# Copyright 2016 The Kubernetes Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Constants used throughout.
GENERATED_FILE_PREFIX := zz_generated.

# Code-generation logic.
#
# This stuff can be pretty tricky, and there's probably some corner cases that
# we don't handle well.  That said, here's a straightforward test to prove that
# the most common cases work.  Sadly, it is manual.
#
#     make clean
#     find . -name .make\* | xargs rm -f
#     find . -name zz_generated\* | xargs rm -f
#     # verify `find . -name zz_generated.deepcopy.go | wc -l` is 0
#     # verify `find . -name .make | wc -l` is 0
#
#     make nonexistent
#     # expect "No rule to make target"
#     # verify `find .make/ -type f | wc -l` has many files
#
#     make gen_deepcopy
#     # expect deepcopy-gen is built exactly once
#     # expect many files to be regenerated
#     # verify `find . -name zz_generated.deepcopy.go | wc -l` has files
#     make gen_deepcopy
#     # expect nothing to be rebuilt, finish in O(seconds)
#     touch pkg/api/types.go
#     make gen_deepcopy
#     # expect one file to be regenerated
#     make gen_deepcopy
#     # expect nothing to be rebuilt, finish in O(seconds)
#     touch cmd/libs/go2idl/deepcopy-gen/main.go
#     make gen_deepcopy
#     # expect deepcopy-gen is built exactly once
#     # expect many files to be regenerated
#     # verify `find . -name zz_generated.deepcopy.go | wc -l` has files
#     make gen_deepcopy
#     # expect nothing to be rebuilt, finish in O(seconds)
#
#     make gen_conversion
#     # expect conversion-gen is built exactly once
#     # expect many files to be regenerated
#     # verify `find . -name zz_generated.conversion.go | wc -l` has files
#     make gen_conversion
#     # expect nothing to be rebuilt, finish in O(seconds)
#     touch pkg/api/types.go
#     make gen_conversion
#     # expect one file to be regenerated
#     make gen_conversion
#     # expect nothing to be rebuilt, finish in O(seconds)
#     touch cmd/libs/go2idl/conversion-gen/main.go
#     make gen_conversion
#     # expect conversion-gen is built exactly once
#     # expect many files to be regenerated
#     # verify `find . -name zz_generated.conversion.go | wc -l` has files
#     make gen_conversion
#     # expect nothing to be rebuilt, finish in O(seconds)
#
#     make all
#     # expect it to build
#
#     make test
#     # expect it to pass
#
#     make clean
#     # verify `find . -name zz_generated.deepcopy.go | wc -l` is 0
#     # verify `find . -name .make | wc -l` is 0
#
#     make all WHAT=cmd/kube-proxy
#     # expect it to build
#
#     make clean
#     make test WHAT=cmd/kube-proxy
#     # expect it to pass

# This variable holds a list of every directory that contains Go files in this
# project.  Other rules and variables can use this as a starting point to
# reduce filesystem accesses.
ifeq ($(DBG_MAKEFILE),1)
    $(warning ***** finding all *.go dirs)
endif
ALL_GO_DIRS := $(shell             \
    find .                         \
        -not \(                    \
            \(                     \
                -path ./vendor -o  \
                -path ./_\* -o     \
                -path ./.\* -o     \
                -path ./docs -o    \
                -path ./examples   \
            \) -prune              \
        \)                         \
        -type f -name \*.go        \
        | sed 's|^./||'            \
        | xargs -n1 dirname        \
        | sort -u                  \
)

# The name of the make metadata file listing Go files.
GOFILES_META := gofiles.mk

# Establish a dependency between the deps file and the dir.  Whenever a dir
# changes (files added or removed) the deps file will be considered stale.
#
# The variable value was set in $(GOFILES_META) and included as part of the
# dependency management logic.
#
# This is looser than we really need (e.g. we don't really care about non *.go
# files or even *_test.go files), but this is much easier to represent.
#
# Because we 'sinclude' the deps file, it is considered for rebuilding, as part
# of make's normal evaluation.  If it gets rebuilt, make will restart.
#
# The '$(eval)' is needed because this has a different RHS for each LHS, and
# would otherwise produce results that make can't parse.
$(foreach dir, $(ALL_GO_DIRS), $(eval           \
    $(META_DIR)/$(dir)/$(GOFILES_META): $(dir)  \
))

