CURDIR		:= $(shell pwd)
BASEDIR		:= $(abspath $(dir $(CURDIR)))
PROJECT		?= git
PROJECT		:= $(strip $(PROJECT))

ERL_CXXFLAGS ?= $(shell erl -noshell -noinput -eval "io:format(\"-I~ts/erts-~ts/include -I~ts\", [code:root_dir(), erlang:system_info(version), code:lib_dir(erl_interface, include)]), halt(0).")
ERL_LDFLAGS  ?= $(shell erl -noshell -noinput -eval "io:format(\"-L~ts\", [code:lib_dir(erl_interface, lib)]), halt(0).")

ifneq ($(shell which g++),)
  CXX ?= g++
else ifneq ($(shell which clang++),)
  CXX ?= clang++
else
  CXX ?= g++
endif

DEBUG     ?= 0
NIF_DEBUG ?= $(DEBUG)
NIF_PRINT := $(if $(NIF_PRINT),-DNIF_DEBUG)
CXX_VSN   ?= $(shell $(CXX) --version | sed -n '1s/^[^0-9]\+\([0-9]\+\)\(.[0-9-]\)\+.*$$/\1/p')

ifeq ($(basename $(CXX)),g++)
  ifeq ($(shell expr $(CXX_VSN) \>= 13),1)
    C20_FEATURES=1
  endif
else ifeq ($(basename $(CXX)),clang++)
  ifeq ($(shell expr $(CXX_VSN) \>= 15),1)
    C20_FEATURES=1
  endif
endif

HAVE_FORMAT ?= $(C20_FEATURES)
HAVE_SRCLOC ?= $(C20_FEATURES)
HAVE_FMTLIB := $(shell pkg-config --cflags fmt)
FMTLIB_ARGS := -DFMT_HEADER_ONLY $(if $(HAVE_FMTLIB),$(HAVE_FMTLIB),-Ifmt/include) -Wno-array-bounds -Wno-stringop-overflow

CPPFLAGS += \
  $(if $(findstring $(HAVE_FORMAT),1),-DHAVE_FORMAT,$(FMTLIB_ARGS)) \
  $(if $(findstring $(HAVE_SRCLOC),1),-DHAVE_SRCLOC) \
  $(shell pkg-config --cflags libgit2)

# System type and C compiler/flags.

ifeq ($(NIF_DEBUG),0)
  OPTIMIZE = -O3 -DNDEBUG
else
  OPTIMIZE = -O0 -g
endif

CXXFLAGS   ?= -finline-functions -Wall -std=c++20

CXXFLAGS   += $(OPTIMIZE) -fPIC $(ERL_CXXFLAGS)
LDFLAGS    += $(ERL_LDFLAGS) -lei $(shell pkg-config --libs libgit2) -shared

UNAME_SYS  := $(shell uname -s)
ifeq ($(UNAME_SYS),Darwin)
  LDFLAGS  += -flat_namespace -undefined suppress
endif

SRC_DIR     = $(CURDIR)
SO_OUTPUT  ?= $(BASEDIR)/priv/$(PROJECT).so

SOURCES    := $(wildcard $(SRC_DIR)/*.cpp)
OBJECTS     = $(addsuffix .o, $(basename $(SOURCES)))

COMPILE_CPP = $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(NIF_PRINT) -c

# Targets

all: $(SO_OUTPUT)

clean:
	rm -f $(SO_OUTPUT) *.o

info:
	@echo CXX=$(CXX)
	@echo NIF_PRINT=$(NIF_PRINT)
	@echo NIF_DEBUG=$(NIF_DEBUG)
	@echo COMPILE_CPP=$(COMPILE_CPP)

$(SO_OUTPUT): $(OBJECTS)
	@mkdir -p $(BASEDIR)/priv/
	$(CXX) $(OBJECTS) $(LDFLAGS) -o $(SO_OUTPUT)

%.o: %.cpp $(wildcard *.hpp)
	@if [ -z $(findstring $(HAVE_FORMAT),1) ] && [ -z "$(HAVE_FMTLIB)"]; then \
	  echo "==> Updating fmt submodule"; \
		[ -z "$(shell git config --global safe.directory)" ] && git config --global --add safe.directory '*' || true; \
		git submodule update --init --recursive; \
	fi
	$(COMPILE_CPP) $(OUTPUT_OPTION) $<