"""OAuth2 Client model."""
import json
import datetime
from pathlib import Path

from uuid import UUID
from dataclasses import dataclass
from functools import cached_property
from typing import Sequence, Optional

from authlib.jose import KeySet, JsonWebKey
from authlib.oauth2.rfc6749 import ClientMixin
from pymonad.maybe import Just, Maybe, Nothing

from gn_auth.auth.db import sqlite3 as db
from gn_auth.auth.errors import NotFoundError
from gn_auth.auth.authentication.users import (User,
                                               fetch_users,
                                               user_by_id,
                                               same_password)


@dataclass(frozen=True)
class OAuth2Client(ClientMixin):
    """
    Client to the OAuth2 Server.

    This is defined according to the mixin at
    https://docs.authlib.org/en/latest/specs/rfc6749.html#authlib.oauth2.rfc6749.ClientMixin
    """
    client_id: UUID
    client_secret: str
    client_id_issued_at: datetime.datetime
    client_secret_expires_at: datetime.datetime
    client_metadata: dict
    user: User

    def check_client_secret(self, client_secret: str) -> bool:
        """Check whether the `client_secret` matches this client."""
        return same_password(client_secret, self.client_secret)

    @cached_property
    def token_endpoint_auth_method(self) -> str:
        """Return the token endpoint authorisation method."""
        return self.client_metadata.get("token_endpoint_auth_method", ["none"])

    @cached_property
    def client_type(self) -> str:
        """
        Return the token endpoint authorisation method.

        Acceptable client types:
        * public: Unable to use registered client secrets, e.g. browsers, apps
          on mobile devices.
        * confidential: able to securely authenticate with authorisation server
          e.g. being able to keep their registered client secret safe.
        """
        return self.client_metadata.get("client_type", "public")

    @cached_property
    def jwks(self) -> KeySet:
        """Return this client's KeySet."""
        def __parse_key__(keypath: Path) -> JsonWebKey:# pylint: disable=[unspecified-encoding]
            with open(keypath) as _key:
                return JsonWebKey.import_key(_key.read())

        return KeySet([
            __parse_key__(Path(pth))
            for pth in self.client_metadata.get("public_keys", [])])

    def check_endpoint_auth_method(self, method: str, endpoint: str) -> bool:
        """
        Check if the client supports the given method for the given endpoint.

        Acceptable methods:
        * none: Client is a public client and does not have a client secret
        * client_secret_post: Client uses the HTTP POST parameters
        * client_secret_basic: Client uses HTTP Basic
        """
        if endpoint == "token":
            return (method in self.token_endpoint_auth_method
                    and method == "client_secret_post")
        if endpoint in ("introspection", "revoke"):
            return (method in self.token_endpoint_auth_method
                    and method == "client_secret_basic")
        return False

    @cached_property
    def id(self):  # pylint: disable=[invalid-name]
        """Return the client_id."""
        return self.client_id

    @cached_property
    def grant_types(self) -> Sequence[str]:
        """
        Return the grant types that this client supports.

        Valid grant types:
        * authorisation_code
        * implicit
        * client_credentials
        * password
        """
        return self.client_metadata.get("grant_types", [])

    def check_grant_type(self, grant_type: str) -> bool:
        """
        Validate that client can handle the given grant types
        """
        return grant_type in self.grant_types

    @cached_property
    def redirect_uris(self) -> Sequence[str]:
        """Return the redirect_uris that this client supports."""
        return self.client_metadata.get('redirect_uris', [])

    def check_redirect_uri(self, redirect_uri: str) -> bool:
        """
        Check whether the given `redirect_uri` is one of the expected ones.
        """
        return redirect_uri in self.redirect_uris

    @cached_property
    def response_types(self) -> Sequence[str]:
        """Return the response_types that this client supports."""
        return self.client_metadata.get("response_type", [])

    def check_response_type(self, response_type: str) -> bool:
        """Check whether this client supports `response_type`."""
        return response_type in self.response_types

