feat(wasserfoerderung): downloadable region packs for Einsatzgebiet (#150)

src/LageBuch.App.Android/MainActivity.cs

@@ -65,6 +65,7 @@ protected override AppBuilder CustomizeAppBuilder(AppBuilder builder)
             new NoopIncidentHostController(),
             new LageBuch.App.Shared.Services.AvaloniaUiDispatcher(),
             typeof(MainActivity).Assembly.GetName().Version?.ToString() ?? "0.0.0",
+            AndroidAppPaths.RegionsDir(this),
             lastSaveFolder: null,
             attachmentCacheRoot: AndroidAppPaths.AttachmentCacheDir(this));
         return base.CustomizeAppBuilder(builder).WithInterFont();

src/LageBuch.App.Android/Services/AndroidAppPaths.cs

@@ -27,4 +27,7 @@ public static string RecentFilesJsonPath(Context context) =>
 
     public static string AttachmentCacheDir(Context context) =>
         System.IO.Path.Combine(CacheDir(context), "attachment-cache");
+
+    public static string RegionsDir(Context context) =>
+        System.IO.Path.Combine(context.FilesDir!.AbsolutePath, "regions");
 }

src/LageBuch.App.Shared/CompositionRoot.cs

@@ -14,6 +14,13 @@ namespace LageBuch.App.Shared;
 /// </summary>
 public static class CompositionRoot
 {
+    /// <summary>
+    /// Raw-served manifest of published Wasserförderung region packs (#150 follow-up) — see
+    /// tools/build-region-pack/README.md for how a pack is built and published here.
+    /// </summary>
+    public const string RegionPackManifestUrl =
+        "https://raw.githubusercontent.com/CodeForFire/lagebuch-regions/main/regions.json";
+
     public static MainWindowViewModel CreateMainWindowViewModel(
         IIncidentStore store,
         IMasterDataProvider masterData,
@@ -26,11 +33,15 @@ public static MainWindowViewModel CreateMainWindowViewModel(
         IIncidentHostController hostController,
         IUiDispatcher uiDispatcher,
         string appVersion,
+        string regionsDir,
         ILastSaveFolderStore? lastSaveFolder = null,
         string? attachmentCacheRoot = null)
     {
         var home = new HomeViewModel(store, masterData, recent, dialogs, clock, ticker, alarm, hostController, appVersion, uiDispatcher, lastSaveFolder, attachmentCacheRoot, new RouteOverviewRenderer());
-        var editor = new MasterDataEditorViewModel(masterData, dialogs, masterDataFileService);
+        var httpClient = new HttpClient();
+        var regionCatalog = new RegionPackCatalogService(httpClient, RegionPackManifestUrl);
+        var regionInstaller = new RegionPackInstaller(httpClient, regionsDir);
+        var editor = new MasterDataEditorViewModel(masterData, dialogs, masterDataFileService, regionCatalog, regionInstaller);
         return new MainWindowViewModel(home, editor, dialogs, appVersion);
     }
 }

src/LageBuch.App.Shared/Views/MasterDataEditorView.axaml

@@ -2,6 +2,7 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:vm="clr-namespace:LageBuch.AppLogic.ViewModels;assembly=LageBuch.AppLogic"
              xmlns:md="clr-namespace:LageBuch.Persistence.MasterData;assembly=LageBuch.Persistence"
+             xmlns:services="clr-namespace:LageBuch.AppLogic.Services;assembly=LageBuch.AppLogic"
              x:Class="LageBuch.App.Shared.Views.MasterDataEditorView"
              x:DataType="vm:MasterDataEditorViewModel">
   <Panel>
@@ -108,18 +109,63 @@
                 </ScrollViewer>
               </DataTemplate>
 
