Implement real GIS data import and PostGIS spatial queries

2026-03-16 20:32:22 +00:00
parent e764efb189
commit ad07a70125
4 changed files with 312 additions and 56 deletions
@@ -1,66 +1,106 @@
 const express = require('express');
 const cors = require('cors');
+const { Pool } = require('pg');
 require('dotenv').config();

 const app = express();
 const PORT = process.env.PORT || 3001;

+// Database connection pool
+const pool = new Pool({
+  connectionString: process.env.DATABASE_URL || 'postgresql://line_of_sight:line_of_sight_pass@postgres:5432/line_of_sight'
+});
+
 app.use(cors());
 app.use(express.json());

-// Mock conurbation data for MVP
-const MOCK_CONURBATIONS = [
-  { id: 1, name: "London", population: 9000000, distance_km: 0, lat: 51.5074, lon: -0.1278 },
-  { id: 2, name: "Paris", population: 2161000, distance_km: 344, lat: 48.8566, lon: 2.3522 },
-  { id: 3, name: "Berlin", population: 3644000, distance_km: 878, lat: 52.5200, lon: 13.4050 },
-  { id: 4, name: "Warsaw", population: 1793000, distance_km: 1200, lat: 52.2297, lon: 21.0122 },
-  { id: 5, name: "Moscow", population: 12506000, distance_km: 2063, lat: 55.7558, lon: 37.6173 },
-  { id: 6, name: "Kazan", population: 1257000, distance_km: 2850, lat: 55.7897, lon: 49.1219 },
-  { id: 7, name: "Almaty", population: 2000000, distance_km: 3900, lat: 43.2220, lon: 76.8512 },
-  { id: 8, name: "Urumqi", population: 3500000, distance_km: 4500, lat: 43.8256, lon: 87.6168 },
-  { id: 9, name: "Lahore", population: 11126000, distance_km: 5400, lat: 31.5204, lon: 74.3587 },
-  { id: 10, name: "New Delhi", population: 29399000, distance_km: 5800, lat: 28.6139, lon: 77.2090 },
-  { id: 11, name: "Dhaka", population: 21006000, distance_km: 6200, lat: 23.8103, lon: 90.4125 },
-  { id: 12, name: "Chennai", population: 10971000, distance_km: 6500, lat: 13.0827, lon: 80.2707 },
-  { id: 13, name: "Bangkok", population: 10539000, distance_km: 7200, lat: 13.7563, lon: 100.5018 },
-  { id: 14, name: "Jakarta", population: 10562000, distance_km: 8100, lat: -6.2088, lon: 106.8456 },
-  { id: 15, name: "Singapore", population: 5686000, distance_km: 8300, lat: 1.3521, lon: 103.8198 },
-  { id: 16, name: "Manila", population: 17801000, distance_km: 8700, lat: 14.5995, lon: 120.9842 },
-  { id: 17, name: "Tokyo", population: 37400000, distance_km: 9500, lat: 35.6762, lon: 139.6503 },
-  { id: 18, name: "Seoul", population: 9720000, distance_km: 9200, lat: 37.5665, lon: 126.9780 },
-  { id: 19, name: "Beijing", population: 21540000, distance_km: 8900, lat: 39.9042, lon: 116.4074 },
-  { id: 20, name: "Shanghai", population: 27058000, distance_km: 9000, lat: 31.2304, lon: 121.4737 }
-];
+// Helper to calculate destination point given start, bearing, and distance (km)
+const calculateDestination = (lat, lon, bearing, distance) => {
+  const R = 6371;
+  const brng = (bearing * Math.PI) / 180;
+  const φ1 = (lat * Math.PI) / 180;
+  const λ1 = (lon * Math.PI) / 180;
+  const δ = distance / R;

