feat(api): add OAuth2Controller (Google authorize/callback), SyncController (on-demand trigger); register IHttpContextAccessor

src/presentation/DigitalData.MessagingService.API/Controllers/OAuth2Controller.cs

@@ -0,0 +1,95 @@
+using DigitalData.MessagingService.Application.OAuth2.Commands;
+using DigitalData.MessagingService.Application.OAuth2.Queries;
+using MediatR;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DigitalData.MessagingService.API.Controllers;
+
+/// <summary>
+/// Manages the OAuth2 authorization code flow for email accounts.
+/// Use these endpoints to authorize Google accounts without manually
+/// obtaining refresh tokens via external tools.
+/// </summary>
+[ApiController]
+[Route("api/[controller]")]
+public class OAuth2Controller(IMediator mediator, IHttpContextAccessor httpContextAccessor) : ControllerBase
+{
+    #region Google Authorization Flow
+
+    /// <summary>
+    /// Step 1: Redirects the user to Google's consent screen for the specified email account.
+    /// After consent, Google redirects to <c>/api/oauth2/google/callback</c> with an authorization code.
+    /// </summary>
+    /// <param name="accountId">ID of the email account to authorize.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>HTTP 302 redirect to Google consent screen.</returns>
+    [HttpGet("google/authorize/{accountId:int}")]
+    [ProducesResponseType(StatusCodes.Status302Found)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<IActionResult> AuthorizeGoogle(int accountId, CancellationToken cancellationToken)
+    {
+        var redirectUri = BuildCallbackUri();
+
+        var authUrl = await mediator.Send(new GetOAuth2AuthorizationUrlQuery
+        {
+            AccountId   = accountId,
+            RedirectUri = redirectUri
+        }, cancellationToken);
+
+        return Redirect(authUrl);
+    }
+
+    /// <summary>
+    /// Step 2: Google callback endpoint. Exchanges the authorization code for a refresh token
+    /// and saves it to the email account. This endpoint is called automatically by Google
+    /// after the user grants consent — do not call it directly.
+    /// </summary>
+    /// <param name="code">Authorization code provided by Google.</param>
+    /// <param name="state">Account ID passed as state in the authorization request.</param>
+    /// <param name="error">Error message if the user denied access.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>HTTP 200 on success, HTTP 400 if access was denied.</returns>
+    [HttpGet("google/callback")]
+    [ProducesResponseType(StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    public async Task<IActionResult> GoogleCallback(
+        [FromQuery] string? code,
+        [FromQuery] string? state,
+        [FromQuery] string? error,
+        CancellationToken cancellationToken)
+    {
+        if (!string.IsNullOrWhiteSpace(error))
+            return BadRequest(new { Error = error, Message = "User denied access or an error occurred during Google OAuth2 authorization." });
+
+        if (string.IsNullOrWhiteSpace(code))
+            return BadRequest(new { Error = "missing_code", Message = "Authorization code not received from Google." });
+
+        if (!int.TryParse(state, out var accountId))
+            return BadRequest(new { Error = "invalid_state", Message = "Invalid state parameter — could not determine account ID." });
+
+        var redirectUri = BuildCallbackUri();
+
+        var result = await mediator.Send(new CompleteOAuth2AuthorizationCommand
+        {
+            AccountId   = accountId,
+            Code        = code,
+            RedirectUri = redirectUri
+        }, cancellationToken);
+
+        return Ok(new
+        {
+            result.Success,
+            result.Username,
+            Message = $"Google OAuth2 authorization completed. Refresh token saved for account '{result.Username}'."
+        });
+    }
+
+    #endregion
+
+    private string BuildCallbackUri()
+    {
+        var request = httpContextAccessor.HttpContext!.Request;
+        return $"{request.Scheme}://{request.Host}/api/oauth2/google/callback";
+    }
+}

src/presentation/DigitalData.MessagingService.API/Controllers/SyncController.cs

@@ -0,0 +1,35 @@
+using DigitalData.MessagingService.Infrastructure.Services.Background;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Hosting;
+
+namespace DigitalData.MessagingService.API.Controllers;
+
+/// <summary>
+/// Controls email synchronization operations.
+/// </summary>
+[ApiController]
+[Route("api/[controller]")]
+public class SyncController(IEnumerable<IHostedService> hostedServices) : ControllerBase
+{
+    /// <summary>
+    /// Triggers an immediate email sync cycle for all configured accounts,
+    /// skipping the remaining interval wait.
+    /// If a sync is already in progress, the next cycle will start immediately after it completes.
+    /// </summary>
+    /// <returns>HTTP 202 Accepted.</returns>
+    [HttpPost("trigger")]
+    [ProducesResponseType(StatusCodes.Status202Accepted)]
+    [ProducesResponseType(StatusCodes.Status503ServiceUnavailable)]
+    public IActionResult TriggerSync()
+    {
+        var syncWorker = hostedServices.OfType<EmailSyncWorker>().FirstOrDefault();
+
+        if (syncWorker is null)
+            return StatusCode(StatusCodes.Status503ServiceUnavailable,
+                new { Message = "EmailSyncWorker is not running." });
+
+        syncWorker.TriggerSync();
+
+        return Accepted(new { Message = "Sync triggered. The next cycle will start immediately." });
+    }
+}

src/presentation/DigitalData.MessagingService.API/Program.cs

@@ -71,6 +71,9 @@ try
     builder.Services.AddEndpointsApiExplorer();
     builder.Services.AddSwaggerGen();
 
+    // Required by OAuth2Controller to build callback URIs
+    builder.Services.AddHttpContextAccessor();
+
     // Register Serilog.UI with SQLite provider for web log viewer
     builder.Services.AddSerilogUi(options =>
     {