add project

Services/EventStore.cs

@@ -0,0 +1,140 @@
+using System.Text;
+using System.Text.Json;
+using DatabaseSnapshotsService.Models;
+
+namespace DatabaseSnapshotsService.Services
+{
+    public class EventStore
+    {
+        private readonly EventStoreConfig _config;
+        private readonly string _eventsPath;
+        private readonly string _indexPath;
+        private readonly object _writeLock = new object();
+        private long _currentEventId = 0;
+        private string _currentEventFile = string.Empty;
+        private StreamWriter? _currentWriter;
+        private long _currentFileSize = 0;
+
+        public EventStore(EventStoreConfig config)
+        {
+            _config = config;
+            _eventsPath = Path.GetFullPath(config.Path);
+            _indexPath = Path.Combine(_eventsPath, "index");
+            
+            // Ensure directories exist
+            Directory.CreateDirectory(_eventsPath);
+            Directory.CreateDirectory(_indexPath);
+            
+            // Load next event ID and initialize current file
+            LoadNextEventId();
+            InitializeCurrentFile();
+        }
+
+        public async Task<long> StoreEventAsync(DatabaseEvent evt)
+        {
+            lock (_writeLock)
+            {
+                evt.Id = ++_currentEventId;
+                evt.Timestamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
+                evt.Checksum = CalculateEventChecksum(evt);
+                
+                // Check if we need to rotate the file
+                if (_currentFileSize > _config.MaxFileSize || _currentWriter == null)
+                {
+                    RotateEventFile();
+                }
+                
+                // Write event to current file
+                var json = JsonSerializer.Serialize(evt);
+                _currentWriter?.WriteLine(json);
+                _currentWriter?.Flush();
+                _currentFileSize += json.Length + Environment.NewLine.Length;
+                
+                // Update index
+                UpdateEventIndex(evt);
+                
+                return evt.Id;
+            }
+        }
+
+        public async Task<long> GetLastEventIdAsync()
+        {
+            var eventFiles = Directory.GetFiles(_eventsPath, "events_*.json");
+            long lastId = 0;
+            
+            foreach (var file in eventFiles.OrderByDescending(f => f))
+            {
+                var lines = await File.ReadAllLinesAsync(file);
+                if (lines.Length > 0)
+                {
+                    var lastLine = lines.Last();
+                    try
+                    {
+                        var lastEvent = JsonSerializer.Deserialize<DatabaseEvent>(lastLine);
+                        if (lastEvent != null && lastEvent.Id > lastId)
+                        {
+                            lastId = lastEvent.Id;
+                        }
+                    }
+                    catch (JsonException)
+                    {
+                        // Skip malformed JSON
+                        continue;
+                    }
+                }
+            }
+            
+            return lastId;
+        }
+
+        private void LoadNextEventId()
+        {
+            var lastId = GetLastEventIdAsync().GetAwaiter().GetResult();
+            _currentEventId = lastId;
+        }
+
+        private void InitializeCurrentFile()
+        {
+            var timestamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
+            _currentEventFile = Path.Combine(_eventsPath, $"events_{timestamp}.json");
+            _currentWriter = new StreamWriter(_currentEventFile, true, Encoding.UTF8);
+            _currentFileSize = 0;
+        }
+
+        private void RotateEventFile()
+        {
+            // Close current writer and delete file if empty
+            if (_currentWriter != null)
+            {
+                _currentWriter.Close();
+                if (!string.IsNullOrEmpty(_currentEventFile) && File.Exists(_currentEventFile))
+                {
+                    var fileInfo = new FileInfo(_currentEventFile);
+                    if (fileInfo.Length == 0)
+                    {
+                        File.Delete(_currentEventFile);
+                    }
+                }
+            }
+            _currentEventFile = Path.Combine(_eventsPath, $"events_{DateTime.UtcNow:yyyyMMdd_HHmmss}_{_currentEventId}.json");
+            _currentWriter = new StreamWriter(_currentEventFile, append: false, Encoding.UTF8);
+            _currentFileSize = 0;
+        }
+
+        private string CalculateEventChecksum(DatabaseEvent evt)
+        {
+            var data = $"{evt.Id}{evt.Timestamp}{evt.Type}{evt.Table}{evt.Operation}{evt.Data}{evt.BinlogPosition}{evt.ServerId}";
+            using var sha256 = System.Security.Cryptography.SHA256.Create();
+            var hash = sha256.ComputeHash(Encoding.UTF8.GetBytes(data));
+            return Convert.ToHexString(hash).ToLower();
+        }
+
+        private void UpdateEventIndex(DatabaseEvent evt)
+        {
+            var indexFile = Path.Combine(_indexPath, Path.GetFileNameWithoutExtension(_currentEventFile) + ".idx");
+            var indexEntry = $"{evt.Id},{evt.Timestamp},{evt.Table},{evt.Operation}";
+            
+            File.AppendAllText(indexFile, indexEntry + Environment.NewLine);
+        }
+    }
+}