#  Pyrofork - Telegram MTProto API Client Library for Python
#  Copyright (C) 2017-present Dan <https://github.com/delivrance>
#  Copyright (C) 2022-present Mayuri-Chan <https://github.com/Mayuri-Chan>
#
#  This file is part of Pyrofork.
#
#  Pyrofork is free software: you can redistribute it and/or modify
#  it under the terms of the GNU Lesser General Public License as published
#  by the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#
#  Pyrofork is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU Lesser General Public License for more details.
#
#  You should have received a copy of the GNU Lesser General Public License
#  along with Pyrofork.  If not, see <http://www.gnu.org/licenses/>.

import asyncio
import bisect
import contextlib
import logging
import os
from datetime import datetime, timedelta
from hashlib import sha1
from io import BytesIO
from typing import Optional

import pyrogram
from pyrogram import raw
from pyrogram.connection import Connection
from pyrogram.crypto import mtproto
from pyrogram.errors import (
    RPCError, InternalServerError, AuthKeyDuplicated,
    FloodWait, FloodPremiumWait,
    ServiceUnavailable, BadMsgNotification,
    SecurityCheckMismatch, Unauthorized
)
from pyrogram.raw.all import layer
from pyrogram.raw.core import TLObject, MsgContainer, Int, FutureSalts
from .internals import MsgId, MsgFactory

log = logging.getLogger(__name__)


class Result:
    def __init__(self):
        self.value = None
        self.event = asyncio.Event()


class Session:
    START_TIMEOUT = 2
    WAIT_TIMEOUT = 15
    SLEEP_THRESHOLD = 10
    MAX_RETRIES = 10
    ACKS_THRESHOLD = 10
    PING_INTERVAL = 5
    STORED_MSG_IDS_MAX_SIZE = 500
    RECONNECT_THRESHOLD = timedelta(seconds=10)

    TRANSPORT_ERRORS = {
        404: "auth key not found",
        429: "transport flood",
        444: "invalid DC"
    }

    def __init__(
        self,
        client: "pyrogram.Client",
        dc_id: int,
        auth_key: bytes,
        test_mode: bool,
        is_media: bool = False,
        is_cdn: bool = False
    ):
        self.client = client
        self.dc_id = dc_id
        self.auth_key = auth_key
        self.test_mode = test_mode
        self.is_media = is_media
        self.is_cdn = is_cdn

        self.connection: Optional[Connection] = None

        self.auth_key_id = sha1(auth_key).digest()[-8:]

        self.session_id = os.urandom(8)
        self.msg_factory = MsgFactory()

        self.salt = 0

        self.pending_acks = set()

        self.results = {}

        self.stored_msg_ids = []

        self.ping_task = None
        self.ping_task_event = asyncio.Event()

        self.recv_task = None

        self.is_started = asyncio.Event()

        self.last_reconnect_attempt = None

    async def start(self):
        if not self.test_mode:
            address, port = await self.client.storage.get_dc_address(self.dc_id, self.client.ipv6, self.is_media)
        else:
            address = self.client.test_addr
            port = self.client.test_port
            if address is None or port is None:
                raise ValueError("Test address and port must be set for test mode.")
        while True:
            self.connection = self.client.connection_factory(
                dc_id=self.dc_id,
                test_mode=self.test_mode,
                server_ip=address,
                server_port=port,
                ipv6=self.client.ipv6,
                alt_port=self.client.alt_port,
                proxy=self.client.proxy,
                media=self.is_media,
                protocol_factory=self.client.protocol_factory,
                loop=self.client.loop
            )

            try:
                await self.connection.connect()

                self.recv_task = self.client.loop.create_task(self.recv_worker())

                await self.send(raw.functions.Ping(ping_id=0), timeout=self.START_TIMEOUT)

                if not self.is_cdn:
                    await self.send(
                        raw.functions.InvokeWithLayer(
                            layer=layer,
                            query=raw.functions.InitConnection(
                                api_id=await self.client.storage.api_id(),
                                app_version=self.client.app_version,
                                device_model=self.client.device_model,
                                system_version=self.client.system_version,
                                system_lang_code=self.client.lang_code,
                                lang_code=self.client.lang_code,
                                lang_pack="",
                                query=raw.functions.help.GetConfig(),
                            )
                        ),
                        timeout=self.START_TIMEOUT
                    )

                self.ping_task = self.client.loop.create_task(self.ping_worker())

                log.info("Session initialized: Layer %s", layer)
                log.info("Device: %s - %s", self.client.device_model, self.client.app_version)
                log.info("System: %s (%s)", self.client.system_version, self.client.lang_code)
            except AuthKeyDuplicated as e:
                await self.stop()
                raise e
            except (OSError, RPCError):
                await self.stop()
            except Exception as e:
                await self.stop()
                raise e
            else:
                break

