#!/bin/bash

# eccc_merger.sh - Merge Environment and Climate change Canada historical data
# Copyright (C) 2020, 2021  Pierre Choffet
#
# 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, either version 3 of the License, or
# (at your option) any later version.
#
# 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/>.

set -e

# User parameters
PATHS="${@}"

function usage() {
	cat <<-EOF
		Merge XMLs provided by Environment and Climate change Canada
		Usage: eccc_merger.sh <ECCC XML path> <ECCC XML path> [ECCC XML path […]]
		
		At least two XML files must be provided for them to be merged (obviously…).
		Subsequent files will be merged as well, result is written to standard
		output.
		All XMLs must be valid to commons_rules.xsd and be same type (monthly or
		almanach)
		EOF
	exit
}

# Auto detect input types
MERGE_TYPE=''
for path in $@
do
	# Check file exists
	if [ ! -f "${path}" ]
	then
		echo "File ${path} doesn't exist" >&2
		exit 1
	fi
	
	# Check merge type
	FILE_TYPE=$(xmlstarlet sel -t -i '/climatedata/month' -o almanach --elif '/climatedata/stationdata' -o monthly --else -o ''  "${path}")
	
	if [ "${MERGE_TYPE}" != '' ]
	then
		if [ "${FILE_TYPE}" != "${MERGE_TYPE}" ]
		then
			echo 'All XMLs must be the same type' >&2
			exit 1
		fi
	else
		MERGE_TYPE="${FILE_TYPE}"
	fi
done

# Select stylesheet to be used
if [ "${MERGE_TYPE}" == 'almanach' ]
then
	STYLESHEET='eccc_merger_almanach.xslt'
elif [ "${MERGE_TYPE}" == 'monthly' ]
then
	STYLESHEET='eccc_merger_monthly.xslt'
	echo 'Not working with monthly data for now. Exiting.'
	exit
fi

# Merge
FIRST_PASS=1
for path in ${PATHS}
do
	if [ "${FIRST_PASS}" -eq 1 ]
	then
		FIRST_PASS=0
		FIRST_PATH="$(mktemp)"
		cp "${path}" "${FIRST_PATH}"
		continue
	fi
	
	SECOND_PATH="${path}"
	OUT_PATH="$(mktemp)"
	xmlstarlet tr "${STYLESHEET}" -s "merge-path=${SECOND_PATH}" "${FIRST_PATH}" > "${OUT_PATH}"
	
	rm "${FIRST_PATH}"
	FIRST_PATH="${OUT_PATH}"
done

cat "${OUT_PATH}"
rm "${OUT_PATH}"