# Custom Logger Project

A flexible .NET logging library that supports both console and file logging with configurable options.

## Features

- **Multiple Output Targets**: Log to console and file simultaneously
- **Configurable Log Levels**: Trace, Debug, Info, Warning, Error, Fatal
- **File Rotation**: Automatically rotates log files based on size limits
- **Colored Console Output**: Different colors for each log level
- **Thread-Safe**: Safe for multi-threaded applications
- **Flexible Configuration**: Customize file names, directories, and size limits

## Log Levels

| Level | Value | Description |
|-------|-------|-------------|
| Trace | 0 | Very detailed diagnostic information |
| Debug | 1 | Detailed information for debugging |
| Info | 2 | Informational messages |
| Warning | 3 | Warning messages for potentially harmful situations |
| Error | 4 | Error messages for error events |
| Fatal | 5 | Fatal error messages |

## Usage

### Basic Setup in Program.cs

```csharp
using Logger;

var builder = WebApplication.CreateBuilder(args);

// Configure file logger options
var fileLoggerOptions = new FileLoggerOptions
{
    FileName = "app.log",           // Name of the log file
    LogDirectory = "Logs",          // Directory to store logs
    MaxFileSizeBytes = 10 * 1024 * 1024,  // 10 MB
    MaxBackupFiles = 5,             // Keep 5 backup files
    MinimumLevel = LogLevel.Info    // Only log Info and above to file
};

// Create and register the composite logger (console + file)
builder.Services.AddSingleton<Logger.ILogger>(
    Logger.LoggerFactory.CreateCompositeLogger(Logger.LogLevel.Debug, fileLoggerOptions));

var app = builder.Build();
```

### Using the Logger in Controllers

```csharp
using Logger;

[ApiController]
[Route("api/[controller]")]
public class AuthController : ControllerBase
{
    private readonly Logger.ILogger _logger;

    public AuthController(Logger.ILogger logger)
    {
        _logger = logger;
    }

    [HttpPost("login")]
    public IActionResult Login([FromBody] LoginRequest request)
    {
        _logger.Info($"Login attempt for user: {request.Email}");
        
        try
        {
            // authentication logic
            _logger.Info($"User {request.Email} logged in successfully");
            return Ok(new { token = "..." });
        }
        catch (Exception ex)
        {
            _logger.Error($"Login failed for user {request.Email}: {ex.Message}");
            return Unauthorized();
        }
    }
}
```

### Using Different Logger Types

```csharp
// Console only
var consoleLogger = Logger.LoggerFactory.CreateConsoleLogger(Logger.LogLevel.Debug);

// File only
var fileLogger = Logger.LoggerFactory.CreateFileLogger(fileLoggerOptions);

// Console and file (composite)
var compositeLogger = Logger.LoggerFactory.CreateCompositeLogger(
    Logger.LogLevel.Debug, 
    fileLoggerOptions
);
```

## Configuration Options

### FileLoggerOptions

| Property | Type | Default | Description |
|----------|------|---------|-------------|
| FileName | string | "app.log" | Name of the log file |
| LogDirectory | string | "Logs" | Directory where logs are stored |
| MaxFileSizeBytes | long | 10485760 (10 MB) | Maximum size before rotation |
| MaxBackupFiles | int | 5 | Number of backup files to keep |
| MinimumLevel | LogLevel | Info | Minimum level to log to file |

## Log Output Format

Logs are formatted with timestamps and log levels:

```
[2024-01-15 14:30:45.123] [Info] User authentication successful
[2024-01-15 14:30:46.456] [Error] Database connection timeout
[2024-01-15 14:30:47.789] [Warning] High memory usage detected
```

## File Rotation

When a log file reaches the `MaxFileSizeBytes` limit:

1. The current log file is renamed with a timestamp: `app_2024-01-15_14-30-45.log`
2. A new `app.log` file is created
3. Old backup files exceeding `MaxBackupFiles` limit are automatically deleted

## Thread Safety

The FileLogger uses a lock mechanism to ensure thread-safe file writing. Multiple threads can safely call logging methods simultaneously.

## Error Handling

If any logging operation fails:
- Console errors are written to `Console.Error`
- Errors in one logger don't affect others (in composite logger)
- The application continues running normally