# matrix-appservice-kakaotalk - A Matrix-KakaoTalk puppeting bridge.
# Copyright (C) 2022 Tulir Asokan, Andrew Ferrazzutti
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
#import time

#from yarl import URL

from mautrix.bridge.commands import HelpSection, command_handler
from mautrix.errors import MForbidden
#from mautrix.util.signed_token import sign_token

from ..kt.client import Client as KakaoTalkClient
from ..kt.client.errors import (
    AnotherLogonDetected,
    CommandException,
    DeviceVerificationRequired,
    IncorrectPasscode,
    IncorrectPassword,
)

from .. import puppet as pu
from ..db import LoginCredential

from .typehint import CommandEvent

SECTION_AUTH = HelpSection("Authentication", 10, "")

""" TODO Implement web login
web_unsupported = (
    "This instance of the KakaoTalk bridge does not support the web-based login interface"
)
alternative_web_login = (
    "Alternatively, you may use [the web-based login interface]({url}) "
    "to prevent the bridge and homeserver from seeing your password"
)
forced_web_login = (
    "This instance of the KakaoTalk bridge does not allow in-Matrix login. "
    "Please use [the web-based login interface]({url})."
)
"""
send_password = "Please send your password here to log in"
missing_email = "Please use `$cmdprefix+sp login <email>` to log in here"
try_again_or_cancel = "Try again, or say `$cmdprefix+sp cancel` to give up."

_CMD_CONTINUE_LOGIN = "continue-login"


@command_handler(
    needs_auth=False,
    management_only=True,
    help_section=SECTION_AUTH,
    help_text="Log in to KakaoTalk. Optionally save login credentials & have the bridge use them when needed to automatically restore your login session.",
    help_args="[--save] [_email_]",
)
async def login(evt: CommandEvent) -> None:
    if await evt.sender.is_logged_in():
        await evt.reply("You're already logged in")
        return

    save = len(evt.args) > 0 and evt.args[0] == "--save"
    email = evt.args[0 if not save else 1] if len(evt.args) > 0 else None

    if email:
        evt.sender.command_status = {
            "action": "Login",
            "room_id": evt.room_id,
            "next": _enter_password,
            "email": email,
            "save": save,
            "forced": evt.sender.force_login,
        }
        try:
            creds = await LoginCredential.get_by_mxid(evt.sender.mxid)
        except:
            evt.log.exception("Exception while looking for saved password")
            creds = None
        if creds and creds.email == email:
            await evt.reply("Logging in with saved password")
            await _login_with_password(
                evt,
                evt.sender.command_status.pop("email"),
                creds.password,
                evt.sender.command_status.pop("forced"),
            )
            return

    """ TODO Implement web login
    if evt.bridge.public_website:
        external_url = URL(evt.config["appservice.public.external"])
        token = sign_token(
            evt.bridge.public_website.secret_key,
            {
                "mxid": evt.sender.mxid,
                "expiry": int(time.time()) + 30 * 60,
            },
        )
        url = (external_url / "login.html").with_fragment(token)
        if not evt.config["appservice.public.allow_matrix_login"]:
            await evt.reply(forced_web_login.format(url=url))
        elif email:
            await evt.reply(f"{send_password}. {alternative_web_login.format(url=url)}.")
        else:
            await evt.reply(f"{missing_email}. {alternative_web_login.format(url=url)}.")
    elif not email:
        await evt.reply(f"{missing_email}. {web_unsupported}.")
    else:
        await evt.reply(f"{send_password}. {web_unsupported}.")
    """
    if not email:
        await evt.reply(f"{missing_email}.")
    else:
        save_warning = (
            " NOTE: When saving your credentials, the bridge will store your KakaoTalk password **unencrypted** until you discard it with `$cmdprefix+sp forget-password`."
            " If you would rather not have the bridge save your password, type `$cmdprefix+sp cancel`, then `$cmdprefix+sp login [_email_]` without `--save`."
        ) if save else ""
        await evt.reply(f"{send_password}.{save_warning}")


