# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
#
# 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.
#
# To simplify the build process of PaddlePaddle, we defined couple of
# fundamental abstractions, e.g., how to build library, binary and
# test in C++, CUDA and Go.
#
# -------------------------------------------
#     C++        CUDA C++       Go
# -------------------------------------------
# cc_library    nv_library   go_library
# cc_binary     nv_binary    go_binary
# cc_test       nv_test      go_test
# -------------------------------------------
#
# cmake_parse_arguments can help us to achieve this goal.
# https://cmake.org/cmake/help/v3.0/module/CMakeParseArguments.html
#
# cc_library|nv_library(<target_name> [STATIC SHARED] SRCS <file>... DEPS <libs>...)
#
# cc_library and nv_library can generate *.a, or *.so
# if the corresponding keyword STATIC or SHARED is specified.
#
# cc_binary|nv_binary(<target_name> SRCS <file>... DEPS <libs>...)
#
# cc_binary and nv_binary can build souce code and link the dependent
# libraries to generate a binary.
#
# cc_test|nv_test(<target_name> SRCS <file>... DEPS <libs>...)
#
# cc_test and nv_test can build test code, link gtest and other dependent
# libraries to generate test suite.
#
# For example, in one folder, it contains
#   ddim{.h, .cc, _test.cc, _test.cu}
#   place{.h, cc, _test.cc}
#
# We can add build script as follows: 
# 
# cc_library(place STATIC SRCS place.cc)
#
# place.cc -> place.a
# cc_library's STATIC OPTION will generate libplace.a.
#
# cc_test(place_test
#    SRCS place_test.cc
#    DEPS place glog gflags)
#
# place_test.cc, place, glog, gflags -> place_test
# cc_test will combine place_test.cc, libplace.a with libglog.a.
# and libgflags.a to generate place_test.
#
# cc_library(ddim STATIC SRCS ddim.cc)
#
# ddim.cc -> ddim.a
# cc_library's STATIC OPTION will generate libddim.a.
#
# cc_test(ddim_test
#    SRCS ddim_test.cc
#    DEPS ddim)
#
# ddim_test.cc, ddim.a -> ddim_test
# cc_test will build ddim_test.cc with libddim.a to generate ddim_test.
#
# nv_test(dim_test
#    SRCS dim_test.cu
#    DEPS ddim)
#
# dim_test.cu, ddim.a -> dim_test
# nv_test will build dim_test.cu with libddim.a to generate dim_test.
#
# cc_library(framework DEPS place ddim)
#
# place.a, ddim.a -> framework.a
# If no SRCS exists, merging libplace.a and libddim.a to generate libframework.a.
#

if(NOT APPLE)
    find_package(Threads REQUIRED)
    link_libraries(${CMAKE_THREAD_LIBS_INIT})
endif(NOT APPLE)

function(merge_static_libs TARGET_NAME)
  set(libs ${ARGN})
  list(REMOVE_DUPLICATES libs)

  # First get the file names of the libraries to be merged
  foreach(lib ${libs})
    get_target_property(libtype ${lib} TYPE)
    if(NOT libtype STREQUAL "STATIC_LIBRARY")
      message(FATAL_ERROR "merge_static_libs can only process static libraries")
    endif()
    set(libfiles ${libfiles} $<TARGET_FILE:${lib}>)
  endforeach()

  if(APPLE) # Use OSX's libtool to merge archives
    add_custom_target(${TARGET_NAME}_archive
      COMMAND libtool -static -o "${CMAKE_CURRENT_BINARY_DIR}/lib${TARGET_NAME}.a" ${libfiles}
      WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
      DEPENDS ${libs}
      )
    add_library(${TARGET_NAME} STATIC IMPORTED GLOBAL)
    set_property(TARGET ${TARGET_NAME} PROPERTY
      IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/lib${TARGET_NAME}.a")
    add_dependencies(${TARGET_NAME} ${TARGET_NAME}_archive)
	else() # general UNIX: use "ar" to extract objects and re-add to a common lib
    foreach(lib ${libs})
      set(objlistfile ${lib}.objlist) # list of objects in the input library
      set(objdir ${lib}.objdir)

      add_custom_command(OUTPUT ${objdir}
        COMMAND ${CMAKE_COMMAND} -E make_directory ${objdir})

      add_custom_command(OUTPUT ${objlistfile}
        COMMAND ${CMAKE_AR} -x "$<TARGET_FILE:${lib}>"
        COMMAND ${CMAKE_AR} -t "$<TARGET_FILE:${lib}>" > ../${objlistfile}
        DEPENDS ${lib} ${objdir}
        WORKING_DIRECTORY ${objdir})

