from PIL import Image
import os
import sys

# 定義可以識別的圖片文件類型，可以自行擴充
valid_file_type = ['.jpg', '.png']
# 定義壓縮比，數(shù)值越大，壓縮越小
SIZE_normal = 1.0
SIZE_small = 1.5
SIZE_more_small = 2.0


def make_directory(directory):
  """創(chuàng)建目錄"""
  os.makedirs(directory)


def directory_exists(directory):
  """判斷目錄是否存在"""
  if os.path.exists(directory):
    return True
  else:
    return False


def list_img_file(directory):
  """列出目錄下所有文件，并篩選出圖片文件列表返回"""
  old_list = os.listdir(directory)
  # print old_list
  new_list = []
  for filename in old_list:
    if os.path.isfile(filename):
      f, e = os.path.splitext(filename)
      if e in valid_file_type:
        new_list.append(filename)
      else:
        pass
    else:
      pass
  # print new_list
  return new_list


def print_help():
  print """
  This program helps compress many image files
  you can choose which scale you want to compress your img(jpg/png/etc)
  1) normal compress(4M to 1M around)
  2) small compress(4M to 500K around)
  3) smaller compress(4M to 300K around)
  """


def compress(choose, des_dir, file_list):
  """壓縮算法，img.thumbnail對圖片進行壓縮，還可以改變寬高數(shù)值進行壓縮"""
  if choose == '1':
    scale = SIZE_normal
  if choose == '2':
    scale = SIZE_small
  if choose == '3':
    scale = SIZE_more_small
  for infile in file_list:
    img = Image.open(infile)
    # size_of_file = os.path.getsize(infile)
    w, h = img.size
    img.thumbnail((int(w/scale), int(h/scale)))
    img.save(des_dir + '/' + infile)


if __name__ == "__main__":
  src_dir, des_dir = sys.argv[1], sys.argv[2]
  if directory_exists(src_dir):
    if not directory_exists(des_dir):
      make_directory(des_dir)
    # business logic
    file_list = list_img_file(src_dir)
    # print file_list
    if file_list:
      print_help()
      choose = raw_input("enter your choice:")
      compress(choose, des_dir, file_list)
    else:
      pass
  else:
    print "source directory not exist!"