Makefile.generated_files

# 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.

# Don't allow users to call this directly.  There are too many variables this
# assumes to inherit from the main Makefile.  This is not a user-facing file.
ifeq ($(CALLED_FROM_MAIN_MAKEFILE),)
    $(error Please use the main Makefile, e.g. `make generated_files`)
endif

# Don't allow an implicit 'all' rule.  This is not a user-facing file.
ifeq ($(MAKECMDGOALS),)
    $(error This Makefile requires an explicit rule to be specified)
endif

ifeq ($(DBG_MAKEFILE),1)
    $(warning ***** starting Makefile.generated_files for goal(s) "$(MAKECMDGOALS)")
    $(warning ***** $(shell date))
endif


# It's necessary to set this because some environments don't link sh -> bash.
SHELL := /bin/bash

# This rule collects all the generated file sets into a single rule.  Other
# rules should depend on this to ensure generated files are rebuilt.
.PHONY: generated_files
generated_files: gen_deepcopy gen_defaulter gen_conversion gen_openapi

# 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                                                   \
    hack/make-rules/helpers/cache_go_dirs.sh $(META_DIR)/all_go_dirs.mk  \
)

# The name of the metadata file which lists *.go files in each pkg.
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 $@
# This is required to fill in the DAG, since some cases (e.g. 'make clean all')
# will reference the .stamp file when it doesn't exist.  We don't need to
# rebuild it in that case, just keep make happy.
$(foreach dir, $(ALL_GO_DIRS),  \
    $(META_DIR)/$(dir)/$(GOFILES_META).stamp):

# 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                                          \
        | LC_ALL=C 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)                         \
	        --v $(KUBE_VERBOSE)                                         \
	        --logtostderr                                               \
	        -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)
	mkdir -p $$(dirname $(META_DIR)/$(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=$$(go list -f '{{.Dir}} {{.Dir}}/*.go'         \
	     ./cmd/libs/go2idl/deepcopy-gen);                  \
	 INDIRECT=$$(go list                                   \
	     -f '{{range .Deps}}{{.}}{{"\n"}}{{end}}'          \
	     ./cmd/libs/go2idl/deepcopy-gen                    \
	     | grep --color=never "^$(PRJ_SRC_PATH)"           \
	     | sed 's|^$(PRJ_SRC_PATH)|./|'                    \
	     | xargs go list -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 $@

#
# Defaulter generation
#
# Any package that wants defaulter functions generated must include a
# comment-tag in column 0 of one file of the form:
#     // +k8s:defaulter-gen=<VALUE>
#
# The <VALUE> depends on context:
#     on types:
#       true:  always generate a defaulter for this type
#       false: never generate a defaulter for this type
#     on functions:
#       covers: if the function name matches SetDefault_NAME, instructs
#               the generator not to recurse
#     on packages:
#       FIELDNAME: any object with a field of this name is a candidate
#                  for having a defaulter generated

# The result file, in each pkg, of defaulter generation.
DEFAULTER_BASENAME := $(GENERATED_FILE_PREFIX)defaults
DEFAULTER_FILENAME := $(DEFAULTER_BASENAME).go

# The tool used to generate defaulters.
DEFAULTER_GEN := $(BIN_DIR)/defaulter-gen

# All directories that request any form of defaulter generation.
ifeq ($(DBG_MAKEFILE),1)
    $(warning ***** finding all +k8s:defaulter-gen tags)
endif
DEFAULTER_DIRS := $(shell                                            \
    grep --color=never -l '+k8s:defaulter-gen=' $(ALL_K8S_TAG_FILES) \
        | xargs -n1 dirname                                          \
        | LC_ALL=C sort -u                                           \
)

DEFAULTER_FILES := $(addsuffix /$(DEFAULTER_FILENAME), $(DEFAULTER_DIRS))

# This rule aggregates the set of files to generate and then generates them all
# in a single run of the tool.
.PHONY: gen_defaulter
gen_defaulter: $(DEFAULTER_FILES)
	if [[ -f $(META_DIR)/$(DEFAULTER_GEN).todo ]]; then                  \
	    ./hack/run-in-gopath.sh $(DEFAULTER_GEN)                         \
	        --v $(KUBE_VERBOSE)                                          \
	        --logtostderr                                                \
	        -i $$(cat $(META_DIR)/$(DEFAULTER_GEN).todo | paste -sd, -)  \
	        --extra-peer-dirs $$(echo $(addprefix $(PRJ_SRC_PATH)/, $(DEFAULTER_DIRS)) | sed 's/ /,/g') \
	        -O $(DEFAULTER_BASENAME);                                    \
	fi

# For each dir in DEFAULTER_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, $(DEFAULTER_DIRS), $(eval                                    \
    $(dir)/$(DEFAULTER_FILENAME): $(META_DIR)/$(dir)/$(GOFILES_META).stamp  \
                                   $(gofiles__$(dir))                       \
))

# For each dir in DEFAULTER_DIRS, for each target in $(defaulters__$(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, $(DEFAULTER_DIRS),                                               \
    $(foreach tgt, $(defaulters__$(dir)), $(eval                                \
        $(dir)/$(DEFAULTER_FILENAME): $(META_DIR)/$(tgt)/$(GOFILES_META).stamp  \
                                       $(gofiles__$(tgt))                       \
    ))                                                                          \
)

