Add CSV export handler to main event log endpoint.

Closes #245.

lib/www/server/api/middleware/event/list/csv.js

@@ -0,0 +1,83 @@
+const { stringify } = require('csv');
+const { event } = require('../../../../lib/db');
+const { ALERT, ERROR, INFO, DEBUG } = require('DOUGAL_ROOT/debug')(__filename);
+
+const csv = async function (req, res, next) {
+	try {
+		const events = await event.list(req.params.project, req.query);
+		if ("download" in req.query || "d" in req.query) {
+			const extension = "csv";
+			const tstamp = (new Date()).toISOString();
+			const filename = `${req.params.project}-event-log-${tstamp}.${extension}`;
+			res.set("Content-Disposition", `attachment; filename="${filename}"`);
+		}
+
+		const columns = {
+			id: "id",
+			unix_epoch: (row) => Math.floor(row.tstamp/1000),
+			timestamp: (row) => (new Date(row.tstamp)).toISOString(),
+			sequence: "sequence",
+			point: "point",
+			text: "remarks",
+			labels: (row) => row.labels.join(";"),
+			latitude: (row) => {
+				if (row.meta.geometry?.type == "Point" && row.meta.geometry?.coordinates) {
+					return row.meta.geometry.coordinates[1];
+				}
+			},
+			longitude: (row) => {
+				if (row.meta.geometry?.type == "Point" && row.meta.geometry?.coordinates) {
+					return row.meta.geometry.coordinates[0];
+				}
+			}
+		};
+
+		let fields = [ "timestamp", "sequence", "point", "text", "labels", "latitude", "longitude", "id" ];
+
+		if (req.query.fields) {
+			fields = req.query.fields.split(/[,;:.\s+*|]+/);
+		}
+
+		let delimiter = req.query.delimiter ?? ",";
+
+		const stringifier = stringify({delimiter});
+		stringifier.on('error', (err) => {
+			ERROR(err);
+		});
+
+		stringifier.on('readable', () => {
+			while((row = stringifier.read()) !== null) {
+				res.write(row);
+			}
+		});
+
+		stringifier.on('end', () => {
+			DEBUG("Transform complete");
+			res.end();
+			next();
+		});
+
+		res.status(200);
+
+		if (!req.query.header || req.query.header.toLowerCase() == "true" || req.query.header == "1") {
+			// Send header
+			stringifier.write(fields);
+		}
+
+		events.forEach( event => {
+			stringifier.write(fields.map( field => {
+				if (typeof columns[field] === "function") {
+					return columns[field](event);
+				} else {
+					return event[columns[field]];
+				}
+			}));
+		});
+
+		stringifier.end();
+	} catch (err) {
+		next(err);
+	}
+};
+
+module.exports = csv;

lib/www/server/api/middleware/event/list/index.js

@@ -1,13 +1,15 @@
 const json = require('./json');
 const geojson = require('./geojson');
 const seis = require('./seis');
+const csv = require('./csv');
 
 module.exports = async function (req, res, next) {
 	try {
 		const handlers = {
 			"application/json": json,
 			"application/geo+json": geojson,
-			"application/vnd.seis+json": seis
+			"application/vnd.seis+json": seis,
+			"text/csv": csv
 		};
 
 		const mimetype = (handlers[req.query.mime] && req.query.mime) || req.accepts(Object.keys(handlers));