"""
NHTSA VIN Decoder API client for the AUTOPARTES console application.

Wraps the National Highway Traffic Safety Administration (NHTSA) Vehicle
Product Information Catalog (vPIC) DecodeVin endpoint to retrieve vehicle
specifications from a 17-character VIN.
"""

import requests

from console.config import NHTSA_API_URL


# NHTSA result variables we care about, mapped to our internal keys.
_FIELD_MAP = {
    "Make":                        "make",
    "Model":                       "model",
    "Model Year":                  "year",
    "Body Class":                  "body_class",
    "Drive Type":                  "drive_type",
    "Displacement (L)":            "displacement_l",
    "Engine Number of Cylinders":  "cylinders",
    "Fuel Type - Primary":         "fuel_type",
    "Engine Brake (hp) From":      "power_hp",
}


def decode_vin_nhtsa(vin: str) -> dict:
    """Decode a VIN using the NHTSA vPIC API.

    Parameters
    ----------
    vin : str
        A 17-character Vehicle Identification Number.

    Returns
    -------
    dict
        On success::

            {
                "make": "TOYOTA",
                "model": "Corolla",
                "year": "2020",
                "body_class": "Sedan/Saloon",
                "drive_type": "FWD",
                "engine_info": {
                    "displacement_l": "2.0",
                    "cylinders": "4",
                    "fuel_type": "Gasoline",
                    "power_hp": "169",
                    "raw": { ... full variable->value mapping ... },
                },
            }

        On error::

            {"error": "<description>"}
    """
    try:
        url = f"{NHTSA_API_URL}/{vin}"
        response = requests.get(url, params={"format": "json"}, timeout=15)
        response.raise_for_status()

        data = response.json()
        results = data.get("Results", [])

        # Build a flat lookup: variable name -> value (skip empty/None)
        raw: dict[str, str] = {}
        for item in results:
            var = item.get("Variable", "")
            val = item.get("Value")
            if val and str(val).strip():
                raw[var] = str(val).strip()

        # Extract top-level vehicle fields
        vehicle: dict = {}
        engine_info: dict = {"raw": raw}

        engine_keys = {"displacement_l", "cylinders", "fuel_type", "power_hp"}

        for nhtsa_var, our_key in _FIELD_MAP.items():
            value = raw.get(nhtsa_var, "")
            if our_key in engine_keys:
                engine_info[our_key] = value
            else:
                vehicle[our_key] = value

        vehicle["engine_info"] = engine_info
        return vehicle

    except Exception as e:
        return {"error": str(e)}