    @cached_property
    def scope(self) -> Sequence[str]:
        """Return valid scopes for this client."""
        return tuple(set(self.client_metadata.get("scope", [])))

    def get_allowed_scope(self, scope: str) -> str:
        """Return list of scopes in `scope` that are supported by this
        client."""
        if not bool(scope):
            return ""
        requested = scope.split()
        return " ".join(sorted(set(
            scp for scp in requested if scp in self.scope)))

    def get_client_id(self):
        """Return this client's identifier."""
        return self.client_id

    def get_default_redirect_uri(self) -> str:
        """Return the default redirect uri"""
        return self.client_metadata.get("default_redirect_uri", "")


def client(conn: db.DbConnection, client_id: UUID,
           user: Optional[User] = None) -> Maybe:
    """Retrieve a client by its ID"""
    with db.cursor(conn) as cursor:
        cursor.execute(
            "SELECT * FROM oauth2_clients WHERE client_id=?",
            (str(client_id),))
        result = cursor.fetchone()
        _user = user
        if result:
            if not bool(_user):
                try:
                    _user = user_by_id(conn, result["user_id"])
                except NotFoundError:
                    _user = None

            return Just(
                OAuth2Client(
                    client_id=UUID(result["client_id"]),
                    client_secret=result["client_secret"],
                    client_id_issued_at=datetime.datetime.fromtimestamp(
                        result["client_id_issued_at"]
                    ),
                    client_secret_expires_at=datetime.datetime.fromtimestamp(
                        result["client_secret_expires_at"]
                    ),
                    client_metadata=json.loads(result["client_metadata"]),
                    user=_user)  # type: ignore[arg-type]
            )
    return Nothing


def client_by_id_and_secret(conn: db.DbConnection, client_id: UUID,
                            client_secret: str) -> OAuth2Client:
    """Retrieve a client by its ID and secret"""
    with db.cursor(conn) as cursor:
        cursor.execute(
            "SELECT * FROM oauth2_clients WHERE client_id=?",
            (str(client_id),))
        row = cursor.fetchone()
        if bool(row) and same_password(client_secret, row["client_secret"]):
            return OAuth2Client(
                client_id=client_id,
                client_secret=client_secret,
                client_id_issued_at=datetime.datetime.fromtimestamp(
                    row["client_id_issued_at"]
                ),
                client_secret_expires_at=datetime.datetime.fromtimestamp(
                    row["client_secret_expires_at"]
                ),
                client_metadata=json.loads(row["client_metadata"]),
                user=user_by_id(conn, UUID(row["user_id"]))
            )
        raise NotFoundError(
            "Could not find client with the given credentials."
        )


def save_client(
        conn: db.DbConnection, the_client: OAuth2Client
) -> OAuth2Client:
    """Persist the client details into the database."""
    with db.cursor(conn) as cursor:
        query = (
            "INSERT INTO oauth2_clients "
            "(client_id, client_secret, client_id_issued_at, "
            "client_secret_expires_at, client_metadata, user_id) "
            "VALUES "
            "(:client_id, :client_secret, :client_id_issued_at, "
            ":client_secret_expires_at, :client_metadata, :user_id) "
            "ON CONFLICT (client_id) DO UPDATE SET "
            "client_secret=:client_secret, "
            "client_id_issued_at=:client_id_issued_at, "
            "client_secret_expires_at=:client_secret_expires_at, "
            "client_metadata=:client_metadata, user_id=:user_id")
        cursor.execute(
            query,
            {
                "client_id": str(the_client.client_id),
                "client_secret": the_client.client_secret,
                "client_id_issued_at": (
                    the_client.client_id_issued_at.timestamp()),
                "client_secret_expires_at": (
                    the_client.client_secret_expires_at.timestamp()),
                "client_metadata": json.dumps(the_client.client_metadata),
                "user_id": str(the_client.user.user_id)
            })
        return the_client


def oauth2_clients(conn: db.DbConnection) -> tuple[OAuth2Client, ...]:
    """Fetch a list of all OAuth2 clients."""
    with db.cursor(conn) as cursor:
        cursor.execute("SELECT * FROM oauth2_clients")
        clients_rs = cursor.fetchall()
        the_users = {
            usr.user_id: usr for usr in fetch_users(
                conn, tuple({UUID(result["user_id"])
                             for result in clients_rs}))
        }
        return tuple(
            OAuth2Client(
                client_id=UUID(result["client_id"]),
                client_secret=result["client_secret"],
                client_id_issued_at=datetime.datetime.fromtimestamp(
                    result["client_id_issued_at"]),
                client_secret_expires_at=datetime.datetime.fromtimestamp(
                    result["client_secret_expires_at"]),
                client_metadata=json.loads(result["client_metadata"]),
                user=the_users[UUID(result["user_id"])]
            ) for result in clients_rs
        )


def delete_client(
        conn: db.DbConnection, the_client: OAuth2Client
) -> OAuth2Client:
    """Delete the given client from the database"""
    with db.cursor(conn) as cursor:
        params = (str(the_client.client_id),)
        cursor.execute("DELETE FROM authorisation_code WHERE client_id=?",
                       params)
        cursor.execute("DELETE FROM oauth2_tokens WHERE client_id=?", params)
        cursor.execute("DELETE FROM oauth2_clients WHERE client_id=?", params)
        return the_client