# Logger Package

A structured, high-performance logging package built on top of Logrus with the following features:

## Features

- **Structured Logging**: JSON and Text formats supported
- **Level-based Logging**: Debug, Info, Warn, Error, Fatal, Panic, Trace
- **Performance Optimized**: Low allocation design with sync.Pool
- **Context Support**: Add request-scoped fields
- **Caller Information**: Automatically include file and line numbers
- **Multiple Outputs**: Stdout/Stderr separation
- **Thread-safe**: Safe for concurrent use
- **Customizable**: Various configuration options

## Installation

```go
import "starter-kit/internal/helper/logger"
```

## Basic Usage

### Initialization

```go
// Initialize with default configuration
logger.Init(&logger.LogConfig{
    Level:        "info",
    Format:       "json",
    EnableCaller: true,
    ReportCaller: true,
})
```

### Logging Messages

```go
// Simple logging
logger.Info("Application started")
logger.Debug("Debug information")
logger.Warn("Warning message")
logger.Error("Error occurred")

// With fields
logger.WithFields(logger.Fields{
    "key": "value",
    "num": 42,
}).Info("Log with fields")

// With error
if err != nil {
    logger.WithError(err).Error("Operation failed")
}
```

## Configuration Options

| Option | Type | Default | Description |
|--------|------|---------|-------------|
| Level | string | "info" | Log level (debug, info, warn, error, fatal, panic) |
| Format | string | "json" | Output format (json, text) |
| EnableCaller | bool | true | Include caller information |
| BufferSize | int | 256 | Buffer size for async logging |
| DisableColor | bool | false | Disable colored output (text format only) |
| ReportCaller | bool | true | Report the calling method |

## Best Practices

1. **Use Appropriate Log Levels**:
   - ERROR: Something failed, needs attention
   - WARN: Unexpected but handled situation
   - INFO: Important business process has started/ended
   - DEBUG: Detailed information for debugging

2. **Structured Logging**:
   - Always use fields for structured data
   - Keep log messages concise and consistent

3. **Performance**:
   - Use `WithFields` when logging multiple key-value pairs
   - Avoid expensive operations in log statements

## Example Output

### JSON Format
```json
{
  "@timestamp": "2023-04-01T12:00:00Z",
  "level": "info",
  "message": "Request processed",
  "caller": "handler/user.go:42",
  "method": "GET",
  "path": "/api/users",
  "status": 200,
  "duration": 42.5,
  "request_id": "abc123"
}
```

### Text Format
```
INFO[0000] Request processed  caller=handler/user.go:42 method=GET path=/api/users status=200 duration=42.5 request_id=abc123
```

## Testing

```bash
# Run tests
go test -v ./...

# Run with race detector
go test -race ./...
```

## License

[MIT](LICENSE)