean ALIAS ocean)
set_target_properties(ocean PROPERTIES EXPORT_NAME Ocean)

# --------------------------
# 4) Installation
install(
  TARGETS
    ocean_base
    ocean_cv
    ocean_math
    ocean
  EXPORT OceanTargets
  ARCHIVE      DESTINATION ${CMAKE_INSTALL_LIBDIR}
  INCLUDES     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
)
install(
  DIRECTORY ${ocean_SOURCE_DIR}/impl/
  DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
  FILES_MATCHING PATTERN "*.h"
)
install(
  EXPORT OceanTargets
  FILE   FindOceanTargets.cmake
  NAMESPACE Ocean::
  DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/Ocean
)

# --------------------------
# 5) In-tree find_package support
set(Ocean_FOUND     TRUE)
set(Ocean_LIBRARIES Ocean::Ocean)
set(Ocean_INCLUDE_DIRS "${ocean_SOURCE_DIR}/impl")
include(FindPackageHandleStandardArgs)
find_package_handle_standard_args(Ocean
  REQUIRED_VARS Ocean_LIBRARIES
)