From 82e03978b89938219958032efb1448cc76baa181 Mon Sep 17 00:00:00 2001
From: Saumit <justsaumit@protonmail.com>
Date: Sat, 27 Sep 2025 02:14:26 +0530
Subject: Initial snapshot - OpenTelemetry demo 2.1.3 -f

---
 src/accounting/Consumer.cs | 153 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 src/accounting/Consumer.cs

(limited to 'src/accounting/Consumer.cs')

diff --git a/src/accounting/Consumer.cs b/src/accounting/Consumer.cs
new file mode 100644
index 0000000..89ede49
--- /dev/null
+++ b/src/accounting/Consumer.cs
@@ -0,0 +1,153 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using Confluent.Kafka;
+using Microsoft.Extensions.Logging;
+using Oteldemo;
+using Microsoft.EntityFrameworkCore;
+using System.Diagnostics;
+
+namespace Accounting;
+
+internal class DBContext : DbContext
+{
+    public DbSet<OrderEntity> Orders { get; set; }
+    public DbSet<OrderItemEntity> CartItems { get; set; }
+    public DbSet<ShippingEntity> Shipping { get; set; }
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+        var connectionString = Environment.GetEnvironmentVariable("DB_CONNECTION_STRING");
+
+        optionsBuilder.UseNpgsql(connectionString).UseSnakeCaseNamingConvention();
+    }
+}
+
+
+internal class Consumer : IDisposable
+{
+    private const string TopicName = "orders";
+
+    private ILogger _logger;
+    private IConsumer<string, byte[]> _consumer;
+    private bool _isListening;
+    private DBContext? _dbContext;
+    private static readonly ActivitySource MyActivitySource = new("Accounting.Consumer");
+
+    public Consumer(ILogger<Consumer> logger)
+    {
+        _logger = logger;
+
+        var servers = Environment.GetEnvironmentVariable("KAFKA_ADDR")
+            ?? throw new ArgumentNullException("KAFKA_ADDR");
+
+        _consumer = BuildConsumer(servers);
+        _consumer.Subscribe(TopicName);
+
+        _logger.LogInformation($"Connecting to Kafka: {servers}");
+        _dbContext = Environment.GetEnvironmentVariable("DB_CONNECTION_STRING") == null ? null : new DBContext();
+    }
+
+    public void StartListening()
+    {
+        _isListening = true;
+
+        try
+        {
+            while (_isListening)
+            {
+                try
+                {
+                    using var activity = MyActivitySource.StartActivity("order-consumed",  ActivityKind.Internal);
+                    var consumeResult = _consumer.Consume();
+                    ProcessMessage(consumeResult.Message);
+                }
+                catch (ConsumeException e)
+                {
+                    _logger.LogError(e, "Consume error: {0}", e.Error.Reason);
+                }
+            }
+        }
+        catch (OperationCanceledException)
+        {
+            _logger.LogInformation("Closing consumer");
+
+            _consumer.Close();
+        }
+    }
+
+    private void ProcessMessage(Message<string, byte[]> message)
+    {
+        try
+        {
+            var order = OrderResult.Parser.ParseFrom(message.Value);
+            Log.OrderReceivedMessage(_logger, order);
+
+            if (_dbContext == null)
+            {
+                return;
+            }
+
+            var orderEntity = new OrderEntity
+            {
+                Id = order.OrderId
+            };
+            _dbContext.Add(orderEntity);
+            foreach (var item in order.Items)
+            {
+                var orderItem = new OrderItemEntity
+                {
+                    ItemCostCurrencyCode = item.Cost.CurrencyCode,
+                    ItemCostUnits = item.Cost.Units,
+                    ItemCostNanos = item.Cost.Nanos,
+                    ProductId = item.Item.ProductId,
+                    Quantity = item.Item.Quantity,
+                    OrderId = order.OrderId
+                };
+
+                _dbContext.Add(orderItem);
+            }
+
+            var shipping = new ShippingEntity
+            {
+                ShippingTrackingId = order.ShippingTrackingId,
+                ShippingCostCurrencyCode = order.ShippingCost.CurrencyCode,
+                ShippingCostUnits = order.ShippingCost.Units,
+                ShippingCostNanos = order.ShippingCost.Nanos,
+                StreetAddress = order.ShippingAddress.StreetAddress,
+                City = order.ShippingAddress.City,
+                State = order.ShippingAddress.State,
+                Country = order.ShippingAddress.Country,
+                ZipCode = order.ShippingAddress.ZipCode,
+                OrderId = order.OrderId
+            };
+            _dbContext.Add(shipping);
+            _dbContext.SaveChanges();
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Order parsing failed:");
+        }
+    }
+
+    private IConsumer<string, byte[]> BuildConsumer(string servers)
+    {
+        var conf = new ConsumerConfig
+        {
+            GroupId = $"accounting",
+            BootstrapServers = servers,
+            // https://github.com/confluentinc/confluent-kafka-dotnet/tree/07de95ed647af80a0db39ce6a8891a630423b952#basic-consumer-example
+            AutoOffsetReset = AutoOffsetReset.Earliest,
+            EnableAutoCommit = true
+        };
+
+        return new ConsumerBuilder<string, byte[]>(conf)
+            .Build();
+    }
+
+    public void Dispose()
+    {
+        _isListening = false;
+        _consumer?.Dispose();
+    }
+}
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