        self.is_started.set()

        log.info("Session started")

    async def stop(self):
        self.is_started.clear()

        self.stored_msg_ids.clear()

        self.ping_task_event.set()

        if self.ping_task is not None:
            await self.ping_task

        self.ping_task_event.clear()

        await self.connection.close()

        if self.recv_task:
            self.recv_task.cancel()
            with contextlib.suppress(asyncio.CancelledError):
                await self.recv_task

        if not self.is_media and callable(self.client.disconnect_handler):
            try:
                await self.client.disconnect_handler(self.client)
            except Exception as e:
                log.exception(e)

        log.info("Session stopped")

    async def restart(self):
        now = datetime.now()
        if (
            self.last_reconnect_attempt
            and now - self.last_reconnect_attempt < self.RECONNECT_THRESHOLD
        ):
            log.info("Reconnecting too frequently, sleeping for a while")
            await asyncio.sleep(5)

        self.last_reconnect_attempt = now
        await self.stop()
        await self.start()

    async def handle_packet(self, packet):
        try:
            data = await self.client.loop.run_in_executor(
                pyrogram.crypto_executor,
                mtproto.unpack,
                BytesIO(packet),
                self.session_id,
                self.auth_key,
                self.auth_key_id
            )
        except ValueError as e:
            log.debug(e)
            self.client.loop.create_task(self.restart())
            return

        messages = (
            data.body.messages
            if isinstance(data.body, MsgContainer)
            else [data]
        )

        log.debug("Received: %s", data)

        for msg in messages:
            if msg.seq_no % 2 != 0:
                if msg.msg_id in self.pending_acks:
                    continue
                else:
                    self.pending_acks.add(msg.msg_id)

            try:
                if len(self.stored_msg_ids) > Session.STORED_MSG_IDS_MAX_SIZE:
                    del self.stored_msg_ids[:Session.STORED_MSG_IDS_MAX_SIZE // 2]

                if self.stored_msg_ids:
                    if msg.msg_id < self.stored_msg_ids[0]:
                        raise SecurityCheckMismatch("The msg_id is lower than all the stored values")

                    if msg.msg_id in self.stored_msg_ids:
                        raise SecurityCheckMismatch("The msg_id is equal to any of the stored values")

                    time_diff = (msg.msg_id - MsgId()) / 2 ** 32

                    if time_diff > 30:
                        raise SecurityCheckMismatch("The msg_id belongs to over 30 seconds in the future. "
                                                    "Most likely the client time has to be synchronized.")

                    if time_diff < -300:
                        raise SecurityCheckMismatch("The msg_id belongs to over 300 seconds in the past. "
                                                    "Most likely the client time has to be synchronized.")
            except SecurityCheckMismatch as e:
                log.info("Discarding packet: %s", e)
                await self.connection.close()
                return
            else:
                bisect.insort(self.stored_msg_ids, msg.msg_id)

            if isinstance(msg.body, (raw.types.MsgDetailedInfo, raw.types.MsgNewDetailedInfo)):
                self.pending_acks.add(msg.body.answer_msg_id)
                continue

            if isinstance(msg.body, raw.types.NewSessionCreated):
                continue

            msg_id = None

            if isinstance(msg.body, (raw.types.BadMsgNotification, raw.types.BadServerSalt)):
                msg_id = msg.body.bad_msg_id
            elif isinstance(msg.body, (FutureSalts, raw.types.RpcResult)):
                msg_id = msg.body.req_msg_id
            elif isinstance(msg.body, raw.types.Pong):
                msg_id = msg.body.msg_id
            else:
                if self.client is not None:
                    self.client.loop.create_task(self.client.handle_updates(msg.body))

            if msg_id in self.results:
                self.results[msg_id].value = getattr(msg.body, "result", msg.body)
                self.results[msg_id].event.set()

        if len(self.pending_acks) >= self.ACKS_THRESHOLD:
            log.debug("Sending %s acks", len(self.pending_acks))

            try:
                await self.send(raw.types.MsgsAck(msg_ids=list(self.pending_acks)), False)
            except OSError:
                pass
            else:
                self.pending_acks.clear()

    async def ping_worker(self):
        log.info("PingTask started")

        while True:
            try:
                await asyncio.wait_for(self.ping_task_event.wait(), self.PING_INTERVAL)
            except asyncio.TimeoutError:
                pass
            else:
                break

            try:
                await self.send(
                    raw.functions.PingDelayDisconnect(
                        ping_id=0, disconnect_delay=self.WAIT_TIMEOUT + 10
                    ), False
                )
            except OSError:
                self.client.loop.create_task(self.restart())
                break
            except RPCError:
                pass

        log.info("PingTask stopped")

    async def recv_worker(self):
        log.info("NetworkTask started")

