###############################################################################
# Uncomment for debugging
# DEBUG := 1
# Pretty build
# Q ?= @

CXX := g++
PYTHON := python
NVCC := /usr/local/cuda/bin/nvcc

# PYTHON Header path
PYTHON_HEADER_DIR := $(shell $(PYTHON) -c 'from distutils.sysconfig import get_python_inc; print(get_python_inc())')
PYTORCH_INCLUDES := $(shell $(PYTHON) -c 'from torch.utils.cpp_extension import include_paths; [print(p) for p in include_paths()]')
PYTORCH_LIBRARIES := $(shell $(PYTHON) -c 'from torch.utils.cpp_extension import library_paths; [print(p) for p in library_paths()]')

# CUDA ROOT DIR that contains bin/ lib64/ and include/
# CUDA_DIR := /usr/local/cuda
CUDA_DIR := $(shell $(PYTHON) -c 'from torch.utils.cpp_extension import _find_cuda_home; print(_find_cuda_home())')

INCLUDE_DIRS := ./ $(CUDA_DIR)/include

INCLUDE_DIRS += $(PYTHON_HEADER_DIR)
INCLUDE_DIRS += $(PYTORCH_INCLUDES)

# Custom (MKL/ATLAS/OpenBLAS) include and lib directories.
# Leave commented to accept the defaults for your choice of BLAS
# (which should work)!
# BLAS_INCLUDE := /path/to/your/blas
# BLAS_LIB := /path/to/your/blas

###############################################################################
SRC_DIR := ./src
OBJ_DIR := ./objs
CPP_SRCS := $(wildcard $(SRC_DIR)/*.cpp)
CU_SRCS := $(wildcard $(SRC_DIR)/*.cu)
OBJS := $(patsubst $(SRC_DIR)/%.cpp,$(OBJ_DIR)/%.o,$(CPP_SRCS))
CU_OBJS := $(patsubst $(SRC_DIR)/%.cu,$(OBJ_DIR)/cuda/%.o,$(CU_SRCS))
STATIC_LIB := $(OBJ_DIR)/libmake_pytorch.a

# CUDA architecture setting: going with all of them.
# For CUDA < 6.0, comment the *_50 through *_61 lines for compatibility.
# For CUDA < 8.0, comment the *_60 and *_61 lines for compatibility.
CUDA_ARCH :=	-gencode arch=compute_61,code=sm_61 \
		-gencode arch=compute_61,code=compute_61 \
		-gencode arch=compute_52,code=sm_52

# We will also explicitly add stdc++ to the link target.
LIBRARIES += stdc++ cudart c10 caffe2 torch torch_python caffe2_gpu

# Debugging
ifeq ($(DEBUG), 1)
	COMMON_FLAGS += -DDEBUG -g -O0
	# https://gcoe-dresden.de/reaching-the-shore-with-a-fog-warning-my-eurohack-day-4-morning-session/
	NVCCFLAGS += -g -G # -rdc true
else
	COMMON_FLAGS += -DNDEBUG -O3
endif

WARNINGS := -Wall -Wno-sign-compare -Wcomment

INCLUDE_DIRS += $(BLAS_INCLUDE)

# Automatic dependency generation (nvcc is handled separately)
CXXFLAGS += -MMD -MP

# Complete build flags.
COMMON_FLAGS += $(foreach includedir,$(INCLUDE_DIRS),-I$(includedir)) \
	     -DTORCH_API_INCLUDE_EXTENSION_H -D_GLIBCXX_USE_CXX11_ABI=0
CXXFLAGS += -pthread -fPIC -fwrapv -std=c++11 $(COMMON_FLAGS) $(WARNINGS)
NVCCFLAGS += -std=c++11 -ccbin=$(CXX) -Xcompiler -fPIC $(COMMON_FLAGS)

all: $(STATIC_LIB)
	$(PYTHON) setup.py build
	@ mv build/lib.linux-x86_64-3.6/StructuralLosses ..
	@ mv build/lib.linux-x86_64-3.6/*.so ../StructuralLosses/
	@- $(RM) -rf $(OBJ_DIR) build objs

$(OBJ_DIR):
	@ mkdir -p $@
	@ mkdir -p $@/cuda

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp | $(OBJ_DIR)
	@ echo CXX $<
	$(Q)$(CXX) $< $(CXXFLAGS) -c -o $@

$(OBJ_DIR)/cuda/%.o: $(SRC_DIR)/%.cu | $(OBJ_DIR)
	@ echo NVCC $<
	$(Q)$(NVCC) $(NVCCFLAGS) $(CUDA_ARCH) -M $< -o ${@:.o=.d} \
		-odir $(@D)
	$(Q)$(NVCC) $(NVCCFLAGS) $(CUDA_ARCH) -c $< -o $@

$(STATIC_LIB): $(OBJS) $(CU_OBJS) | $(OBJ_DIR)
	$(RM) -f $(STATIC_LIB)
	$(RM) -rf build dist
	@ echo LD -o $@
	ar rc $(STATIC_LIB) $(OBJS) $(CU_OBJS)

clean:
	@- $(RM) -rf $(OBJ_DIR) build dist ../StructuralLosses