package slog

import (
	"fmt"
	"io"
	"os"
	"sync"
)

type FileLogger struct {
	w *os.File
	l sync.Mutex
}

func (f *FileLogger) Write(p []byte) (n int, err error) {
	if f.w == nil {
		return 0, fmt.Errorf("No file handle available")
	}

	f.l.Lock()
	defer func() {
		f.w.Sync()
		f.l.Unlock()
	}()

	return f.w.Write(p)
}

func (f *FileLogger) Close() error {
	if f.w == nil {
		return nil
	}

	f.l.Lock()
	defer f.l.Unlock()

	return f.w.Close()
}

func NewFileLogger(file string) (ret io.WriteCloser, err error) {
	rret := &FileLogger{}

	if rret.w, err = os.OpenFile(file, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644); err != nil {
		return nil, err
	}

	return rret, nil
}