package fileutil

import (
	"log"
	"os"
	"path"
	"sort"
	"strings"
	"time"
)

func PurgeFile(dirname string, suffix string, max uint, interval time.Duration, stop <-chan struct{}) <-chan error {
	errC := make(chan error, 1)
	go func() {
		for {
			fnames, err := ReadDir(dirname)
			if err != nil {
				errC <- err
				return
			}
			newfnames := make([]string, 0)
			for _, fname := range fnames {
				if strings.HasSuffix(fname, suffix) {
					newfnames = append(newfnames, fname)
				}
			}
			sort.Strings(newfnames)
			for len(newfnames) > int(max) {
				f := path.Join(dirname, newfnames[0])
				err := os.Remove(f)
				if err != nil {
					errC <- err
					return
				}
				log.Printf("filePurge: successfully remvoed file %s", f)
				newfnames = newfnames[1:]
			}
			select {
			case <-time.After(interval):
			case <-stop:
				return
			}
		}
	}()
	return errC
}