Add Google Calendar OAuth broker

OtthonApi/Program.cs

@@ -1,9 +1,12 @@
 using System.Net.Http.Headers;
 using System.Security.Claims;
+using System.Security.Cryptography;
+using System.Text;
 using System.Text.Json;
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Authentication.Cookies;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.EntityFrameworkCore;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -151,6 +154,214 @@ app.MapGet("/api/app-config", async (HttpContext context, OtthonDbContext db) =>
         !string.IsNullOrWhiteSpace(googleClientId)));
 });
 
+app.MapGet("/api/google/oauth/start", async (
+    HttpContext context,
+    OtthonDbContext db) =>
+{
+    if (!HasApiToken(context))
+    {
+        return Results.Unauthorized();
+    }
+
+    var workspaceToken = GetWorkspaceToken(context);
+    if (string.IsNullOrWhiteSpace(workspaceToken))
+    {
+        return Results.BadRequest(new { message = "Missing X-Workspace-Token header." });
+    }
+
+    var clientId = await GetGoogleClientId(db);
+    var clientSecret = await GetGoogleClientSecret(db);
+    if (string.IsNullOrWhiteSpace(clientId) || string.IsNullOrWhiteSpace(clientSecret))
+    {
+        return Results.BadRequest(new { message = "Google OAuth client is not configured." });
+    }
+
+    var stateValue = RandomToken(32);
+    db.GoogleOAuthStates.Add(new GoogleOAuthState
+    {
+        State = stateValue,
+        WorkspaceToken = workspaceToken,
+        CreatedUtc = DateTimeOffset.UtcNow,
+        ExpiresUtc = DateTimeOffset.UtcNow.AddMinutes(15)
+    });
+    await db.SaveChangesAsync();
+
+    var redirectUri = GoogleOAuthRedirectUri();
+    var authUri = QueryHelpers.AddQueryString("https://accounts.google.com/o/oauth2/v2/auth", new Dictionary<string, string?>
+    {
+        ["client_id"] = clientId,
+        ["redirect_uri"] = redirectUri,
+        ["response_type"] = "code",
+        ["scope"] = "openid email https://www.googleapis.com/auth/calendar.readonly",
+        ["access_type"] = "offline",
+        ["prompt"] = "consent",
+        ["state"] = stateValue
+    });
+
+    return Results.Ok(new GoogleOAuthStartResponse(authUri));
+});
+
+app.MapGet("/api/google/oauth/callback", async (
+    string? code,
+    string? state,
+    string? error,
+    OtthonDbContext db,
+    IHttpClientFactory httpClientFactory) =>
+{
+    if (!string.IsNullOrWhiteSpace(error))
+    {
+        return Results.Content(GoogleOAuthResultPage(false, $"Google rejected the request: {Html(error)}"), "text/html; charset=utf-8");
+    }
+
+    if (string.IsNullOrWhiteSpace(code) || string.IsNullOrWhiteSpace(state))
+    {
+        return Results.Content(GoogleOAuthResultPage(false, "Missing OAuth code or state."), "text/html; charset=utf-8");
+    }
+
+    var savedState = await db.GoogleOAuthStates.FindAsync(state);
+    if (savedState is null || savedState.ExpiresUtc < DateTimeOffset.UtcNow)
+    {
+        return Results.Content(GoogleOAuthResultPage(false, "OAuth session expired. Start Google connection again from the tablet."), "text/html; charset=utf-8");
+    }
+
+    var clientId = await GetGoogleClientId(db);
+    var clientSecret = await GetGoogleClientSecret(db);
+    if (string.IsNullOrWhiteSpace(clientId) || string.IsNullOrWhiteSpace(clientSecret))
+    {
+        return Results.Content(GoogleOAuthResultPage(false, "Google OAuth client is not configured in JARVIS."), "text/html; charset=utf-8");
+    }
+
+    var http = httpClientFactory.CreateClient();
+    var tokenResponse = await http.PostAsync(
+        "https://oauth2.googleapis.com/token",
+        new FormUrlEncodedContent(new Dictionary<string, string>
+        {
+            ["code"] = code,
+            ["client_id"] = clientId,
+            ["client_secret"] = clientSecret,
+            ["redirect_uri"] = GoogleOAuthRedirectUri(),
+            ["grant_type"] = "authorization_code"
+        }));
+    var tokenBody = await tokenResponse.Content.ReadAsStringAsync();
+    if (!tokenResponse.IsSuccessStatusCode)
+    {
+        return Results.Content(GoogleOAuthResultPage(false, $"Token exchange failed: {Html(tokenBody)}"), "text/html; charset=utf-8");
+    }
+
+    using var tokenJson = JsonDocument.Parse(tokenBody);
+    var accessToken = GetString(tokenJson.RootElement, "access_token");
+    var refreshToken = GetString(tokenJson.RootElement, "refresh_token");
+    var expiresIn = tokenJson.RootElement.TryGetProperty("expires_in", out var expiresElement)
+        ? expiresElement.GetInt32()
+        : 3600;
+
+    if (string.IsNullOrWhiteSpace(accessToken))
+    {
+        return Results.Content(GoogleOAuthResultPage(false, "Google did not return an access token."), "text/html; charset=utf-8");
