# 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
#
#     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.

# Creates an alias for SOURCE, called DESTINATION.
#
# On platforms that support them, this rule will effectively create a symlink.
#
# SOURCE may be relative to CMAKE_CURRENT_SOURCE_DIR, or absolute.
# DESTINATION may relative to CMAKE_CURRENT_BINARY_DIR, or absolute.
#
# Adapted from https://github.com/google/binexport/blob/master/util.cmake
function(create_directory_symlink SOURCE DESTINATION)
  get_filename_component(_destination_parent "${DESTINATION}" DIRECTORY)
  file(MAKE_DIRECTORY "${_destination_parent}")

  if(WIN32)
    file(TO_NATIVE_PATH "${SOURCE}" _native_source)
    file(TO_NATIVE_PATH "${DESTINATION}" _native_destination)
    execute_process(COMMAND $ENV{ComSpec} /c
        mklink /J "${_native_destination}" "${_native_source}" ERROR_QUIET)
  else()
    execute_process(COMMAND ${CMAKE_COMMAND} -E
      create_symlink "${SOURCE}" "${DESTINATION}")
  endif()
endfunction()

# Implements list(JOIN ...) for CMake < 3.12.
function(list_join LIST SEP OUTPUT)
  foreach(item IN LISTS ${LIST})
    set(_concat "${_concat}${SEP}${item}")
  endforeach()
  string(LENGTH "${SEP}" _len)
  string(SUBSTRING "${_concat}" ${_len} -1 _concat)
  set(${OUTPUT} "${_concat}" PARENT_SCOPE)
endfunction()

# Helper function that behaves just like Protobuf's protobuf_generate_cpp(),
# except that it strips import paths. This is necessary, because CMake's
# protobuf rules don't work well with imports across different directories.
function(sapi_protobuf_generate_cpp SRCS HDRS)
  cmake_parse_arguments(_pb "" "EXPORT_MACRO" "" ${ARGN})
  if(NOT _pb_UNPARSED_ARGUMENTS)
    message(FATAL_ERROR "sapi_protobuf_generate_cpp() missing proto files")
    return()
  endif()

  foreach(_file IN LISTS _pb_UNPARSED_ARGUMENTS)
    file(READ "${_file}" _pb_orig)
    string(REGEX REPLACE "import \".*/([^/]+\\.proto)\""
                         "import \"\\1\"" _pb_repl "${_pb_orig}")
    set(_file "${CMAKE_CURRENT_BINARY_DIR}/${_file}")
    file(WRITE "${_file}" "${_pb_repl}")
    list(APPEND _pb_files "${_file}")
  endforeach()

  set(_outvar)
  sapi_protobuf_generate(APPEND_PATH
                         LANGUAGE cpp
                         EXPORT_MACRO ${_pb_EXPORT_MACRO}
                         OUT_VAR _outvar
                         PROTOS ${_pb_files})
  set(${SRCS})
  set(${HDRS})
  foreach(_file IN LISTS _outvar)
    if(_file MATCHES "cc$")
      list(APPEND ${SRCS} ${_file})
    else()
      list(APPEND ${HDRS} ${_file})
    endif()
  endforeach()
  set(${SRCS} ${${SRCS}} PARENT_SCOPE)
  set(${HDRS} ${${HDRS}} PARENT_SCOPE)
endfunction()

# Runs the protocol buffer compiler on the given proto files. Compatible
# with the upstream version and included here so we can add_subdirectory()
# the protobuf source tree.
# One difference to the protobuf version is that this function handles
# relative paths differently, which is relevant when Sandboxed API is
# embedded in another project.
# TODO(cblichmann): We should try and upstream this behavior.
function(sapi_protobuf_generate)
  set(_options APPEND_PATH)
  set(_singleargs LANGUAGE OUT_VAR EXPORT_MACRO PROTOC_OUT_DIR TARGET)
  set(_multiargs PROTOS IMPORT_DIRS GENERATE_EXTENSIONS)
  cmake_parse_arguments(_pb "${_options}" "${_singleargs}" "${_multiargs}"
                            "${ARGN}")

  if(NOT _pb_PROTOS AND NOT _pb_TARGET)
    message(FATAL_ERROR "sapi_protobuf_generate missing targets or sources")
    return()
  endif()

