# 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.
"""
Functions for setting up and importing a new Nominatim database.
"""
from typing import Tuple, Optional, Union, Sequence, MutableMapping, Any
import logging
import os
import subprocess
import asyncio
from pathlib import Path

import psutil
import psycopg
from psycopg import sql as pysql

from ..errors import UsageError
from ..config import Configuration
from ..db.connection import connect, get_pg_env, Connection, server_version_tuple, \
                            postgis_version_tuple, drop_tables, table_exists, execute_scalar
from ..db.sql_preprocessor import SQLPreprocessor
from ..db.query_pool import QueryPool
from .exec_utils import run_osm2pgsql
from ..version import POSTGRESQL_REQUIRED_VERSION, POSTGIS_REQUIRED_VERSION

LOG = logging.getLogger()


def _require_version(module: str, actual: Tuple[int, int], expected: Tuple[int, int]) -> None:
    """ Compares the version for the given module and raises an exception
        if the actual version is too old.
    """
    if actual < expected:
        LOG.fatal('Minimum supported version of %s is %d.%d. '
                  'Found version %d.%d.',
                  module, expected[0], expected[1], actual[0], actual[1])
        raise UsageError(f'{module} is too old.')


def _require_loaded(extension_name: str, conn: Connection) -> None:
    """ Check that the given extension is loaded. """
    with conn.cursor() as cur:
        cur.execute('SELECT * FROM pg_extension WHERE extname = %s', (extension_name, ))
        if cur.rowcount <= 0:
            LOG.fatal('Required module %s is not loaded.', extension_name)
            raise UsageError(f'{extension_name} is not loaded.')


def check_existing_database_plugins(dsn: str) -> None:
    """ Check that the database has the required plugins installed."""
    with connect(dsn) as conn:
        _require_version('PostgreSQL server',
                         server_version_tuple(conn),
                         POSTGRESQL_REQUIRED_VERSION)
        _require_version('PostGIS',
                         postgis_version_tuple(conn),
                         POSTGIS_REQUIRED_VERSION)
        _require_loaded('hstore', conn)


def setup_database_skeleton(dsn: str, rouser: Optional[str] = None) -> None:
    """ Create a new database for Nominatim and populate it with the
        essential extensions.

        The function fails when the database already exists or Postgresql or
        PostGIS versions are too old.

        Uses `createdb` to create the database.

        If 'rouser' is given, then the function also checks that the user
        with that given name exists.

        Requires superuser rights by the caller.
    """
    proc = subprocess.run(['createdb'], env=get_pg_env(dsn), check=False)

    if proc.returncode != 0:
        raise UsageError('Creating new database failed.')

    with connect(dsn) as conn:
        _require_version('PostgreSQL server',
                         server_version_tuple(conn),
                         POSTGRESQL_REQUIRED_VERSION)

        if rouser is not None:
            cnt = execute_scalar(conn, 'SELECT count(*) FROM pg_user where usename = %s',
                                 (rouser, ))
            if cnt == 0:
                LOG.fatal("Web user '%s' does not exist. Create it with:\n"
                          "\n      createuser %s", rouser, rouser)
                raise UsageError('Missing read-only user.')

        # Create extensions.
        with conn.cursor() as cur:
            cur.execute('CREATE EXTENSION IF NOT EXISTS hstore')
            cur.execute('CREATE EXTENSION IF NOT EXISTS postgis')
            cur.execute('CREATE EXTENSION IF NOT EXISTS postgis_raster')

        conn.commit()

        _require_version('PostGIS',
                         postgis_version_tuple(conn),
                         POSTGIS_REQUIRED_VERSION)


def import_osm_data(osm_files: Union[Path, Sequence[Path]],
                    options: MutableMapping[str, Any],
                    drop: bool = False, ignore_errors: bool = False) -> None:
    """ Import the given OSM files. 'options' contains the list of
        default settings for osm2pgsql.
    """
    options['import_file'] = osm_files
    options['append'] = False
    options['threads'] = 1

    if not options['flatnode_file'] and options['osm2pgsql_cache'] == 0:
        # Make some educated guesses about cache size based on the size
        # of the import file and the available memory.
        mem = psutil.virtual_memory()
        fsize = 0
        if isinstance(osm_files, list):
            for fname in osm_files:
                fsize += os.stat(str(fname)).st_size
        else:
            fsize = os.stat(str(osm_files)).st_size
        options['osm2pgsql_cache'] = int(min((mem.available + mem.cached) * 0.75,
                                             fsize * 2) / 1024 / 1024) + 1

    run_osm2pgsql(options)

    with connect(options['dsn']) as conn:
        if not ignore_errors:
            with conn.cursor() as cur:
                cur.execute('SELECT true FROM place LIMIT 1')
                if cur.rowcount == 0:
                    raise UsageError('No data imported by osm2pgsql.')