# How to rebuild a deps file.  When make determines that the deps file is stale
# (see above), it executes this rule, and then re-loads the deps file.
#
# This is looser than we really need (e.g. we don't really care about test
# files), but this is MUCH faster than calling `go list`.
#
# We regenerate the output file in order to satisfy make's "newer than" rules,
# but we only need to rebuild targets if the contents actually changed.  That
# is what the .stamp file represents.
$(foreach dir, $(ALL_GO_DIRS), $(META_DIR)/$(dir)/$(GOFILES_META)):
	FILES=$$(ls $</*.go | grep --color=never -v $(GENERATED_FILE_PREFIX));  \
	mkdir -p $(@D);                                           \
	echo "gofiles__$< := $$(echo $${FILES})" >$@.tmp;         \
	cmp -s $@.tmp $@ || touch $@.stamp;                       \
	mv $@.tmp $@

# Include any deps files as additional Makefile rules.  This triggers make to
# consider the deps files for rebuild, which makes the whole
# dependency-management logic work.  'sinclude' is "silent include" which does
# not fail if the file does not exist.
$(foreach dir, $(ALL_GO_DIRS), $(eval            \
    sinclude $(META_DIR)/$(dir)/$(GOFILES_META)  \
))

# Generate a list of all files that have a `+k8s:` comment-tag.  This will be
# used to derive lists of files/dirs for generation tools.
ifeq ($(DBG_MAKEFILE),1)
    $(warning ***** finding all +k8s: tags)
endif
ALL_K8S_TAG_FILES := $(shell                             \
    find $(ALL_GO_DIRS) -maxdepth 1 -type f -name \*.go  \
        | xargs grep --color=never -l '^// *+k8s:'       \
)

#
# Deep-copy generation
#
# Any package that wants deep-copy functions generated must include a
# comment-tag in column 0 of one file of the form:
#     // +k8s:deepcopy-gen=<VALUE>
#
# The <VALUE> may be one of:
#     generate: generate deep-copy functions into the package
#     register: generate deep-copy functions and register them with a
#               scheme

# The result file, in each pkg, of deep-copy generation.
DEEPCOPY_BASENAME := $(GENERATED_FILE_PREFIX)deepcopy
DEEPCOPY_FILENAME := $(DEEPCOPY_BASENAME).go

# The tool used to generate deep copies.
DEEPCOPY_GEN := $(BIN_DIR)/deepcopy-gen

# Find all the directories that request deep-copy generation.
ifeq ($(DBG_MAKEFILE),1)
    $(warning ***** finding all +k8s:deepcopy-gen tags)
endif
DEEPCOPY_DIRS := $(shell                               \
    grep --color=never -l '+k8s:deepcopy-gen=' $(ALL_K8S_TAG_FILES)  \
        | xargs -n1 dirname                            \
        | sort -u                                      \
)
DEEPCOPY_FILES := $(addsuffix /$(DEEPCOPY_FILENAME), $(DEEPCOPY_DIRS))

# This rule aggregates the set of files to generate and then generates them all
# in a single run of the tool.
.PHONY: gen_deepcopy
gen_deepcopy: $(DEEPCOPY_FILES)
	if [[ -f $(META_DIR)/$(DEEPCOPY_GEN).todo ]]; then                  \
	    ./hack/run-in-gopath.sh $(DEEPCOPY_GEN)                         \
	        -i $$(cat $(META_DIR)/$(DEEPCOPY_GEN).todo | paste -sd, -)  \
	        --bounding-dirs $(PRJ_SRC_PATH)                             \
	        -O $(DEEPCOPY_BASENAME);                                    \
	fi

