refactor(DocumentController): migrate from legacy service to MediatR pattern

- Replace obsolete DocumentController implementation using EnvelopeOldService and direct dependencies
- Migrate to MediatR-based query handling via ReadEnvelopeReceiverAsync
- Remove obsolete constructors and actions marked for deprecation
- Add proper error handling with NotFoundException for missing envelope or document data
- Improve logging with structured JSON output for diagnostics
- Update base class from BaseController to ControllerBase and add ApiController attribute
- Rename action to GetDocument and apply explicit HttpGet routing
- Use IMediator for clean separation of concerns and alignment with CQRS pattern

EnvelopeGenerator.Web/Controllers/DocumentController.cs

@@ -1,35 +1,50 @@
-using Microsoft.AspNetCore.Mvc;
-using EnvelopeGenerator.CommonServices;
+using DigitalData.Core.Exceptions;
+using EnvelopeGenerator.Application.EnvelopeReceivers.Queries;
 using EnvelopeGenerator.Web.Services;
+using MediatR;
 using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
 
 namespace EnvelopeGenerator.Web.Controllers;
 
 [Authorize(Roles = Domain.Constants.ReceiverRole.FullyAuth)]
+[ApiController]
 [Route("api/[controller]")]
-public class DocumentController : BaseController
+public class DocumentController : ControllerBase
 {
-    private readonly EnvelopeOldService envelopeService;
-    private readonly ActionService? actionService;
+    private readonly IMediator _mediator;
+        
+    private readonly ILogger<DocumentController> _logger;
 
-    [Obsolete("Use MediatR")]
-    public DocumentController(DatabaseService database, EnvelopeOldService envelope, ILogger<DocumentController> logger) : base(database, logger)
+    public DocumentController(IMediator mediator, ILogger<DocumentController> logger)
     {
-        envelopeService = envelope;
-        actionService = database.Services?.actionService;
+        _mediator = mediator;
+        _logger = logger;
     }
 
-    [Obsolete("Use MediatR")]
-    [NonAction]
-    public async Task<IActionResult> Get([FromRoute] string envelopeKey, [FromQuery] int index)
+    [HttpGet("{envelopeKey}")]
+    public async Task<IActionResult> GetDocument([FromRoute] string envelopeKey, CancellationToken cancel)
     {
-        // Load document info
-        var document = await envelopeService.GetDocument(index, envelopeKey);
+        var envRcv = await _mediator.ReadEnvelopeReceiverAsync(envelopeKey, cancel) ?? throw new NotFoundException("Envelope Receiver is not found.");
 
-        // Load the document from disk
-        var bytes = await envelopeService.GetDocumentContents(document);
+        var byteData = envRcv.Envelope?.Documents?.FirstOrDefault()?.ByteData;
 
-        // Return the document as bytes
-        return File(bytes, "application/octet-stream");
+        if(byteData is null || byteData.Length == 0)
+        {
+            _logger.LogError("Document byte data is null or empty for envelope-receiver entity:\n{envelopeKey}.",
+                JsonConvert.SerializeObject(envRcv, JsonFormattingForDiagnostics));
+            throw new NotFoundException("Document is empty.");
+        }
+
+        return File(byteData, "application/octet-stream");
     }
+
+    private static readonly JsonSerializerSettings JsonFormattingForDiagnostics = new()
+    {
+        ContractResolver = new CamelCasePropertyNamesContractResolver(),
+        Formatting = Formatting.Indented,
+        NullValueHandling = NullValueHandling.Include
+    };
 }