async def _enter_password(evt: CommandEvent) -> None:
    try:
        await evt.az.intent.redact(evt.room_id, evt.event_id)
    except MForbidden:
        await evt.mark_read()
    assert evt.sender.command_status
    await _login_with_password(
        evt,
        evt.sender.command_status.pop("email"),
        evt.content.body,
        evt.sender.command_status.pop("forced"),
    )

async def _login_with_password(evt: CommandEvent, email: str, password: str, forced: bool) -> None:
    req = {
        "uuid": await evt.sender.get_uuid(),
        "form": {
            "email": email,
            "password": password,
        },
        "forced": forced,
    }
    await _try_login(evt, req)

async def _try_login(evt: CommandEvent, req: dict) -> None:
    save = (
        evt.sender.command_status.get("save", False)
        if evt.sender.command_status
        else False
    )
    try:
        await _do_login(evt, req, save)
    except DeviceVerificationRequired as e:
        if evt.sender.command_status and evt.sender.command_status.get("next") != _enter_dv_code:
            await evt.reply(
                "Open KakaoTalk on your smartphone. It should show a device registration passcode. "
                "Enter that passcode here."
            )
            evt.sender.command_status = {
                "action": "Login",
                "room_id": evt.room_id,
                "next": _enter_dv_code,
                "save": save,
                "req": req,
            }
        else:
            evt.log.error("Device registration still required after having just registered")
            await _handle_login_failure(evt, e)
    except AnotherLogonDetected as e:
        if not req["forced"]:
            await evt.reply(
                 "You are currently logged in to KakaoTalk on a PC or another bridge. "
                 "In order to log in to this bridge, you will be forced to log out from your other session. "
                f"To proceed, type `$cmdprefix+sp {_CMD_CONTINUE_LOGIN}`. Otherwise, type `$cmdprefix+sp cancel`."
            )
            evt.sender.command_status = {
                "action": "Login",
                "room_id": evt.room_id,
                "next": _force_login,
                "save": save,
                "req": req,
            }
        else:
            evt.log.error("Failed to force-login while logged in elsewhere")
            await _handle_login_failure(evt, e)
    except IncorrectPassword:
        await evt.reply(f"Incorrect password. {try_again_or_cancel}")
        evt.sender.command_status = {
            "action": "Login",
            "room_id": evt.room_id,
            "next": _enter_password,
            "email": req["form"]["email"],
            "save": save,
            "forced": req["forced"],
        }
    #except OAuthException as e:
    #    await evt.reply(f"Error from KakaoTalk:\n\n> {e}")
    except Exception as e:
        await _handle_login_failure(evt, e)


async def _enter_dv_code(evt: CommandEvent) -> None:
    assert evt.sender.command_status
    req: dict = evt.sender.command_status.pop("req")
    passcode = evt.content.body
    await evt.mark_read()
    try:
        await KakaoTalkClient.register_device(passcode, **req)
    except IncorrectPasscode:
        await evt.reply(f"Incorrect device registration passcode. {try_again_or_cancel}")
    #except OAuthException as e:
    #    await evt.reply(f"Error from KakaoTalk:\n\n> {e}")
    except Exception as e:
        await _handle_login_failure(evt, e)
    else:
        await _try_login(evt, req)


async def _force_login(evt: CommandEvent) -> None:
    command = evt.content.body
    if command != _CMD_CONTINUE_LOGIN:
        await evt.reply(
            f"Unknown action `{command}`. "
            f"Use `$cmdprefix+sp {_CMD_CONTINUE_LOGIN}` or `$cmdprefix+sp cancel`."
        )
        return
    assert evt.sender.command_status
    evt.sender.command_status["forced"] = True
    await evt.mark_read()
    await _try_login(evt, evt.sender.command_status.pop("req"))


