#!/usr/bin/python3

import sys
import piexif as x
import datetime as dt

shift = dt.timedelta(hours = 1)
print('Shift exif date time by', shift)

if len(sys.argv) < 1:
    print('shift img1.jpg img2.jpg')
    quit()


timeTagCodes = [36867, 36868]

filenames = sys.argv[1:]

formatDate = '%Y:%m:%d %H:%M:%S'
formatFrom = f"b'{formatDate}'"

def describeExif(exif):
    for k in timeTagCodes:
        if k in exif.keys():
            t = dt.datetime.strptime(str(exif[k]), formatFrom)
            print('Exif[', k, ']=', t, '->', x.TAGS['Exif'][k]['name'])
        else:
            print('Exif[', k, ']=', '?', '->', x.TAGS['Exif'][k]['name'])
    return t


def shiftThisFile(filename: str):
    m = x.load(filename)
    e = m['Exif']
    t = describeExif(e)

    targetDateTime = t + shift
    print('Shifting')
    print(t)
    print('to')
    print(targetDateTime)

    for k in timeTagCodes:
        e[k] = targetDateTime.strftime(formatDate).encode()

    describeExif(e)
    return m


for filename in filenames:
    print(filename)
    exifDict = shiftThisFile(filename)
    exifBytes = x.dump(exifDict)
    x.insert(exifBytes, filename)
    print()