# -----------------------------------------------------------------------------

# Copyright (c) 2014--, The Qiita Development Team.

#

# Distributed under the terms of the BSD 3-clause License.

#

# The full license is in the file LICENSE, distributed with this software.

# -----------------------------------------------------------------------------

import qiita_db as qdb

from jose import jwt as jose_jwt

from datetime import datetime, timezone

from qiita_core.qiita_settings import qiita_config

class DownloadLink(qdb.base.QiitaObject):

    r"""

    A shortened url for downloading artifacts

    alongside a signed jwt and expiration

    Methods

    -------

    delete_expired

    See Also

    --------

    qiita_db.QiitaObject

    """

    _table = "download_link"

    @classmethod

    def create(cls, jwt):

        r"""Creates a new object with a new id on the storage system

        Parameters

        ----------

        jwt : Json Web Token signing the access link.

        This jwt will have, at a minimum, jti and exp fields

        Raises

        ------

        IncompetentQiitaDeveloperError

            If the jwt is improperly signed or doesn't contain a jti or exp

        QiitaDBDuplicateError

            If the jti already exists in the database

        """

        jwt_data = jose_jwt.decode(jwt,

                                   qiita_config.jwt_secret,

                                   algorithms='HS256')

        jti = jwt_data["jti"]

        exp = datetime.utcfromtimestamp(jwt_data["exp"] / 1000)

        with qdb.sql_connection.TRN:

            if cls.exists(jti):

                raise qdb.exceptions.QiitaDBDuplicateError(

                    "JTI Already Exists")

            # insert token into database

            sql = """INSERT INTO qiita.{0} (jti, jwt, exp)

            VALUES (%s, %s, %s) RETURNING jti""".format(cls._table)

            qdb.sql_connection.TRN.add(sql, [jti, jwt, exp])

            qdb.sql_connection.TRN.execute()

    @classmethod

    def delete(cls, jti):

        r"""Deletes the link with specified jti from the storage system

        Parameters

        ----------

        jti : object

            The jwt token identifier

        """

        sql = """DELETE FROM qiita.{0} WHERE jti=%s""".format(cls._table)

        qdb.sql_connection.perform_as_transaction(sql, [jti])

    @classmethod

    def exists(cls, jti):

        r"""Checks if a link with specified jti exists

        Returns

        -------

        bool

            True if link exists else false

        """

        with qdb.sql_connection.TRN:

            sql = """SELECT COUNT(jti) FROM qiita.{0}

                     WHERE jti=%s""".format(cls._table)

            qdb.sql_connection.TRN.add(sql, [jti])

            return qdb.sql_connection.TRN.execute_fetchlast() == 1

    @classmethod

    def delete_expired(cls):

        r"""Deletes all expired download links"""

        now = datetime.now(timezone.utc)

        sql = """DELETE FROM qiita.{0} WHERE exp<%s""".format(cls._table)

        qdb.sql_connection.perform_as_transaction(sql, [now])

    @classmethod

    def get(cls, jti):

        r"""Retrieves a jwt by its jti

        Returns

        -------

        str

            A JSON web token

        """

        with qdb.sql_connection.TRN:

            sql = """SELECT jwt FROM qiita.{0}

                     WHERE jti=%s""".format(cls._table)

            qdb.sql_connection.TRN.add(sql, [jti])

            return qdb.sql_connection.TRN.execute_fetchlast()