+    }
+
+    var email = await LoadGoogleEmail(http, accessToken);
+    var auth = await db.GoogleCalendarAuths.FindAsync(savedState.WorkspaceToken);
+    if (auth is null)
+    {
+        auth = new GoogleCalendarAuth
+        {
+            WorkspaceToken = savedState.WorkspaceToken,
+            AccessToken = accessToken,
+            RefreshToken = refreshToken ?? "",
+            Email = email,
+            ExpiresUtc = DateTimeOffset.UtcNow.AddSeconds(Math.Max(60, expiresIn - 60)),
+            UpdatedUtc = DateTimeOffset.UtcNow
+        };
+        db.GoogleCalendarAuths.Add(auth);
+    }
+    else
+    {
+        auth.AccessToken = accessToken;
+        if (!string.IsNullOrWhiteSpace(refreshToken))
+        {
+            auth.RefreshToken = refreshToken;
+        }
+        auth.Email = email ?? auth.Email;
+        auth.ExpiresUtc = DateTimeOffset.UtcNow.AddSeconds(Math.Max(60, expiresIn - 60));
+        auth.UpdatedUtc = DateTimeOffset.UtcNow;
+    }
+
+    db.GoogleOAuthStates.Remove(savedState);
+    await db.SaveChangesAsync();
+    return Results.Content(GoogleOAuthResultPage(true, $"Google Calendar connected for {Html(auth.Email ?? "the selected account")}."), "text/html; charset=utf-8");
+});
+
+app.MapGet("/api/google/oauth/status", async (HttpContext context, OtthonDbContext db) =>
+{
+    if (!HasApiToken(context)) return Results.Unauthorized();
+    var workspaceToken = GetWorkspaceToken(context);
+    if (string.IsNullOrWhiteSpace(workspaceToken))
+    {
+        return Results.BadRequest(new { message = "Missing X-Workspace-Token header." });
+    }
+    var auth = await db.GoogleCalendarAuths.FindAsync(workspaceToken);
+    return Results.Ok(new GoogleOAuthStatusResponse(auth is not null, auth?.Email, auth?.UpdatedUtc));
+});
+
+app.MapGet("/api/google/calendars", async (
+    HttpContext context,
+    OtthonDbContext db,
+    IHttpClientFactory httpClientFactory) =>
+{
+    if (!HasApiToken(context)) return Results.Unauthorized();
+    var workspaceToken = GetWorkspaceToken(context);
+    if (string.IsNullOrWhiteSpace(workspaceToken))
+    {
+        return Results.BadRequest(new { message = "Missing X-Workspace-Token header." });
+    }
+    var token = await GetGoogleAccessToken(db, httpClientFactory, workspaceToken);
+    if (token is null) return Results.BadRequest(new { message = "Google Calendar is not connected." });
+
+    var http = httpClientFactory.CreateClient();
+    var request = new HttpRequestMessage(HttpMethod.Get, "https://www.googleapis.com/calendar/v3/users/me/calendarList?minAccessRole=reader&showHidden=true");
+    request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
+    var response = await http.SendAsync(request);
+    var body = await response.Content.ReadAsStringAsync();
+    return Results.Content(body, "application/json; charset=utf-8", statusCode: (int)response.StatusCode);
+});
+
+app.MapGet("/api/google/events", async (
+    HttpContext context,
+    string calendarId,
+    string? timeMin,
+    string? timeMax,
+    OtthonDbContext db,
+    IHttpClientFactory httpClientFactory) =>
+{
+    if (!HasApiToken(context)) return Results.Unauthorized();
+    var workspaceToken = GetWorkspaceToken(context);
+    if (string.IsNullOrWhiteSpace(workspaceToken))
+    {
+        return Results.BadRequest(new { message = "Missing X-Workspace-Token header." });
+    }
+    var token = await GetGoogleAccessToken(db, httpClientFactory, workspaceToken);
+    if (token is null) return Results.BadRequest(new { message = "Google Calendar is not connected." });
+
+    var query = new Dictionary<string, string?>
+    {
+        ["singleEvents"] = "true",
+        ["orderBy"] = "startTime",
+        ["timeMin"] = timeMin,
+        ["timeMax"] = timeMax,
+        ["maxResults"] = "2500"
+    };
+    var uri = QueryHelpers.AddQueryString(
+        $"https://www.googleapis.com/calendar/v3/calendars/{Uri.EscapeDataString(calendarId)}/events",
+        query);
+    var http = httpClientFactory.CreateClient();
+    var request = new HttpRequestMessage(HttpMethod.Get, uri);
+    request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
+    var response = await http.SendAsync(request);
+    var body = await response.Content.ReadAsStringAsync();
+    return Results.Content(body, "application/json; charset=utf-8", statusCode: (int)response.StatusCode);
+});
+
 app.MapPost("/api/devices/register", async (
     DeviceRegistrationRequest request,
     HttpContext context,
@@ -661,6 +872,88 @@ static async Task SetSetting(OtthonDbContext db, string key, string value)
     await db.SaveChangesAsync();
 }
 