async def _do_login(evt: CommandEvent, req: dict, save: bool) -> None:
    oauth_credential = await KakaoTalkClient.login(**req)
    await evt.sender.on_logged_in(oauth_credential)
    evt.sender.command_status = None
    await evt.reply("Successfully logged in")
    try:
        if save:
            email = req["form"]["email"]
            password = req["form"]["password"]
            creds = await LoginCredential.get_by_mxid(evt.sender.mxid)
            if creds:
                evt.log.warning("Found pre-existing login credentials, so updating them now")
                creds.email = email
                creds.password = password
                await creds.save()
            else:
                await LoginCredential(evt.sender.mxid, email, password).insert()
        else:
            await LoginCredential.delete_by_mxid(evt.sender.mxid)
    except:
        evt.log.exception("Error updating saved credentials after successful login")

async def _handle_login_failure(evt: CommandEvent, e: Exception) -> None:
    evt.sender.command_status = None
    if isinstance(e, CommandException):
        message = "Failed to log in"
        evt.log.error(message)
    else:
        message = "Error while logging in"
        evt.log.exception(message)
    await evt.reply(f"{message}: {e}")


@command_handler(
    needs_auth=True,
    management_only=True,
    help_section=SECTION_AUTH,
    help_text="Delete saved login credentials, if they were saved"
)
async def forget_password(evt: CommandEvent) -> None:
    creds = await LoginCredential.get_by_mxid(evt.sender.mxid)
    if not creds:
        await evt.reply("The bridge wasn't storing your login credentials, so there was nothing to forget.")
    else:
        await creds.delete()
        await evt.reply(
            "This bridge is no longer storing your login credentials. "
            "If you get logged out unexpectedly, you will have to manually log back in."
        )


@command_handler(
    needs_auth=True,
    help_section=SECTION_AUTH,
    help_text="Log out of KakaoTalk (and optionally change your virtual device ID for next login)",
    help_args="[--reset-device]",
)
async def logout(evt: CommandEvent) -> None:
    if len(evt.args) >= 1:
        if evt.args[0] == "--reset-device":
            reset_device = True
        else:
            await evt.reply("**Usage:** `$cmdprefix+sp logout [--reset-device]`")
            return
    else:
        reset_device = False

    puppet = await pu.Puppet.get_by_ktid(evt.sender.ktid)
    await evt.sender.logout(reset_device=reset_device)
    if puppet.is_real_user:
        await puppet.switch_mxid(None, None)

    message = "Successfully logged out"
    if reset_device:
        message += (
            ", and your next login will use a different device ID.\n\n"
            "The old device must be manually de-registered from the KakaoTalk app."
        )
    await evt.reply(message)


@command_handler(needs_auth=False, help_section=SECTION_AUTH, help_text="Change your virtual device ID for next login")
async def reset_device(evt: CommandEvent) -> None:
    if await evt.sender.is_logged_in():
        await evt.reply("This command requires you to be logged out.")
    else:
        await evt.mark_read()
        await evt.sender.logout(reset_device=True)
        await evt.reply(
            "Your next login will use a different device ID.\n\n"
            "The old device must be manually de-registered from the KakaoTalk app."
        )


@command_handler(
    needs_auth=False,
    help_section=SECTION_AUTH,
    help_text="When logging in, automatically log out of any other existing KakaoTalk session"
)
async def enable_forced_login(evt: CommandEvent) -> None:
    if evt.sender.force_login:
        await evt.reply("Forced login is already enabled.")
        return
    evt.sender.force_login = True
    await evt.sender.save()
    await evt.reply("Forced login is now enabled.")

@command_handler(
    needs_auth=False,
    help_section=SECTION_AUTH,
    help_text="When logging in, ask before logging out of another existing KakaoTalk session, if one exists"
)
async def disable_forced_login(evt: CommandEvent) -> None:
    if not evt.sender.force_login:
        await evt.reply("Forced login is already disabled.")
        return
    evt.sender.force_login = False
    await evt.sender.save()
    await evt.reply("Forced login is now disabled.")