# -*- coding: utf-8; mode: makefile-gmake -*-
# SPDX-License-Identifier: AGPL-3.0-or-later

PHONY += make-help
make-help:
	@echo  'options:'
	@echo  '  make V=0|1 [targets] 0 => quiet build (default), 1 => verbose build'
	@echo  '  make V=2   [targets] 2 => give reason for rebuild of target'

ifeq ("$(origin V)", "command line")
  VERBOSE = $(V)
endif
ifndef VERBOSE
  VERBOSE = 0
endif

export VERBOSE

ifeq ($(VERBOSE),1)
  quiet =
  Q =
else
  quiet=quiet_
  Q = @
endif

# stolen from linux/scripts/Kbuild.include
#

# Convenient variables
squote  := '
#' this comment is only for emacs highlighting

# Find any prerequisites that is newer than target or that does not exist.
# PHONY targets skipped in both cases.
any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
#
###
# why - tell why a a target got build
#       enabled by make V=2
#       Output (listed in the order they are checked):
#          (1) - due to target is PHONY
#          (2) - due to target missing
#          (3) - due to: file1.h file2.h
#          (4) - due to command line change
#          (5) - due to missing .cmd file
#          (6) - due to target not in $(targets)
# (1) PHONY targets are always build
# (2) No target, so we better build it
# (3) Prerequisite is newer than target
# (4) The command line stored in the file named dir/.target.cmd
#     differed from actual command line. This happens when compiler
#     options changes
# (5) No dir/.target.cmd file (used to store command line)
# (6) No dir/.target.cmd file and target not listed in $(targets)
#     This is a good hint that there is a bug in the kbuild file
ifeq ($(VERBOSE),2)
why =                                                                        \
    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
        $(if $(wildcard $@),                                                 \
            $(if $(strip $(any-prereq)),- due to: $(any-prereq),             \
                $(if $(arg-check),                                           \
                    $(if $(cmd_$@),- due to command line change,             \
                        $(if $(filter $@, $(targets)),                       \
                            - due to missing .cmd file,                      \
                            - due to $(notdir $@) not in $$(targets)         \
                         )                                                   \
                     )                                                       \
                 )                                                           \
             ),                                                              \
             - due to target missing                                         \
         )                                                                   \
     )

echo-why = $(call escsq, $(strip $(why)))
endif
#
###
# Escape single quote for use in echo statements
escsq = $(subst $(squote),'\$(squote)',$1)
#
# echo command.
# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
echo-cmd = $(if $($(quiet)cmd_$(1)),echo '$(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
#
# printing commands
cmd = @$(echo-cmd) $(cmd_$(1))

.PHONY: $(PHONY)
