Map caching in Redis

ems/src/index.ts

@@ -2,6 +2,8 @@ import express, { Request, Response } from 'express'
 import { Redis } from 'ioredis'
 import dotenv from 'dotenv'
 import bodyParser from 'body-parser'
+import { SatelliteMapsProvider } from './interfaces/map'
+const axios = require('axios');
 
 const cors = require('cors')
 
@@ -19,6 +21,61 @@ const port = process.env.EMS_PORT
 // Middleware to parse JSON requests
 app.use(bodyParser.json())
 
+const getTileUrl = (provider: string, x: string, y: string, z: string) => {
+    if (provider === 'google') {
+        return `https://khms2.google.com/kh/v=984?x=${x}&y=${y}&z=${z}`;
+    } else if (provider === 'yandex') {
+        return `https://core-sat.maps.yandex.net/tiles?l=sat&x=${x}&y=${y}&z=${z}&scale=1&lang=ru_RU`;
+    }
+    throw new Error('Invalid provider');
+}
+
+app.get('/tile/:provider/:z/:x/:y', async (req, res) => {
+    const { provider, x, y, z } = req.params;
+    const cacheKey = `${provider}:${z}:${x}:${y}`;
+
+    try {
+        // Check if tile is in cache
+        redis.get(cacheKey, async (err, cachedTile) => {
+            if (err) {
+                console.error('Redis GET error:', err);
+                return res.status(500).send('Server error');
+            }
+
+            if (cachedTile) {
+                // If cached, return tile
+                console.log('Tile served from cache');
+                const imgBuffer = Buffer.from(cachedTile, 'base64');
+                res.writeHead(200, {
+                    'Content-Type': 'image/png',
+                    'Content-Length': imgBuffer.length,
+                });
+                return res.end(imgBuffer);
+            } else {
+                // Fetch tile from provider
+                const tileUrl = getTileUrl(provider, x, y, z);
+                const response = await axios.get(tileUrl, {
+                    responseType: 'arraybuffer',
+                });
+
+                // Cache the tile in Redis
+                const base64Tile = Buffer.from(response.data).toString('base64');
+                redis.setex(cacheKey, 3600 * 24 * 30, base64Tile); // Cache for 1 hour
+
+                // Return the tile to the client
+                res.writeHead(200, {
+                    'Content-Type': 'image/png',
+                    'Content-Length': response.data.length,
+                });
+                return res.end(response.data);
+            }
+        });
+    } catch (error) {
+        console.error('Error fetching tile:', error);
+        res.status(500).send('Error fetching tile');
+    }
+})
+
 app.get('/hello', cors(), (req: Request, res: Response) => {
     res.send('Hello, World!')
 })

ems/src/interfaces/map.ts

@@ -0,0 +1,5 @@
+export interface SatelliteMapsProviders {
+    google: 'google';
+    yandex: 'yandex';
+}
+export type SatelliteMapsProvider = SatelliteMapsProviders[keyof SatelliteMapsProviders]