+static string RandomToken(int byteCount)
+{
+    var bytes = RandomNumberGenerator.GetBytes(byteCount);
+    return Convert.ToBase64String(bytes)
+        .Replace("+", "-")
+        .Replace("/", "_")
+        .TrimEnd('=');
+}
+
+static string GoogleOAuthRedirectUri() =>
+    "https://api-test.a-web.hu/api/google/oauth/callback";
+
+static string GoogleCalendarServerClientIdSettingKey() => "GoogleCalendarServerClientId";
+static string GoogleCalendarClientSecretSettingKey() => "GoogleCalendarClientSecret";
+
+static async Task<string?> GetGoogleClientId(OtthonDbContext db) =>
+    await GetSetting(db, GoogleCalendarServerClientIdSettingKey());
+
+static async Task<string?> GetGoogleClientSecret(OtthonDbContext db) =>
+    await GetSetting(db, GoogleCalendarClientSecretSettingKey());
+
+static async Task<string?> LoadGoogleEmail(HttpClient http, string accessToken)
+{
+    try
+    {
+        var request = new HttpRequestMessage(HttpMethod.Get, "https://www.googleapis.com/oauth2/v2/userinfo");
+        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
+        var response = await http.SendAsync(request);
+        if (!response.IsSuccessStatusCode) return null;
+        var body = await response.Content.ReadAsStringAsync();
+        using var json = JsonDocument.Parse(body);
+        return GetString(json.RootElement, "email");
+    }
+    catch
+    {
+        return null;
+    }
+}
+
+static async Task<string?> GetGoogleAccessToken(
+    OtthonDbContext db,
+    IHttpClientFactory httpClientFactory,
+    string workspaceToken)
+{
+    var auth = await db.GoogleCalendarAuths.FindAsync(workspaceToken);
+    if (auth is null) return null;
+    if (auth.ExpiresUtc > DateTimeOffset.UtcNow.AddMinutes(2))
+    {
+        return auth.AccessToken;
+    }
+    if (string.IsNullOrWhiteSpace(auth.RefreshToken)) return null;
+
+    var clientId = await GetGoogleClientId(db);
+    var clientSecret = await GetGoogleClientSecret(db);
+    if (string.IsNullOrWhiteSpace(clientId) || string.IsNullOrWhiteSpace(clientSecret)) return null;
+
+    var http = httpClientFactory.CreateClient();
+    var response = await http.PostAsync(
+        "https://oauth2.googleapis.com/token",
+        new FormUrlEncodedContent(new Dictionary<string, string>
+        {
+            ["client_id"] = clientId,
+            ["client_secret"] = clientSecret,
+            ["refresh_token"] = auth.RefreshToken,
+            ["grant_type"] = "refresh_token"
+        }));
+    var body = await response.Content.ReadAsStringAsync();
+    if (!response.IsSuccessStatusCode) return null;
+
+    using var json = JsonDocument.Parse(body);
+    var accessToken = GetString(json.RootElement, "access_token");
+    if (string.IsNullOrWhiteSpace(accessToken)) return null;
+    var expiresIn = json.RootElement.TryGetProperty("expires_in", out var expiresElement)
+        ? expiresElement.GetInt32()
+        : 3600;
+    auth.AccessToken = accessToken;
+    auth.ExpiresUtc = DateTimeOffset.UtcNow.AddSeconds(Math.Max(60, expiresIn - 60));
+    auth.UpdatedUtc = DateTimeOffset.UtcNow;
+    await db.SaveChangesAsync();
+    return auth.AccessToken;
+}
+
 static void ApplyProductLookup(Product target, Product lookup, string source)
 {
     target.Name = lookup.Name;
@@ -747,6 +1040,7 @@ static async Task EnsureDatabaseReady(OtthonDbContext db, ILogger logger)
             await EnsureFoodLearningSchemaAsync(db);
             await EnsureWorkspaceSchemaAsync(db);
             await EnsureAppSettingsSchemaAsync(db);
+            await EnsureGoogleCalendarSchemaAsync(db);
             return;
         }
         catch (Exception ex) when (attempt < maxAttempts)
@@ -765,6 +1059,7 @@ static async Task EnsureDatabaseReady(OtthonDbContext db, ILogger logger)
     await EnsureFoodLearningSchemaAsync(db);
     await EnsureWorkspaceSchemaAsync(db);
     await EnsureAppSettingsSchemaAsync(db);
+    await EnsureGoogleCalendarSchemaAsync(db);
 }
 