-              <!-- Wasserförderung region of operation (#150 phase 2) -->
+              <!-- Wasserförderung region of operation (#150 phase 2 + region-pack follow-up):
+                   pick a published pack from the catalog and download it; manual folder entry
+                   stays available under "Erweitert" for a self-built or hand-placed pack. -->
               <DataTemplate x:DataType="vm:EinsatzgebietSection">
-                <StackPanel Spacing="12" MaxWidth="440" HorizontalAlignment="Left">
-                  <StackPanel Spacing="4">
-                    <TextBlock Text="NAME" Classes="overline" FontSize="10" />
-                    <TextBox Text="{Binding Name}" PlaceholderText="z. B. Landkreis Fürstenfeldbruck" />
-                  </StackPanel>
-                  <StackPanel Spacing="4">
-                    <TextBlock Text="ORDNER (region.mbtiles + region.dem)" Classes="overline" FontSize="10" />
-                    <TextBox Text="{Binding FolderPath}" PlaceholderText="z. B. /var/lib/lagebuch/regions/ffb" />
+                <ScrollViewer>
+                  <StackPanel Spacing="12" MaxWidth="480" HorizontalAlignment="Left">
+                    <StackPanel Spacing="4">
+                      <TextBlock Text="KARTENPAKET" Classes="overline" FontSize="10" />
+                      <Grid ColumnDefinitions="*,Auto" ColumnSpacing="8">
+                        <ComboBox x:Name="RegionComboBox" Grid.Column="0" HorizontalAlignment="Stretch"
+                                  ItemsSource="{Binding AvailableRegions}"
+                                  SelectedItem="{Binding SelectedRegion}"
+                                  PlaceholderText="Region auswählen…">
+                          <ComboBox.ItemTemplate>
+                            <DataTemplate x:DataType="services:RegionPackInfo">
+                              <TextBlock Text="{Binding Name}" />
+                            </DataTemplate>
+                          </ComboBox.ItemTemplate>
+                        </ComboBox>
+                        <Button x:Name="DownloadButton" Grid.Column="1" Content="HERUNTERLADEN"
+                                Command="{Binding DownloadSelectedRegionCommand}" />
+                      </Grid>
+                    </StackPanel>
+
+                    <Border x:Name="CatalogStatusBanner"
+                            IsVisible="{Binding CatalogStatus, Converter={x:Static ObjectConverters.IsNotNull}}"
+                            Background="#241608" BorderBrush="{StaticResource AmberBrush}" BorderThickness="1"
+                            CornerRadius="{StaticResource RadiusSm}" Padding="8,6">
+                      <TextBlock Text="{Binding CatalogStatus}" FontSize="12"
+                                 Foreground="{StaticResource AmberBrush}" TextWrapping="Wrap" />
+                    </Border>
+
+                    <ProgressBar x:Name="DownloadProgressBar" Minimum="0" Maximum="1"
+                                 Value="{Binding DownloadProgress}" Height="4" />
+
+                    <TextBlock x:Name="AttributionText" Text="{Binding SelectedRegion.Attribution}"
+                               IsVisible="{Binding SelectedRegion, Converter={x:Static ObjectConverters.IsNotNull}}"
+                               Classes="secondary" FontSize="11" TextWrapping="Wrap" />
+
+                    <TextBlock x:Name="KartendatenStatusText" Text="{Binding KartendatenStatus}"
+                               IsVisible="{Binding KartendatenStatus, Converter={x:Static ObjectConverters.IsNotNull}}"
+                               FontSize="12" TextWrapping="Wrap" />
+
+                    <Expander Header="Erweitert (manueller Ordnerpfad)">
+                      <StackPanel Spacing="12" Margin="0,12,0,0">
+                        <StackPanel Spacing="4">
+                          <TextBlock Text="NAME" Classes="overline" FontSize="10" />
+                          <TextBox Text="{Binding Name}" PlaceholderText="z. B. Landkreis Fürstenfeldbruck" />
+                        </StackPanel>
+                        <StackPanel Spacing="4">
+                          <TextBlock Text="ORDNER (region.mbtiles + region.dem)" Classes="overline" FontSize="10" />
+                          <TextBox Text="{Binding FolderPath}" PlaceholderText="z. B. /var/lib/lagebuch/regions/ffb" />
+                        </StackPanel>
+                      </StackPanel>
+                    </Expander>
                   </StackPanel>
-                </StackPanel>
+                </ScrollViewer>
               </DataTemplate>
 
               <!-- String-list / checklist editor -->

src/LageBuch.App/AppPaths.cs

@@ -13,6 +13,9 @@ public static class AppPaths
 
     public static string AttachmentCacheDir => Path.Combine(AppDataDir, "attachment-cache");
 
+    /// <summary>Where downloaded Wasserförderung region packs (#150 follow-up) get extracted, one subfolder per slug.</summary>
+    public static string RegionsDir => Path.Combine(AppDataDir, "regions");
+
     public static string GetAppDataDir(string baseDir)
     {
         var dir = Path.Combine(baseDir, "Lagebuch");

src/LageBuch.App/Program.cs

@@ -37,6 +37,7 @@ private static MainWindowViewModel CreateMainViewModel()
             new IncidentHostController(clock, version, uiDispatcher),
             uiDispatcher,
             version,
+            AppPaths.RegionsDir,
             new JsonLastSaveFolderStore(AppPaths.LastSaveFolderJsonPath),
             AppPaths.AttachmentCacheDir);
     }

