Implement real GIS data import and PostGIS spatial queries

backend/scripts/import_cities.js

@@ -0,0 +1,82 @@
+const { Client } = require('pg');
+const axios = require('axios');
+require('dotenv').config();
+
+const DATA_URL = 'https://raw.githubusercontent.com/nvkelso/natural-earth-vector/master/geojson/ne_10m_populated_places_simple.geojson';
+
+async function importCities() {
+  const client = new Client({
+    connectionString: process.env.DATABASE_URL || 'postgresql://line_of_sight:line_of_sight_pass@localhost:5432/line_of_sight'
+  });
+
+  try {
+    console.log('Connecting to database...');
+    await client.connect();
+
+    console.log('Downloading Natural Earth data (GeoJSON)...');
+    const response = await axios.get(DATA_URL);
+    const data = response.data;
+
+    console.log(`Downloaded ${data.features.length} features. Preparing database...`);
+
+    // Ensure table exists and is clean
+    await client.query('TRUNCATE TABLE cities');
+
+    let count = 0;
+    const batchSize = 100;
+
+    for (let i = 0; i < data.features.length; i += batchSize) {
+      const batch = data.features.slice(i, i + batchSize);
+      
+      const values = [];
+      const queryParts = [];
+      
+      batch.forEach((feature, index) => {
+        const props = feature.properties;
+        const coords = feature.geometry.coordinates; // [lon, lat]
+        
+        const name = props.NAME || 'Unknown';
+        const population = props.POP_MAX || 0;
+        const country = props.ADM0NAME || 'Unknown';
+        const lon = coords[0];
+        const lat = coords[1];
+
+        const baseIndex = index * 4;
+        queryParts.push(`($${baseIndex + 1}, $${baseIndex + 2}, $${baseIndex + 3}, ST_SetSRID(ST_MakePoint($${baseIndex + 4}, $${baseIndex + 1}), 4326)::geography)`);
+        values.push(lat, name, population, country, lon); // Note: ST_MakePoint takes lon, lat
+      });
+
+      // Simple positional mapping for query (lat, name, pop, country, lon)
+      // Actually let's refine the query to be clearer
+      const refinedQueryParts = [];
+      const refinedValues = [];
+      
+      batch.forEach((feature, index) => {
+        const p = feature.properties;
+        const c = feature.geometry.coordinates;
+        const base = index * 5;
+        refinedQueryParts.push(`($${base + 1}, $${base + 2}, $${base + 3}, ST_SetSRID(ST_MakePoint($${base + 4}, $${base + 5}), 4326)::geography)`);
+        refinedValues.push(p.NAME || 'Unknown', p.POP_MAX || 0, p.ADM0NAME || 'Unknown', c[0], c[1]);
+      });
+
+      await client.query(
+        `INSERT INTO cities (name, population, country, geom) VALUES ${refinedQueryParts.join(',')}`,
+        refinedValues
+      );
+      
+      count += batch.length;
+      if (count % 1000 === 0 || count === data.features.length) {
+        console.log(`Imported ${count}/${data.features.length} cities...`);
+      }
+    }
+
+    console.log('SUCCESS: Natural Earth data import complete.');
+
+  } catch (err) {
+    console.error('ERROR during import:', err);
+  } finally {
+    await client.end();
+  }
+}
+
+importCities();