#!python

from multiprocessing import Pool
import os
import requests
import time
from PIL import Image

TAG = 'arundel_ms_263'
LAST_PAGE = 283

ZOOM = 11
TILE_W = 4
TILE_H = 3

# ZOOM = 13
# TILE_W = 16
# TILE_H = 12

# ZOOM = 14
# TILE_W = 33
# TILE_H = 24

headers = {
  'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36',
}

def fetch_file(url, fn, **kwargs):
  try:
    resp = requests.get(url, params=kwargs, headers=headers, verify=False)
    if resp.status_code != 200:
      return None
  except:
    return None
  size = 0
  if os.path.exists(fn):
    return
  with open(fn, 'wb') as f:
    for chunk in resp.iter_content(chunk_size=1024):
      if chunk:
        size += len(chunk)
        f.write(chunk)
  print("{} kb. {}".format(round(size / 1024), fn))
  return None

# Run this with a pool of 5 agents having a chunksize of 3 until finished
def parallel_fetch(dataset):
  print("Fetching {} tiles".format(len(dataset)))
  agents = 5
  chunksize = 3
  with Pool(processes=agents) as pool:
    pool.starmap(fetch_file, dataset, chunksize)

def load_image(fn):
  try:
    image = Image.open(fn)
    width, height = image.size
    return image, width, height
  except:
    return None, 0, 0

# Fetch all the tiles from a tile server and then compose them into a single image
def grab(s, n):
  out_fn = "./{}/{}/{}_{}.jpg".format(TAG, ZOOM, page, ZOOM)
  if os.path.exists(out_fn):
    return

  page = "{:03d}{}".format(n, s)
  print("Fetching {}...".format(page))
  os.makedirs("./{}/{}/{}".format(TAG, ZOOM, page), exist_ok=True)
  dataset = []
  for i in range(0, TILE_W + 1):
    for j in range(0, TILE_H + 1):
      url = "http://www.bl.uk/manuscripts/Proxy.ashx?view={}_f{}_files/{}/{}_{}.jpg".format(TAG, page, ZOOM, i, j)
      fn = "./{}/{}/{}/{}_{}.jpg".format(TAG, ZOOM, page, i, j)
      if not os.path.exists(fn):
        dataset.append((url, fn,))

  # Fetch all the images we don't have
  if len(dataset):
    parallel_fetch(dataset)

  # Get the dimensions of the final image (interior plus corners)
  ww = 258 * (TILE_W - 1)
  hh = 258 * (TILE_H - 1)

  fn = "./{}/{}/{}/{}_{}.jpg".format(TAG, ZOOM, page, 0, 0)
  image, width, height = load_image(fn)
  ww += width
  hh += height

  fn = "./{}/{}/{}/{}_{}.jpg".format(TAG, ZOOM, page, TILE_W, TILE_H)
  image, width, height = load_image(fn)
  ww += width
  hh += height

  # Build the new canvas by pasting the tiles across it
  canvas = Image.new('RGB', (ww, hh,))
  x = 0
  for i in range(0, TILE_W + 1):
    y = 0
    for j in range(0, TILE_H + 1):
      fn = "./{}/{}/{}/{}_{}.jpg".format(TAG, ZOOM, page, i, j)
      image, width, height = load_image(fn)
      if image:
        canvas.paste(image, (x, y))
        y += height
    x += width
  canvas.save(out_fn)

if __name__ == '__main__':
  os.makedirs("{}/{}".format(TAG, ZOOM), exist_ok=True)
  for n in range(1, LAST_PAGE + 1):
    grab('v', n)
    grab('r', n)