# SPDX-License-Identifier: GPL-3.0-or-later
#
# This file is part of Nominatim. (https://nominatim.org)
#
# Copyright (C) 2024 by the Nominatim developer community.
# For a full list of authors see the git log.
"""
Access and helper functions for the status and status log table.
"""
from typing import Optional, Tuple
import datetime as dt
import logging
import re

from .connection import Connection, table_exists, execute_scalar
from ..utils.url_utils import get_url
from ..errors import UsageError

LOG = logging.getLogger()
ISODATE_FORMAT = '%Y-%m-%dT%H:%M:%S'


def compute_database_date(conn: Connection, offline: bool = False) -> dt.datetime:
    """ Determine the date of the database from the newest object in the
        data base.
    """
    # If there is a date from osm2pgsql available, use that.
    if table_exists(conn, 'osm2pgsql_properties'):
        with conn.cursor() as cur:
            cur.execute(""" SELECT value FROM osm2pgsql_properties
                            WHERE property = 'current_timestamp' """)
            row = cur.fetchone()
            if row is not None:
                return dt.datetime.strptime(row[0], "%Y-%m-%dT%H:%M:%SZ")\
                                  .replace(tzinfo=dt.timezone.utc)

    if offline:
        raise UsageError("Cannot determine database date from data in offline mode.")

    # Else, find the node with the highest ID in the database
    if table_exists(conn, 'place'):
        osmid = execute_scalar(conn, "SELECT max(osm_id) FROM place WHERE osm_type='N'")
    else:
        osmid = execute_scalar(conn, "SELECT max(osm_id) FROM placex WHERE osm_type='N'")

    if osmid is None:
        LOG.fatal("No data found in the database.")
        raise UsageError("No data found in the database.")

    LOG.info("Using node id %d for timestamp lookup", osmid)
    # Get the node from the API to find the timestamp when it was created.
    node_url = f'https://www.openstreetmap.org/api/0.6/node/{osmid}/1'
    data = get_url(node_url)

    match = re.search(r'timestamp="((\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}))Z"', data)

    if match is None:
        LOG.fatal("The node data downloaded from the API does not contain valid data.\n"
                  "URL used: %s", node_url)
        raise UsageError("Bad API data.")

    LOG.debug("Found timestamp %s", match.group(1))

    return dt.datetime.strptime(match.group(1), ISODATE_FORMAT).replace(tzinfo=dt.timezone.utc)


def set_status(conn: Connection, date: Optional[dt.datetime],
               seq: Optional[int] = None, indexed: bool = True) -> None:
    """ Replace the current status with the given status. If date is `None`
        then only sequence and indexed will be updated as given. Otherwise
        the whole status is replaced.
        The change will be committed to the database.
    """
    assert date is None or date.tzinfo == dt.timezone.utc
    with conn.cursor() as cur:
        if date is None:
            cur.execute("UPDATE import_status set sequence_id = %s, indexed = %s",
                        (seq, indexed))
        else:
            cur.execute("TRUNCATE TABLE import_status")
            cur.execute("""INSERT INTO import_status (lastimportdate, sequence_id, indexed)
                           VALUES (%s, %s, %s)""", (date, seq, indexed))

    conn.commit()


def get_status(conn: Connection) -> Tuple[Optional[dt.datetime], Optional[int], Optional[bool]]:
    """ Return the current status as a triple of (date, sequence, indexed).
        If status has not been set up yet, a triple of None is returned.
    """
    with conn.cursor() as cur:
        cur.execute("SELECT * FROM import_status LIMIT 1")
        if cur.rowcount < 1:
            return None, None, None

        row = cur.fetchone()
        assert row
        return row.lastimportdate, row.sequence_id, row.indexed


def set_indexed(conn: Connection, state: bool) -> None:
    """ Set the indexed flag in the status table to the given state.
    """
    with conn.cursor() as cur:
        cur.execute("UPDATE import_status SET indexed = %s", (state, ))
    conn.commit()


def log_status(conn: Connection, start: dt.datetime,
               event: str, batchsize: Optional[int] = None) -> None:
    """ Write a new status line to the `import_osmosis_log` table.
    """
    with conn.cursor() as cur:
        cur.execute("""INSERT INTO import_osmosis_log
                       (batchend, batchseq, batchsize, starttime, endtime, event)
                       SELECT lastimportdate, sequence_id, %s, %s, now(), %s FROM import_status""",
                    (batchsize, start, event))
    conn.commit()