# Copyright (C) 2012  W. Trevor King
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Declare variables describing package information.
#   http://www.gnu.org/software/make/manual/html_node/Setting.html
# The $(...) syntax references a variable's value.
#   http://www.gnu.org/software/make/manual/html_node/Reference.html
# You can override variables from the command line.  For example
#   $ make VERSION=2 dist
# will generate phys405-hw0-2.tar.gz
COURSE = phys405
PACKAGE = hw0
VERSION = 1
RELEASE = $(COURSE)-$(PACKAGE)-$(VERSION)
PROGRAM = hello_world

# Define the source files that will be distributed in the tarball
SOURCE = *.c COPYING Makefile README

# Define a list of object files needed to link PROGRAM
OBJECTS = $(PROGRAM).o

# You may want to link agains external libraries.  For example, to
# link against the system math library, use.
#   LIBS = -lm
LIBS =

# Define useful programs (this makes it easy to swap in alternates)
CP = cp
GREP = grep
MKDIR = mkdir
RM = rm
TAR = tar

# Declare targets that do not generate files of the same name.
#   http://www.gnu.org/software/make/manual/html_node/Phony-Targets.html
.PHONY: all help clean dist run print- printvars

# target: all - the default target
all: $(PROGRAM)

# target: help - display callable targets
# Use `grep` to search this file for target comments
help:
	$(GREP) '^# target:' [Mm]akefile

# target: clean - remove automatically generated files
clean:
	$(RM) -rf $(PROGRAM) *.o $(RELEASE)*

# target: dist - generate a tarball packaging the source
# Here, we move the source into a temporary release directory, tar the
# release directory, and remove the release directory.
dist:
	$(MKDIR) $(RELEASE)
	$(CP) -r $(SOURCE) $(RELEASE)
	$(TAR) -czf $(RELEASE).tar.gz $(RELEASE)
	$(RM) -rf $(RELEASE)

# target: hello_world - compile the hello_world program
# Use GCC to link the program from object files.
$(PROGRAM): $(OBJECTS)
	$(CC) $(LDFLAGS) -o $@ $^ $(LIBS)

# target: run - use the program for its intended purpose
# Here we just execute PROGRAM, but you could also use something like
#   run: $(PROGRAM) plot.gp
#     ./$(PROGRAM) > data
#     gnuplot plot.gp
# where plot.gp was a gnuplot script for plotting data generated by
# PROGRAM.
run: $(PROGRAM)
	./$(PROGRAM)

# Matching rule for compiling object files from C++ source
# There is an implicit rule for this in GNU make
#   http://www.gnu.org/software/make/manual/html_node/Catalogue-of-Rules.html
# but I redefine it here for clarity.
#
# CXX and CXXFLAGS have defaults defined by make
#   http://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html
# but they can also be come from the environment
#   http://www.gnu.org/software/make/manual/html_node/Environment.html
# for example, try
#    $ make CXX=/usr/local/bin/g++ CXXFLAGS=-Wall
%.o: %.cpp
	$(CXX) $(CXXFLAGS) -c $<

# Matching rule for compiling object files from C source
# The comments from the C++ rule above also apply here
%.o: %.c
	$(CC) $(CFLAGS) -c $<

# target: print-% - display a variable value (e.g. print-PROGRAMS)
# Take some of the mystery out of variable manipulation.  For example,
#   $ make print-hello_world_OBJECTS
# The `@` suppresses recipe echoing.  See
#   http://www.gnu.org/software/make/manual/html_node/Echoing.html
# The `info` function acts like the shell `echo` command.  See
#   http://www.gnu.org/software/make/manual/html_node/Make-Control-Functions.html
# For an explanation of $* and other special variables, see
#   http://www.gnu.org/software/make/manual/html_node/Automatic-Variables.html
print-%:
	@$(info $* = $($*))

# target: printvars - display all non-default variables
# .VARIBALES holds a list of all global variables.  See
#   http://www.gnu.org/software/make/manual/html_node/Special-Variables.html
# The functions---`sort`, `if`, `filter-out`, `origin`, `warning`, and
# `value`--- are discussed, respectively, here:
#   http://www.gnu.org/software/make/manual/html_node/Text-Functions.html#index-sort-580
#   http://www.gnu.org/software/make/manual/html_node/Conditional-Functions.html
#   http://www.gnu.org/software/make/manual/html_node/Text-Functions.html#index-filter_002dout-577
#   http://www.gnu.org/software/make/manual/html_node/Origin-Function.html
#   http://www.gnu.org/software/make/manual/html_node/Value-Function.html
printvars:
	@$(foreach V, \
		$(sort $(.VARIABLES)), \
		$(if \
			$(filter-out environment default automatic, \
				$(origin $V)), \
			$(info $V=$($V) (origin: $(origin $V), value: $(value $V))) \
			) \
		)