refine hazard history matching and hazard list SQL selection

src/hazard-history.mjs

@@ -1,6 +1,7 @@
 import { getPool } from './mysql.mjs';
 
 const MAX_HISTORY_ENTRIES = 7;
+const PRACTICAL_LOCATION_RADIUS_KM = 50;
 
 const toIsoString = (value) => {
 	if (!value) return null;
@@ -20,6 +21,60 @@ const mapRowToHistoryEntry = (row) => ({
 	ongoing: Boolean(row.ongoing),
 });
 
+const parseLocationKey = (locationKey) => {
+	if (typeof locationKey !== 'string') return null;
+	const [latText, lonText] = locationKey.split(',');
+	const lat = Number.parseFloat(latText);
+	const lon = Number.parseFloat(lonText);
+	if (!Number.isFinite(lat) || !Number.isFinite(lon)) return null;
+	return { lat, lon };
+};
+
+const distanceKm = (a, b) => {
+	const toRadians = (value) => value * (Math.PI / 180);
+	const earthRadiusKm = 6371;
+	const dLat = toRadians(b.lat - a.lat);
+	const dLon = toRadians(b.lon - a.lon);
+	const lat1 = toRadians(a.lat);
+	const lat2 = toRadians(b.lat);
+	const haversine = Math.sin(dLat / 2) ** 2
+		+ Math.cos(lat1) * Math.cos(lat2) * Math.sin(dLon / 2) ** 2;
+	return 2 * earthRadiusKm * Math.atan2(Math.sqrt(haversine), Math.sqrt(1 - haversine));
+};
+
+const isSamePracticalLocation = (row, location, locationKey) => {
+	if (row.location_key === locationKey) return true;
+	if (row.location_label !== location) return false;
+	const rowCoords = parseLocationKey(row.location_key);
+	const currentCoords = parseLocationKey(locationKey);
+	if (!rowCoords || !currentCoords) return false;
+	return distanceKm(rowCoords, currentCoords) <= PRACTICAL_LOCATION_RADIUS_KM;
+};
+
+const getCandidateRows = async (connection, location, locationKey) => {
+	const [rows] = await connection.execute(
+		`SELECT
+			id,
+			location_label,
+			location_key,
+			hazard_type,
+			source,
+			severity,
+			latest_hazard_id,
+			encountered_at,
+			last_seen_at,
+			ongoing
+		FROM hazard_history
+		WHERE location_key = ?
+		   OR location_label = ?`,
+		[locationKey, location],
+	);
+
+	return rows.filter((row) => isSamePracticalLocation(row, location, locationKey));
+};
+
+const buildHazardIdentity = (hazardType, source) => `${hazardType}::${source}`;
+
 /**
  * Format location label from weather parameters
  * @param {string} city - City name
@@ -43,17 +98,34 @@ const formatLocation = (city, state, country, countryCode) => {
 const getHistory = async () => {
 	const [rows] = await getPool().query(
 		`SELECT
-			location_label,
-			location_key,
-			hazard_type,
-			source,
-			severity,
-			latest_hazard_id,
-			encountered_at,
-			last_seen_at,
-			ongoing
-		FROM hazard_history
-		ORDER BY last_seen_at DESC
+			h.location_label,
+			h.location_key,
+			h.hazard_type,
+			h.source,
+			h.severity,
+			h.latest_hazard_id,
+			h.encountered_at,
+			h.last_seen_at,
+			h.ongoing
+		FROM hazard_history h
+		WHERE NOT EXISTS (
+			SELECT 1
+			FROM hazard_history h2
+			WHERE h2.location_key = h.location_key
+			  AND (
+				h2.last_seen_at > h.last_seen_at
+				OR (
+					h2.last_seen_at = h.last_seen_at
+					AND h2.ongoing > h.ongoing
+				)
+				OR (
+					h2.last_seen_at = h.last_seen_at
+					AND h2.ongoing = h.ongoing
+					AND h2.id > h.id
+				)
+			  )
+		)
+		ORDER BY h.last_seen_at DESC, h.ongoing DESC, h.id DESC
 		LIMIT ?`,
 		[MAX_HISTORY_ENTRIES],
 	);
@@ -69,32 +141,64 @@ const updateHistory = async (payload) => {
 
 	try {
 		await connection.beginTransaction();
+		const candidateRows = await getCandidateRows(connection, location, locationKey);
+		const activeHazardKeys = new Set(validHazards.map((hazard) => buildHazardIdentity(hazard.hazardType, hazard.source)));
 
 		if (validHazards.length === 0) {
-			await connection.execute(
-				`UPDATE hazard_history
-				SET ongoing = 0,
-				    last_seen_at = UTC_TIMESTAMP()
-				WHERE location_key = ?
-				  AND ongoing = 1`,
-				[locationKey],
-			);
+			const idsToEnd = candidateRows.filter((row) => row.ongoing).map((row) => row.id);
+			if (idsToEnd.length > 0) {
+				const placeholders = idsToEnd.map(() => '?').join(', ');
+				await connection.execute(
+					`UPDATE hazard_history
+					SET ongoing = 0,
+					    last_seen_at = UTC_TIMESTAMP()
+					WHERE id IN (${placeholders})
+					  AND ongoing = 1`,
+					idsToEnd,
+				);
+			}
 		} else {
-			const keepClauses = validHazards.map(() => '(hazard_type = ? AND source = ?)').join(' OR ');
-			const keepParams = validHazards.flatMap((hazard) => [hazard.hazardType, hazard.source]);
-
-			await connection.execute(
-				`UPDATE hazard_history
-				SET ongoing = 0,
-				    last_seen_at = UTC_TIMESTAMP()
-				WHERE location_key = ?
-				  AND ongoing = 1
-				  AND NOT (${keepClauses})`,
-				[locationKey, ...keepParams],
-			);
+			const idsToEnd = candidateRows
+				.filter((row) => row.ongoing && !activeHazardKeys.has(buildHazardIdentity(row.hazard_type, row.source)))
+				.map((row) => row.id);
+			if (idsToEnd.length > 0) {
+				const placeholders = idsToEnd.map(() => '?').join(', ');
+				await connection.execute(
+					`UPDATE hazard_history
+					SET ongoing = 0,
+					    last_seen_at = UTC_TIMESTAMP()
+					WHERE id IN (${placeholders})
+					  AND ongoing = 1`,
+					idsToEnd,
+				);
+			}
 		}
 
 		for (const hazard of validHazards) {
+			const nearbyMatch = candidateRows.find((row) => row.hazard_type === hazard.hazardType
+				&& row.source === hazard.source
+				&& row.location_key !== locationKey);
+
+			if (nearbyMatch) {
+				await connection.execute(
+					`UPDATE hazard_history
+					SET location_key = ?,
+					    location_label = ?,
+					    severity = ?,
+					    latest_hazard_id = ?,
+					    last_seen_at = UTC_TIMESTAMP(),
+					    ongoing = 1
+					WHERE id = ?`,
+					[
+						locationKey,
+						location,
+						hazard.severity ?? null,
+						hazard.id ?? null,
+						nearbyMatch.id,
+					],
+				);
+			}
+
 			await connection.execute(
 				`INSERT INTO hazard_history (
 					location_label,