# For each dir in DEEPCOPY_DIRS, this establishes a dependency between the
# output file and the input files that should trigger a rebuild.
#
# Note that this is a deps-only statement, not a full rule (see below).  This
# has to be done in a distinct step because wildcards don't work in static
# pattern rules.
#
# The '$(eval)' is needed because this has a different RHS for each LHS, and
# would otherwise produce results that make can't parse.
#
# We depend on the $(GOFILES_META).stamp to detect when the set of input files
# has changed.  This allows us to detect deleted input files.
$(foreach dir, $(DEEPCOPY_DIRS), $(eval                                    \
    $(dir)/$(DEEPCOPY_FILENAME): $(META_DIR)/$(dir)/$(GOFILES_META).stamp  \
                                   $(gofiles__$(dir))                      \
))

# Unilaterally remove any leftovers from previous runs.
$(shell rm -f $(META_DIR)/$(DEEPCOPY_GEN)*.todo)

# How to regenerate deep-copy code.  This is a little slow to run, so we batch
# it up and trigger the batch from the 'generated_files' target.
$(DEEPCOPY_FILES): $(DEEPCOPY_GEN)
	echo $(PRJ_SRC_PATH)/$(@D) >> $(META_DIR)/$(DEEPCOPY_GEN).todo

# This calculates the dependencies for the generator tool, so we only rebuild
# it when needed.  It is PHONY so that it always runs, but it only updates the
# file if the contents have actually changed.  We 'sinclude' this later.
.PHONY: $(META_DIR)/$(DEEPCOPY_GEN).mk
$(META_DIR)/$(DEEPCOPY_GEN).mk:
	mkdir -p $(@D);                                        \
	(echo -n "$(DEEPCOPY_GEN): ";                          \
	 DIRECT=$$(go list -e -f '{{.Dir}} {{.Dir}}/*.go'      \
	     ./cmd/libs/go2idl/deepcopy-gen);                  \
	 INDIRECT=$$(go list -e                                \
	     -f '{{range .Deps}}{{.}}{{"\n"}}{{end}}'          \
	     ./cmd/libs/go2idl/deepcopy-gen                    \
	     | grep --color=never "^$(PRJ_SRC_PATH)"           \
	     | sed 's|^$(PRJ_SRC_PATH)|./|'                    \
	     | xargs go list -e -f '{{.Dir}} {{.Dir}}/*.go');  \
	 echo $$DIRECT $$INDIRECT                              \
	     | sed 's/ / \\=,/g'                               \
	     | tr '=,' '\n\t';                                 \
	) | sed "s|$$(pwd -P)/||" > $@.tmp;                    \
	cmp -s $@.tmp $@ || cat $@.tmp > $@ && rm -f $@.tmp

# Include dependency info for the generator tool.  This will cause the rule of
# the same name to be considered and if it is updated, make will restart.
sinclude $(META_DIR)/$(DEEPCOPY_GEN).mk

# How to build the generator tool.  The deps for this are defined in
# the $(DEEPCOPY_GEN).mk, above.
#
# A word on the need to touch: This rule might trigger if, for example, a
# non-Go file was added or deleted from a directory on which this depends.
# This target needs to be reconsidered, but Go realizes it doesn't actually
# have to be rebuilt.  In that case, make will forever see the dependency as
# newer than the binary, and try to rebuild it over and over.  So we touch it,
# and make is happy.
$(DEEPCOPY_GEN):
	hack/make-rules/build.sh cmd/libs/go2idl/deepcopy-gen
	touch $@

#
# Conversion generation
#
# Any package that wants conversion functions generated must include one or
# more comment-tags in any .go file, in column 0, of the form:
#     // +k8s:conversion-gen=<CONVERSION_TARGET_DIR>
#
# The CONVERSION_TARGET_DIR is a project-local path to another directory which
# should be considered when evaluating peer types for conversions.  Types which
# are found in the source package (where conversions are being generated)
# but do not have a peer in one of the target directories will not have
# conversions generated.
#
# TODO: it might be better in the long term to make peer-types explicit in the
# IDL.