  if(NOT _pb_OUT_VAR AND NOT _pb_TARGET)
    message(FATAL_ERROR "sapi_protobuf_generate missing target or output var")
    return()
  endif()

  if(NOT _pb_LANGUAGE)
    set(_pb_LANGUAGE cpp)
  else()
    string(TOLOWER ${_pb_LANGUAGE} _pb_LANGUAGE)
  endif()

  if(NOT _pb_PROTOC_OUT_DIR)
    set(_pb_PROTOC_OUT_DIR ${CMAKE_CURRENT_BINARY_DIR})
  endif()

  if(_pb_EXPORT_MACRO AND _pb_LANGUAGE STREQUAL cpp)
    set(_dll_export_decl "dllexport_decl=${_pb_EXPORT_MACRO}:")
  endif()

  if(NOT _pb_GENERATE_EXTENSIONS)
    if(_pb_LANGUAGE STREQUAL cpp)
      set(_pb_GENERATE_EXTENSIONS .pb.h .pb.cc)
    elseif(_pb_LANGUAGE STREQUAL python)
      set(_pb_GENERATE_EXTENSIONS _pb2.py)
    else()
      message(FATAL_ERROR
          "sapi_protobuf_generate given unknown language ${_pb_LANGUAGE}")
      return()
    endif()
  endif()

  if(_pb_TARGET)
    get_target_property(_source_list ${_pb_TARGET} SOURCES)
    foreach(_file IN LISTS _source_list)
      if(_file MATCHES "proto$")
        list(APPEND _pb_PROTOS "${_file}")
      endif()
    endforeach()
  endif()

  if(NOT _pb_PROTOS)
    message(FATAL_ERROR
            "sapi_protobuf_generate could not find any .proto files")
    return()
  endif()

  # Create an include path for each file specified
  foreach(_file ${_pb_PROTOS})
    get_filename_component(_abs_file ${_file} ABSOLUTE)
    get_filename_component(_abs_path ${_abs_file} PATH)
    list(FIND _protobuf_include_path "${_abs_path}" _contains_already)
    if(${_contains_already} EQUAL -1)
      list(APPEND _protobuf_include_path -I ${_abs_path})
    endif()
  endforeach()

  foreach(_dir IN LISTS _pb_IMPORT_DIRS)
    get_filename_component(_abs_path "${_dir}" ABSOLUTE)
    list(FIND _protobuf_include_path "${_abs_path}" _contains_already)
    if(${_contains_already} EQUAL -1)
      list(APPEND _protobuf_include_path -I "${_abs_path}")
    endif()
  endforeach()

  set(_generated_srcs_all)
  foreach(_proto IN LISTS _pb_PROTOS)
    get_filename_component(_abs_file ${_proto} ABSOLUTE)
    get_filename_component(_abs_dir ${_abs_file} DIRECTORY)
    get_filename_component(_basename ${_proto} NAME_WE)

    set(_generated_srcs)
    foreach(_ext ${_pb_GENERATE_EXTENSIONS})
      # Use _pb_PROTOC_OUT_DIR directly without computing a relative path
      list(APPEND _generated_srcs "${_pb_PROTOC_OUT_DIR}/${_basename}${_ext}")
    endforeach()
    list(APPEND _generated_srcs_all ${_generated_srcs})

    add_custom_command(OUTPUT ${_generated_srcs}
                       COMMAND  protobuf::protoc
                       ARGS --${_pb_LANGUAGE}_out
                            ${_dll_export_decl}${_pb_PROTOC_OUT_DIR}
                            ${_protobuf_include_path}
                            ${_abs_file}
                       DEPENDS ${_abs_file} protobuf::protoc
                       COMMENT "Running ${_pb_LANGUAGE} protoc on ${_proto}"
                       VERBATIM)
  endforeach()

  set_source_files_properties(${_generated_srcs_all}
                              PROPERTIES GENERATED TRUE)
  if(_pb_OUT_VAR)
    set(${_pb_OUT_VAR} ${_generated_srcs_all} PARENT_SCOPE)
  endif()
  if(_pb_TARGET)
    target_sources(${_pb_TARGET} PRIVATE ${_generated_srcs_all})
  endif()
endfunction()