academy-chauffeurs - backup.go

     1  package main
     2  
     3  import (
     4  	"io"
     5  	"net/http"
     6  	"os"
     7  	"path"
     8  	"regexp"
     9  	"sort"
    10  	"time"
    11  )
    12  
    13  const (
    14  	backupDir  = "backup"
    15  	maxBackups = 5
    16  )
    17  
    18  func backupDatabase(fname string) error {
    19  	if _, err := os.Stat(fname); err != nil {
    20  		if os.IsNotExist(err) {
    21  			return nil
    22  		}
    23  		return err
    24  	}
    25  	nfn := "backup_" + time.Now().Format("2006-01-02") + ".db"
    26  	if _, err := os.Stat(backupDir); err != nil {
    27  		if os.IsNotExist(err) {
    28  			if err := os.Mkdir(backupDir, 0o755); err != nil {
    29  				return err
    30  			}
    31  		} else {
    32  			return err
    33  		}
    34  	} else if _, err = os.Stat(path.Join(backupDir, nfn)); err == nil || !os.IsNotExist(err) {
    35  		return err
    36  	}
    37  
    38  	nf, err := os.Create(path.Join(backupDir, nfn))
    39  	if err != nil {
    40  		return err
    41  	}
    42  	defer nf.Close()
    43  	of, err := os.Open(fname)
    44  	if err != nil {
    45  		return err
    46  	}
    47  	defer of.Close()
    48  	_, err = io.Copy(nf, of)
    49  	if err != nil {
    50  		os.Remove(path.Join(backupDir, nfn))
    51  		return err
    52  	}
    53  
    54  	files, err := readBackupDir(nfn)
    55  	if err != nil {
    56  		return err
    57  	}
    58  	for len(files) >= maxBackups {
    59  		os.Remove(path.Join(backupDir, files[0]))
    60  		files = files[1:]
    61  	}
    62  
    63  	return nil
    64  }
    65  
    66  func readBackupDir(except string) ([]string, error) {
    67  	d, _ := os.Open(backupDir)
    68  	fis, err := d.Readdir(-1)
    69  	d.Close()
    70  	if err != nil {
    71  		return nil, err
    72  	}
    73  	files := make([]string, 0, maxBackups)
    74  	regex := regexp.MustCompile(`backup_[0-9]{4}-[0-9]{2}-[0-9]{2}\.db`)
    75  	for _, file := range fis {
    76  		filename := file.Name()
    77  		if filename == except {
    78  			continue
    79  		}
    80  		if regex.MatchString(filename) {
    81  			files = append(files, filename)
    82  		}
    83  	}
    84  	sort.Strings(files)
    85  	return files, nil
    86  }
    87  
    88  func getDatabase(w http.ResponseWriter, r *http.Request) {
    89  	files, err := readBackupDir("")
    90  	if err != nil {
    91  		w.WriteHeader(http.StatusInternalServerError)
    92  		io.WriteString(w, err.Error())
    93  		return
    94  	}
    95  	if len(files) == 0 {
    96  		w.WriteHeader(http.StatusNotFound)
    97  		return
    98  	}
    99  	http.ServeFile(w, r, path.Join(backupDir, files[len(files)-1]))
   100  }
   101