src/LageBuch.AppLogic/Services/IRegionPackCatalogService.cs

@@ -0,0 +1,28 @@
+namespace LageBuch.AppLogic.Services;
+
+/// <summary>
+/// Lists the region packs (map tiles + elevation) publicly available for download (#150 follow-up)
+/// — the map-side counterpart to Stammdaten's Einsatzgebiet, which used to require hand-preparing
+/// region.mbtiles/region.dem with no guidance at all.
+/// </summary>
+public interface IRegionPackCatalogService
+{
+    /// <summary>
+    /// Never throws — a Stammdaten editor must stay usable offline, so a fetch/parse failure
+    /// yields an empty list rather than propagating an exception.
+    /// </summary>
+    Task<IReadOnlyList<RegionPackInfo>> GetAvailableRegionsAsync(CancellationToken ct = default);
+}
+
+/// <summary>One published, downloadable region pack.</summary>
+public sealed record RegionPackInfo(
+    string Name,
+    string Slug,
+    string DownloadUrl,
+    long SizeBytes,
+    double MinLat,
+    double MinLon,
+    double MaxLat,
+    double MaxLon,
+    string BuiltAt,
+    string Attribution);

src/LageBuch.AppLogic/Services/IRegionPackInstaller.cs

@@ -0,0 +1,8 @@
+namespace LageBuch.AppLogic.Services;
+
+/// <summary>Downloads and unpacks a region pack (#150 follow-up) into a local folder.</summary>
+public interface IRegionPackInstaller
+{
+    /// <summary>Returns the folder the pack was extracted into (ready to use as Einsatzgebiet.FolderPath).</summary>
+    Task<string> DownloadAndInstallAsync(RegionPackInfo pack, IProgress<double>? progress, CancellationToken ct = default);
+}

src/LageBuch.AppLogic/Services/RegionPackCatalogJson.cs

@@ -0,0 +1,85 @@
+using System.Text.Json;
+using System.Text.RegularExpressions;
+
+namespace LageBuch.AppLogic.Services;
+
+/// <summary>
+/// Reads the region-pack manifest format (#150 follow-up) — a flat JSON array, each entry
+/// describing one downloadable pack. Defensive like <c>MasterDataJson</c>: malformed input, or an
+/// entry missing a required field, is skipped rather than thrown — the manifest is fetched from a
+/// third-party-controlled URL, so a partially bad response must degrade gracefully, not crash
+/// Stammdaten.
+/// </summary>
+public static class RegionPackCatalogJson
+{
+    // RegionPackInstaller joins this straight onto a base directory (<regionsBaseDir>/<slug>) —
+    // reject anything that could escape that directory (path separators, "..", empty) here rather
+    // than trusting the installer alone to catch it.
+    private static readonly Regex SafeSlug = new("^[a-z0-9][a-z0-9_-]{0,63}$", RegexOptions.Compiled);
+
+    public static IReadOnlyList<RegionPackInfo> Parse(string json)
+    {
+        try
+        {
+            using var doc = JsonDocument.Parse(json);
+            if (doc.RootElement.ValueKind != JsonValueKind.Array)
+                return Array.Empty<RegionPackInfo>();
+
+            var result = new List<RegionPackInfo>();
+            foreach (var entry in doc.RootElement.EnumerateArray())
+            {
+                if (TryParseEntry(entry, out var region))
+                    result.Add(region);
+            }
+            return result;
+        }
+        catch (JsonException)
+        {
+            return Array.Empty<RegionPackInfo>();
+        }
+    }
+
+    private static bool TryParseEntry(JsonElement entry, out RegionPackInfo region)
+    {
+        region = null!;
+        if (entry.ValueKind != JsonValueKind.Object)
+            return false;
+
+        if (!TryGetString(entry, "name", out var name) ||
+            !TryGetString(entry, "slug", out var slug) || !SafeSlug.IsMatch(slug) ||
+            !TryGetString(entry, "downloadUrl", out var downloadUrl) ||
+            !TryGetString(entry, "builtAt", out var builtAt) ||
+            !TryGetString(entry, "attribution", out var attribution) ||
+            !entry.TryGetProperty("sizeBytes", out var sizeBytesEl) || sizeBytesEl.ValueKind != JsonValueKind.Number ||
+            !entry.TryGetProperty("boundingBox", out var bbox) || bbox.ValueKind != JsonValueKind.Object ||
+            !TryGetNumber(bbox, "minLat", out var minLat) ||
+            !TryGetNumber(bbox, "minLon", out var minLon) ||
+            !TryGetNumber(bbox, "maxLat", out var maxLat) ||
+            !TryGetNumber(bbox, "maxLon", out var maxLon))
+        {
+            return false;
+        }
+
+        region = new RegionPackInfo(name, slug, downloadUrl, sizeBytesEl.GetInt64(),
+            minLat, minLon, maxLat, maxLon, builtAt, attribution);
+        return true;
+    }
+
+    private static bool TryGetString(JsonElement e, string prop, out string value)
+    {
+        value = string.Empty;
+        if (!e.TryGetProperty(prop, out var v) || v.ValueKind != JsonValueKind.String)
+            return false;
+        value = v.GetString()!;
+        return true;
+    }
+
+    private static bool TryGetNumber(JsonElement e, string prop, out double value)
+    {
+        value = 0;
+        if (!e.TryGetProperty(prop, out var v) || v.ValueKind != JsonValueKind.Number)
+            return false;
+        value = v.GetDouble();
+        return true;
+    }
+}

