"""VIN decode router - Gemini-powered VIN string decoding."""
import logging
import re
import time

from fastapi import APIRouter, HTTPException

from app.engines.gemini_engine import (
    GeminiEngine,
    GeminiProcessingError,
    GeminiUnavailableError,
)
from app.models import VinDecodeRequest, VinDecodeResponse

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/decode", tags=["decode"])

_VIN_REGEX = re.compile(r"^[A-HJ-NPR-Z0-9]{17}$")

# Shared engine instance (lazy init on first request)
_gemini_engine = GeminiEngine()


@router.post("/vin", response_model=VinDecodeResponse)
async def decode_vin(request: VinDecodeRequest) -> VinDecodeResponse:
    """Decode a VIN string into structured vehicle data using Gemini.

    Accepts a 17-character VIN and returns year, make, model, trim, etc.
    """
    vin = request.vin.upper().strip()

    if not _VIN_REGEX.match(vin):
        raise HTTPException(
            status_code=400,
            detail=f"Invalid VIN format: must be 17 alphanumeric characters (excluding I, O, Q). Got: {vin}",
        )

    start_ms = time.monotonic_ns() // 1_000_000

    try:
        result = _gemini_engine.decode_vin(vin)
    except GeminiUnavailableError as exc:
        logger.error("Gemini unavailable for VIN decode: %s", exc)
        raise HTTPException(status_code=503, detail=str(exc)) from exc
    except GeminiProcessingError as exc:
        logger.error("Gemini processing error for VIN %s: %s", vin, exc)
        raise HTTPException(status_code=422, detail=str(exc)) from exc

    elapsed_ms = (time.monotonic_ns() // 1_000_000) - start_ms

    return VinDecodeResponse(
        success=True,
        vin=vin,
        year=result.year,
        make=result.make,
        model=result.model,
        trimLevel=result.trim_level,
        bodyType=result.body_type,
        driveType=result.drive_type,
        fuelType=result.fuel_type,
        engine=result.engine,
        transmission=result.transmission,
        confidence=result.confidence,
        processingTimeMs=elapsed_ms,
        error=None,
    )