#!/bin/bash

# dllist - Set of tools to replicate Environment and Climate change Canada data
#          on Wikimedia Commons
# Copyright (C) 2019-2020  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/>.

STATION_INVENTORY_URL='ftp://client_climate@ftp.tor.ec.gc.ca/Pub/Get_More_Data_Plus_de_donnees/Station Inventory EN.csv'
XML_PREFIX='https://climate.weather.gc.ca/climate_data/bulk_data_e.html?format=xml'
CSV_COLUMNS=19

set -e

function generateStation() {
	local -r cid="${1}"
	local -ir sid="${2}"
	local -ir monthly_start_year="${3}"
	local -ir monthly_end_year="${4}"
	local -ir daily_start_year="${5}"
	local -ir daily_end_year="${6}"
	local -ir hourly_start_year="${7}"
	local -ir hourly_end_year="${8}"

	# Generate monthly link
	if [ "${monthly_start_year}" -ne 0 ]&&[ "${monthly_end_year}" -ne 0 ]
	then
		cat <<-EOF >&1
		url = "${XML_PREFIX}&timeframe=3&stationID=${sid}"
		output = "${OUTPUT_PREFIX}/monthly/${cid}.xml"

		EOF
	fi

	# Generate daily links
	if [ "${daily_start_year}" -ne 0 ]&&[ "${daily_end_year}" -ne 0 ]
	then
		for year in $(seq ${daily_start_year} ${daily_end_year})
		do
			cat <<-EOF >&1
			url = "${XML_PREFIX}&timeframe=2&stationID=${sid}&Year=${year}&Month=1"
			output = "${OUTPUT_PREFIX}/daily/${cid}/${year}.xml"

			EOF
		done
	fi

	# Generate hourly links
	if [ "${hourly_start_year}" -ne 0 ]&&[ "${hourly_end_year}" -ne 0 ]
	then
		for year in $(seq ${hourly_start_year} ${hourly_end_year})
		do
			for month in $(seq 1 12)
			do
				# Avoid future stats
				if [ "${year}" -eq "${NOW_YEAR}" ]&&[ "${month}" -gt "${NOW_MONTH}" ]
				then
					continue
				fi

				cat <<-EOF >&1
				url = "${XML_PREFIX}&timeframe=1&stationID=${sid}&Year=${year}&Month=${month}&Day=1"
				output = "${OUTPUT_PREFIX}/hourly/${cid}/${year}-$(printf "%02i" ${month}).xml"

				EOF
			done
		done
	fi

	# Generate almanac link
	cat <<-EOF >&1
	url = "${XML_PREFIX}&timeframe=4&stationID=${sid}"
	output = "${OUTPUT_PREFIX}/almanac/${cid}.xml"

	EOF
}


# Check user input
if [ "${1}" == '' ]
then
	echo "No download folder given"
	exit 1
else
	OUTPUT_PREFIX=$(realpath "${1}")
fi

# Get stations inventory
STATION_INVENTORY_PATH="$(mktemp)"
EXPECTED_COMMAS_COUNT="$((${CSV_COLUMNS} - 1))"
EXPECTED_QUOTES_COUNT="$((${CSV_COLUMNS} * 2))"

# Date
NOW_YEAR=$(date +%Y)
NOW_MONTH=$(date +%m)

curl "${STATION_INVENTORY_URL}" > "${STATION_INVENTORY_PATH}"

# Read stations ids
HEADER=1
while IFS= read -r station
do
	# WARNING: This is a very naive reading of a csv line. Add some sanity checks
	#          so we can fail gracefully if escaped '"' or ',' added in source.
	COMMAS=${station//[^,]}
	QUOTES=${station//[^\"]}

	if [ ${#COMMAS} -eq ${EXPECTED_COMMAS_COUNT} ]||[ ${#QUOTES} -eq ${EXPECTED_QUOTES_COUNT} ]
	then
		# Parsing inside CSV content
		if [ ${HEADER} -ne 0 ]
		then
			# First valid file is columns name, continue
			HEADER=0
			continue
		fi

		CLIMATE_ID="$(echo "${station}" | awk -F'"' '{print $6}')"
		STATION_ID="$(echo "${station}" | awk -F'"' '{print $8}')"
		STATION_HOURLY_START=$(echo "${station}" | awk -F'"' '{print $28}')
		STATION_HOURLY_END=$(echo "${station}" | awk -F'"' '{print $30}')
		STATION_DAILY_START=$(echo "${station}" | awk -F'"' '{print $32}')
		STATION_DAILY_END=$(echo "${station}" | awk -F'"' '{print $34}')
		STATION_MONTHLY_START=$(echo "${station}" | awk -F'"' '{print $36}')
		STATION_MONTHLY_END=$(echo "${station}" | awk -F'"' '{print $38}')
		generateStation "${CLIMATE_ID}" "${STATION_ID}" "${STATION_MONTHLY_START}" "${STATION_MONTHLY_END}" "${STATION_DAILY_START}" "${STATION_DAILY_END}" "${STATION_HOURLY_START}" "${STATION_HOURLY_END}"
	else
		if [ "${HEADER}" -eq 0 ]
		then
			# NOTE: Script requests CSV contains 19 columns. If structure changed, please warn the developers.
			echo "Structure of station inventory file changed. See comment above line ${LINENO} for more explanation. Exiting." >&2
			exit 1
		else
			# Inside header, we can continue
			continue
		fi

	fi
done < "${STATION_INVENTORY_PATH}"

# Clean
rm "${STATION_INVENTORY_PATH}"