# The result file, in each pkg, of conversion generation.
CONVERSION_BASENAME := $(GENERATED_FILE_PREFIX)conversion
CONVERSION_FILENAME := $(CONVERSION_BASENAME).go

# The tool used to generate conversions.
CONVERSION_GEN := $(BIN_DIR)/conversion-gen

# The name of the make metadata file controlling conversions.
CONVERSIONS_META := conversions.mk

# All directories that request any form of conversion generation.
ifeq ($(DBG_MAKEFILE),1)
    $(warning ***** finding all +k8s:conversion-gen tags)
endif
CONVERSION_DIRS := $(shell                                \
    grep --color=never '^// *+k8s:conversion-gen=' $(ALL_K8S_TAG_FILES) \
        | cut -f1 -d:                                     \
        | xargs -n1 dirname                               \
        | sort -u                                         \
)

CONVERSION_FILES := $(addsuffix /$(CONVERSION_FILENAME), $(CONVERSION_DIRS))

# This rule aggregates the set of files to generate and then generates them all
# in a single run of the tool.
.PHONY: gen_conversion
gen_conversion: $(CONVERSION_FILES)
	if [[ -f $(META_DIR)/$(CONVERSION_GEN).todo ]]; then                  \
	    ./hack/run-in-gopath.sh $(CONVERSION_GEN)                         \
	        -i $$(cat $(META_DIR)/$(CONVERSION_GEN).todo | paste -sd, -)  \
	        -O $(CONVERSION_BASENAME);                                    \
	fi

# Establish a dependency between the deps file and the dir.  Whenever a dir
# changes (files added or removed) the deps file will be considered stale.
#
# This is looser than we really need (e.g. we don't really care about non *.go
# files or even *_test.go files), but this is much easier to represent.
#
# Because we 'sinclude' the deps file, it is considered for rebuilding, as part
# of make's normal evaluation.  If it gets rebuilt, make will restart.
#
# The '$(eval)' is needed because this has a different RHS for each LHS, and
# would otherwise produce results that make can't parse.
$(foreach dir, $(CONVERSION_DIRS), $(eval           \
    $(META_DIR)/$(dir)/$(CONVERSIONS_META): $(dir)  \
))

# How to rebuild a deps file.  When make determines that the deps file is stale
# (see above), it executes this rule, and then re-loads the deps file.
#
# This is looser than we really need (e.g. we don't really care about test
# files), but this is MUCH faster than calling `go list`.
#
# We regenerate the output file in order to satisfy make's "newer than" rules,
# but we only need to rebuild targets if the contents actually changed.  That
# is what the .stamp file represents.
$(foreach dir, $(CONVERSION_DIRS), $(META_DIR)/$(dir)/$(CONVERSIONS_META)):
	TAGS=$$(grep --color=never -h '^// *+k8s:conversion-gen=' $</*.go  \
	    | cut -f2- -d=                                    \
	    | sed 's|$(PRJ_SRC_PATH)/||');                    \
	mkdir -p $(@D);                                       \
	echo "conversions__$< := $$(echo $${TAGS})" >$@.tmp;  \
	cmp -s $@.tmp $@ || touch $@.stamp;                   \
	mv $@.tmp $@

# Include any deps files as additional Makefile rules.  This triggers make to
# consider the deps files for rebuild, which makes the whole
# dependency-management logic work.  'sinclude' is "silent include" which does
# not fail if the file does not exist.
$(foreach dir, $(CONVERSION_DIRS), $(eval            \
    sinclude $(META_DIR)/$(dir)/$(CONVERSIONS_META)  \
))

# For each dir in CONVERSION_DIRS, this establishes a dependency between the
# output file and the input files that should trigger a rebuild.
#
# The variable value was set in $(GOFILES_META) and included as part of the
# dependency management logic.
#
# Note that this is a deps-only statement, not a full rule (see below).  This
# has to be done in a distinct step because wildcards don't work in static
# pattern rules.
#
# The '$(eval)' is needed because this has a different RHS for each LHS, and
# would otherwise produce results that make can't parse.
#
# We depend on the $(GOFILES_META).stamp to detect when the set of input files
# has changed.  This allows us to detect deleted input files.
$(foreach dir, $(CONVERSION_DIRS), $(eval                                    \
    $(dir)/$(CONVERSION_FILENAME): $(META_DIR)/$(dir)/$(GOFILES_META).stamp  \
                                   $(gofiles__$(dir))                        \
))