src/LageBuch.AppLogic/Services/RegionPackCatalogService.cs

@@ -0,0 +1,23 @@
+namespace LageBuch.AppLogic.Services;
+
+/// <summary>
+/// Fetches the region-pack manifest over HTTP (#150 follow-up). The one place this offline-first
+/// app makes an unprompted network call — but only when the operator opens the Einsatzgebiet
+/// section, and it degrades to an empty list rather than surfacing any error, so Stammdaten stays
+/// fully usable without a connection.
+/// </summary>
+public sealed class RegionPackCatalogService(HttpClient httpClient, string manifestUrl) : IRegionPackCatalogService
+{
+    public async Task<IReadOnlyList<RegionPackInfo>> GetAvailableRegionsAsync(CancellationToken ct = default)
+    {
+        try
+        {
+            var json = await httpClient.GetStringAsync(manifestUrl, ct);
+            return RegionPackCatalogJson.Parse(json);
+        }
+        catch (HttpRequestException)
+        {
+            return Array.Empty<RegionPackInfo>();
+        }
+    }
+}

src/LageBuch.AppLogic/Services/RegionPackInstaller.cs

@@ -0,0 +1,63 @@
+using System.IO.Compression;
+
+namespace LageBuch.AppLogic.Services;
+
+/// <summary>
+/// Downloads a region pack's zip (region.mbtiles + region.dem) and extracts it into
+/// <c>&lt;regionsBaseDir&gt;/&lt;slug&gt;</c> (#150 follow-up). A re-install of the same slug replaces the
+/// folder outright, so a pack update never leaves stale files from a previous version behind.
+/// </summary>
+public sealed class RegionPackInstaller(HttpClient httpClient, string regionsBaseDir) : IRegionPackInstaller
+{
+    // Downloading is the slow part; reserve a small tail of the progress range for extraction so
+    // the caller sees forward motion continue past "download done" instead of jumping straight to 1.0.
+    private const double DownloadProgressShare = 0.9;
+
+    public async Task<string> DownloadAndInstallAsync(RegionPackInfo pack, IProgress<double>? progress, CancellationToken ct = default)
+    {
+        progress?.Report(0.0);
+
+        var zipBytes = await DownloadAsync(pack.DownloadUrl, progress, ct);
+
+        // Defense in depth: RegionPackCatalogJson already rejects unsafe slugs when parsing the
+        // manifest, but a slug ending up here from anywhere else must not be able to escape
+        // regionsBaseDir either.
+        var baseFull = Path.GetFullPath(regionsBaseDir) + Path.DirectorySeparatorChar;
+        var folder = Path.GetFullPath(Path.Combine(regionsBaseDir, pack.Slug));
+        if (!folder.StartsWith(baseFull, StringComparison.Ordinal))
+            throw new InvalidOperationException($"Region slug '{pack.Slug}' escapes the regions directory.");
+
+        if (Directory.Exists(folder))
+            Directory.Delete(folder, recursive: true);
+        Directory.CreateDirectory(folder);
+
+        using (var zip = new ZipArchive(new MemoryStream(zipBytes), ZipArchiveMode.Read))
+            zip.ExtractToDirectory(folder);
+
+        progress?.Report(1.0);
+        return folder;
+    }
+
+    private async Task<byte[]> DownloadAsync(string url, IProgress<double>? progress, CancellationToken ct)
+    {
+        using var response = await httpClient.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, ct);
+        response.EnsureSuccessStatusCode();
+
+        var totalBytes = response.Content.Headers.ContentLength;
+        await using var source = await response.Content.ReadAsStreamAsync(ct);
+        using var buffer = new MemoryStream();
+
+        var chunk = new byte[81920];
+        long readSoFar = 0;
+        int read;
+        while ((read = await source.ReadAsync(chunk, ct)) > 0)
+        {
+            await buffer.WriteAsync(chunk.AsMemory(0, read), ct);
+            readSoFar += read;
+            if (totalBytes is > 0)
+                progress?.Report(Math.Min(DownloadProgressShare, (double)readSoFar / totalBytes.Value * DownloadProgressShare));
+        }
+
+        return buffer.ToArray();
+    }
+}