# Python modules can't start with a number...
import asyncio
import random
import string
from math import ceil

import aiohttp
from numpy import array_split

import db
import util

# CONFIGURATION #

# Number of 4chan threads to request at once
THREADS_CONCURRENT = 1000

# Seconds to wait between every THREADS_CONCURRENT requests
THREADS_DELAY = 0.1

# Seconds to wait between crawls
CRAWL_DELAY = 5

# Semaphore value ?
THREADS_SEMAPHORE = 1000

# CONFIGURATION END #


class Chan4(object):
    """
    4chan indexer, crawler and ingester.
    """

    def __init__(self):
        name = self.__class__.__name__
        self.log = util.get_logger(name)

        self.api_endpoint = "https://a.4cdn.org"
        # self.boards = ["out", "g", "a", "3", "pol"] #
        self.boards = []

        # self.thread_deferreds = []
        # self.content_deferreds = []

        self.log.info(f"Starting crawler bot to {self.api_endpoint}")

        self.hash_key = db.r.get("hashing_key")
        if not self.hash_key:
            letters = string.ascii_lowercase
            self.hash_key = "".join(random.choice(letters) for i in range(16))
            self.log.debug(f"Created new hash key: {self.hash_key}")
            db.r.set("hashing_key", self.hash_key)
        else:

            self.hash_key = self.hash_key.decode("ascii")
            self.log.debug(f"Decoded hash key: {self.hash_key}")

    async def run(self):
        await self.get_board_list()
        while True:
            await self.get_thread_lists(self.boards)
            await asyncio.sleep(CRAWL_DELAY)

    async def get_board_list(self):
        responses = await self.api_call({"_": "boards.json"})
        for mapped, response in responses:
            if not response:
                continue
            for board in response["boards"]:
                self.boards.append(board["board"])
            self.log.debug(f"Got boards: {self.boards}")

    async def get_thread_lists(self, boards):
        # self.log.debug(f"Getting thread list for {boards}")
        board_urls = {board: f"{board}/catalog.json" for board in boards}
        responses = await self.api_call(board_urls)
        to_get = []
        flat_map = [board for board, thread in responses]
        self.log.debug(f"Got thread list for {flat_map}: {len(responses)}")
        for mapped, response in responses:
            if not response:
                continue
            for page in response:
                for threads in page["threads"]:
                    no = threads["no"]
                    to_get.append((mapped, no))

        if not to_get:
            return
        split_threads = array_split(to_get, ceil(len(to_get) / THREADS_CONCURRENT))
        for threads in split_threads:
            await self.get_threads_content(threads)
            await asyncio.sleep(THREADS_DELAY)
        # await self.get_threads_content(to_get)

    def take_items(self, dict_list, n):
        i = 0
        try:
            for x in list(dict_list.keys()):
                for item in list(dict_list[x]):
                    yield (x, item)
                    dict_list[x].remove(item)
                    i += 1
                    if i == n:
                        raise StopIteration
        except StopIteration:
            print("Take items took", i, "items")

    async def get_threads_content(self, thread_list):
        thread_urls = {
            (board, thread): f"{board}/thread/{thread}.json"
            for board, thread in thread_list
        }
        # self.log.debug(f"Getting information for threads: {thread_urls}")
        responses = await self.api_call(thread_urls)
        self.log.debug(f"Got information for {len(responses)} threads")

        all_posts = {}
        for mapped, response in responses:
            if not response:
                continue
            board, thread = mapped
            all_posts[mapped] = response["posts"]

        if not all_posts:
            return
        await self.handle_posts(all_posts)

    async def handle_posts(self, posts):
        to_store = []
        for key, post_list in posts.items():
            board, thread = key
            for index, post in enumerate(post_list):
                posts[key][index]["type"] = "msg"

                posts[key][index]["src"] = "4ch"
                posts[key][index]["net"] = board
                posts[key][index]["channel"] = thread

                to_store.append(posts[key][index])

        if to_store:
            await db.queue_message_bulk(to_store)

    async def fetch(self, url, session, mapped):
        async with session.get(url) as response:
            try:
                return (mapped, await response.json())
            except:  # noqa
                return (mapped, None)

    async def bound_fetch(self, sem, url, session, mapped):
        # Getter function with semaphore.
        async with sem:
            try:
                return await self.fetch(url, session, mapped)
            except:  # noqa
                return (mapped, None)

    async def api_call(self, methods={}):
        tasks = []
        sem = asyncio.Semaphore(THREADS_SEMAPHORE)
        connector = aiohttp.TCPConnector(limit=None)
        async with aiohttp.ClientSession(connector=connector) as session:
            for mapped, method in methods.items():
                url = f"{self.api_endpoint}/{method}"
                # self.log.debug(f"GET {url}")
                task = asyncio.create_task(self.bound_fetch(sem, url, session, mapped))
                # task = asyncio.ensure_future(self.bound_fetch(sem, url, session))
                tasks.append(task)
            responses = await asyncio.gather(*tasks)
            return responses