# For each dir in CONVERSION_DIRS, for each target in $(conversions__$(dir)),
# this establishes a dependency between the output file and the input files
# that should trigger a rebuild.
#
# The variable value was set in $(GOFILES_META) and included as part of the
# dependency management logic.
#
# Note that this is a deps-only statement, not a full rule (see below).  This
# has to be done in a distinct step because wildcards don't work in static
# pattern rules.
#
# The '$(eval)' is needed because this has a different RHS for each LHS, and
# would otherwise produce results that make can't parse.
#
# We depend on the $(GOFILES_META).stamp to detect when the set of input files
# has changed.  This allows us to detect deleted input files.
$(foreach dir, $(CONVERSION_DIRS),                                               \
    $(foreach tgt, $(conversions__$(dir)), $(eval                                \
        $(dir)/$(CONVERSION_FILENAME): $(META_DIR)/$(tgt)/$(GOFILES_META).stamp  \
                                       $(gofiles__$(tgt))                        \
    ))                                                                           \
)

# Unilaterally remove any leftovers from previous runs.
$(shell rm -f $(META_DIR)/$(CONVERSION_GEN)*.todo)

# How to regenerate conversion code.  This is a little slow to run, so we batch
# it up and trigger the batch from the 'generated_files' target.
$(CONVERSION_FILES): $(CONVERSION_GEN)
	echo $(PRJ_SRC_PATH)/$(@D) >> $(META_DIR)/$(CONVERSION_GEN).todo

# This calculates the dependencies for the generator tool, so we only rebuild
# it when needed.  It is PHONY so that it always runs, but it only updates the
# file if the contents have actually changed.  We 'sinclude' this later.
.PHONY: $(META_DIR)/$(CONVERSION_GEN).mk
$(META_DIR)/$(CONVERSION_GEN).mk:
	mkdir -p $(@D);                                        \
	(echo -n "$(CONVERSION_GEN): ";                        \
	 DIRECT=$$(go list -e -f '{{.Dir}} {{.Dir}}/*.go'      \
	     ./cmd/libs/go2idl/conversion-gen);                \
	 INDIRECT=$$(go list -e                                \
	     -f '{{range .Deps}}{{.}}{{"\n"}}{{end}}'          \
	     ./cmd/libs/go2idl/conversion-gen                  \
	     | grep --color=never "^$(PRJ_SRC_PATH)"           \
	     | sed 's|^$(PRJ_SRC_PATH)|./|'                    \
	     | xargs go list -e -f '{{.Dir}} {{.Dir}}/*.go');  \
	 echo $$DIRECT $$INDIRECT                              \
	     | sed 's/ / \\=,/g'                               \
	     | tr '=,' '\n\t';                                 \
	) | sed "s|$$(pwd -P)/||" > $@.tmp;                    \
	cmp -s $@.tmp $@ || cat $@.tmp > $@ && rm -f $@.tmp

# Include dependency info for the generator tool.  This will cause the rule of
# the same name to be considered and if it is updated, make will restart.
sinclude $(META_DIR)/$(CONVERSION_GEN).mk

# How to build the generator tool.  The deps for this are defined in
# the $(CONVERSION_GEN).mk, above.
#
# A word on the need to touch: This rule might trigger if, for example, a
# non-Go file was added or deleted from a directory on which this depends.
# This target needs to be reconsidered, but Go realizes it doesn't actually
# have to be rebuilt.  In that case, make will forever see the dependency as
# newer than the binary, and try to rebuild it over and over.  So we touch it,
# and make is happy.
$(CONVERSION_GEN):
	hack/make-rules/build.sh cmd/libs/go2idl/conversion-gen
	touch $@

# This rule collects all the generated file sets into a single dep, which is
# defined BELOW the *_FILES variables and leaves higher-level rules clean.
# Top-level rules should depend on this to ensure generated files are rebuilt.
.PHONY: generated_files
generated_files: gen_deepcopy gen_conversion

# Remove all auto-generated artifacts.
#
# Example:
#   make clean_generated
.PHONY: clean_generated
clean_generated:
	find . -type f -name $(GENERATED_FILE_PREFIX)\* | xargs rm -f