1 files changed, 217 insertions, 0 deletions
diff --git a/src/Enmarcha.Backend/Controllers/TileController.cs b/src/Enmarcha.Backend/Controllers/TileController.cs
new file mode 100644
index 0000000..3459997
--- /dev/null
+++ b/src/Enmarcha.Backend/Controllers/TileController.cs
@@ -0,0 +1,217 @@
+using NetTopologySuite.Features;
+using NetTopologySuite.IO.VectorTiles;
+using NetTopologySuite.IO.VectorTiles.Mapbox;
+
+using Microsoft.AspNetCore.Mvc;
+
+using Microsoft.Extensions.Caching.Memory;
+using System.Text.Json;
+using Enmarcha.Sources.OpenTripPlannerGql;
+using Enmarcha.Sources.OpenTripPlannerGql.Queries;
+using Enmarcha.Backend.Configuration;
+using Enmarcha.Backend.Helpers;
+using Enmarcha.Backend.Services;
+using Microsoft.Extensions.Options;
+
+namespace Enmarcha.Backend.Controllers;
+
+[ApiController]
+[Route("api/tiles")]
+public class TileController : ControllerBase
+{
+    private readonly ILogger<TileController> _logger;
+    private readonly IMemoryCache _cache;
+    private readonly HttpClient _httpClient;
+    private readonly FeedService _feedService;
+    private readonly AppConfiguration _config;
+
+    public TileController(
+        ILogger<TileController> logger,
+        IMemoryCache cache,
+        HttpClient httpClient,
+        FeedService feedService,
+        IOptions<AppConfiguration> configOptions
+    )
+    {
+        _logger = logger;
+        _cache = cache;
+        _httpClient = httpClient;
+        _feedService = feedService;
+        _config = configOptions.Value;
+    }
+
+    [HttpGet("stops/{z:int}/{x:int}/{y:int}")]
+    public async Task<IActionResult> Stops(int z, int x, int y)
+    {
+        if (z is < 9 or > 20)
+        {
+            return BadRequest("Zoom level out of range (9-20)");
+        }
+
+        var cacheHit = _cache.TryGetValue($"stops-tile-{z}-{x}-{y}", out byte[]? cachedTile);
+        if (cacheHit && cachedTile != null)
+        {
+            Response.Headers.Append("X-Cache-Hit", "true");
+            return File(cachedTile, "application/x-protobuf");
+        }
+
+        // Calculate bounding box in EPSG:4326
+        var n = Math.Pow(2, z);
+        var lonMin = x / n * 360.0 - 180.0;
+        var lonMax = (x + 1) / n * 360.0 - 180.0;
+
+        var latMaxRad = Math.Atan(Math.Sinh(Math.PI * (1 - 2 * y / n)));
+        var latMax = latMaxRad * 180.0 / Math.PI;
+
+        var latMinRad = Math.Atan(Math.Sinh(Math.PI * (1 - 2 * (y + 1) / n)));
+        var latMin = latMinRad * 180.0 / Math.PI;
+
+        var requestContent = StopTileRequestContent.Query(new StopTileRequestContent.Bbox(lonMin, latMin, lonMax, latMax));
+        var request = new HttpRequestMessage(HttpMethod.Post, $"{_config.OpenTripPlannerBaseUrl}/gtfs/v1");
+        request.Content = JsonContent.Create(new GraphClientRequest
+        {
+            Query = requestContent
+        });
+
+        var response = await _httpClient.SendAsync(request);
+        var responseBody = await response.Content.ReadFromJsonAsync<GraphClientResponse<StopTileResponse>>();
+
+        if (responseBody is not { IsSuccess: true })
+        {
+            _logger.LogError(
+                "Error fetching stop data, received {StatusCode} {ResponseBody}",
+                response.StatusCode,
+                await response.Content.ReadAsStringAsync()
+            );
+            return StatusCode(500, "Error fetching stop data");
+        }
+
+        var tileDef = new NetTopologySuite.IO.VectorTiles.Tiles.Tile(x, y, z);
+        VectorTile vt = new() { TileId = tileDef.Id };
+        var stopsLayer = new Layer { Name = "stops" };
+
+        responseBody.Data?.StopsByBbox?.ForEach(stop =>
+        {
+            var idParts = stop.GtfsId.Split(':', 2);
+            string feedId = idParts[0];
+            string codeWithinFeed = _feedService.NormalizeStopCode(feedId, stop.Code ?? string.Empty);
+
+            if (_feedService.IsStopHidden($"{feedId}:{codeWithinFeed}"))
+            {
+                return;
+            }
+
+            // TODO: Duplicate from ArrivalsController
+            var (Color, TextColor) = _feedService.GetFallbackColourForFeed(idParts[0]);
