#=============================================================================
# SPDX-FileCopyrightText: Copyright (c) 2022-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#=============================================================================

include_guard(GLOBAL)

function(
  find_or_configure_legion_impl
  version
  git_repo
  git_branch
  shallow
  exclude_from_all
)
  include("${LEGATE_CMAKE_DIR}/Modules/cpm_helpers.cmake")
  get_cpm_git_args(
    legion_cpm_git_args
    REPOSITORY "${git_repo}"
    BRANCH "${git_branch}"
    SHALLOW "${shallow}"
  )

  string(REGEX REPLACE "0([0-9]+)" "\\1" version "${version}")

  if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
    set(Legion_BACKTRACE_USE_LIBDW ON)
  else()
    set(Legion_BACKTRACE_USE_LIBDW OFF)
  endif()

  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${Legion_CXX_FLAGS}")
  set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} ${Legion_CUDA_FLAGS}")
  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${Legion_LINKER_FLAGS}")
  set(CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} ${Legion_LINKER_FLAGS}")

  if(BUILD_SHARED_LIBS)
    set(Legion_CUDA_DYNAMIC_LOAD ON)
  else()
    set_ifndef(Legion_CUDA_DYNAMIC_LOAD OFF)
  endif()

  # Maintain the default behavior of using the MPI bootstrap plugin for UCX.
  set(Legion_UCX_MPI_BOOTSTRAP ON)
  # If we are building wheels, we don't want to dynamically link against the CUDA runtime.
  if(LEGATE_BUILD_PIP_WHEELS)
    set(Legion_CUDA_DYNAMIC_LOAD OFF)
    set(Legion_UCX_MPI_BOOTSTRAP OFF)
  endif()

  set_ifndef(Legion_EMBED_GASNet_CONFIGURE_ARGS "--with-ibv-max-hcas=8")

  message(VERBOSE "legate: Legion version: ${version}")
  message(VERBOSE "legate: Legion git_repo: ${git_repo}")
  message(VERBOSE "legate: Legion git_branch: ${git_branch}")
  message(VERBOSE "legate: Legion exclude_from_all: ${exclude_from_all}")

  rapids_cpm_find(
    Legion
    "${version}"
    BUILD_EXPORT_SET legate-exports
    INSTALL_EXPORT_SET legate-exports
    GLOBAL_TARGETS Legion::Regent Legion::Legion Legion::LegionRuntime
    CPM_ARGS
      ${legion_cpm_git_args}
      SYSTEM TRUE
      EXCLUDE_FROM_ALL ${exclude_from_all}
      OPTIONS
        "Legion_REDOP_HALF OFF"
        "Legion_REDOP_COMPLEX OFF"
        "Legion_UCX_DYNAMIC_LOAD ON"
        # We never want local fields
        "Legion_DEFAULT_LOCAL_FIELDS 0"
        "Legion_MAX_DIM ${Legion_MAX_DIM}"
        "Legion_MAX_FIELDS ${Legion_MAX_FIELDS}"
        "Legion_HIJACK_CUDART OFF"
        "Legion_BUILD_BINDINGS OFF"
        "Legion_EMBED_GASNet_CONFIGURE_ARGS ${Legion_EMBED_GASNet_CONFIGURE_ARGS}"
        "Legion_UCX_MPI_BOOTSTRAP ${Legion_UCX_MPI_BOOTSTRAP}"
        "Legion_USE_ZLIB OFF"
        "Legion_CUDA_DYNAMIC_LOAD ${Legion_CUDA_DYNAMIC_LOAD}"
        "CMAKE_INSTALL_BINDIR ${legate_DEP_INSTALL_BINDIR}"
        "CMAKE_INSTALL_INCLUDEDIR ${legate_DEP_INSTALL_INCLUDEDIR}"
        "INSTALL_SUFFIX -legate"
        "CMAKE_SUPPRESS_DEVELOPER_WARNINGS ON"
  )

  if(NOT CPM_Legion_SOURCE AND NOT Legion_ROOT AND NOT Legion_DIR)
    if(
      DEFINED CPM_PACKAGE_Legion_SOURCE_DIR
      AND EXISTS "${CPM_PACKAGE_Legion_SOURCE_DIR}/VERSION"
    )
      file(READ "${CPM_PACKAGE_Legion_SOURCE_DIR}/VERSION" legion_version_actual)
      string(STRIP "${legion_version_actual}" legion_version_actual)
      string(REGEX REPLACE "^legion-" "" legion_version_actual "${legion_version_actual}")
      if(NOT legion_version_actual VERSION_EQUAL version)
        message(
          FATAL_ERROR
          "Legion version mismatch: expected ${version}, got ${legion_version_actual}"
        )
      endif()
    endif()
  endif()

  legate_export_variables(Legion)
  set_parent_scope(Legion_VERSION)
  set(Legion_GIT_REPO "${git_repo}" PARENT_SCOPE)
  set(Legion_GIT_BRANCH "${git_branch}" PARENT_SCOPE)
  set_parent_scope(Legion_USE_CUDA)
  set_parent_scope(Legion_USE_OpenMP)
  set_parent_scope(Legion_USE_Python)
  set_parent_scope(Legion_CUDA_ARCH)
  set_parent_scope(Legion_BOUNDS_CHECKS)
  set_parent_scope(Legion_NETWORKS)
endfunction()

function(find_or_configure_legion)
  list(APPEND CMAKE_MESSAGE_CONTEXT "legion")

  if(Legion_HIJACK_CUDART)
    message(
      FATAL_ERROR
      [=[
#####################################################################
Error: Realm's CUDA runtime hijack is incompatible with NCCL.
Please note that your code will crash catastrophically as soon as it
calls into NCCL either directly or through some other Legate library.
#####################################################################
]=]
    )
  endif()

  legate_maybe_override_package_info(Legion "${legate_LEGION_BRANCH}")
  legate_load_overrideable_package_info(
    Legion
    version
    git_repo
    git_branch
    shallow
    exclude_from_all
  )

  find_or_configure_legion_impl(
    "${version}"
    "${git_repo}"
    "${git_branch}"
    "${shallow}"
    "${exclude_from_all}"
  )

  set(
    legion_vars
    Legion_VERSION
    Legion_GIT_REPO
    Legion_GIT_BRANCH
    Legion_USE_CUDA
    Legion_USE_OpenMP
    Legion_USE_Python
    Legion_CUDA_ARCH
    Legion_BOUNDS_CHECKS
    Legion_NETWORKS
  )
  foreach(var IN LISTS legion_vars)
    message(VERBOSE "${var}=${${var}}")
    set_parent_scope(${var})
  endforeach()
  legate_export_variables(Legion)
endfunction()