#!/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 provides PDF metadata of given files. It calls the tool pdfinfo.

# With no options it returns just number of pages (or 0 if the file is not a PDF).

# Specific attributes can be selected using options – e.g. --option 'attribute' 'Author'

# List of available attributes can be obtained by directly calling the pdfinfo command on a PDF file.

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

processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES_METADATA() {

	pdfFields=()

	for (( i=0; i<${#optionNames[@]}; i++)); do

		if [[ "x${optionNames[$i]}" == "xattribute" ]]; then

			pdfFields+=("${optionValues[$i]}");

		elif [[ "x${optionNames[$i]}" == "xprefix" ]]; then

			pdfPrefix="${optionValues[$i]}";

		else

			echo "Unsupported option: ${optionNames[$i]}" >&2

		fi

	done

	if [[ -z "$pdfFields" ]]; then

		pdfFields=( "Pages" );

	fi

	for (( i=0; i<${#pdfFields[@]}; i++)); do

		if [[ "x${pdfFields[$i]}" == "xPages" ]]; then local type="integer"; else local type="string"; fi

		send OUTPUT_ATTRIBUTE_METADATA "${outputAttributeAliases[$i]-$pdfPrefix${pdfFields[$i]}}"    "$type"

	done

	send WAITING_FOR_INPUT_ATTRIBUTES

}

processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES() {

	local pdfInfo pdfValid value isNull;

	[[ -d "$currentFile" ]] || pdfInfo="$(pdfinfo -isodates "$currentFile")";

	pdfValid="$?";

	for (( i=0; i<${#pdfFields[@]}; i++)); do

		value="$(echo "$pdfInfo" | grep -P "^\Q${pdfFields[$i]}\E:" | sed -E 's/[^:]+:\s+(.*)/\1/g' | tr -d '\n';)"; # the field name must not contain "\E"

		if [[ ! "x$pdfValid" == "x0" ]] || [[ "x$value" == "x" ]]; then isNull="true";

		else                                                            isNull="false";

		fi

		send OUTPUT_ATTRIBUTE "$value"    "$isNull";

	done

	send WAITING_FOR_INPUT_ATTRIBUTES;

}

initialize

processMessages