"""Berlin-Bezirke taxonomy + PLZ lookup.

The user-visible taxonomy is the 12 Berlin Bezirke. We derive the Bezirk
from the flat's freeform address by extracting the 5-digit PLZ and
looking it up in PLZ_TO_DISTRICT.

Some PLZs straddle two Bezirke in reality. Each is mapped to its
dominant Bezirk — close enough for a list filter. Unmapped PLZs / flats
without a parseable address resolve to None; the filter treats those as
"unknown" and excludes them when any Bezirk filter is active.
"""
import re

DISTRICTS: list[str] = [
    "Mitte",
    "Friedrichshain-Kreuzberg",
    "Pankow",
    "Charlottenburg-Wilmersdorf",
    "Spandau",
    "Steglitz-Zehlendorf",
    "Tempelhof-Schöneberg",
    "Neukölln",
    "Treptow-Köpenick",
    "Marzahn-Hellersdorf",
    "Lichtenberg",
    "Reinickendorf",
]

_DISTRICT_PLZ: dict[str, tuple[str, ...]] = {
    "Mitte": (
        "10115", "10117", "10119", "10178", "10179",
        "10551", "10553", "10555", "10557", "10559",
        "13347", "13349", "13351", "13353", "13355", "13357", "13359",
    ),
    "Friedrichshain-Kreuzberg": (
        "10243", "10245", "10247", "10249",
        "10961", "10963", "10965", "10967", "10969",
        "10997", "10999",
    ),
    "Pankow": (
        "10405", "10407", "10409",
        "10435", "10437", "10439",
        "13086", "13088", "13089",
        "13125", "13127", "13129",
        "13156", "13158", "13159",
        "13187", "13189",
    ),
    "Charlottenburg-Wilmersdorf": (
        "10585", "10587", "10589",
        "10623", "10625", "10627", "10629",
        "10707", "10709", "10711", "10713", "10715", "10717", "10719",
        "10789",
        "14050", "14052", "14053", "14055", "14057", "14059",
        "14193", "14195", "14197", "14199",
    ),
    "Spandau": (
        "13581", "13583", "13585", "13587", "13589",
        "13591", "13593", "13595", "13597", "13599",
        "14089",
    ),
    "Steglitz-Zehlendorf": (
        "12157", "12159", "12161", "12163", "12165", "12167", "12169",
        "12203", "12205", "12207", "12209",
        "12247", "12249",
        "14109", "14129",
        "14163", "14165", "14167", "14169",
    ),
    "Tempelhof-Schöneberg": (
        "10777", "10779", "10781", "10783", "10785", "10787",
        "10823", "10825", "10827", "10829",
        "12099", "12101", "12103", "12105", "12107", "12109",
        "12277", "12279",
        "12305", "12307", "12309",
    ),
    "Neukölln": (
        "12043", "12045", "12047", "12049",
        "12051", "12053", "12055", "12057", "12059",
        "12347", "12349",
        "12351", "12353", "12355", "12357", "12359",
    ),
    "Treptow-Köpenick": (
        "12435", "12437", "12439",
        "12459", "12487", "12489",
        "12524", "12526", "12527",
        "12555", "12557", "12559",
        "12587", "12589",
    ),
    "Marzahn-Hellersdorf": (
        "12619", "12621", "12623", "12627", "12629",
        "12679", "12681", "12683", "12685", "12687", "12689",
    ),
    "Lichtenberg": (
        "10315", "10317", "10318",
        "10365", "10367", "10369",
        "13051", "13053", "13055", "13057", "13059",
    ),
    "Reinickendorf": (
        "13403", "13405", "13407", "13409",
        "13435", "13437", "13439",
        "13465", "13467", "13469",
        "13503", "13505", "13507", "13509",
    ),
}

PLZ_TO_DISTRICT: dict[str, str] = {
    plz: district
    for district, plzs in _DISTRICT_PLZ.items()
    for plz in plzs
}

_PLZ_RE = re.compile(r"\b(\d{5})\b")


def district_for_address(address: str | None) -> str | None:
    if not address:
        return None
    m = _PLZ_RE.search(address)
    if not m:
        return None
    return PLZ_TO_DISTRICT.get(m.group(1))