#!/usr/bin/env python3
import requests
import threading
import random
import urllib3

from queue import Queue
from bs4 import BeautifulSoup
from fb import Database
from fb.util import get_fb_url, get_useragent
from argparse import ArgumentParser, ArgumentError
from sqlite3 import IntegrityError

db: Database

my_proxies = """
127.0.0.1:1077
127.0.0.1:1079
127.0.0.1:1074
127.0.0.1:1076
127.0.0.1:1071
127.0.0.1:1081
127.0.0.1:1069
"""
my_proxies = list(set(my_proxies.strip().split()))


class TooManyRequests(Exception):
    pass


def parse_book_page(book_id: int, proxy: str):
    headers = {
        'User-Agent': get_useragent()
    }

    url = get_fb_url(book_id)
    proxy = f'socks5://{proxy}'
    r = requests.get(url,
                     headers=headers,
                     proxies=dict(http=proxy, https=proxy))
    if r.status_code != 200:
        if r.status_code == 429:
            raise TooManyRequests()

        # print(f'{book_id} code {r.status_code}')
        return False

    html = BeautifulSoup(r.text, "html.parser")
    desc = html.select_one('meta[name="description"]')['content']

    # extract useful info from meta tags
    metainfo = []
    try:
        if desc.startswith('; '):
            desc = desc[2:]
        for item in desc.split('; '):
            colon_pos = item.index(':')
            key = item[0:colon_pos]
            val = item[colon_pos+2:]
            metainfo.append([key, val])
    except ValueError:
        metainfo.append(desc)
        pass

    # parse name and author
    name = html.select_one('div.overview h1').text
    author = html.select_one('div.overview h2 i').text

    # parse breadcrumbs hierarchy
    bc = html.select('ul.breadcrumb li.breadcrumb-item')
    bc_hierarchy = []
    bc_first_skipped = False
    if bc:
        for bc_item in bc:
            if not bc_first_skipped:
                bc_first_skipped = True
                continue
            bc_hierarchy.append(bc_item.text)

    # book info table
    details = {}
    rows = html.select('table[width="400"] tr')
    if rows:
        for r in rows:
            cols = r.select('td')
            details[cols[0].text] = cols[1].text

    db.add_book(book_id, name, author, metainfo, bc_hierarchy, details)
    return True


def worker(task_queue, print_lock, proxy):
    while not task_queue.empty():
        book_id = task_queue.get()
        db_error = False
        result = None

        try:
            result = parse_book_page(book_id, proxy)
        except IntegrityError:
            db_error = True
        except (requests.exceptions.ConnectionError, requests.exceptions.ConnectTimeout, urllib3.exceptions.ProtocolError, TooManyRequests):
            task_queue.put(book_id)
            db.add_failed_book(book_id)
            print(f'{book_id}: failed due to network error, proxy = {proxy}')
            continue
        except requests.exceptions.ChunkedEncodingError:
            print(f'{book_id} causes weird error')
            continue

        if result is not False:
            with print_lock:
                print(f"{book_id} " + ("done" if not db_error else " raised db error"))
        task_queue.task_done()


if __name__ == '__main__':
    parser = ArgumentParser()
    parser.add_argument('--book-id', type=int)
    parser.add_argument('--continue', action='store_true')
    parser.add_argument('--max-book-id', type=int, default=1500000)
    parser.add_argument('--find-gaps', action='store_true')
    args = parser.parse_args()

    db = Database()

    if args.find_gaps:
        id_from = 100000
        id_to = 1400000
        ids_in_db = db.get_ids(id_from, id_to)
        task_queue = Queue()
        print_lock = threading.Lock()

        for i in range(id_from, id_to+1):
            if i not in ids_in_db:
                task_queue.put(i)

        threads = []
        for proxy in my_proxies:
            for i in range(4):
                thread = threading.Thread(target=worker, args=(task_queue, print_lock, proxy))
                thread.start()
                threads.append(thread)

        for thread in threads:
            thread.join()

    elif hasattr(args, 'continue') and getattr(args, 'continue') is True:
        if args.book_id:
            last_book_id = args.book_id
        else:
            last_book_id = db.get_max_book_id()
            if last_book_id is None:
                last_book_id = 0

        task_queue = Queue()
        print_lock = threading.Lock()

        for task_number in range(last_book_id + 1, args.max_book_id):
            task_queue.put(task_number)

        threads = []
        for proxy in my_proxies:
            for i in range(3):
                thread = threading.Thread(target=worker, args=(task_queue, print_lock, proxy))
                thread.start()
                threads.append(thread)

        for thread in threads:
            thread.join()
    else:
        if not args.book_id:
            raise ArgumentError(None, '--book-id is required')
        proxy = random.choice(my_proxies)
        book = db.get_book(args.book_id)
        if book:
            raise RuntimeError('this book is already in the database')
        parse_book_page(args.book_id, proxy)