"""Intent routing — pure regex, no AI, sub-millisecond.

Loco-Soft Komm-Nr Format:
  Type-Buchstabe + 4-6 stellige Zahl, optional Space dazwischen.
  Type-Letter: N=Neu, T=Tageszul., V=Vorfuehr, D=Differenzbest., G=Gebraucht, L=Leihgabe.
  Beispiele: 'D9094', 'd9094', 'D 9094', 'n8093', 'L9083'

Pure 4-6 stellige Zahlen werden als DVN-Lookup behandelt (DVN ist eindeutig).
"""
import re
from dataclasses import dataclass
from typing import Literal


# Komm-Nr: Type + DVN (mit oder ohne Space)
KOMM_NR_RE = re.compile(r"^[NTVDGLntvdgl]\s*\d{4,6}$")
# DVN allein: pure Zahl 4-6 Stellen
DVN_RE = re.compile(r"^\d{4,6}$")
# VIN: 17 chars, no I/O/Q
VIN_RE = re.compile(r"^[A-HJ-NPR-Z0-9]{17}$")


@dataclass
class Intent:
    type: Literal[
        "komm_nr",
        "dvn",
        "vin",
        "autocomplete_only",
        "keyword_search",
        "empty",
    ]
    direct_redirect: bool = False
    normalized_query: str = ""


def route(raw_query: str) -> Intent:
    q = (raw_query or "").strip()

    if not q:
        return Intent(type="empty", normalized_query="")

    # Rule 1: Komm-Nr (Type + DVN, e.g. 'D9094', 'D 9094', 'd9094')
    if KOMM_NR_RE.match(q):
        # Normalize: remove spaces, uppercase the type letter
        cleaned = q.replace(" ", "")
        normalized = cleaned[0].upper() + cleaned[1:]
        return Intent(
            type="komm_nr",
            direct_redirect=True,
            normalized_query=normalized,
        )

    # Rule 2: Pure 4-6 digit number = DVN lookup (eindeutig)
    if DVN_RE.match(q):
        return Intent(
            type="dvn",
            direct_redirect=True,
            normalized_query=q,
        )

    # Rule 3: 17-char alphanumeric (no IOQ) = VIN
    upper = q.upper().replace(" ", "")
    if VIN_RE.match(upper):
        return Intent(
            type="vin",
            direct_redirect=True,
            normalized_query=upper,
        )

    # Rule 4: Single char only -> autocomplete (FTS unbrauchbar bei 1 Zeichen)
    if len(q) < 2:
        return Intent(
            type="autocomplete_only",
            normalized_query=q.lower(),
        )

    # Rule 5: Default — keyword + fuzzy search
    return Intent(
        type="keyword_search",
        normalized_query=q.lower(),
    )