        while True:
            packet = await self.connection.recv()

            if packet is None or len(packet) == 4:
                if packet:
                    error_code = -Int.read(BytesIO(packet))

                    if error_code == 404:
                        raise Unauthorized(
                            "Auth key not found in the system. You must delete your session file "
                            "and log in again with your phone number or bot token."
                        )

                    log.warning(
                        "Server sent transport error: %s (%s)",
                        error_code, Session.TRANSPORT_ERRORS.get(error_code, "unknown error")
                    )

                if self.is_started.is_set():
                    self.client.loop.create_task(self.restart())

                break

            self.client.loop.create_task(self.handle_packet(packet))

        log.info("NetworkTask stopped")

    async def send(self, data: TLObject, wait_response: bool = True, timeout: float = WAIT_TIMEOUT, retry: int = 0):
        message = self.msg_factory(data)
        msg_id = message.msg_id

        if wait_response:
            self.results[msg_id] = Result()

        log.debug("Sent: %s", message)

        payload = await self.client.loop.run_in_executor(
            pyrogram.crypto_executor,
            mtproto.pack,
            message,
            self.salt,
            self.session_id,
            self.auth_key,
            self.auth_key_id
        )

        try:
            await self.connection.send(payload)
        except OSError as e:
            self.results.pop(msg_id, None)
            raise e

        if wait_response:
            try:
                await asyncio.wait_for(self.results[msg_id].event.wait(), timeout)
            except asyncio.TimeoutError:
                pass

            result = self.results.pop(msg_id).value

            if result is None:
                raise TimeoutError("Request timed out")

            if isinstance(result, raw.types.RpcError):
                if isinstance(data, (raw.functions.InvokeWithoutUpdates, raw.functions.InvokeWithTakeout)):
                    data = data.query

                RPCError.raise_it(result, type(data))

            if isinstance(result, raw.types.BadMsgNotification):
                if retry > 1:
                    raise BadMsgNotification(result.error_code)

                self._handle_bad_notification()
                await self.send(data, wait_response, timeout, retry + 1)

            if isinstance(result, raw.types.BadServerSalt):
                self.salt = result.new_server_salt
                return await self.send(data, wait_response, timeout)

            return result

    def _handle_bad_notification(self):
        new_msg_id = MsgId()
        if self.stored_msg_ids[len(self.stored_msg_ids)-1] >= new_msg_id:
            new_msg_id = self.stored_msg_ids[len(self.stored_msg_ids)-1] + 4
            log.debug("Changing msg_id old=%s new=%s", self.stored_msg_ids[len(self.stored_msg_ids)-1], new_msg_id)
        self.stored_msg_ids[len(self.stored_msg_ids)-1] = new_msg_id

    async def invoke(
        self,
        query: TLObject,
        retries: int = MAX_RETRIES,
        timeout: float = WAIT_TIMEOUT,
        sleep_threshold: float = SLEEP_THRESHOLD
    ):
        try:
            await asyncio.wait_for(self.is_started.wait(), self.WAIT_TIMEOUT)
        except asyncio.TimeoutError:
            pass

        if isinstance(query, (raw.functions.InvokeWithoutUpdates, raw.functions.InvokeWithTakeout)):
            inner_query = query.query
        else:
            inner_query = query

        query_name = ".".join(inner_query.QUALNAME.split(".")[1:])

        while retries > 0:
            try:
                if (
                    self.connection is None
                    or self.connection.protocol is None
                    or getattr(self.connection.protocol, "closed", True)
                ):
                    log.warning(
                        "[%s] Connection is closed or not established. Attempting to reconnect...",
                        self.client.name,
                    )
                    await self.restart()
                    await asyncio.sleep(1)
                    continue

                return await self.send(query, timeout=timeout)
            except (FloodWait, FloodPremiumWait) as e:
                amount = e.value

                if amount > sleep_threshold >= 0:
                    raise

                log.warning('[%s] Waiting for %s seconds before continuing (required by "%s")',
                            self.client.name, amount, query_name)

                await asyncio.sleep(amount)
            except (OSError, InternalServerError, ServiceUnavailable) as e:
                retries -= 1
                if retries == 0:
                    raise e

                (log.warning if retries < 2 else log.info)(
                    '[%s] Retrying "%s" due to: %s',
                    Session.MAX_RETRIES - retries,
                    query_name, str(e) or repr(e)
                )

                if isinstance(e, OSError) and retries > 1:
                    try:
                        await self.restart()
                    except Exception as restart_error:
                        log.warning(
                            "[%s] Failed to restart session: %s",
                            self.client.name,
                            str(restart_error) or repr(restart_error),
                        )

                await asyncio.sleep(0.5)

        raise TimeoutError("Exceeded maximum number of retries")