add SatelliteDownloader

2026-04-22 11:36:38 +00:00 · 2025-10-25 23:13:06 +03:00
parent c354661a10
commit e71b806e04
8 changed files with 294 additions and 0 deletions
@@ -0,0 +1,107 @@
+using System.Collections.Concurrent;
+using Microsoft.Extensions.Options;
+using Newtonsoft.Json;
+using SatelliteProvider.Configs;
+using SatelliteProvider.DTO;
+using SixLabors.ImageSharp;
+
+namespace SatelliteProvider;
+
+public interface ISatelliteDownloader
+{
+    Task GetTiles(GeoPoint geoPoint, double radiusM, int zoomLevel, CancellationToken token = default);
+}
+
+public class SatelliteDownloader(ILogger<SatelliteDownloader> logger, IOptions<MapConfig> mapConfig, IHttpClientFactory httpClientFactory)
+    : ISatelliteDownloader
+{
+    private const string TILE_URL_TEMPLATE = "https://mt{0}.google.com/vt/lyrs=s&x={1}&y={2}&z={3}&token={4}";
+    private const int NUM_SERVERS = 4;
+    private readonly string _apiKey = mapConfig.Value.ApiKey;
+
+    private readonly string _satDirectory = Path.Combine(Directory.GetCurrentDirectory(), "maps");
+
+
+    private record SessionResponse(string Session);
+
+    private async Task<string?> GetSessionToken()
+    {
+        var url = $"https://tile.googleapis.com/v1/createSession?key={_apiKey}";
+        using var httpClient = httpClientFactory.CreateClient();
+        try
+        {
+            var str = JsonConvert.SerializeObject(new { mapType = "satellite" });
+            var response = await httpClient.PostAsync(url, new StringContent(str));
+            response.EnsureSuccessStatusCode();
+            var sessionResponse = await response.Content.ReadFromJsonAsync<SessionResponse>();
+            return sessionResponse?.Session;
+        }
+        catch (Exception e)
+        {
+            logger.LogError(e, e.Message);
+            throw;
+        }
+    }
+
+    public async Task GetTiles(GeoPoint centerGeoPoint, double radiusM, int zoomLevel, CancellationToken token = default)
+    {
+        var (latMin, latMax, lonMin, lonMax) = GeoUtils.GetBoundingBox(centerGeoPoint, radiusM);
+
+        var (xMin, yMin) = GeoUtils.WorldToTilePos(latMax, lonMin, zoomLevel); // Top-left corner
+        var (xMax, yMax) = GeoUtils.WorldToTilePos(latMin, lonMax, zoomLevel); // Bottom-right corner
+
+        var tilesToDownload = new ConcurrentQueue<SatTile>();
+        var server = 0;
+        var sessionToken = await GetSessionToken();
+
+        for (var y = yMin; y <= yMax + 1; y++)
+            for (var x = xMin; x <= xMax + 1; x++)
+            {
+                token.ThrowIfCancellationRequested();
+                var url = string.Format(TILE_URL_TEMPLATE, server, x, y, zoomLevel, sessionToken);
+
+                tilesToDownload.Enqueue(new SatTile(x, y, zoomLevel, url));
+                server = (server + 1) % NUM_SERVERS;
+            }
+
+        var downloadTasks = new List<Task>();
+        int downloadedCount = 0;
+
+
+        for (int i = 0; i < NUM_SERVERS; i++)
+        {
+            downloadTasks.Add(Task.Run(async () =>
+            {
+                using var httpClient = httpClientFactory.CreateClient();
+
+                while (tilesToDownload.TryDequeue(out var tileInfo))
+                {
+                    if (token.IsCancellationRequested) break;
+                    try
+                    {
+                        httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.0.0 Safari/537.36");
+                        var response = await httpClient.GetAsync(tileInfo.Url, token);
+                        response.EnsureSuccessStatusCode();
+                        var tileData = await response.Content.ReadAsByteArrayAsync(token);
+                        using var tileImage = Image.Load(tileData);
+                        await tileImage.SaveAsync(Path.Combine(_satDirectory, tileInfo.FileName), token);
+                        if (tileData.Length > 0)
+                        {
+                            Interlocked.Increment(ref downloadedCount);
+                        }
+                    }
+                    catch (HttpRequestException requestException)
+                    {
+                        logger.LogError(requestException, $"Fail to download tile! Url: {tileInfo.Url}. {requestException.Message}");
+                    }
+                    catch (Exception e)
+                    {
+                        logger.LogError(e, $"Fail to download tile! {e.Message}");
+                    }
+                }
+            }, token));
+        }
+
+        await Task.WhenAll(downloadTasks);
+    }
+}