package tracking

import (
	"bufio"
	"os"
	"time"
)

type LogTailer struct {
	filePath    string
	handleLine  func(string)
	stopChan    chan struct{}
	isRunning   bool
}

func NewLogTailer(filePath string, handleLine func(string)) *LogTailer {
	return &LogTailer{
		filePath:   filePath,
		handleLine: handleLine,
		stopChan:   make(chan struct{}),
	}
}

func (t *LogTailer) Start() {
	if t.isRunning {
		return
	}
	t.isRunning = true

	go func() {
		var lastSize int64 = 0
		for {
			select {
			case <-t.stopChan:
				t.isRunning = false
				return
			default:
				// Try to open and read the file
				if file, err := os.Open(t.filePath); err == nil {
					stat, err := file.Stat()
					if err != nil {
						file.Close()
						time.Sleep(time.Second)
						continue
					}

					// If file was truncated, start from beginning
					if stat.Size() < lastSize {
						lastSize = 0
					}

					// Seek to last read position
					if lastSize > 0 {
						file.Seek(lastSize, 0)
					}

					scanner := bufio.NewScanner(file)
					for scanner.Scan() {
						t.handleLine(scanner.Text())
						lastSize, _ = file.Seek(0, 1) // Get current position
					}

					file.Close()
				}

				// Wait before next attempt
				time.Sleep(time.Second)
			}
		}
	}()
}

func (t *LogTailer) Stop() {
	if !t.isRunning {
		return
	}
	close(t.stopChan)
}