#!/usr/bin/make -f
# Copyright © 2013-2014 Luke Shumaker <lukeshu@sbcglobal.net>
# This work is free. You can redistribute it and/or modify it under the
# terms of the Do What The Fuck You Want To Public License, Version 2,
# as published by Sam Hocevar. See the COPYING file for more details.

# Install paths
DESTDIR ?=
MAVEN_LOCAL_REPO ?= ~/.m2

# Utilities
CP         = cp
ECHO       = echo
EXISTS     = test -e
FAIL       = exit 1
FIND       = find
INSTALL    = install
JAR        = jar
JAVA       = java
JAVAC      = javac
MKDIRS     = mkdir -p
PRINTF     = printf
RM         = rm -f
SED        = sed
TOUCH      = touch
XMLSTARLET = xml

JAVAC_FLAGS += $(if $(javac_source),-source $(javac_source))
JAVAC_FLAGS += $(if $(javac_target),-target $(javac_target))
JAVAC_FLAGS += $(if $(javac_encoding),-encoding $(javac_encoding))

# Detect information from POMs
pom_get = $(shell $(XMLSTARLET) sel -T -t $(foreach xpath,$1, -v '$(subst /,/_:,$(xpath))' -n) pom.xml)
plugin_conf = /project/build/plugins/plugin[./artifactId[text()="$1"]]/configuration/$2

artifactId      :=             $(call pom_get,/project/artifactId)
version         := $(firstword $(call pom_get,/project/version /project/parent/version) $(value version))
groupId         := $(firstword $(call pom_get,/project/groupId /project/parent/groupId))

sourceDirectory := $(firstword $(call pom_get,/project/build/sourceDirectory) $(value sourceDirectory) src/main/java     )
resources       := $(firstword $(call pom_get,/project/build/resources      ) $(value resources)       src/main/resources)

# The order of precidence with these isn't quite right, but it's rare that multiple are set.
javac_source    := $(firstword $(call pom_get,/project/properties/maven.compile.source /project/properties/maven.compiler.source $(call plugin_conf,maven-compiler-plugin,source)  ) $(value javac_source))
javac_target    := $(firstword $(call pom_get,/project/properties/maven.compile.target /project/properties/maven.compiler.target $(call plugin_conf,maven-compiler-plugin,target)  ) $(value javac_target))
javac_encoding  := $(firstword $(call pom_get,/project/properties/project.build.sourceEncoding                                   $(call plugin_conf,maven-compiler-plugin,encoding)) $(value javac_encoding))

basedir         := $(shell pwd)
project.basedir  = $(basedir)
subdirs          = $(patsubst %/pom.xml,%,$(wildcard */pom.xml))
targets          = pom $(if $(wildcard $(sourceDirectory) $(resources)),jar)

# Post-processing

inherit_vars = version sourceDirectory resources javac_source javac_target javac_encoding
$(foreach var,$(inherit_vars),$(eval $(var) = $($(var))))

$(if $(extra_makefiles),$(eval include $(extra_makefiles)))

subdirs := $(subdirs)
targets := $(targets)

################################################################################

dep_dir = $1 $(shell $(FIND) $1 2>/dev/null)
dep_optdir = $(shell $(FIND) $1 2>/dev/null)

all: PHONY \
    $(addprefix target/$(artifactId)-$(version).,$(targets)) \
    $(addsuffix /all,$(subdirs))

# generate-sources #############################################################

generate-sources: PHONY target/generated-sources
target/generated-sources:
	$(if $^,for dep in $^; do $(EXISTS) $$dep || { $(RM) -r $@; $(FAIL); }; done,$(MKDIRS) $@)
	$(TOUCH) $@

# generate-resources ###########################################################

generate-resources: PHONY target/generated-resources
target/generated-resources: \
    target/generated-resources/META-INF/maven/$(groupId)/$(artifactId)/pom.properties \
    target/generated-resources/META-INF/maven/$(groupId)/$(artifactId)/pom.xml
	for dep in $^; do $(EXISTS) $$dep || { $(RM) -r $@; $(FAIL); }; done
	$(TOUCH) $@

target/generated-resources/META-INF/maven/$(groupId)/$(artifactId)/pom.xml: pom.xml
	$(INSTALL) -Dm644 $< $@

# This is almost the default date format for locale=C, but the DOM is
# 0-padded instead of space-padded.
target/generated-resources/META-INF/maven/$(groupId)/$(artifactId)/pom.properties: pom.xml
	$(MKDIRS) $(@D)
	$(PRINTF) '#Generated by %s\n#%s\n\nversion=%s\ngroupId=%s\nartifactId=%s\n' \
		Make "$$(LC_ALL=C date '+%a %b %d %H:%M:%S %Z %Y')" '$(version)' '$(groupId)' '$(artifactId)' \
		> $@

# compile ######################################################################

compile: PHONY target/classes

# Maven puts `target/classes` in the classpath, but that's unnecessary
# here, as we don't do incremental/segmented compilation.
target/classes: \
    $(call dep_optdir,$(sourceDirectory) $(resources)) \
    $(call dep_dir,target/generated-sources target/generated-resources)
	$(RM) -r $@
	$(MKDIRS) $@
	$(FIND) $(wildcard $(resources) target/generated-resources) -mindepth 1 -maxdepth 1 -exec $(CP) -r {} $@ \; || { $(RM) -r $@; $(FAIL); } # process-resources
	$(FIND) $(wildcard $(sourceDirectory) target/generated-sources) -name '*.java' -exec $(JAVAC) $(JAVAC_FLAGS) -d $@ {} + || { $(RM) -r $@; $(FAIL); } # compile
	$(TOUCH) $@
	$(process-classes)

# package ######################################################################

package: PHONY \
    target/$(artifactId)-$(version).pom \
    target/$(artifactId)-$(version).jar

target/$(artifactId)-$(version).pom: pom.xml
	$(INSTALL) -Dm644 $< $@

target/$(artifactId)-$(version).jar: target/classes
	$(JAR) -cf $@ -C $< .

# install ######################################################################

mvndir = $(subst .,/,$(groupId))/$(artifactId)/$(version)

install: PHONY \
    $(addprefix $(DESTDIR)$(MAVEN_LOCAL_REPO)/$(mvndir)/$(artifactId)-$(version).,$(targets)) \
    $(addsuffix /install,$(subdirs))

$(DESTDIR)$(MAVEN_LOCAL_REPO)/$(mvndir)/%: target/%
	$(INSTALL) -Dm644 $< $@

# clean ########################################################################

clean: PHONY $(addsuffix /clean,$(subdirs))
	rm -rf target

# recurse ######################################################################

deps2jars = $(wildcard $(patsubst %/all,%/target/*.jar,$(filter $(addsuffix /all,$(subdirs)),$1)))
deps2classpath = $(shell $(ECHO) $(abspath $(call deps2jars,$1)) $(CLASSPATH) | $(SED) 'y/ /:/')

define recurse-rule
$1/%: PHONY $(addsuffix /all,$($1_deps))
	CLASSPATH='$$(call deps2classpath,$$^)' $(foreach var,$(inherit_vars),$(subst .,_,$(var))='$$(value $(var))') $$(MAKE) -C '$1' -f '$$(abspath $$(firstword $$(MAKEFILE_LIST)))' '$$*'
endef
$(foreach subdir,$(subdirs),$(eval $(call recurse-rule,$(subdir))))

# boilerplate ##################################################################

.PHONY: PHONY FORCE
.DELETE_ON_ERROR:
.SECONDARY: