2026-04-13-2

apps/api/src/maps/traffic-grid.service.ts

@@ -0,0 +1,125 @@
+import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
+import { DataSource } from 'typeorm';
+
+/**
+ * Traffic Grid Service - In-Memory GeoHash Grid
+ * نظام شبكة التنبؤ المروري الذكي: يحول بيانات قاعدة البيانات إلى خارطة سرعة في الذاكرة
+ */
+@Injectable()
+export class TrafficGridService implements OnModuleInit {
+  private readonly logger = new Logger(TrafficGridService.name);
+  
+  // Key: "geohash:hr:dow", Value: trafficFactor
+  private grid: Map<string, number> = new Map();
+  private readonly GEOHASH_PRECISION = 6; // ~100m accuracy
+
+  constructor(private dataSource: DataSource) {}
+
+  async onModuleInit() {
+    await this.refreshGrid();
+  }
+
+  /**
+   * Rebuilds the in-memory lookup table from PostGIS
+   * إعادة بناء الجدول المرجعي في الذاكرة من قاعدة البيانات
+   */
+  async refreshGrid() {
+    this.logger.log('📡 Rebuilding Traffic Grid v3 (In-Memory Lookup)...');
+    try {
+      const startTime = Date.now();
+      
+      const data = await this.dataSource.query(`
+        SELECT 
+          ST_X(ST_Centroid(geometry::geometry)) as lng,
+          ST_Y(ST_Centroid(geometry::geometry)) as lat,
+          p."hourOfDay", p."dayOfWeek", p."averageSpeed",
+          s."averageSpeed" as base_speed
+        FROM road_speed_profiles p
+        JOIN road_segment_stats s ON p."segmentId" = s."segmentId"
+        WHERE s.geometry IS NOT NULL
+      `);
+
+      this.grid.clear();
+      let count = 0;
+
+      for (const row of data) {
+        const gh = this.encodeGeohash(row.lat, row.lng, this.GEOHASH_PRECISION);
+        const factor = row.base_speed / Math.max(row.averageSpeed, 1);
+        
+        // Key includes time buckets to handle day/night variations
+        const key = `${gh}:${row.hourOfDay}:${row.dayOfWeek}`;
+        this.grid.set(key, factor);
+        count++;
+      }
+
+      this.logger.log(`✅ Grid rebuilt in ${Date.now() - startTime}ms. Cached ${count} cells (${this.grid.size} unique keys).`);
+    } catch (e) {
+      this.logger.error('❌ Failed to refresh traffic grid:', e.message);
+    }
+  }
+
+  /**
+   * Fetches the average traffic factor for a decoded polyline
+   * جلب معامل الازدحام المتوسط لمخطط الرحلة من الذاكرة
+   */
+  getTrafficFactor(coords: [number, number][], hr: number, dow: number): number {
+    if (this.grid.size === 0) return 1.0;
+
+    let totalFactor = 0;
+    let matches = 0;
+
+    // We sample points every ~100m to speed up (every 2nd or 3rd coord)
+    for (let i = 0; i < coords.length; i += 2) {
+      const [lng, lat] = coords[i];
+      const gh = this.encodeGeohash(lat, lng, this.GEOHASH_PRECISION);
+      const key = `${gh}:${hr}:${dow}`;
+      
+      const factor = this.grid.get(key);
+      if (factor) {
+        totalFactor += factor;
+        matches++;
+      }
+    }
+
+    if (matches === 0) return 1.0;
+    
+    // Average factor clipped to sane ranges (0.8 - 3.0)
+    let finalFactor = totalFactor / matches;
+    return Math.min(Math.max(finalFactor, 0.8), 3.0);
+  }
+
+  /**
+   * Pure Math GeoHash implementation (No outside dependencies)
+   */
+  private encodeGeohash(lat: number, lng: number, precision: number): string {
+    const BASE32 = "0123456789bcdefghjkmnpqrstuvwxyz";
+    let minLat = -90, maxLat = 90;
+    let minLng = -180, maxLng = 180;
+    let result = "";
+    let isEven = true;
+    let bit = 0;
+    let ch = 0;
+
+    while (result.length < precision) {
+      if (isEven) {
+        let mid = (minLng + maxLng) / 2;
+        if (lng > mid) { ch |= (1 << (4 - bit)); minLng = mid; }
+        else { maxLng = mid; }
+      } else {
+        let mid = (minLat + maxLat) / 2;
+        if (lat > mid) { ch |= (1 << (4 - bit)); minLat = mid; }
+        else { maxLat = mid; }
+      }
+
+      isEven = !isEven;
+      if (bit < 4) {
+        bit++;
+      } else {
+        result += BASE32[ch];
+        bit = 0;
+        ch = 0;
+      }
+    }
+    return result;
+  }
+}