main.go

package main

import (
	"bufio"
	"crypto/sha1"
	"fmt"
	"image"
	"io"
	"os"
	"os/exec"
	"time"

	_ "image/jpeg"
	_ "image/png"

	"github.com/rwcarlsen/goexif/exif"
)

func process(fn string) {
	f, err := os.Open(fn)
	if err != nil {
		fmt.Fprintf(os.Stderr, "file=%q action=open err=%q\n", fn, err)
		return
	}
	defer f.Close()

	stat, err := f.Stat()
	if err != nil {
		fmt.Fprintf(os.Stderr, "file=%q action=stat err=%q\n", fn, err)
		return
	}

	img, format, err := image.Decode(f)
	if err != nil {
		fmt.Fprintf(os.Stderr, "file=%q action=image_decode err=%q\n", fn, err)
		return
	}

	if _, err := f.Seek(0, 0); err != nil {
		fmt.Fprintf(os.Stderr, "file=%q action=rewind err=%q\n", fn, err)
		return
	}

	exif, err := exif.Decode(f)
	if err != nil {
		fmt.Fprintf(os.Stderr, "file=%q image_format=%q action=exif_decode err=%q\n", fn, format, err)
	}

	var exifTime time.Time
	if exif != nil {
		dateTimeTag, err := exif.Get("DateTime")
		if err != nil {
			fmt.Fprintf(os.Stderr, "file=%q image_format=%q action=exif_get_datetime err=%q\n", fn, format, err)
		} else {
			exifTime, _ = time.ParseInLocation("2006:01:02 15:04:05", dateTimeTag.StringVal(), time.Local)
		}
	}

	bounds := img.Bounds()

	var canonTime time.Time
	if exifTime.IsZero() {
		canonTime = stat.ModTime()
	} else {
		canonTime = exifTime
	}

	if _, err := f.Seek(0, 0); err != nil {
		fmt.Fprintf(os.Stderr, "file=%q action=rewind err=%q\n", fn, err)
		return
	}

	shaHash := sha1.New()
	if _, err := io.Copy(shaHash, f); err != nil {
		fmt.Fprintf(os.Stderr, "file=%q image_format=%q action=shasum err=%q\n", fn, format, err)
		return
	}

	dir := fmt.Sprintf("final/%s", canonTime.Format("2006/01/02"))
	path := fmt.Sprintf("%s/%s_%x.%s", dir, canonTime.Format("2006-01-02-15-04-05"), shaHash.Sum(nil), format)

	fmt.Printf("file=%q mtime=%q image_format=%q resolution=%v exif_time=%q canon_time=%q path=%q\n", fn, stat.ModTime(), format, bounds.Max, exifTime, canonTime, path)

	os.MkdirAll(dir, 0755)
	cpCmd := exec.Command("cp", "-p", fn, path)
	if err := cpCmd.Run(); err != nil {
		fmt.Fprintf(os.Stderr, "file=%q image_format=%q path=%q action=cp err=%q\n", fn, format, path, err)
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)

	for scanner.Scan() {
		fn := scanner.Text()
		process(fn)
	}

	if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "reading standard input:", err)
	}
}