"""
Functions for bringing auxiliary data in the database up-to-date.
"""
import json
import logging
import re
from textwrap import dedent

from psycopg2.extras import execute_values

from ..db.utils import execute_file

LOG = logging.getLogger()

def update_postcodes(dsn, sql_dir):
    """ Recalculate postcode centroids and add, remove and update entries in the
        location_postcode table. `conn` is an opne connection to the database.
    """
    execute_file(dsn, sql_dir / 'update-postcodes.sql')


def recompute_word_counts(dsn, sql_dir):
    """ Compute the frequency of full-word search terms.
    """
    execute_file(dsn, sql_dir / 'words_from_search_name.sql')


def _add_address_level_rows_from_entry(rows, entry):
    """ Converts a single entry from the JSON format for address rank
        descriptions into a flat format suitable for inserting into a
        PostgreSQL table and adds these lines to `rows`.
    """
    countries = entry.get('countries') or (None, )
    for key, values in entry['tags'].items():
        for value, ranks in values.items():
            if isinstance(ranks, list):
                rank_search, rank_address = ranks
            else:
                rank_search = rank_address = ranks
            if not value:
                value = None
            for country in countries:
                rows.append((country, key, value, rank_search, rank_address))

def load_address_levels(conn, table, levels):
    """ Replace the `address_levels` table with the contents of `levels'.

        A new table is created any previously existing table is dropped.
        The table has the following columns:
            country, class, type, rank_search, rank_address
    """
    rows = []
    for entry in levels:
        _add_address_level_rows_from_entry(rows, entry)

    with conn.cursor() as cur:
        cur.execute('DROP TABLE IF EXISTS {}'.format(table))

        cur.execute("""CREATE TABLE {} (country_code varchar(2),
                                        class TEXT,
                                        type TEXT,
                                        rank_search SMALLINT,
                                        rank_address SMALLINT)""".format(table))

        execute_values(cur, "INSERT INTO {} VALUES %s".format(table), rows)

        cur.execute('CREATE UNIQUE INDEX ON {} (country_code, class, type)'.format(table))

    conn.commit()

def load_address_levels_from_file(conn, config_file):
    """ Replace the `address_levels` table with the contents of the config
        file.
    """
    with config_file.open('r') as fdesc:
        load_address_levels(conn, 'address_levels', json.load(fdesc))

PLPGSQL_BASE_MODULES = (
    'utils.sql',
    'normalization.sql',
    'ranking.sql',
    'importance.sql',
    'address_lookup.sql',
    'interpolation.sql'
)

PLPGSQL_TABLE_MODULES = (
    ('place', 'place_triggers.sql'),
    ('placex', 'placex_triggers.sql'),
    ('location_postcode', 'postcode_triggers.sql')
)

def _get_standard_function_sql(conn, config, sql_dir, enable_diff_updates, enable_debug):
    """ Read all applicable SQLs containing PL/pgSQL functions, replace
        placefolders and execute them.
    """
    sql_func_dir = sql_dir / 'functions'
    sql = ''

    # Get the basic set of functions that is always imported.
    for sql_file in PLPGSQL_BASE_MODULES:
        with (sql_func_dir / sql_file).open('r') as fdesc:
            sql += fdesc.read()

    # Some files require the presence of a certain table
    for table, fname in PLPGSQL_TABLE_MODULES:
        if conn.table_exists(table):
            with (sql_func_dir / fname).open('r') as fdesc:
                sql += fdesc.read()

    # Replace placeholders.
    sql = sql.replace('{modulepath}',
                      config.DATABASE_MODULE_PATH or str((config.project_dir / 'module').resolve()))

    if enable_diff_updates:
        sql = sql.replace('RETURN NEW; -- %DIFFUPDATES%', '--')

    if enable_debug:
        sql = sql.replace('--DEBUG:', '')

    if config.get_bool('LIMIT_REINDEXING'):
        sql = sql.replace('--LIMIT INDEXING:', '')

    if not config.get_bool('USE_US_TIGER_DATA'):
        sql = sql.replace('-- %NOTIGERDATA% ', '')

    if not config.get_bool('USE_AUX_LOCATION_DATA'):
        sql = sql.replace('-- %NOAUXDATA% ', '')

    reverse_only = 'false' if conn.table_exists('search_name') else 'true'

    return sql.replace('%REVERSE-ONLY%', reverse_only)


def replace_partition_string(sql, partitions):
    """ Replace a partition template with the actual partition code.
    """
    for match in re.findall('^-- start(.*?)^-- end', sql, re.M | re.S):
        repl = ''
        for part in partitions:
            repl += match.replace('-partition-', str(part))
        sql = sql.replace(match, repl)

    return sql

def _get_partition_function_sql(conn, sql_dir):
    """ Create functions that work on partition tables.
    """
    with conn.cursor() as cur:
        cur.execute('SELECT distinct partition FROM country_name')
        partitions = set([0])
        for row in cur:
            partitions.add(row[0])

    with (sql_dir / 'partition-functions.src.sql').open('r') as fdesc:
        sql = fdesc.read()

    return replace_partition_string(sql, sorted(partitions))

def create_functions(conn, config, sql_dir,
                     enable_diff_updates=True, enable_debug=False):
    """ (Re)create the PL/pgSQL functions.
    """
    sql = _get_standard_function_sql(conn, config, sql_dir,
                                     enable_diff_updates, enable_debug)
    sql += _get_partition_function_sql(conn, sql_dir)

    with conn.cursor() as cur:
        cur.execute(sql)

    conn.commit()