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

# How to regenerate defaulter code.  This is a little slow to run, so we batch
# it up and trigger the batch from the 'generated_files' target.
$(DEFAULTER_FILES): $(DEFAULTER_GEN)
	mkdir -p $$(dirname $(META_DIR)/$(DEFAULTER_GEN))
	echo $(PRJ_SRC_PATH)/$(@D) >> $(META_DIR)/$(DEFAULTER_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: $(META_DIR)/$(DEFAULTER_GEN).mk
$(META_DIR)/$(DEFAULTER_GEN).mk:
	mkdir -p $(@D);                                        \
	(echo -n "$(DEFAULTER_GEN): ";                         \
	 DIRECT=$$(go list -f '{{.Dir}} {{.Dir}}/*.go'         \
	     ./cmd/libs/go2idl/defaulter-gen);                 \
	 INDIRECT=$$(go list                                   \
	     -f '{{range .Deps}}{{.}}{{"\n"}}{{end}}'          \
	     ./cmd/libs/go2idl/defaulter-gen                   \
	     | grep --color=never "^$(PRJ_SRC_PATH)"           \
	     | sed 's|^$(PRJ_SRC_PATH)|./|'                    \
	     | xargs go list -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 $(META_DIR)/$(DEFAULTER_GEN).mk

# How to build the generator tool.  The deps for this are defined in
# the $(DEFAULTER_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.
$(DEFAULTER_GEN):
	hack/make-rules/build.sh cmd/libs/go2idl/defaulter-gen
	touch $@

#
# Open-api generation
#
# Any package that wants open-api functions generated must include a
# comment-tag in column 0 of one file of the form:
#     // +k8s:openapi-gen=true
#
# The result file, in each pkg, of open-api generation.
OPENAPI_BASENAME := $(GENERATED_FILE_PREFIX)openapi
OPENAPI_FILENAME := $(OPENAPI_BASENAME).go
OPENAPI_OUTPUT_PKG := pkg/generated/openapi

# The tool used to generate open apis.
OPENAPI_GEN := $(BIN_DIR)/openapi-gen

# Find all the directories that request open-api generation.
ifeq ($(DBG_MAKEFILE),1)
    $(warning ***** finding all +k8s:openapi-gen tags)
endif
OPENAPI_DIRS := $(shell                                             \
    grep --color=never -l '+k8s:openapi-gen=' $(ALL_K8S_TAG_FILES)  \
        | xargs -n1 dirname                                         \
        | LC_ALL=C sort -u                                          \
)

OPENAPI_OUTFILE := $(OPENAPI_OUTPUT_PKG)/$(OPENAPI_FILENAME)

# This rule is the user-friendly entrypoint for openapi generation.
.PHONY: gen_openapi
gen_openapi: $(OPENAPI_OUTFILE)

# For each dir in OPENAPI_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, $(OPENAPI_DIRS), $(eval                                     \
    $(OPENAPI_OUTFILE): $(META_DIR)/$(dir)/$(GOFILES_META).stamp           \
                                 $(gofiles__$(dir))                        \
))

# How to regenerate open-api code.  This emits a single file for all results.
$(OPENAPI_OUTFILE): $(OPENAPI_GEN)
	./hack/run-in-gopath.sh $(OPENAPI_GEN)                                          \
	    --v $(KUBE_VERBOSE)                                                         \
	    --logtostderr                                                               \
	    -i $$(echo $(addprefix $(PRJ_SRC_PATH)/, $(OPENAPI_DIRS)) | sed 's/ /,/g')  \
	    -p $(PRJ_SRC_PATH)/$(OPENAPI_OUTPUT_PKG)                                    \
	    -O $(OPENAPI_BASENAME)

# 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: $(META_DIR)/$(OPENAPI_GEN).mk
$(META_DIR)/$(OPENAPI_GEN).mk:
	mkdir -p $(@D);                                        \
	(echo -n "$(OPENAPI_GEN): ";                           \
	 DIRECT=$$(go list -f '{{.Dir}} {{.Dir}}/*.go'         \
	     ./cmd/libs/go2idl/openapi-gen);                   \
	 INDIRECT=$$(go list                                   \
	     -f '{{range .Deps}}{{.}}{{"\n"}}{{end}}'          \
	     ./cmd/libs/go2idl/openapi-gen                     \
	     | grep --color=never "^$(PRJ_SRC_PATH)"           \
	     | sed 's|^$(PRJ_SRC_PATH)|./|'                    \
	     | xargs go list -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 $(META_DIR)/$(OPENAPI_GEN).mk

# How to build the generator tool.  The deps for this are defined in
# the $(OPENAPI_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.
$(OPENAPI_GEN):
	hack/make-rules/build.sh cmd/libs/go2idl/openapi-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 metadata file listing conversion peers for each pkg.
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                                             \
        | LC_ALL=C 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)                         \
	        --v $(KUBE_VERBOSE)                                           \
	        --logtostderr                                                 \
	        -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)
	mkdir -p $$(dirname $(META_DIR)/$(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=$$(go list -f '{{.Dir}} {{.Dir}}/*.go'         \
	     ./cmd/libs/go2idl/conversion-gen);                \
	 INDIRECT=$$(go list                                   \
	     -f '{{range .Deps}}{{.}}{{"\n"}}{{end}}'          \
	     ./cmd/libs/go2idl/conversion-gen                  \
	     | grep --color=never "^$(PRJ_SRC_PATH)"           \
	     | sed 's|^$(PRJ_SRC_PATH)|./|'                    \
	     | xargs go list -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 $@