#############GUIDE LIST##########################################
#   G1.     CC:                                                 #
#               Flag to mention the C compiler to used.         #
#                                                               #
#   G2.     CFLAGS:                                             #
#           Flag to specify the option for C compiler.          #
#                                                               #
#   G3.     OUTPUT_OPTION:                                      #
#               Tells compiler(mainly gcc or clang) to find     #
#               the dependencies(include header file) of src    #
#               file and add those to *.d files. This is a      #
#               easy workaround for G12.                        #
#                                                               #
#   G4.     CXX:                                                #
#               Flag to mention the C++ compiler to used.       #
#                                                               #
#   G5.     CXXFLAGS:                                           #
#               Flag to specify the option for C++ compiler.    #
#                                                               #
#   G6.     EXE_NAME:                                           #
#               Name of the executable to be created.           #
#                                                               #
#   G7.     SOURCE:                                             #
#               All the source to be used for compilation.      #
#                                                               #
#   G8.     OBJS:                                               #
#               All the object file for linking.                #
#                                                               #
#   G9.     DEPS:                                               #
#               All the dependencies information file.          #
#                                                               #
#   G10.    -include                                            #
#               Tells GNU make to include all the file to       #
#               specify dependencies. Healthy replacment of     #
#               G12.                                            #
#                                                               #
#   G11.    "Mentioned below"                                   #
#                                                               #
#   G12.    "Mentioned below"                                   #
#                                                               #
#   G13.    "Mentioned below"                                   #
#                                                               #
#   G14.    "Mentioned below"                                   #
#################################################################

#include Makefile.config

#Flags
# C program
CC                              = gcc
CFLAGS                          = -g
OUTPUT_OPTION                   = -MMD -MP -o $@
SHARED_LIBRARY_EXTENSION        = so  
SHARED_LIBRARY_FLAG             = -shared

# C++ program
#CXX         = g++
#CXXFLAGS   = -g

#Variables
EXE_NAME    = exe                       #Executable name.
SOURCE      = $(wildcard *.c)           #Source files.
OBJS        = $(SOURCE:.c=.o)           #Object files.
DEPS        = $(SOURCE:.c:.d)           #dependencies (To know the include files used in src)
-include      ${DEPS}
LIB         = lib
# OR can provide name of the file individually.
# The above for files present in the same directory as this
# files is present.
# 
# .d files look like a part of Makefile.
# and it IS the part of Makefile.


##G11.
#####RULES IN MAKEFILE###################################
#   ruleName: "files that are dependencies"             #
#               "Specify the commands to be executed"   #
#                                                       #
#       These are the rules that Makefile uses          #
#       to do the operations, as a build tool.          #
#########################################################


#Executables and library with dependencies

${EXE_NAME}: ${OBJS}
                ${CC} ${OJBS} -o ${EXE_NAME}


##G12.
#####SOURCE FILE DEPENDENT ON HEADER FILE################
#   "src or obj file": "header file"                    #
#            for exe -> src.o: header.h                 #
#                                                       #
#       If the src file of the given header file is     #
#       modified then, this specification ensures       #
#       the compilation of that source file if any      #
#       change is done.                                 #
#########################################################


#Friendly help rule.
help:
        -@echo "Customise the help rule to print help log."


##G13.
#######HIDING AND SKIPPING COMMANDS##########################
# -@ Tells the GNU make to not print the command before     #
#   executing it and enable to skip the command if it       #
#   failed to compile, as make stop if any command fails.   #
#############################################################


#Building the Static library.
${LIB}: ${OBJS}
        ar cr ${LIB}.a ${OBJS}

#Shorthand of doing the above same thing
${LIB}: ${LIB}(${OBJS})


#This link is about creating and using shared library
#https://www.cprogramming.com/tutorial/shared-libraries-linux-gcc.html

#Bulding the dynamic library.
${LIB}.${SHARED_LIBRARY_EXTENSION}: ${OBJS}
        ${CC} ${SHARED_LIBRARY_FLAG} -o $@ $^

##G14.
###MEANING OF $@ AND $^ SYMBOLS ON ABOVE RULE####################
#       $@ -> Replacing itself with rule under which            #
#             its written.                                      #
#       $^ -> Replacing itself with dependencies of rule.       #
#################################################################


#Rules for cleaning.
clean:
        -@rm -f ${OBJS}

realclean: clean
        -@rm -f ${LIB}