# Load the configure script variables
-include configure.mk

##
## Directories
##

# Structure:
#  gray - top level
#  ├── src - source code
#  ├── doc - documentation
#  └── build - build artifacts
#      ├── bin - binaries
#      ├── lib - libraries
#      └── obj - objects
SRCDIR   = src
BUILDDIR = build
SHAREDIR = build/share
BINDIR   = build/bin
LIBDIR   = build/lib
OBJDIR   = build/obj

PREFIX ?= /usr/bin

# Directories that need to be created
DIRS = $(BINDIR) $(OBJDIR) $(LIBDIR) $(SHAREDIR)

##
## Files
##

# All Fortran source files
SOURCES = $(wildcard $(SRCDIR)/*.f90)

# All Generated makefiles describing object dependencies
OBJECTS = $(patsubst $(SRCDIR)/%.f90,$(OBJDIR)/%.o,$(SOURCES))

# Generated makefiles describing object dependencies
DEPS = $(OBJECTS:o=d)

# Fortran modules to be bundled into libraries
MODULES = $(filter-out $(OBJDIR)/main%,$(OBJECTS))

# Build outputs
GRAY      = $(BINDIR)/gray
LIBGRAY   = $(LIBDIR)/libgray
BINARIES  = $(GRAY)
LIBRARIES = $(LIBGRAY).so

##
## Git information (used in the version string)
##

# Short hash of the latest commit
GIT_REV   ?= $(shell git rev-parse --short HEAD)

# Whether the worktree and the latest commit differs
GIT_DIRTY ?= $(shell test -n "$$(git status --porcelain)" && echo "-dirty")

##
## Fortran compiler and flags
##

# Note: can't use ?= for FC because GNU Make defaults to f77
FC        = gfortran
LD        = gfortran
FFLAGS   += -O3 -J$(OBJDIR) -ffree-line-length-none
CPPFLAGS += -DREVISION=\"$(GIT_REV)$(GIT_DIRTY)\" -DPREFIX=\"$(PREFIX)\"

# Static build options
ifdef STATIC
LIBRARIES := $(LIBRARIES:so=a)
LDFLAGS += -static
endif

# Debug build options
ifdef DEBUG
FFLAGS += -ggdb -O0 -Wall -Wunused-parameter
# Tricks to detect uninitialised memory
FFLAGS += -finit-integer=7777777 -finit-real=snan -ffpe-trap=invalid
endif

##
## Targets
##

.PHONY: all clean install docs

all: $(BINARIES) $(LIBRARIES) docs

# Remove all generated files
clean:
	rm -r $(BUILDDIR)

# Install libraries, binaries and documentation
install: $(BINARIES) $(LIBRARIES) $(SHAREDIR)/gray.1
	install -Dm555 -t $(PREFIX)/bin $(BINDIR)/*
	install -Dm555 -t $(PREFIX)/lib $(LIBDIR)/*
	install -Dm644 -t $(PREFIX)/share/doc $(SHAREDIR)/doc/manual.*
	install -Dm644 -t $(PREFIX)/share/doc/res $(SHAREDIR)/doc/res/*
	install -Dm644 -t $(PREFIX)/share/man/man1 $(SHAREDIR)/*.1

# GRAY binary
$(GRAY): $(shell ./depend $(OBJDIR)/main.o) | $(BINDIR)
	$(LD) $(LDFLAGS) -o '$@' $^

# GRAY shared library
$(LIBGRAY).so: $(MODULES) | $(LIBDIR)
	$(LD) -shared $(LDFLAGS) -o '$@' $^

# GRAY static library
$(LIBGRAY).a($(MODULES)): | $(LIBDIR)
$(LIBGRAY).a: $(LIBGRAY).a($(MODULES))

# All documentation
docs: | $(SHAREDIR)
	+make -C doc
	cp -t $(SHAREDIR) -r doc/build/*

# Generated man pages
$(SHAREDIR)/gray.1: $(GRAY) doc/gray.1 | $(SHAREDIR)
	help2man '$<' -i doc/gray.1 -N -n 'beam-tracing code for EC waves' > '$@'

# Visualise the dependency graph
# Note: requires makefile2graph and graphviz
graph.svg: Makefile
	make -Bdn                                               \
	| make2graph -b                                         \
	| awk -F'( -> )| ;|[[]' '                               \
		(/label/ && !/(\.o|bin\/gray)/) {bad[$$1]=1; next}    \
	  /->/ {if (bad[$$1] || bad[$$2]) next}                 \
		{print $$0}'                                          \
	| sed 's/label/fontsize=30,label/g; s/\.o//'            \
	| dot -Tsvg -o '$@'

##
## Generic rules
##

# Rebuild everything if the makefile changed
.EXTRA_PREREQS += Makefile

# Automatic generation of the Fortran prerequisites
# Note 1: this is needed because gfortran -M flag doesn't properly work;
# Note 2: this assumes matching module/file names and no circular
#         dependencies (ie. the dependency graph is a DAG);
$(OBJDIR)/%.d: $(SRCDIR)/%.f90 | $(OBJDIR)
	@printf '$(@:d=o): $< \\\n' > '$@'
	@grep -v 'use iso_' '$<' | \
	 sed -n 's@^[^!].*use \([^,]\+\),.*@$(OBJDIR)/\1.o \\@p' | \
	 sort -u >> '$@'

# Load the generated rules
include $(DEPS)

# Compile a generic Fortran source
$(OBJDIR)/%.o: $(SRCDIR)/%.f90 | $(OBJDIR)
	$(FC) -cpp $(CPPFLAGS) $(FFLAGS) -c '$<' -o '$@'

# Create directories
$(DIRS):
	mkdir -p '$@'