ProcessDocumentFunction.cs

using Azure.Messaging.ServiceBus;
using DocumentProcessorFunction.Model;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Extensions.Logging;
using System;
using System.Text.Json;
using System.Threading.Tasks;

namespace DocumentProcessorFunction;

public class ProcessDocumentFunction
{
    private readonly IDocumentEmbeddingService _embeddingService;
    private readonly ILogger<ProcessDocumentFunction> _logger;

    public ProcessDocumentFunction(
         IDocumentEmbeddingService embeddingService,
         ILogger<ProcessDocumentFunction> logger)
    {
        _embeddingService = embeddingService;
        _logger = logger;
    }

    [Function(nameof(ProcessDocumentFunction))]
    public async Task Run(
        [ServiceBusTrigger("document-queue", Connection = "ServiceBusConnection")]
        string messageBody)
    {
        _logger.LogInformation($"[Worker] Raw payload received from queue: {messageBody}");

        DocumentMessageDto? documentData;

        try
        {
            documentData = JsonSerializer.Deserialize<DocumentMessageDto>(messageBody);
        }
        catch (JsonException ex)
        {
            _logger.LogError(ex, "[Worker] JSON Deserialization error. Message will retry / move to DLQ.");
            throw;
        }

        if (documentData == null || string.IsNullOrWhiteSpace(documentData.DocumentId))
        {
            _logger.LogWarning("[Worker] Invalid payload: Missing DocumentId.");
            throw new ArgumentException("Payload must contain a valid DocumentId.");
        }

        await _embeddingService.GenerateAndIndexEmbeddingsAsync(documentData);
    }
}