 static async Task EnsureProductSchemaAsync(OtthonDbContext db)
@@ -815,6 +1110,33 @@ END
     await db.Database.ExecuteSqlRawAsync(sql);
 }
 
+static async Task EnsureGoogleCalendarSchemaAsync(OtthonDbContext db)
+{
+    var sql = """
+IF OBJECT_ID('GoogleCalendarAuths', 'U') IS NULL
+BEGIN
+    CREATE TABLE GoogleCalendarAuths (
+        WorkspaceToken nvarchar(160) NOT NULL CONSTRAINT PK_GoogleCalendarAuths PRIMARY KEY,
+        Email nvarchar(320) NULL,
+        AccessToken nvarchar(max) NOT NULL,
+        RefreshToken nvarchar(max) NOT NULL,
+        ExpiresUtc datetimeoffset NOT NULL,
+        UpdatedUtc datetimeoffset NOT NULL
+    );
+END
+IF OBJECT_ID('GoogleOAuthStates', 'U') IS NULL
+BEGIN
+    CREATE TABLE GoogleOAuthStates (
+        [State] nvarchar(160) NOT NULL CONSTRAINT PK_GoogleOAuthStates PRIMARY KEY,
+        WorkspaceToken nvarchar(160) NOT NULL,
+        CreatedUtc datetimeoffset NOT NULL,
+        ExpiresUtc datetimeoffset NOT NULL
+    );
+END
+""";
+    await db.Database.ExecuteSqlRawAsync(sql);
+}
+
 static async Task EnsureFoodLearningSchemaAsync(OtthonDbContext db)
 {
     var sql = """
@@ -1047,9 +1369,27 @@ static string SettingsPage(string googleClientId) => $$"""
 </html>
 """;
 