      # Empty dummy source file that goes into merged library
      set(mergebase ${lib}.mergebase.c)
      add_custom_command(OUTPUT ${mergebase}
        COMMAND ${CMAKE_COMMAND} -E touch ${mergebase}
        DEPENDS ${objlistfile})

      list(APPEND mergebases "${mergebase}")
    endforeach()

    # We need a target for the output merged library
    add_library(${TARGET_NAME} STATIC ${mergebases})
    set(outlibfile "$<TARGET_FILE:${TARGET_NAME}>")

    foreach(lib ${libs})
    add_custom_command(TARGET ${TARGET_NAME} POST_BUILD
      COMMAND ${CMAKE_AR} ru ${outlibfile} @"../${objlistfile}"
      WORKING_DIRECTORY ${objdir})
    endforeach()

    add_custom_command(TARGET ${TARGET_NAME} POST_BUILD
      COMMAND ${CMAKE_RANLIB} ${outlibfile})
  endif()
endfunction(merge_static_libs)

function(cc_library TARGET_NAME)
  set(options STATIC static SHARED shared)
  set(oneValueArgs "")
  set(multiValueArgs SRCS DEPS)
  cmake_parse_arguments(cc_library "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
  if (cc_library_SRCS)
    if (cc_library_SHARED OR cc_library_shared) # build *.so
      add_library(${TARGET_NAME} SHARED ${cc_library_SRCS})
    else()
      add_library(${TARGET_NAME} STATIC ${cc_library_SRCS})
    endif()
    if (cc_library_DEPS)
      add_dependencies(${TARGET_NAME} ${cc_library_DEPS})
    endif()
  else(cc_library_SRCS)
    if (cc_library_DEPS)
      merge_static_libs(${TARGET_NAME} ${cc_library_DEPS})
    else()
      message(FATAL "Please specify source file or library in cc_library.")
    endif()
  endif(cc_library_SRCS)
endfunction(cc_library)

function(cc_binary TARGET_NAME)
  set(options "")
  set(oneValueArgs "")
  set(multiValueArgs SRCS DEPS)
  cmake_parse_arguments(cc_binary "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
  add_executable(${TARGET_NAME} ${cc_binary_SRCS})
  if(cc_binary_DEPS)
    target_link_libraries(${TARGET_NAME} ${cc_binary_DEPS})
    add_dependencies(${TARGET_NAME} ${cc_binary_DEPS})
  endif()
endfunction(cc_binary)

function(cc_test TARGET_NAME)
  if(WITH_TESTING)
    set(options "")
    set(oneValueArgs "")
    set(multiValueArgs SRCS DEPS)
    cmake_parse_arguments(cc_test "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
    add_executable(${TARGET_NAME} ${cc_test_SRCS})
    target_link_libraries(${TARGET_NAME} ${cc_test_DEPS} gtest gtest_main)
    add_dependencies(${TARGET_NAME} ${cc_test_DEPS} gtest gtest_main)
    add_test(${TARGET_NAME} ${TARGET_NAME})
  endif()
endfunction(cc_test)

function(nv_library TARGET_NAME)
  if (WITH_GPU)
    set(options STATIC static SHARED shared)
    set(oneValueArgs "")
    set(multiValueArgs SRCS DEPS)
    cmake_parse_arguments(nv_library "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
    if(nv_library_SRCS)
      if (nv_library_SHARED OR nv_library_shared) # build *.so
        cuda_add_library(${TARGET_NAME} SHARED ${nv_library_SRCS})
      else()
          cuda_add_library(${TARGET_NAME} STATIC ${nv_library_SRCS})
      endif()
      if (nv_library_DEPS)
        add_dependencies(${TARGET_NAME} ${nv_library_DEPS})
      endif()
    else(nv_library_SRCS)
      if (nv_library_DEPS)
        merge_static_libs(${TARGET_NAME} ${nv_library_DEPS})
      else()
        message(FATAL "Please specify source file or library in nv_library.")
      endif()
    endif(nv_library_SRCS)
  endif()
endfunction(nv_library)

function(nv_binary TARGET_NAME)
  if (WITH_GPU)
    set(options "")
    set(oneValueArgs "")
    set(multiValueArgs SRCS DEPS)
    cmake_parse_arguments(nv_binary "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
    cuda_add_executable(${TARGET_NAME} ${nv_binary_SRCS})
    if(nv_binary_DEPS)
      target_link_libraries(${TARGET_NAME} ${nv_binary_DEPS})
      add_dependencies(${TARGET_NAME} ${nv_binary_DEPS})
    endif()
  endif()
endfunction(nv_binary)

