#!/usr/bin/make -f

#
# \brief  Download, verify, and extract depot archives
# \author Norman Feske
# \date   2017-03-23
#

export GENODE_DIR := $(realpath $(dir $(MAKEFILE_LIST))/../../..)

PUBLIC_DIR     ?= $(GENODE_DIR)/public
DEPOT_DIR      ?= $(GENODE_DIR)/depot
DEPOT_TOOL_DIR ?= $(GENODE_DIR)/tool/depot

define HELP_MESSAGE

  Download, verify, and extract depot archives

  usage:

    $(firstword $(MAKEFILE_LIST)) <archive-path>...

endef

include $(DEPOT_TOOL_DIR)/mk/front_end.inc

TARGETS := $(addprefix $(DEPOT_DIR)/,$(MAKECMDGOALS))


#
# Unpack after checking signature against public key as stored in the depot
#
# Unfortunately, gpg does not allow us to specify the armored public-key
# file directly as keyring for the verify operation. So we need to create a
# temporary dearmored version.
#

ARCHIVES := $(MAKECMDGOALS)

include $(DEPOT_TOOL_DIR)/mk/gpg.inc

$(DEPOT_DIR)/% : $(PUBLIC_DIR)/%.tar.xz $(PUBLIC_DIR)/%.tar.xz.sig
	$(VERBOSE)pubkey_file=$(call pubkey_path,$*); \
	          $(GPG) --yes -o $$pubkey_file.dearmored --dearmor $$pubkey_file; \
	          ( $(GPG) --no-tty --no-default-keyring \
	                --keyring $$pubkey_file.dearmored \
	                --verify $(PUBLIC_DIR)/$*.tar.xz.sig 2> /dev/null; retval=$$?; \
	            rm -f $$pubkey_file.dearmored; \
	            exit $$retval \
	          ) || ( echo -e "Error: could not verify '$*', signature does not match\n" \
	                          "      public key '$$pubkey_file'"; \
	                 false )
	$(VERBOSE)mkdir -p $(dir $@)
	$(VERBOSE)tar xfJ $(PUBLIC_DIR)/$*.tar.xz -C $(dir $@)

DOWNLOADED_FILES := $(addprefix $(PUBLIC_DIR)/,$(MAKECMDGOALS:=.tar.xz)) \
                    $(addprefix $(PUBLIC_DIR)/,$(MAKECMDGOALS:=.tar.xz.sig))

.PRECIOUS: $(DOWNLOADED_FILES)

ifneq ($(MISSING_PUBKEY_FILES),)
$(DOWNLOADED_FILES): missing_pubkey_files
endif


#
# Determine download URLs of all origins of the specified archives
#
# The 'ORIGINS' variable contains all users found in the arguments. The
# URL information is obtained from the despective depot/<user>/download
# file and cached in the 'URL(<user>)' variable. The 'file_url' function
# assesses the 'URL' variables to return the complete URL for a given
# relative archive (or signature file) path.
#

ORIGINS := $(sort $(foreach A,$(ARCHIVES),$(call archive_user,$A)))

# return 'download' file located side by side of a given 'pubkey' file
url_file_for_pubkey_file = $(wildcard $(1:pubkey=download))

# return path to 'download' file for a given archive
url_file_path = $(call url_file_for_pubkey_file,$(call pubkey_path,$1))

quotation_sanitized = $(subst ',,$(strip $1))


$(foreach O,$(ORIGINS),\
   $(eval URL($O) := \
      $(call quotation_sanitized,\
         $(call file_content,$(call url_file_path,$O)))))

MISSING_DOWNLOAD_LOCATIONS := $(sort $(foreach O,$(ORIGINS),\
                                        $(if ${URL($O)},,$O)))

ifneq ($(MISSING_DOWNLOAD_LOCATIONS),)
$(DOWNLOADED_FILES): missing_download_locations
endif

missing_download_locations:
	@echo "Error: missing or invalid download location:";\
	 for i in $(MISSING_DOWNLOAD_LOCATIONS); do echo "       $$i"; done; false

file_url = '${URL($(call archive_user,$1))}/$1'


#
# Download rule that is invoked per file
#

$(PUBLIC_DIR)/%:
	@$(ECHO) "$(DARK_COL)download$(DEFAULT_COL) $*"
	$(VERBOSE)mkdir -p $(dir $@)
	$(VERBOSE)curl --silent $(call file_url,$*) -o $@ ||\
		(echo "Error: failed to download $(call file_url,$*)"; rm -f $@; false)

$(MAKECMDGOALS): $(TARGETS)
	@true