import httpx
import asyncio
import json
from . import parser
from . block import Block
from . worker import ExtractWorker
from . patch import Patch
from ... import config
from ... paramgen import arcparam_mining as arcparam
from concurrent.futures import CancelledError
from urllib.parse import quote

headers = config.headers
REPLAY_URL = "https://www.youtube.com/live_chat_replay?continuation="
INTERVAL = 1


def _split(start, end, count, min_interval_sec=120):
    """
    Split section from `start` to `end` into `count` pieces,
    and returns the beginning of each piece.
    The `count` is adjusted so that the length of each piece
    is no smaller than `min_interval`.

    Returns:
    --------
        List of the offset of each block's first chat data.
    """

    if not (isinstance(start, int) or isinstance(start, float)) or \
       not (isinstance(end, int) or isinstance(end, float)):
        raise ValueError("start/end must be int or float")
    if not isinstance(count, int):
        raise ValueError("count must be int")
    if start > end:
        raise ValueError("end must be equal to or greater than start.")
    if count < 1:
        raise ValueError("count must be equal to or greater than 1.")
    if (end - start) / count < min_interval_sec:
        count = int((end - start) / min_interval_sec)
        if count == 0:
            count = 1
    interval = (end - start) / count

    if count == 1:
        return [start]
    return sorted(list(set([int(start + interval * j)
                            for j in range(count)])))


def ready_blocks(video_id, duration, div, callback):
    if div <= 0:
        raise ValueError

    async def _get_blocks(video_id, duration, div, callback):
        async with httpx.ClientSession() as session:
            tasks = [_create_block(session, video_id, seektime, callback)
                     for seektime in _split(0, duration, div)]
            return await asyncio.gather(*tasks)

    async def _create_block(session, video_id, seektime, callback):
        continuation = arcparam.getparam(video_id, seektime=seektime)
        url = (f"{REPLAY_URL}{quote(continuation)}&playerOffsetMs="
               f"{int(seektime*1000)}&hidden=false&pbj=1")
        async with session.get(url, headers=headers) as resp:
            chat_json = await resp.text()
        if chat_json is None:
            return
        continuation, actions = parser.parse(json.loads(chat_json)[1])
        first = seektime
        seektime += INTERVAL
        if callback:
            callback(actions, INTERVAL)
        return Block(
            continuation=continuation,
            chat_data=actions,
            first=first,
            last=seektime,
            seektime=seektime
        )
    """
    fetch initial blocks.
    """
    loop = asyncio.get_event_loop()
    blocks = loop.run_until_complete(
        _get_blocks(video_id, duration, div, callback))
    return blocks


def fetch_patch(callback, blocks, video_id):

    async def _allocate_workers():
        workers = [
            ExtractWorker(
                fetch=_fetch, block=block,
                blocks=blocks, video_id=video_id
            )
            for block in blocks
        ]
        async with httpx.ClientSession() as session:
            tasks = [worker.run(session) for worker in workers]
            return await asyncio.gather(*tasks)

    async def _fetch(seektime, session) -> Patch:
        continuation = arcparam.getparam(video_id, seektime=seektime)
        url = (f"{REPLAY_URL}{quote(continuation)}&playerOffsetMs="
               f"{int(seektime*1000)}&hidden=false&pbj=1")
        async with session.get(url, headers=config.headers) as resp:
            chat_json = await resp.text()
        actions = []
        try:
            if chat_json is None:
                return Patch()
            continuation, actions = parser.parse(json.loads(chat_json)[1])
        except json.JSONDecodeError:
            pass
        if callback:
            callback(actions, INTERVAL)
        return Patch(chats=actions, continuation=continuation,
                     seektime=seektime, last=seektime)
    """
    allocate workers and assign blocks.
    """
    loop = asyncio.get_event_loop()
    try:
        loop.run_until_complete(_allocate_workers())
    except CancelledError:
        pass


async def _shutdown():
    print("\nshutdown...")
    tasks = [t for t in asyncio.all_tasks()
             if t is not asyncio.current_task()]
    for task in tasks:
        task.cancel()
        try:
            await task
        except asyncio.CancelledError:
            pass


def cancel():
    loop = asyncio.get_event_loop()
    loop.create_task(_shutdown())