postit: reverse geocode rdv map selections

src/PostIt/PostIt.Tests/NominatimReverseGeocodingServiceTests.cs

@@ -0,0 +1,72 @@
+using System.Net;
+using System.Text;
+using PostIt.Services;
+
+namespace PostIt.Tests;
+
+public class NominatimReverseGeocodingServiceTests
+{
+    [Fact]
+    public async Task TryResolveAddressAsync_formats_compact_street_address_from_nominatim_payload()
+    {
+        var handler = new StubHandler("""
+            {
+              "display_name": "6, Place de l'Hôtel-de-Ville - Esplanade de la Libération, Paris, 75004, France",
+              "address": {
+                "house_number": "6",
+                "road": "Place de l'Hôtel-de-Ville - Esplanade de la Libération",
+                "postcode": "75004",
+                "city": "Paris"
+              }
+            }
+            """);
+
+        var service = new NominatimReverseGeocodingService(new HttpClient(handler)
+        {
+            BaseAddress = new Uri("https://nominatim.openstreetmap.org/")
+        });
+
+        var result = await service.TryResolveAddressAsync(48.8566, 2.3522);
+
+        Assert.Equal("6, Place de l'Hôtel-de-Ville - Esplanade de la Libération, 75004, Paris", result);
+        Assert.NotNull(handler.LastRequest);
+        Assert.Contains("reverse?format=jsonv2", handler.LastRequest!.RequestUri!.ToString(), StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public async Task TryResolveAddressAsync_returns_null_on_unsuccessful_response()
+    {
+        var handler = new StubHandler("{}", HttpStatusCode.TooManyRequests);
+        var service = new NominatimReverseGeocodingService(new HttpClient(handler)
+        {
+            BaseAddress = new Uri("https://nominatim.openstreetmap.org/")
+        });
+
+        var result = await service.TryResolveAddressAsync(48.8566, 2.3522);
+
+        Assert.Null(result);
+    }
+
+    private sealed class StubHandler : HttpMessageHandler
+    {
+        private readonly string _payload;
+        private readonly HttpStatusCode _statusCode;
+
+        public HttpRequestMessage? LastRequest { get; private set; }
+
+        public StubHandler(string payload, HttpStatusCode statusCode = HttpStatusCode.OK)
+        {
+            _payload = payload;
+            _statusCode = statusCode;
+        }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            LastRequest = request;
+            return Task.FromResult(new HttpResponseMessage(_statusCode)
+            {
+                Content = new StringContent(_payload, Encoding.UTF8, "application/json")
+            });
+        }
+    }
+}

src/PostIt/PostIt/Helpers/ServiceCollectionHelpers.cs

@@ -30,6 +30,7 @@ public static class ServiceCollectionHelpers
             () => settings.Authentication?.Authority);
         var billingClient = new BillingApiClient(api, () => settings.ApiUrl);
         var userDirectory = new UserDirectory(userSearchClient);
+        var reverseGeocoding = new NominatimReverseGeocodingService();
 
         // Vues
         services.AddSingleton<MainView>();
@@ -65,6 +66,7 @@ public static class ServiceCollectionHelpers
         services.AddSingleton(userSearchClient);
         services.AddSingleton(activityClient);
         services.AddSingleton(billingClient);
+        services.AddSingleton<IReverseGeocodingService>(reverseGeocoding);
         services.AddSingleton<IUserDirectory>(userDirectory);
         services.AddSingleton<HomePageViewModel>();
         services.AddSingleton<SignaturePageViewModel>();

src/PostIt/PostIt/Services/IReverseGeocodingService.cs

@@ -0,0 +1,9 @@
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace PostIt.Services;
+
+public interface IReverseGeocodingService
+{
+    Task<string?> TryResolveAddressAsync(double latitude, double longitude, CancellationToken cancellationToken = default);
+}

