#  Pyrogram - Telegram MTProto API Client Library for Python
#  Copyright (C) 2017-2021 Dan <https://github.com/delivrance>
#
#  This file is part of Pyrogram.
#
#  Pyrogram 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.
#
#  Pyrogram 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 Pyrogram.  If not, see <http://www.gnu.org/licenses/>.

import asyncio
import logging
import os
import time
from datetime import datetime, timedelta
from hashlib import sha1
from io import BytesIO

import pyrogram
from pyrogram import __copyright__, __license__, __version__
from pyrogram import raw
from pyrogram.connection import Connection
from pyrogram.crypto import mtproto
from pyrogram.errors import (
    RPCError, InternalServerError, AuthKeyDuplicated, FloodWait, ServiceUnavailable, BadMsgNotification,
    SecurityCheckMismatch
)
from pyrogram.raw.all import layer
from pyrogram.raw.core import TLObject, MsgContainer, Int, FutureSalt, 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 = 1
    WAIT_TIMEOUT = 15
    SLEEP_THRESHOLD = 10
    MAX_RETRIES = 5
    ACKS_THRESHOLD = 8
    PING_INTERVAL = 5

    notice_displayed = False

    def __init__(
        self,
        client: "pyrogram.Client",
        dc_id: int,
        auth_key: bytes,
        test_mode: bool,
        is_media: bool = False,
        is_cdn: bool = False
    ):
        if not Session.notice_displayed:
            print(f"Pyrogram v{__version__}, {__copyright__}")
            print(f"Licensed under the terms of the {__license__}", end="\n\n")
            Session.notice_displayed = True

        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 = None

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

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

        self.current_salt = None

        self.pending_acks = set()

        self.results = {}

        self.stored_msg_ids = []

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

        self.next_salt_task = None
        self.next_salt_task_event = asyncio.Event()

        self.network_task = None

        self.is_connected = asyncio.Event()

        self.loop = asyncio.get_event_loop()

    async def start(self):
        while True:
            self.connection = Connection(
                self.dc_id,
                self.test_mode,
                self.client.ipv6,
                self.client.proxy,
                self.is_media
            )

            try:
                await self.connection.connect()

                self.network_task = self.loop.create_task(self.network_worker())

                self.current_salt = FutureSalt(0, 0, 0)
                self.current_salt = FutureSalt(
                    0, 0,
                    (await self._send(
                        raw.functions.Ping(ping_id=0),
                        timeout=self.START_TIMEOUT
                    )).new_server_salt
                )
                self.current_salt = (await self._send(
                    raw.functions.GetFutureSalts(num=1),
                    timeout=self.START_TIMEOUT)).salts[0]

                self.next_salt_task = self.loop.create_task(self.next_salt_worker())

                if not self.is_cdn:
                    await self._send(
                        raw.functions.InvokeWithLayer(
                            layer=layer,
                            query=raw.functions.InitConnection(
                                api_id=self.client.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.loop.create_task(self.ping_worker())

                log.info(f"Session initialized: Layer {layer}")
                log.info(f"Device: {self.client.device_model} - {self.client.app_version}")
                log.info(f"System: {self.client.system_version} ({self.client.lang_code.upper()})")

            except AuthKeyDuplicated as e:
                await self.stop()
                raise e
            except (OSError, TimeoutError, RPCError):
                await self.stop()
            except Exception as e:
                await self.stop()
                raise e
            else:
                break

        self.is_connected.set()

        log.info("Session started")

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

        self.ping_task_event.set()
        self.next_salt_task_event.set()

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

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

        self.ping_task_event.clear()
        self.next_salt_task_event.clear()

        self.connection.close()

        if self.network_task:
            await self.network_task

        for i in self.results.values():
            i.event.set()

        if not self.is_media and callable(self.client.disconnect_handler):
            try:
                await self.client.disconnect_handler(self.client)
            except Exception as e:
                log.error(e, exc_info=True)

        log.info("Session stopped")

    async def restart(self):
        await self.stop()
        await self.start()

    async def handle_packet(self, packet):
        try:
            data = await self.loop.run_in_executor(
                pyrogram.crypto_executor,
                mtproto.unpack,
                BytesIO(packet),
                self.session_id,
                self.auth_key,
                self.auth_key_id,
                self.stored_msg_ids
            )
        except SecurityCheckMismatch:
            self.connection.close()
            return

