CROSS_COMPILE ?=

TARGET_FILE ?= ftdi_gpio

CC = $(CROSS_COMPILE)gcc
CPP = $(CROSS_COMPILE)cpp
CHECK = cppcheck

SRC_DIR = src
OBJ_DIR = obj
BIN_DIR = bin
UNIT_TEST_SRC_DIR = test/unit
UNIT_TEST_OBJ_DIR = $(OBJ_DIR)/$(UNIT_TEST_SRC_DIR)

INCLUDES := inc

#Alpine Linux names libftdi libftdi1
ifneq "$(findstring Alpine,$(shell head -1 /etc/issue))" ""
INCLUDES += /usr/include/libftdi1
endif

ifneq "$(findstring $(MAKECMDGOALS), build_unit_test exec_unit_test)" ""
INCLUDES += test/inc
else
#Alpine Linux names libftdi libftdi1
ifneq "$(findstring Alpine,$(shell head -1 /etc/issue))" ""
LIBS := ftdi1
else
LIBS := ftdi
endif
endif

LD_FLAGS :=
C_FLAGS := -O0 -g -Wall -Wextra -Werror
CPP_FLAGS := $(addprefix -I, $(INCLUDES))
CHECK_CLAGS := --enable=all --template=gcc --error-exitcode=1 --suppress=missingIncludeSystem

C_SRCS = $(wildcard $(SRC_DIR)/*.c)
C_OBJS = $(patsubst $(SRC_DIR)%,$(OBJ_DIR)%,$(patsubst %.c,%.o,$(C_SRCS)))

UNIT_TEST_SRCS = $(wildcard $(UNIT_TEST_SRC_DIR)/*.c) $(filter-out %main.c,$(C_SRCS))
UNIT_TEST_OBJS = $(patsubst $(SRC_DIR)%,$(OBJ_DIR)%,$(patsubst $(UNIT_TEST_SRC_DIR)%,$(UNIT_TEST_OBJ_DIR)%,$(patsubst %.c,%.o,$(UNIT_TEST_SRCS))))

OBJS = $(C_OBJS)

TARGET = $(BIN_DIR)/$(TARGET_FILE)
UNIT_TEST_TARGET = $(BIN_DIR)/$(UNIT_TEST_SRC_DIR)/$(TARGET_FILE)

THIS_MAKEFILE := $(lastword $(MAKEFILE_LIST))

.PHONY: all
all: $(TARGET)

.PHONY: unit_test
build_unit_test: $(UNIT_TEST_TARGET)

.PHONY: unit_test
exec_unit_test: $(UNIT_TEST_TARGET)
	$(UNIT_TEST_TARGET)

.PHONY: check
check: $(C_SRCS)
	$(CHECK) $(CPP_FLAGS) $(CHECK_CLAGS) $(C_SRCS)

$(UNIT_TEST_TARGET): $(UNIT_TEST_OBJS) $(THIS_MAKEFILE)
	@mkdir -p $(BIN_DIR)/$(UNIT_TEST_SRC_DIR)
	$(CC) $(C_FLAGS) $(LD_FLAGS) $(UNIT_TEST_OBJS) $(addprefix -l,$(LIBS)) -o $@

$(TARGET): $(OBJS) $(THIS_MAKEFILE)
	@mkdir -p $(BIN_DIR)
	$(CC) $(C_FLAGS) $(LD_FLAGS) $(OBJS) $(addprefix -l,$(LIBS)) -o $@

.PRECIOUS: $(OBJ_DIR)/%.d
$(OBJ_DIR)/%.d: $(SRC_DIR)/%.c
	@mkdir -p $(OBJ_DIR)
	$(CPP) -MM -MF $@ -MP -MT $(patsubst %.d,%.o,$@) $(CPP_FLAGS) $(patsubst $(OBJ_DIR)/%.d,$(SRC_DIR)/%.c,$@)

.PRECIOUS: $(UNIT_TEST_OBJ_DIR)/%.d
$(UNIT_TEST_OBJ_DIR)/%.d: $(UNIT_TEST_SRC_DIR)/%.c
	@mkdir -p $(UNIT_TEST_OBJ_DIR)
	$(CPP) -MM -MF $@ -MP -MT $(patsubst %.d,%.o,$@) $(CPP_FLAGS) $(patsubst $(UNIT_TEST_OBJ_DIR)/%.d,$(UNIT_TEST_SRC_DIR)/%.c,$@)

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c $(OBJ_DIR)/%.d
	@mkdir -p $(OBJ_DIR)
	$(CC) -c $(CPP_FLAGS) $(C_FLAGS) $< -o $@

$(UNIT_TEST_OBJ_DIR)/%.o: $(UNIT_TEST_SRC_DIR)/%.c $(UNIT_TEST_OBJ_DIR)/%.d
	@mkdir -p $(UNIT_TEST_OBJ_DIR)
	$(CC) -c $(CPP_FLAGS) $(C_FLAGS) $< -o $@

.PHONY: clean
clean:
	rm -rf $(OBJS) $(patsubst %.o,%.d,$(OBJS)) $(TARGET)
	rm -rf $(UNIT_TEST_OBJS) $(patsubst %.o,%.d,$(UNIT_TEST_OBJS)) $(UNIT_TEST_TARGET)

ifneq ($(MAKECMDGOALS),clean)
-include $(patsubst %.o,%.d,$(OBJS))
endif