Update: 2026-06-21 02:07:00

backend/ride/heatmap/log_demand.php

@@ -0,0 +1,43 @@
+<?php
+require_once __DIR__ . '/../connect.php';
+
+$lat = filterRequest("lat");
+$lng = filterRequest("lng");
+
+if (!$lat || !$lng) {
+    jsonError("Missing coordinates");
+    exit();
+}
+
+if (!isset($redis) || $redis === null) {
+    // If Redis is not available, we fail gracefully.
+    jsonSuccess(null, "Demand logged (fallback)");
+    exit();
+}
+
+// Create a 1.5 km grid cell
+// 1 degree latitude is approximately 111 km. 
+// 1.5 km / 111 km ≈ 0.0135 degrees.
+$grid_size = 0.0135;
+
+$grid_lat = round((float)$lat / $grid_size) * $grid_size;
+$grid_lng = round((float)$lng / $grid_size) * $grid_size;
+
+$grid_id = $grid_lat . "_" . $grid_lng;
+$redisKey = "demand:grid:" . $grid_id;
+
+try {
+    // Increment the demand count for this grid
+    $currentCount = $redis->incr($redisKey);
+    
+    // If this is the first request, set the expiry to 60 seconds
+    if ($currentCount == 1) {
+        $redis->expire($redisKey, 60);
+    }
+    
+    jsonSuccess(["grid_id" => $grid_id, "count" => $currentCount], "Demand logged successfully");
+} catch (Exception $e) {
+    error_log("[log_demand.php] Redis error: " . $e->getMessage());
+    jsonError("Error logging demand");
+}
+?>