"""Time-based One Time Password auth module."""
from __future__ import annotations

import asyncio
from io import BytesIO
from typing import Any

import voluptuous as vol

from homeassistant.auth.models import User
from homeassistant.core import HomeAssistant
from homeassistant.data_entry_flow import FlowResult

from . import (
    MULTI_FACTOR_AUTH_MODULE_SCHEMA,
    MULTI_FACTOR_AUTH_MODULES,
    MultiFactorAuthModule,
    SetupFlow,
)

REQUIREMENTS = ["pyotp==2.6.0", "PyQRCode==1.2.1"]

CONFIG_SCHEMA = MULTI_FACTOR_AUTH_MODULE_SCHEMA.extend({}, extra=vol.PREVENT_EXTRA)

STORAGE_VERSION = 1
STORAGE_KEY = "auth_module.totp"
STORAGE_USERS = "users"
STORAGE_USER_ID = "user_id"
STORAGE_OTA_SECRET = "ota_secret"

INPUT_FIELD_CODE = "code"

DUMMY_SECRET = "FPPTH34D4E3MI2HG"


def _generate_qr_code(data: str) -> str:
    """Generate a base64 PNG string represent QR Code image of data."""
    import pyqrcode  # pylint: disable=import-outside-toplevel

    qr_code = pyqrcode.create(data)

    with BytesIO() as buffer:
        qr_code.svg(file=buffer, scale=4)
        return str(
            buffer.getvalue()
            .decode("ascii")
            .replace("\n", "")
            .replace(
                '<?xml version="1.0" encoding="UTF-8"?>'
                '<svg xmlns="http://www.w3.org/2000/svg"',
                "<svg",
            )
        )


def _generate_secret_and_qr_code(username: str) -> tuple[str, str, str]:
    """Generate a secret, url, and QR code."""
    import pyotp  # pylint: disable=import-outside-toplevel

    ota_secret = pyotp.random_base32()
    url = pyotp.totp.TOTP(ota_secret).provisioning_uri(
        username, issuer_name="Home Assistant"
    )
    image = _generate_qr_code(url)
    return ota_secret, url, image


@MULTI_FACTOR_AUTH_MODULES.register("totp")
class TotpAuthModule(MultiFactorAuthModule):
    """Auth module validate time-based one time password."""

    DEFAULT_TITLE = "Time-based One Time Password"
    MAX_RETRY_TIME = 5

    def __init__(self, hass: HomeAssistant, config: dict[str, Any]) -> None:
        """Initialize the user data store."""
        super().__init__(hass, config)
        self._users: dict[str, str] | None = None
        self._user_store = hass.helpers.storage.Store(
            STORAGE_VERSION, STORAGE_KEY, private=True, atomic_writes=True
        )
        self._init_lock = asyncio.Lock()

    @property
    def input_schema(self) -> vol.Schema:
        """Validate login flow input data."""
        return vol.Schema({vol.Required(INPUT_FIELD_CODE): str})

    async def _async_load(self) -> None:
        """Load stored data."""
        async with self._init_lock:
            if self._users is not None:
                return

            if (data := await self._user_store.async_load()) is None:
                data = {STORAGE_USERS: {}}

            self._users = data.get(STORAGE_USERS, {})

    async def _async_save(self) -> None:
        """Save data."""
        await self._user_store.async_save({STORAGE_USERS: self._users})

    def _add_ota_secret(self, user_id: str, secret: str | None = None) -> str:
        """Create a ota_secret for user."""
        import pyotp  # pylint: disable=import-outside-toplevel

        ota_secret: str = secret or pyotp.random_base32()

        self._users[user_id] = ota_secret  # type: ignore[index]
        return ota_secret

    async def async_setup_flow(self, user_id: str) -> SetupFlow:
        """Return a data entry flow handler for setup module.

        Mfa module should extend SetupFlow
        """
        user = await self.hass.auth.async_get_user(user_id)
        assert user is not None
        return TotpSetupFlow(self, self.input_schema, user)

    async def async_setup_user(self, user_id: str, setup_data: Any) -> str:
        """Set up auth module for user."""
        if self._users is None:
            await self._async_load()

        result = await self.hass.async_add_executor_job(
            self._add_ota_secret, user_id, setup_data.get("secret")
        )

        await self._async_save()
        return result

    async def async_depose_user(self, user_id: str) -> None:
        """Depose auth module for user."""
        if self._users is None:
            await self._async_load()

        if self._users.pop(user_id, None):  # type: ignore[union-attr]
            await self._async_save()

    async def async_is_user_setup(self, user_id: str) -> bool:
        """Return whether user is setup."""
        if self._users is None:
            await self._async_load()

        return user_id in self._users  # type: ignore[operator]

    async def async_validate(self, user_id: str, user_input: dict[str, Any]) -> bool:
        """Return True if validation passed."""
        if self._users is None:
            await self._async_load()

        # user_input has been validate in caller
        # set INPUT_FIELD_CODE as vol.Required is not user friendly
        return await self.hass.async_add_executor_job(
            self._validate_2fa, user_id, user_input.get(INPUT_FIELD_CODE, "")
        )

    def _validate_2fa(self, user_id: str, code: str) -> bool:
        """Validate two factor authentication code."""
        import pyotp  # pylint: disable=import-outside-toplevel

        if (ota_secret := self._users.get(user_id)) is None:  # type: ignore[union-attr]
            # even we cannot find user, we still do verify
            # to make timing the same as if user was found.
            pyotp.TOTP(DUMMY_SECRET).verify(code, valid_window=1)
            return False

        return bool(pyotp.TOTP(ota_secret).verify(code, valid_window=1))


class TotpSetupFlow(SetupFlow):
    """Handler for the setup flow."""

    def __init__(
        self, auth_module: TotpAuthModule, setup_schema: vol.Schema, user: User
    ) -> None:
        """Initialize the setup flow."""
        super().__init__(auth_module, setup_schema, user.id)
        # to fix typing complaint
        self._auth_module: TotpAuthModule = auth_module
        self._user = user
        self._ota_secret: str = ""
        self._url: str | None = None
        self._image: str | None = None

    async def async_step_init(
        self, user_input: dict[str, str] | None = None
    ) -> FlowResult:
        """Handle the first step of setup flow.

        Return self.async_show_form(step_id='init') if user_input is None.
        Return self.async_create_entry(data={'result': result}) if finish.
        """
        import pyotp  # pylint: disable=import-outside-toplevel

        errors: dict[str, str] = {}

        if user_input:
            verified = await self.hass.async_add_executor_job(
                pyotp.TOTP(self._ota_secret).verify, user_input["code"]
            )
            if verified:
                result = await self._auth_module.async_setup_user(
                    self._user_id, {"secret": self._ota_secret}
                )
                return self.async_create_entry(
                    title=self._auth_module.name, data={"result": result}
                )

            errors["base"] = "invalid_code"

        else:
            hass = self._auth_module.hass
            (
                self._ota_secret,
                self._url,
                self._image,
            ) = await hass.async_add_executor_job(
                _generate_secret_and_qr_code,
                str(self._user.name),
            )

        return self.async_show_form(
            step_id="init",
            data_schema=self._setup_schema,
            description_placeholders={
                "code": self._ota_secret,
                "url": self._url,
                "qr_code": self._image,
            },
            errors=errors,
        )