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

        # Call log.debug twice because calling it once by appending "data" to the previous string (i.e. f"Kind: {data}")
        # will cause "data" to be evaluated as string every time instead of only when debug is actually enabled.
        log.debug("Received:")
        log.debug(data)

        for msg in messages:
            if msg.seq_no == 0:
                MsgId.set_server_time(msg.msg_id / (2 ** 32))

            if msg.seq_no % 2 != 0:
                if msg.msg_id not in self.pending_acks:
                    self.pending_acks.add(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.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(f"Send {len(self.pending_acks)} acks")

            try:
                await self._send(raw.types.MsgsAck(msg_ids=list(self.pending_acks)), False)
            except (OSError, TimeoutError):
                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, TimeoutError, RPCError):
                pass

        log.info("PingTask stopped")

    async def next_salt_worker(self):
        log.info("NextSaltTask started")

        while True:
            now = datetime.fromtimestamp(time.perf_counter() - MsgId.reference_clock + MsgId.server_time)

            # Seconds to wait until middle-overlap, which is
            # 15 minutes before/after the current/next salt end/start time
            valid_until = datetime.fromtimestamp(self.current_salt.valid_until)
            dt = (valid_until - now).total_seconds() - 900

            minutes, seconds = divmod(int(dt), 60)
            log.info(f"Next salt in {minutes:.0f}m {seconds:.0f}s (at {now + timedelta(seconds=dt)})")

            try:
                await asyncio.wait_for(self.next_salt_task_event.wait(), dt)
            except asyncio.TimeoutError:
                pass
            else:
                break

            try:
                self.current_salt = (await self._send(raw.functions.GetFutureSalts(num=1))).salts[0]
            except (OSError, TimeoutError, RPCError):
                self.connection.close()
                break

        log.info("NextSaltTask stopped")

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

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

            if packet is None or len(packet) == 4:
                if packet:
                    log.warning(f'Server sent "{Int.read(BytesIO(packet))}"')

                if self.is_connected.is_set():
                    self.loop.create_task(self.restart())

                break

            self.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):
        message = self.msg_factory(data)
        msg_id = message.msg_id

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

        # Call log.debug twice because calling it once by appending "data" to the previous string (i.e. f"Kind: {data}")
        # will cause "data" to be evaluated as string every time instead of only when debug is actually enabled.
        log.debug(f"Sent:")
        log.debug(message)

        payload = await self.loop.run_in_executor(
            pyrogram.crypto_executor,
            mtproto.pack,
            message,
            self.current_salt.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
            finally:
                result = self.results.pop(msg_id).value

            if result is None:
                raise TimeoutError
            elif isinstance(result, raw.types.RpcError):
                if isinstance(data, (raw.functions.InvokeWithoutUpdates, raw.functions.InvokeWithTakeout)):
                    data = data.query

                RPCError.raise_it(result, type(data))
            elif isinstance(result, raw.types.BadMsgNotification):
                raise BadMsgNotification(result.error_code)
            else:
                return result

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

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

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

        while True:
            try:
                return await self._send(data, timeout=timeout)
            except FloodWait as e:
                amount = e.x

                if amount > sleep_threshold >= 0:
                    raise

                log.warning(f'[{self.client.session_name}] Sleeping for {amount}s (required by "{query}")')

                await asyncio.sleep(amount)
            except (OSError, TimeoutError, InternalServerError, ServiceUnavailable) as e:
                if retries == 0:
                    raise e from None

                (log.warning if retries < 2 else log.info)(
                    f'[{Session.MAX_RETRIES - retries + 1}] Retrying "{query}" due to {str(e) or repr(e)}')

                await asyncio.sleep(0.5)

                return await self.send(data, retries - 1, timeout)