Good Makefile

# credits:
# https://www.youtube.com/watch?v=noBh17uxQ1E

# compiler and linker flags
CC        := g++
SRC_DIR   := src
BIN_DIR   := bin
BIN_EXE   := $(BIN_DIR)/main
OUTPUT    := $(if $(findstring Windows_NT, $(OS)), $(BIN_EXE).exe, $(BIN_EXE).out)
OBJ_DIR   := $(BIN_DIR)/obj
INC_DIRS  := -I$(SRC_DIR)
LIB_DIRS  :=
SRC_FILES := $(wildcard $(SRC_DIR)/*.cpp)
H_FILES   := $(wildcard $(SRC_DIR)/*.h)
OBJ_FILES := $(patsubst $(SRC_DIR)/%.cpp, $(OBJ_DIR)/%.o, $(SRC_FILES))
CPP_FLAGS := -std=c++17
LD_FLAGS  :=
MAKEFLAGS += -j8

# compile the object files and place them in their own directory
$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp $(H_FILES)
    $(CC) $(CPP_FLAGS) $(INC_DIRS) -c -o $@ $<

# link the object files together to create the final executable
$(OUTPUT): $(OBJ_FILES) Makefile
    $(CC) $(LIB_DIRS) $(LD_FLAGS) $(OBJ_FILES) -o $(OUTPUT)

# when we type make, compile and link the executable
all: $(OUTPUT)

# if we type 'make run' it will build and run the executable
run: $(OUTPUT)
    $(if $(findstring Windows_NT, $(OS)), cd bin && main.exe && cd .., cd bin && ./main.out && cd ..)

# if we type 'make clean' it will clean up all the object files and the executable
clean:
    $(if $(findstring Windows_NT, $(OS)), del bin\obj\*.o && del bin\main.exe, rm $(OBJ_DIR)/*.o && rm $(OUTPUT))