function(nv_test TARGET_NAME)
  if (WITH_GPU AND WITH_TESTING)
    set(options "")
    set(oneValueArgs "")
    set(multiValueArgs SRCS DEPS)
    cmake_parse_arguments(nv_test "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
    cuda_add_executable(${TARGET_NAME} ${nv_test_SRCS})
    target_link_libraries(${TARGET_NAME} ${nv_test_DEPS} gtest gtest_main)
    add_dependencies(${TARGET_NAME} ${nv_test_DEPS} gtest gtest_main)
    add_test(${TARGET_NAME} ${TARGET_NAME})
  endif()
endfunction(nv_test)

set(GOPATH "${CMAKE_CURRENT_BINARY_DIR}/go")
file(MAKE_DIRECTORY ${GOPATH})

# Because api.go defines a GO wrapper to ops and tensor, it depends on
# both.  This implies that if any of tensor.{h,cc}, ops.{h,cu}, or
# api.go is changed, api need to be re-built.
# go_library(api
#   SRCS
#   api.go
#   DEPS
#   tensor # Because ops depend on tensor, this line is optional.
#   ops)
function(go_library TARGET_NAME)
  set(options OPTIONAL)
  set(oneValueArgs "")
  set(multiValueArgs SRCS DEPS)
  cmake_parse_arguments(go_library "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
  if (${go_library_OPTIONAL} STREQUAL "SHARED")
    set(BUILD_MODE "-buildmode=c-shared")
    if(APPLE)
      set(LIB_NAME "lib${TARGET_NAME}.dylib")
    else()
      set(LIB_NAME "lib${TARGET_NAME}.so")
    endif()
  else()
    set(BUILD_MODE "-buildmode=c-archive")
    set(LIB_NAME "lib${TARGET_NAME}.a")
  endif()
  add_custom_command(OUTPUT ${TARGET_NAME}_timestamp
    COMMAND env GOPATH=${GOPATH} ${CMAKE_Go_COMPILER} build ${BUILD_MODE}
    -o "${CMAKE_CURRENT_BINARY_DIR}/${LIB_NAME}"
    ${go_library_SRCS}
    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
  add_custom_target(${TARGET_NAME}_lib ALL DEPENDS ${TARGET_NAME}_timestamp ${go_library_DEPS})
  add_library(${TARGET_NAME} STATIC IMPORTED)
  set_property(TARGET ${TARGET_NAME} PROPERTY
    IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/${LIB_NAME}")
  add_dependencies(${TARGET_NAME} ${TARGET_NAME}_lib)
endfunction(go_library)

function(go_binary TARGET_NAME)
  set(options OPTIONAL)
  set(oneValueArgs "")
  set(multiValueArgs SRCS DEPS)
  cmake_parse_arguments(go_binary "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
  add_custom_command(OUTPUT ${TARGET_NAME}_timestamp
    COMMAND env GOPATH=${GOPATH} ${CMAKE_Go_COMPILER} build
    -o "${CMAKE_CURRENT_BINARY_DIR}/${TARGET_NAME}"
    ${go_library_SRCS}
    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
  add_custom_target(${TARGET_NAME} ALL DEPENDS ${TARGET_NAME}_timestamp ${go_binary_DEPS})
  install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${TARGET_NAME} DESTINATION bin)
endfunction(go_binary)

function(go_test TARGET_NAME)
  set(options OPTIONAL)
  set(oneValueArgs "")
  set(multiValueArgs SRCS DEPS)
  cmake_parse_arguments(go_test "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
  add_custom_command(OUTPUT ${TARGET_NAME}_timestamp
    COMMAND env GOPATH=${GOPATH} ${CMAKE_Go_COMPILER} test
    -c -o "${CMAKE_CURRENT_BINARY_DIR}/${TARGET_NAME}"
    ${go_test_SRCS}
    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
  add_custom_target(${TARGET_NAME} ALL DEPENDS ${TARGET_NAME}_timestamp ${go_test_DEPS})
  add_test(${TARGET_NAME} ${CMAKE_CURRENT_BINARY_DIR}/${TARGET_NAME})
endfunction(go_test)

# go_extern will download extern go project.
# go_extern(target_name extern_source)
# go_extern(go_redis github.com/hoisie/redis)
function(go_extern TARGET_NAME)
  add_custom_target(${TARGET_NAME} env GOPATH=${GOPATH} ${CMAKE_Go_COMPILER} get ${ARGN})
endfunction(go_extern)