#  Pyrogram - Telegram MTProto API Client Library for Python
#  Copyright (C) 2017-2020 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 base64
import functools
import hashlib
import os
import struct
from concurrent.futures.thread import ThreadPoolExecutor
from getpass import getpass
from typing import List
from typing import Union

from pyrogram import raw
from pyrogram import types
from pyrogram.scaffold import Scaffold


def decode_file_id(s: str) -> bytes:
    s = base64.urlsafe_b64decode(s + "=" * (-len(s) % 4))
    r = b""

    major = s[-1]
    minor = s[-2] if major != 2 else 0

    assert minor in (0, 22, 24)

    skip = 2 if minor else 1

    i = 0

    while i < len(s) - skip:
        if s[i] != 0:
            r += bytes([s[i]])
        else:
            r += b"\x00" * s[i + 1]
            i += 1

        i += 1

    return r


def encode_file_id(s: bytes) -> str:
    r = b""
    n = 0

    for i in s + bytes([22]) + bytes([4]):
        if i == 0:
            n += 1
        else:
            if n:
                r += b"\x00" + bytes([n])
                n = 0

            r += bytes([i])

    return base64.urlsafe_b64encode(r).decode().rstrip("=")


def encode_file_ref(file_ref: bytes) -> str:
    return base64.urlsafe_b64encode(file_ref).decode().rstrip("=")


def decode_file_ref(file_ref: str) -> bytes:
    if file_ref is None:
        return b""

    return base64.urlsafe_b64decode(file_ref + "=" * (-len(file_ref) % 4))


async def ainput(prompt: str = "", *, hide: bool = False):
    with ThreadPoolExecutor(1) as executor:
        func = functools.partial(getpass if hide else input, prompt)
        return await asyncio.get_event_loop().run_in_executor(executor, func)


def get_offset_date(dialogs):
    for m in reversed(dialogs.messages):
        if isinstance(m, raw.types.MessageEmpty):
            continue
        else:
            return m.date
    else:
        return 0


def get_input_media_from_file_id(
    file_id_str: str,
    file_ref: str = None,
    expected_media_type: int = None
) -> Union["raw.types.InputMediaPhoto", "raw.types.InputMediaDocument"]:
    try:
        decoded = decode_file_id(file_id_str)
    except Exception:
        raise ValueError(f"Failed to decode file_id: {file_id_str}")
    else:
        media_type = decoded[0]

        if expected_media_type is not None:
            if media_type != expected_media_type:
                media_type_str = Scaffold.MEDIA_TYPE_ID.get(media_type, None)
                expected_media_type_str = Scaffold.MEDIA_TYPE_ID.get(expected_media_type, None)

                raise ValueError(f'Expected: "{expected_media_type_str}", got "{media_type_str}" file_id instead')

        if media_type in (0, 1, 14):
            raise ValueError(f"This file_id can only be used for download: {file_id_str}")

        if media_type == 2:
            unpacked = struct.unpack("<iiqqqiiii", decoded)
            dc_id, file_id, access_hash, volume_id, _, _, type, local_id = unpacked[1:]

            return raw.types.InputMediaPhoto(
                id=raw.types.InputPhoto(
                    id=file_id,
                    access_hash=access_hash,
                    file_reference=decode_file_ref(file_ref)
                )
            )

        if media_type in (3, 4, 5, 8, 9, 10, 13):
            unpacked = struct.unpack("<iiqq", decoded)
            dc_id, file_id, access_hash = unpacked[1:]

            return raw.types.InputMediaDocument(
                id=raw.types.InputDocument(
                    id=file_id,
                    access_hash=access_hash,
                    file_reference=decode_file_ref(file_ref)
                )
            )

        raise ValueError(f"Unknown media type: {file_id_str}")


async def parse_messages(client, messages: "raw.types.messages.Messages", replies: int = 1) -> List["types.Message"]:
    users = {i.id: i for i in messages.users}
    chats = {i.id: i for i in messages.chats}

    if not messages.messages:
        return types.List()

    parsed_messages = []

    for message in messages.messages:
        parsed_messages.append(await types.Message._parse(client, message, users, chats, replies=0))

    if replies:
        messages_with_replies = {i.id: getattr(i, "reply_to_msg_id", None) for i in messages.messages}
        reply_message_ids = [i[0] for i in filter(lambda x: x[1] is not None, messages_with_replies.items())]

        if reply_message_ids:
            # We need a chat id, but some messages might be empty (no chat attribute available)
            # Scan until we find a message with a chat available (there must be one, because we are fetching replies)
            for m in parsed_messages:
                if m.chat:
                    chat_id = m.chat.id
                    break
            else:
                chat_id = 0