-// Mock API endpoint - returns dummy conurbations based on input coordinates
-app.get('/api/line-of-sight', (req, res) => {
+  const φ2 = Math.asin(
+    Math.sin(φ1) * Math.cos(δ) +
+      Math.cos(φ1) * Math.sin(δ) * Math.cos(brng)
+  );
+  const λ2 =
+    λ1 +
+    Math.atan2(
+      Math.sin(brng) * Math.sin(δ) * Math.cos(φ1),
+      Math.cos(δ) - Math.sin(φ1) * Math.sin(φ2)
+    );
+
+  return {
+    lat: (φ2 * 180) / Math.PI,
+    lon: (((λ2 * 180) / Math.PI + 540) % 360) - 180
+  };
+};
+
+// Real API endpoint - uses PostGIS for spatial queries
+app.get('/api/line-of-sight', async (req, res) => {
  const { lat, lon, direction, tolerance } = req.query;
  
-  console.log(`Received request: lat=${lat}, lon=${lon}, direction=${direction}, tolerance=${tolerance}`);
-  
-  // Return mock data for MVP
-  res.json({
-    success: true,
-    data: {
-      start_point: { lat: parseFloat(lat) || 51.5074, lon: parseFloat(lon) || -0.1278 },
-      direction: parseInt(direction) || 45,
-      tolerance_km: parseInt(tolerance) || 50,
-      conurbations: MOCK_CONURBATIONS.slice(0, 20),
-      line_coordinates: [
-        { lat: 51.5074, lon: -0.1278 },
-        { lat: 48.8566, lon: 2.3522 },
-        { lat: 52.5200, lon: 13.4050 },
-        { lat: 55.7558, lon: 37.6173 },
-        { lat: 43.2220, lon: 76.8512 },
-        { lat: 28.6139, lon: 77.2090 },
-        { lat: 13.7563, lon: 100.5018 },
-        { lat: -6.2088, lon: 106.8456 },
-        { lat: 35.6762, lon: 139.6503 },
-        { lat: 51.5074, lon: -0.1278 } // Complete the circle
-      ]
-    },
-    message: "Mock data returned for MVP - Real geospatial calculations coming soon"
-  });
+  const startLat = parseFloat(lat) || 51.5074;
+  const startLon = parseFloat(lon) || -0.1278;
+  const bearing = parseInt(direction) || 0;
+  const toleranceKm = parseInt(tolerance) || 50;
+
+  console.log(`Processing real request: lat=${startLat}, lon=${startLon}, bearing=${bearing}, tolerance=${toleranceKm}`);
+
+  try {
+    // Generate path points for visualization and spatial query
+    const pathPoints = [];
+    const totalDistance = 10000;
+    const steps = 20;
+    
+    for (let i = 0; i <= steps; i++) {
+      const dist = (totalDistance * i) / steps;
+      pathPoints.push(calculateDestination(startLat, startLon, bearing, dist));
+    }
+
+    const lineWKT = `LINESTRING(${pathPoints.map(p => `${p.lon} ${p.lat}`).join(',')})`;
+    
+    const query = `
+      WITH path AS (
+        SELECT ST_GeogFromText($1) as route
+      )
+      SELECT 
+        id, 
+        name, 
+        population, 
+        country,
+        ST_Y(geom::geometry) as lat, 
+        ST_X(geom::geometry) as lon,
+        ST_Distance(geom, (SELECT route FROM path)) / 1000 as distance_to_line_km,
+        ST_LineLocatePoint((SELECT route FROM path)::geometry, geom::geometry) as pos_on_line
+      FROM cities
+      WHERE ST_DWithin(geom, (SELECT route FROM path), $2 * 1000)
+      ORDER BY pos_on_line ASC
+      LIMIT 20;
+    `;
+
+    const result = await pool.query(query, [lineWKT, toleranceKm]);
+
+    res.json({
+      success: true,
+      data: {
+        start_point: { lat: startLat, lon: startLon },
+        direction: bearing,
+        tolerance_km: toleranceKm,
+        conurbations: result.rows.map(row => ({
+          ...row,
+          distance_km: Math.round(row.distance_to_line_km)
+        })),
+        line_coordinates: pathPoints
+      }
+    });
+  } catch (err) {
+    console.error('Database query error:', err);
+    res.status(500).json({ success: false, error: 'Database query failed' });
+  }
 });

 // Health check endpoint