import aiohttp
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
from ... exceptions import UnknownConnectionError
from concurrent.futures import CancelledError
from json import JSONDecodeError
from urllib.parse import quote

headers = config.headers
REPLAY_URL = "https://www.youtube.com/live_chat_replay/" \
             "get_live_chat_replay?continuation="
MAX_RETRY_COUNT = 3

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 aiohttp.ClientSession() as session:
            tasks = [_create_block(session, video_id,  seektime, callback)
                for  seektime in _split(-1, 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)}&pbj=1"
        for _ in range(MAX_RETRY_COUNT):
            try :
                async with session.get(url, headers = headers) as resp:
                    text = await resp.text()
                next_continuation, actions = parser.parse(json.loads(text))
                break
            except JSONDecodeError:
                await asyncio.sleep(3)
        else:
            cancel()
            raise UnknownConnectionError("Abort: Unknown connection error.")

        if actions:
            first = parser.get_offset(actions[0])
            last = parser.get_offset(actions[-1])
            if callback:
                callback(actions,last-first)
            return Block(
                continuation = next_continuation,
                chat_data = actions,
                first = first,
                last = last
            )
            
    """
    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 aiohttp.ClientSession() as session:
            tasks = [worker.run(session) for worker in workers]
            return await asyncio.gather(*tasks)    

    async def _fetch(continuation,session) -> Patch:
        url = f"{REPLAY_URL}{quote(continuation)}&pbj=1"
        for _ in range(MAX_RETRY_COUNT):
            try:
                async with session.get(url,headers = config.headers) as resp:
                    chat_json = await resp.text()
                continuation, actions = parser.parse(json.loads(chat_json))
                break
            except JSONDecodeError:
                await asyncio.sleep(3)
        else:
            cancel()
            raise UnknownConnectionError("Abort: Unknown connection error.")

        if actions:
            last = parser.get_offset(actions[-1])
            first = parser.get_offset(actions[0])
            if callback:
                callback(actions, last - first)
            return Patch(actions, continuation, first, last)
        return Patch(continuation = continuation)

    """
    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())