            reply_messages = await client.get_messages(
                chat_id,
                reply_to_message_ids=reply_message_ids,
                replies=replies - 1
            )

            for message in parsed_messages:
                reply_id = messages_with_replies[message.message_id]

                for reply in reply_messages:
                    if reply.message_id == reply_id:
                        message.reply_to_message = reply

    return types.List(parsed_messages)


def parse_deleted_messages(client, update) -> List["types.Message"]:
    messages = update.messages
    channel_id = getattr(update, "channel_id", None)

    parsed_messages = []

    for message in messages:
        parsed_messages.append(
            types.Message(
                message_id=message,
                chat=types.Chat(
                    id=get_channel_id(channel_id),
                    type="channel",
                    client=client
                ) if channel_id is not None else None,
                client=client
            )
        )

    return types.List(parsed_messages)


def unpack_inline_message_id(inline_message_id: str) -> "raw.types.InputBotInlineMessageID":
    r = inline_message_id + "=" * (-len(inline_message_id) % 4)
    r = struct.unpack("<iqq", base64.b64decode(r, altchars=b"-_"))

    return raw.types.InputBotInlineMessageID(
        dc_id=r[0],
        id=r[1],
        access_hash=r[2]
    )


MIN_CHANNEL_ID = -1002147483647
MAX_CHANNEL_ID = -1000000000000
MIN_CHAT_ID = -2147483647
MAX_USER_ID = 2147483647


def get_peer_id(peer: raw.base.Peer) -> int:
    if isinstance(peer, raw.types.PeerUser):
        return peer.user_id

    if isinstance(peer, raw.types.PeerChat):
        return -peer.chat_id

    if isinstance(peer, raw.types.PeerChannel):
        return MAX_CHANNEL_ID - peer.channel_id

    raise ValueError(f"Peer type invalid: {peer}")


def get_peer_type(peer_id: int) -> str:
    if peer_id < 0:
        if MIN_CHAT_ID <= peer_id:
            return "chat"

        if MIN_CHANNEL_ID <= peer_id < MAX_CHANNEL_ID:
            return "channel"
    elif 0 < peer_id <= MAX_USER_ID:
        return "user"

    raise ValueError(f"Peer id invalid: {peer_id}")


def get_channel_id(peer_id: int) -> int:
    return MAX_CHANNEL_ID - peer_id


def btoi(b: bytes) -> int:
    return int.from_bytes(b, "big")


def itob(i: int) -> bytes:
    return i.to_bytes(256, "big")


def sha256(data: bytes) -> bytes:
    return hashlib.sha256(data).digest()


def xor(a: bytes, b: bytes) -> bytes:
    return bytes(i ^ j for i, j in zip(a, b))


def compute_password_hash(algo: raw.types.PasswordKdfAlgoSHA256SHA256PBKDF2HMACSHA512iter100000SHA256ModPow,
                          password: str) -> bytes:
    hash1 = sha256(algo.salt1 + password.encode() + algo.salt1)
    hash2 = sha256(algo.salt2 + hash1 + algo.salt2)
    hash3 = hashlib.pbkdf2_hmac("sha512", hash2, algo.salt1, 100000)

    return sha256(algo.salt2 + hash3 + algo.salt2)


# noinspection PyPep8Naming
def compute_password_check(r: raw.types.account.Password, password: str) -> raw.types.InputCheckPasswordSRP:
    algo = r.current_algo

    p_bytes = algo.p
    p = btoi(algo.p)

    g_bytes = itob(algo.g)
    g = algo.g

    B_bytes = r.srp_B
    B = btoi(B_bytes)

    srp_id = r.srp_id

    x_bytes = compute_password_hash(algo, password)
    x = btoi(x_bytes)

    g_x = pow(g, x, p)

    k_bytes = sha256(p_bytes + g_bytes)
    k = btoi(k_bytes)

    kg_x = (k * g_x) % p

    while True:
        a_bytes = os.urandom(256)
        a = btoi(a_bytes)

        A = pow(g, a, p)
        A_bytes = itob(A)

        u = btoi(sha256(A_bytes + B_bytes))

        if u > 0:
            break

    g_b = (B - kg_x) % p

    ux = u * x
    a_ux = a + ux
    S = pow(g_b, a_ux, p)
    S_bytes = itob(S)

    K_bytes = sha256(S_bytes)

    M1_bytes = sha256(
        xor(sha256(p_bytes), sha256(g_bytes))
        + sha256(algo.salt1)
        + sha256(algo.salt2)
        + A_bytes
        + B_bytes
        + K_bytes
    )

    return raw.types.InputCheckPasswordSRP(srp_id=srp_id, A=A_bytes, M1=M1_bytes)