timestamper

timestamper.go

package main

import (
    "fmt"
    "github.com/rwcarlsen/goexif/exif"
    "io/ioutil"
    "log"
    "os"
    "path/filepath"
    "sort"
    "strconv"
)

func GetKey(fname string) (string, error) {
    f, err := os.Open(fname)
    if err != nil {
        return "", err
    }
    defer f.Close()

    x, err := exif.Decode(f)
    if err != nil {
        return "", err
    }

    tm, err := x.DateTime()
    if err != nil {
        return "", err
    }

    layout := "20060102150405"
    return tm.Format(layout), err
}

func main() {
    if len(os.Args) < 3 {
        return
    }

    path := os.Args[1]
    //prefix := os.Args[2]

    if err := os.Chdir(path); err != nil {
        log.Fatal(err)
    }

    files, err := ioutil.ReadDir(".")
    if err != nil {
        log.Fatal(err)
    }

    // Sort files alphabetically
    filenames := make([]string, 0, len(files))
    for _, f := range files {
        filenames = append([]string{f.Name()}, filenames...)
    }
    sort.Strings(filenames)

    // Sort files by generated key (useful to deal with images shot in burst mode)
    newFilenamesMap := make(map[string][]string)
    for _, filename := range filenames {
        if newName, err := GetKey(filename); err == nil {
            if _, ok := newFilenamesMap[newName]; !ok {
                newFilenamesMap[newName] = make([]string, 0)
            }
            newFilenamesMap[newName] = append(newFilenamesMap[newName], filename)
        }
    }

    // Rename files appending an _<index> if necessary
    for key, filenames := range newFilenamesMap {
        if l := len(filenames); l > 1 {
            for i, filename := range filenames {
                newName := key + "_" + strconv.Itoa(i+1) + filepath.Ext(filename)
                fmt.Println("Renamed", newName, "was", filename)
                os.Rename(filename, newName)
            }
        } else {
            newName := key + filepath.Ext(filenames[0])
            fmt.Println("Renamed", newName, "was", filenames[0])
            os.Rename(filenames[0], newName)
        }
    }
}