        if drop:
            drop_tables(conn, 'planet_osm_nodes')
            conn.commit()

    if drop and options['flatnode_file']:
        Path(options['flatnode_file']).unlink()


def create_tables(conn: Connection, config: Configuration, reverse_only: bool = False) -> None:
    """ Create the set of basic tables.
        When `reverse_only` is True, then the main table for searching will
        be skipped and only reverse search is possible.
    """
    sql = SQLPreprocessor(conn, config)
    sql.env.globals['db']['reverse_only'] = reverse_only

    sql.run_sql_file(conn, 'tables.sql')


def create_table_triggers(conn: Connection, config: Configuration) -> None:
    """ Create the triggers for the tables. The trigger functions must already
        have been imported with refresh.create_functions().
    """
    sql = SQLPreprocessor(conn, config)
    sql.run_sql_file(conn, 'table-triggers.sql')


def create_partition_tables(conn: Connection, config: Configuration) -> None:
    """ Create tables that have explicit partitioning.
    """
    sql = SQLPreprocessor(conn, config)
    sql.run_sql_file(conn, 'partition-tables.src.sql')


def truncate_data_tables(conn: Connection) -> None:
    """ Truncate all data tables to prepare for a fresh load.
    """
    with conn.cursor() as cur:
        cur.execute('TRUNCATE placex')
        cur.execute('TRUNCATE place_addressline')
        cur.execute('TRUNCATE location_area')
        cur.execute('TRUNCATE location_area_country')
        cur.execute('TRUNCATE location_property_tiger')
        cur.execute('TRUNCATE location_property_osmline')
        cur.execute('TRUNCATE location_postcode')
        if table_exists(conn, 'search_name'):
            cur.execute('TRUNCATE search_name')
        cur.execute('DROP SEQUENCE IF EXISTS seq_place')
        cur.execute('CREATE SEQUENCE seq_place start 100000')

        cur.execute("""SELECT tablename FROM pg_tables
                       WHERE tablename LIKE 'location_road_%'""")

        for table in [r[0] for r in list(cur)]:
            cur.execute('TRUNCATE ' + table)

    conn.commit()


_COPY_COLUMNS = pysql.SQL(',').join(map(pysql.Identifier,
                                        ('osm_type', 'osm_id', 'class', 'type',
                                         'name', 'admin_level', 'address',
                                         'extratags', 'geometry')))


async def load_data(dsn: str, threads: int) -> None:
    """ Copy data into the word and placex table.
    """
    placex_threads = max(1, threads - 1)

    progress = asyncio.create_task(_progress_print())

    async with QueryPool(dsn, placex_threads + 1) as pool:
        # Copy data from place to placex in <threads - 1> chunks.
        for imod in range(placex_threads):
            await pool.put_query(
                pysql.SQL("""INSERT INTO placex ({columns})
                               SELECT {columns} FROM place
                                WHERE osm_id % {total} = {mod}
                                  AND NOT (class='place'
                                           and (type='houses' or type='postcode'))
                                  AND ST_IsValid(geometry)
                          """).format(columns=_COPY_COLUMNS,
                                      total=pysql.Literal(placex_threads),
                                      mod=pysql.Literal(imod)), None)

        # Interpolations need to be copied seperately
        await pool.put_query("""
                INSERT INTO location_property_osmline (osm_id, address, linegeo)
                  SELECT osm_id, address, geometry FROM place
                  WHERE class='place' and type='houses' and osm_type='W'
                        and ST_GeometryType(geometry) = 'ST_LineString' """, None)

    progress.cancel()

    async with await psycopg.AsyncConnection.connect(dsn) as aconn:
        await aconn.execute('ANALYSE')


async def _progress_print() -> None:
    while True:
        try:
            await asyncio.sleep(1)
        except asyncio.CancelledError:
            print('', flush=True)
            break
        print('.', end='', flush=True)


async def create_search_indices(conn: Connection, config: Configuration,
                                drop: bool = False, threads: int = 1) -> None:
    """ Create tables that have explicit partitioning.
    """

    # If index creation failed and left an index invalid, they need to be
    # cleaned out first, so that the script recreates them.
    with conn.cursor() as cur:
        cur.execute("""SELECT relname FROM pg_class, pg_index
                       WHERE pg_index.indisvalid = false
                             AND pg_index.indexrelid = pg_class.oid""")
        bad_indices = [row[0] for row in list(cur)]
        for idx in bad_indices:
            LOG.info("Drop invalid index %s.", idx)
            cur.execute(pysql.SQL('DROP INDEX {}').format(pysql.Identifier(idx)))
    conn.commit()

    sql = SQLPreprocessor(conn, config)

    await sql.run_parallel_sql_file(config.get_libpq_dsn(),
                                    'indices.sql', min(8, threads), drop=drop)