WEBSITE_SCRIPTS = (
    'deletable.php',
    'details.php',
    'lookup.php',
    'polygons.php',
    'reverse.php',
    'search.php',
    'status.php'
)

# constants needed by PHP scripts: PHP name, config name, type
PHP_CONST_DEFS = (
    ('Database_DSN', 'DATABASE_DSN', str),
    ('Default_Language', 'DEFAULT_LANGUAGE', str),
    ('Log_DB', 'LOG_DB', bool),
    ('Log_File', 'LOG_FILE', str),
    ('Max_Word_Frequency', 'MAX_WORD_FREQUENCY', int),
    ('NoAccessControl', 'CORS_NOACCESSCONTROL', bool),
    ('Places_Max_ID_count', 'LOOKUP_MAX_COUNT', int),
    ('PolygonOutput_MaximumTypes', 'POLYGON_OUTPUT_MAX_TYPES', int),
    ('Search_BatchMode', 'SEARCH_BATCH_MODE', bool),
    ('Search_NameOnlySearchFrequencyThreshold', 'SEARCH_NAME_ONLY_THRESHOLD', str),
    ('Term_Normalization_Rules', 'TERM_NORMALIZATION', str),
    ('Use_Aux_Location_data', 'USE_AUX_LOCATION_DATA', bool),
    ('Use_US_Tiger_Data', 'USE_US_TIGER_DATA', bool),
    ('MapIcon_URL', 'MAPICON_URL', str),
)


def import_wikipedia_articles(dsn, data_path, ignore_errors=False):
    """ Replaces the wikipedia importance tables with new data.
        The import is run in a single transaction so that the new data
        is replace seemlessly.

        Returns 0 if all was well and 1 if the importance file could not
        be found. Throws an exception if there was an error reading the file.
    """
    datafile = data_path / 'wikimedia-importance.sql.gz'

    if not datafile.exists():
        return 1

    pre_code = """BEGIN;
                  DROP TABLE IF EXISTS "wikipedia_article";
                  DROP TABLE IF EXISTS "wikipedia_redirect"
               """
    post_code = "COMMIT"
    execute_file(dsn, datafile, ignore_errors=ignore_errors,
                 pre_code=pre_code, post_code=post_code)

    return 0


def recompute_importance(conn):
    """ Recompute wikipedia links and importance for all entries in placex.
        This is a long-running operations that must not be executed in
        parallel with updates.
    """
    with conn.cursor() as cur:
        cur.execute('ALTER TABLE placex DISABLE TRIGGER ALL')
        cur.execute("""
            UPDATE placex SET (wikipedia, importance) =
               (SELECT wikipedia, importance
                FROM compute_importance(extratags, country_code, osm_type, osm_id))
            """)
        cur.execute("""
            UPDATE placex s SET wikipedia = d.wikipedia, importance = d.importance
             FROM placex d
             WHERE s.place_id = d.linked_place_id and d.wikipedia is not null
                   and (s.wikipedia is null or s.importance < d.importance);
            """)

        cur.execute('ALTER TABLE placex ENABLE TRIGGER ALL')
    conn.commit()


def setup_website(basedir, phplib_dir, config):
    """ Create the website script stubs.
    """
    if not basedir.exists():
        LOG.info('Creating website directory.')
        basedir.mkdir()

    template = dedent("""\
                      <?php

                      @define('CONST_Debug', $_GET['debug'] ?? false);
                      @define('CONST_LibDir', '{}');

                      """.format(phplib_dir))

    for php_name, conf_name, var_type in PHP_CONST_DEFS:
        if var_type == bool:
            varout = 'true' if config.get_bool(conf_name) else 'false'
        elif var_type == int:
            varout = getattr(config, conf_name)
        elif not getattr(config, conf_name):
            varout = 'false'
        else:
            varout = "'{}'".format(getattr(config, conf_name).replace("'", "\\'"))

        template += "@define('CONST_{}', {});\n".format(php_name, varout)

    template += "\nrequire_once('{}/website/{{}}');\n".format(phplib_dir)

    for script in WEBSITE_SCRIPTS:
        (basedir / script).write_text(template.format(script), 'utf-8')