import time

import PIL
import os
import os.path
from PIL import Image
from PIL.Image import Resampling
import threading

Image.LOAD_TRUNCATED_IMAGES = True

f = r'/path to  gallery'
basewidth = 2500



def folderssss(item):
    global running
    running += 1
    print("start thread "+ str(running))
    for file in os.listdir(f+"/"+item):
        if file.lower().endswith(('.png', '.jpg', '.jpeg', '.tiff', '.bmp', '.gif')):
            if file == '.DS_Store':
                continue
            if file == 'Thumbs.db':
                continue
            f_img = f+"/"+item+"/"+file
            velikost_p = os.path.getsize(f_img)
            img = Image.open(f_img)

            wpercent = (basewidth / float(img.size[0]))
            hsize = int((float(img.size[1]) * float(wpercent)))

            if img.size[0] > basewidth:
                try:
                    img = img.resize((basewidth, hsize), Resampling.LANCZOS)
                    img.save(f_img)
                    velikost_z = os.path.getsize(f_img)
                    print(f_img + " - " + str(velikost_p) + " - " + str(velikost_z) + " =  " + str(int((velikost_p-velikost_z)/1000000))+" MB")

                except IOError:
                    print("chyba img "+ f_img)
                    running -= 1

            #img = img.resize((2296,1724))
    running -= 1
    print("end thread " + str(running))

running = 0
dirs = os.listdir( f )
for item in dirs:
    if item == '.DS_Store':
        continue
    example_thread = threading.Thread(target=folderssss, args=(item,))
    example_thread.start()

    while running > 16:
        time.sleep(1)