+            var distinctRoutes = GetDistinctRoutes(feedId, stop.Routes ?? []);
+
+            Feature feature = new()
+            {
+                Geometry = new NetTopologySuite.Geometries.Point(stop.Lon, stop.Lat),
+                Attributes = new AttributesTable
+                {
+                    // The ID will be used to request the arrivals
+                    { "id", stop.GtfsId },
+                    // The feed is the first part of the GTFS ID
+                    { "feed", idParts[0] },
+                    // The public identifier, usually feed:code or feed:id, recognisable by users and in other systems
+                    { "code", $"{idParts[0]}:{codeWithinFeed}" },
+                    { "name", _feedService.NormalizeStopName(feedId, stop.Name) },
+                    { "icon", GetIconNameForFeed(feedId) },
+                    { "transitKind", GetTransitKind(feedId) },
+                    // Routes
+                    { "routes", JsonSerializer
+                        .Serialize(
+                            distinctRoutes.Select(r => {
+                            var colour = r.Color ?? Color;
+                            string textColour;
+
+                            if (r.Color is null) // None is present, use fallback
+                            {
+                                textColour = TextColor;
+                            }
+                            else if (r.TextColor is null || r.TextColor.EndsWith("000000"))
+                            {
+                                // Text colour not provided, or default-black; check the better contrasting
+                                textColour = ContrastHelper.GetBestTextColour(colour);
+                            }
+                            else
+                            {
+                                // Use provided text colour
+                                textColour = r.TextColor;
+                            }
+
+                            return new {
+                                shortName = r.ShortName,
+                                colour,
+                                textColour
+                            };
+                        }))
+                    }
+                }
+            };
+
+            stopsLayer.Features.Add(feature);
+        });
+
+        vt.Layers.Add(stopsLayer);
+
+        using var ms = new MemoryStream();
+        vt.Write(ms, minLinealExtent: 1, minPolygonalExtent: 2);
+
+        _cache.Set($"stops-tile-{z}-{x}-{y}", ms.ToArray(), TimeSpan.FromMinutes(15));
+        Response.Headers.Append("X-Cache-Hit", "false");
+
+        return File(ms.ToArray(), "application/x-protobuf");
+    }
+
+    private string GetIconNameForFeed(string feedId)
+    {
+        return feedId switch
+        {
+            "vitrasa" => "stop-vitrasa",
+            "tussa" => "stop-tussa",
+            "tranvias" => "stop-tranvias",
+            "xunta" => "stop-xunta",
+            "renfe" => "stop-renfe",
+            "feve" => "stop-feve",
+            _ => "stop-generic",
+        };
+    }
+
+    private string GetTransitKind(string feedId)
+    {
+        return feedId switch
+        {
+            "vitrasa" or "tussa" or "tranvias" => "bus",
+            "xunta" => "coach",
+            "renfe" or "feve" => "train",
+            _ => "unknown",
+        };
+    }
+
+    private List<StopTileResponse.Route> GetDistinctRoutes(string feedId, List<StopTileResponse.Route> routes)
+    {
+        List<StopTileResponse.Route> distinctRoutes = [];
+        HashSet<string> seen = new();
+
+        foreach (var route in routes)
+        {
+            var seenId = _feedService.GetUniqueRouteShortName(feedId, route.ShortName ?? string.Empty);
+            route.ShortName = seenId;
+
+            if (seen.Contains(seenId))
+            {
+                continue;
+            }
+
+            seen.Add(seenId);
+            distinctRoutes.Add(route);
+        }
+
+        return [.. distinctRoutes.OrderBy(
+            r => r.ShortName,
+            Comparer<string?>.Create(SortingHelper.SortRouteShortNames)
+        )];
+    }
+}