src/PostIt/PostIt/Services/NominatimReverseGeocodingService.cs

@@ -0,0 +1,119 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace PostIt.Services;
+
+public sealed class NominatimReverseGeocodingService : IReverseGeocodingService
+{
+    private static readonly Uri BaseUri = new("https://nominatim.openstreetmap.org/");
+    private readonly HttpClient _httpClient;
+
+    public NominatimReverseGeocodingService(HttpClient? httpClient = null)
+    {
+        _httpClient = httpClient ?? CreateDefaultClient();
+    }
+
+    public async Task<string?> TryResolveAddressAsync(double latitude, double longitude, CancellationToken cancellationToken = default)
+    {
+        var requestUri = BuildReverseUri(latitude, longitude);
+
+        try
+        {
+            using var response = await _httpClient.GetAsync(requestUri, cancellationToken).ConfigureAwait(false);
+            if (!response.IsSuccessStatusCode)
+                return null;
+
+            await using var stream = await response.Content.ReadAsStreamAsync(cancellationToken).ConfigureAwait(false);
+            using var json = await JsonDocument.ParseAsync(stream, cancellationToken: cancellationToken).ConfigureAwait(false);
+            return FormatAddress(json.RootElement);
+        }
+        catch (OperationCanceledException)
+        {
+            throw;
+        }
+        catch
+        {
+            return null;
+        }
+    }
+
+    private static HttpClient CreateDefaultClient()
+    {
+        var client = new HttpClient
+        {
+            BaseAddress = BaseUri,
+            Timeout = TimeSpan.FromSeconds(10),
+        };
+        client.DefaultRequestHeaders.UserAgent.Clear();
+        client.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("PostIt", "1.1"));
+        client.DefaultRequestHeaders.AcceptLanguage.Add(new StringWithQualityHeaderValue("fr-FR"));
+        client.DefaultRequestHeaders.AcceptLanguage.Add(new StringWithQualityHeaderValue("fr", 0.9));
+        return client;
+    }
+
+    private static Uri BuildReverseUri(double latitude, double longitude)
+    {
+        var lat = latitude.ToString("0.######", CultureInfo.InvariantCulture);
+        var lon = longitude.ToString("0.######", CultureInfo.InvariantCulture);
+        var path = $"reverse?format=jsonv2&addressdetails=1&accept-language=fr&zoom=18&lat={lat}&lon={lon}";
+        return new Uri(path, UriKind.Relative);
+    }
+
+    private static string? FormatAddress(JsonElement root)
+    {
+        if (root.TryGetProperty("address", out var address))
+        {
+            var street = JoinNonEmpty(
+                TryGetString(address, "house_number"),
+                TryGetString(address, "road"));
+
+            var locality = JoinNonEmpty(
+                TryGetString(address, "postcode"),
+                TryGetString(address, "city")
+                    ?? TryGetString(address, "town")
+                    ?? TryGetString(address, "village")
+                    ?? TryGetString(address, "municipality"));
+
+            var formatted = JoinNonEmpty(street, locality);
+            if (!string.IsNullOrWhiteSpace(formatted))
+                return formatted;
+        }
+
+        if (root.TryGetProperty("display_name", out var displayName))
+        {
+            var value = displayName.GetString();
+            if (!string.IsNullOrWhiteSpace(value))
+                return value;
+        }
+
+        return null;
+    }
+
+    private static string? TryGetString(JsonElement element, string propertyName)
+    {
+        return element.TryGetProperty(propertyName, out var property)
+            ? property.GetString()
+            : null;
+    }
+
+    private static string? JoinNonEmpty(params string?[] values)
+    {
+        List<string>? parts = null;
+        foreach (var value in values)
+        {
+            if (string.IsNullOrWhiteSpace(value))
+                continue;
+
+            parts ??= new List<string>();
+            parts.Add(value.Trim());
+        }
+
+        return parts is null || parts.Count == 0 ? null : string.Join(", ", parts);
+    }
+}

src/PostIt/PostIt/ViewModels/Commands/RdvViewModel.cs

@@ -127,6 +127,15 @@ public partial class RdvViewModel : BillingCommandPageViewModel
         this.SetInfoStatus("Position sélectionnée sur la carte.");
     }
 
+    public void ApplyResolvedAddress(string address)
+    {
+        if (string.IsNullOrWhiteSpace(address))
+            return;
+
+        Address = address.Trim();
+        this.SetInfoStatus("Adresse mise à jour depuis la carte.");
+    }
+
 
     protected override async Task SubmitAsync()
     {

src/PostIt/PostIt/Views/Commands/RdvPage.axaml.cs

@@ -1,5 +1,7 @@
+using System;
 using System.ComponentModel;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
@@ -9,6 +11,7 @@ using Mapsui.Projections;
 using Mapsui.Styles;
 using Mapsui.Tiling;
 using Mapsui.UI.Avalonia;
+using PostIt.Services;
 using PostIt.ViewModels.Commands;
 
 namespace PostIt.Views.Commands;
@@ -23,9 +26,17 @@ public partial class RdvPage : ContentPage
     private MapControl? _locationMap;
     private MemoryLayer? _selectionLayer;
     private RdvViewModel? _currentViewModel;
+    private readonly IReverseGeocodingService _reverseGeocodingService;
+    private CancellationTokenSource? _reverseGeocodeCts;
 
     public RdvPage()
+        : this(null)
     {
+    }
+
+    public RdvPage(IReverseGeocodingService? reverseGeocodingService)
+    {
+        _reverseGeocodingService = reverseGeocodingService ?? new NominatimReverseGeocodingService();
         InitializeComponent();
         InitializeMap();
     }
@@ -58,7 +69,7 @@ public partial class RdvPage : ContentPage
         CenterFromViewModel();
     }
 
-    private void OnMapTapped(object? sender, MapEventArgs e)
+    private async void OnMapTapped(object? sender, MapEventArgs e)
     {
         if (DataContext is not RdvViewModel vm)
             return;
@@ -67,6 +78,7 @@ public partial class RdvPage : ContentPage
         vm.ApplyLocationFromMap(latitude, longitude);
         UpdateMarkerFromViewModel();
         CenterMap(latitude, longitude, zoomLevel: SelectedZoomLevel);
+        await TryResolveAddressAsync(vm, latitude, longitude);
     }
 
     private async void OnCenterCurrentLocationClicked(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
@@ -77,6 +89,9 @@ public partial class RdvPage : ContentPage
         await vm.UseCurrentLocationCommand.ExecuteAsync(null);
         UpdateMarkerFromViewModel();
         CenterFromViewModel();
+
+        if (vm.Latitude.HasValue && vm.Longitude.HasValue)
+            await TryResolveAddressAsync(vm, vm.Latitude.Value, vm.Longitude.Value);
     }
 
     private void AttachViewModel(RdvViewModel? vm)
@@ -161,4 +176,24 @@ public partial class RdvPage : ContentPage
             Features = Enumerable.Empty<IFeature>(),
         };
     }
+
+    private async Task TryResolveAddressAsync(RdvViewModel vm, double latitude, double longitude)
+    {
+        _reverseGeocodeCts?.Cancel();
+        _reverseGeocodeCts?.Dispose();
+        _reverseGeocodeCts = new CancellationTokenSource();
+
+        try
+        {
+            var resolved = await _reverseGeocodingService
+                .TryResolveAddressAsync(latitude, longitude, _reverseGeocodeCts.Token)
+                .ConfigureAwait(true);
+
+            if (!string.IsNullOrWhiteSpace(resolved))
+                vm.ApplyResolvedAddress(resolved);
+        }
+        catch (OperationCanceledException)
+        {
+        }
+    }
 }