#!/bin/bash

# Relational pipes
# Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.


# This streamlet computes hashes of given files.
# Default algorithm is sha256.
#
# Any supported hash algorithm can be specified by e.g. --option "attribute" "sha512"
# The hash command is derived from the algorithm name by adding "sum" suffix and must be available at $PATH.
#
# Multiple algorithms can be specified (just repeat the --option).
# But single streamlet instance will run them sequentially.
# When parallell processing is needed (usually faster) then multiple scriptlet instances should be used:
#   --scriptlet hash --option "sha1" --as "sha1" --scriptlet hash --option "sha256" --as "sha256"
# instead of:
#   --scriptlet hash --option "sha1" --as "sha1" --option "sha256" --as "sha256"


. "$(dirname "$(realpath "$0")")/streamlet-common.sh"

processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES_METADATA() {
	hashTypes=()
	hashCommands=()

	for (( i=0; i<${#optionNames[@]}; i++)); do
		if [[ "x${optionNames[$i]}" == "xattribute" ]]; then
			if type "${optionValues[$i]}sum" > /dev/null; then
				hashTypes+=("${optionValues[$i]}");
				hashCommands+=("${optionValues[$i]}sum");
			else
				echo "Unsupported attribute: ${optionValues[$i]}" >&2
			fi
		else
			echo "Unsupported option: ${optionNames[$i]}" >&2
		fi
	done

	if [[ -z "$hashTypes" ]]; then
		hashTypes=("sha256")
		hashCommands=("sha256sum")
	fi

	for (( i=0; i<${#hashTypes[@]}; i++)); do
		send OUTPUT_ATTRIBUTE_METADATA "${outputAttributeAliases[$i]-${hashTypes[$i]}}"    "string"
	done

	send WAITING_FOR_INPUT_ATTRIBUTES
}

processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES() {
	for (( i=0; i<${#hashTypes[@]}; i++)); do
		value=$("${hashCommands[$i]}" "$currentFile" | cut -d" " -f1) 2>/dev/null;
		if [[ -z "$value" ]]; then isNull="true"; else isNull="false"; fi
		send OUTPUT_ATTRIBUTE "$value"    "$isNull";
	done
	
	send WAITING_FOR_INPUT_ATTRIBUTES;
}

initialize
processMessages