-static string Html(string? value) => System.Net.WebUtility.HtmlEncode(value ?? "");
+static string GoogleOAuthResultPage(bool success, string message) => $$"""
+<!doctype html>
+<html lang="hu">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title>Google Calendar connection</title>
+  <style>{{AdminCss()}}</style>
+</head>
+<body>
+  <main class="card narrow">
+    <p class="eyebrow">JARVIS API</p>
+    <h1>{{(success ? "Google Calendar connected" : "Google Calendar error")}}</h1>
+    <p class="{{(success ? "hint" : "error")}}">{{message}}</p>
+    <p>You can close this browser window and return to Közös Tér.</p>
+  </main>
+</body>
+</html>
+""";
 
-static string GoogleCalendarServerClientIdSettingKey() => "GoogleCalendarServerClientId";
+static string Html(string? value) => System.Net.WebUtility.HtmlEncode(value ?? "");
 
 static string AdminCss() => """
 :root { color-scheme: light; font-family: Inter, Segoe UI, Arial, sans-serif; }
@@ -1091,11 +1431,19 @@ public sealed class OtthonDbContext(DbContextOptions<OtthonDbContext> options)
     public DbSet<FoodLearningEvent> FoodLearningEvents => Set<FoodLearningEvent>();
     public DbSet<WorkspaceState> Workspaces => Set<WorkspaceState>();
     public DbSet<AppSetting> AppSettings => Set<AppSetting>();
+    public DbSet<GoogleCalendarAuth> GoogleCalendarAuths => Set<GoogleCalendarAuth>();
+    public DbSet<GoogleOAuthState> GoogleOAuthStates => Set<GoogleOAuthState>();
 
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
         modelBuilder.Entity<AppSetting>().HasKey(setting => setting.Key);
         modelBuilder.Entity<AppSetting>().Property(setting => setting.Key).HasMaxLength(160);
+        modelBuilder.Entity<GoogleCalendarAuth>().HasKey(auth => auth.WorkspaceToken);
+        modelBuilder.Entity<GoogleCalendarAuth>().Property(auth => auth.WorkspaceToken).HasMaxLength(160);
+        modelBuilder.Entity<GoogleCalendarAuth>().Property(auth => auth.Email).HasMaxLength(320);
+        modelBuilder.Entity<GoogleOAuthState>().HasKey(state => state.State);
+        modelBuilder.Entity<GoogleOAuthState>().Property(state => state.State).HasMaxLength(160);
+        modelBuilder.Entity<GoogleOAuthState>().Property(state => state.WorkspaceToken).HasMaxLength(160);
         modelBuilder.Entity<WorkspaceState>().HasKey(workspace => workspace.Token);
         modelBuilder.Entity<WorkspaceState>().Property(workspace => workspace.Token).HasMaxLength(160);
         modelBuilder.Entity<Product>().HasKey(product => product.Barcode);
@@ -1177,6 +1525,24 @@ public sealed class AppSetting
     public DateTimeOffset UpdatedUtc { get; set; }
 }
 
+public sealed class GoogleCalendarAuth
+{
+    public required string WorkspaceToken { get; set; }
+    public string? Email { get; set; }
+    public required string AccessToken { get; set; }
+    public required string RefreshToken { get; set; }
+    public DateTimeOffset ExpiresUtc { get; set; }
+    public DateTimeOffset UpdatedUtc { get; set; }
+}
+
+public sealed class GoogleOAuthState
+{
+    public required string State { get; set; }
+    public required string WorkspaceToken { get; set; }
+    public DateTimeOffset CreatedUtc { get; set; }
+    public DateTimeOffset ExpiresUtc { get; set; }
+}
+
 public sealed record LoginForm(string Password);
 public sealed record GoogleCalendarSettingsForm(string? ServerClientId);
 public sealed record DeviceRegistrationRequest(string? DeviceName, string? Platform);
@@ -1252,6 +1618,13 @@ public sealed record AppConfigResponse(
     string? GoogleCalendarServerClientId,
     bool GoogleCalendarConfigured);
 
+public sealed record GoogleOAuthStartResponse(string AuthorizationUrl);
+
+public sealed record GoogleOAuthStatusResponse(
+    bool Connected,
+    string? Email,
+    DateTimeOffset? UpdatedUtc);
+
 public sealed record ProductResponse(
     bool Found,
     string Barcode,