/*
 * eccc_map - Tool to show a map of ECCC stations and generate a list based on
 *            a polygon drawn by user.
 * Copyright (C) 2020  Pierre Choffet
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/


// Download station inventory as distributed with eccc_map since we cannot
// get the upstream one that is on a ftp server.
// Original URL: ftp://client_climate@ftp.tor.ec.gc.ca/Pub/Get_More_Data_Plus_de_donnees/Station Inventory EN.csv
const csv_url = 'Station Inventory EN.csv';
const map = L.map('map').setView([70.44,-88.07], 4);
const draws = new L.FeatureGroup();
const cluster = L.markerClusterGroup();
const icon = L.icon({iconUrl: 'leaflet/marker-icon.png', shadowUrl: 'leaflet/marker-shadow.png'});
var markers_selected = [];

L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
		id: 'osm',
		attribution: '<a href="https://www.openstreetmap.org/">OpenStreetMap</a> contributors',
		maxZoom: 18,
		tileSize: 256
	}
).addTo(map);

// Activate draw
map.addLayer(draws);
const draw_control = new L.Control.Draw({
	edit: {
		featureGroup: draws
	},
	draw: {
		polygon: {
			showArea: true
		},
		polyline: false,
		rectangle: false,
		circle: false,
		marker: false,
		circlemarker: false
	},
	edit: false
});

map.on(L.Draw.Event.DRAWSTART, function (event) {
	draws.clearLayers();
});

map.on(L.Draw.Event.CREATED, function (event) {
	const layer = event.layer;
	const polygon_latlngs = layer.getLatLngs();
	
	draws.addLayer(layer);
	
	markers_selected = [];
	
	cluster.eachLayer(function(e) {
		if (e instanceof L.Marker) {
			let inside = false;
			const marker_lat = e.getLatLng().lat;
			const marker_lon = e.getLatLng().lng;
			
			for (let latlngs_browse = 0; latlngs_browse < polygon_latlngs.length; ++latlngs_browse){
				let points = polygon_latlngs[latlngs_browse];
				
				for (let i = 0, j = points.length - 1; i < points.length; j = i++) {
					let xi = points[i].lat;
					let yi = points[i].lng;
					let xj = points[j].lat;
					let yj = points[j].lng;
					
					let intersect = ((yi > marker_lon) != (yj > marker_lon)) && (marker_lat < (xj - xi) * (marker_lon - yi) / (yj - yi) + xi);
					if (intersect)
						inside = !inside;
				}
			}
			
			if (inside) {
				markers_selected.push(e);
			}
			
			updateOutput();
		}
	});
});

map.addControl(draw_control);

// Add custom draw button click event
let button = document.getElementById('draw-polygon');
button.addEventListener('click', function() {draw_control._toolbars.draw._modes.polygon.handler.enable();});

// Fetch csv file, read it line by line
async function readStationsEntries(callback) {
	let text = '';
	
	fetch(csv_url).then(
		function(response) {
			return response.body.getReader();
		}
	).then(
		function (reader) {
			reader.read().then(
				function readChunk({done, value}) {
					if (done)
						return;
					
					const decoder = new TextDecoder();
					text += decoder.decode(value);
					
					return reader.read().then(readChunk);
				}
			).then(
				function () {
					const text_split = text.split("\n");
					const lines_count = text_split.length;
					let lines_browse = 0;
					
					// Consume csv header
					for (; lines_browse < lines_count; ++lines_browse) {
						if (text_split[lines_browse].startsWith('"Name",'))
							break;
					}
					++lines_browse;
					
					// Read stations rows
					for (; lines_browse < lines_count - 1; ++lines_browse) {
						// To keep code simple, we expect CSV entries to be surrounded by
						// two '"' characters and containing no additional one in their values.
						// We just count occurences of '"' per line to ensure sanity.
						if (text_split[lines_browse].split('"').length != 39) {
							console.error('Illegal station entry: line '+(lines_browse+1));
							continue;
						}
						
						const entry = text_split[lines_browse].split(',');
						const name = entry[0].replaceAll('"', '');
						const cid = entry[2].replaceAll('"', '');
						const lat = entry[6].replaceAll('"', '');
						const lon = entry[7].replaceAll('"', '');
						
						const marker = L.marker([lat, lon], {icon: icon, cid: cid});
						marker.bindPopup('<h1>'+name+'</h1><h2>'+cid+'</h2>');
						marker.addTo(cluster);
					}
					
					map.addLayer(cluster);
				}
			)
		}
	)
}

function updateOutput() {
	let output = '';
	for (let markers_browse = 0; markers_browse < markers_selected.length; ++markers_browse) {
		if (markers_browse != 0)
			output += document.getElementById('separator').value;
		
		output += document.getElementById('pattern').value.replace('{cid}', markers_selected[markers_browse].options.cid);
	}
	document.getElementById('output').value = output;
}

readStationsEntries();

// Add events in settings fields
document.getElementById('pattern').addEventListener('blur', updateOutput);
document.getElementById('separator').addEventListener('blur', updateOutput);