#!/usr/bin/env python3
from io import BytesIO
from tqdm import tqdm
import os
import requests
import sys

# Decoding thanks to https://github.com/bake/mri/blob/master/mri.go#L34

XOR_KEY = 101

def get_pages(chapter):
    api_response = requests.get(
        'https://api.mangarockhd.com/query/web401/pagesv2',
        params={
            'oid': 'mrs-chapter-' + chapter
        }
    ).json()
    for item in api_response['data']:
        yield item['url']

def decode_ciphertext(byte):
    return byte ^ XOR_KEY

def get_image(url):
    ciphertext = requests.get(url).content
    size = len(ciphertext) + 7
    cleartext = BytesIO()
    cleartext.write('RIFF'.encode('ascii'))
    cleartext.write(bytes([
        size >> 0  & 255,
        size >> 8  & 255,
        size >> 16 & 255,
        size >> 24 & 255
    ]))
    cleartext.write('WEBPVP8'.encode('ascii'))
    cleartext.write(bytes(list(map(decode_ciphertext, ciphertext))))
    cleartext.seek(0)
    return cleartext

requested_chapters = sys.argv[1:]

for chapter_idx, chapter in tqdm(list(enumerate(requested_chapters))):
    chapter_dir = str(chapter_idx+1)
    os.makedirs(chapter_dir, exist_ok=True)
    pages = get_pages(chapter)
    for idx, page in tqdm(list(enumerate(pages))):
        filename = os.path.join(chapter_dir, f'{idx+1:04}.webp')
        if os.path.isfile(filename):
            continue

        image = get_image(page)
        with open(filename, 'wb') as f:
            f.write(image.read())