# /home/Autopartes/pos/services/question_ai.py
"""A7 — Intent classification + suggested answers for MercadoLibre questions.

Given a buyer question (optionally tied to a listing/inventory item) this
service:
  1. Classifies the intent: compatibility | price | shipping | availability | other.
  2. Builds a suggested answer from real data — ``inventory`` (name/brand/price),
     ``inventory_vehicle_compat`` (fitment) and stock — and falls back to the
     LLM (``services.ai_chat``) when the question needs free text.

Public API:
    classify_intent(text) -> (intent, confidence)
    suggest_answer(tenant_conn, question_text, inventory_id=None, ...) -> dict
    get_question_suggestion(tenant_conn, question_id, ...) -> dict

Returned dict:
    {
      "intent": str,
      "suggested_answer": str,
      "confidence": float,        # 0.0 - 1.0 (intent + data certainty)
      "source": str,              # rules | inventory | compat_db | template | llm | none
      "auto_ok": bool,            # safe to auto-send (high confidence + template)
      "evidence": dict            # data used to build the answer
    }
"""

import re

INTENTS = ('compatibility', 'price', 'shipping', 'availability', 'other')

# Ordered by priority: fitment questions often also contain "tienen"/"hay",
# so compatibility is matched first.
_INTENT_PATTERNS = [
    ('compatibility', [
        r'compatib', r'\bsirve\b', r'\bsirven\b', r'le queda', r'queda (a|en|para)',
        r'le queda a', r'es para (un|una|mi)', r'funciona (para|en)', r'aplica para',
        r'\bfits?\b', r'quedar[áa]', r'le sirve', r'modelo \d{4}',
    ]),
    ('price', [
        r'\bprecio\b', r'cu[áa]nto (cuesta|vale|es|sale)', r'\bcosto\b', r'\bvale\b',
        r'\bdescuento\b', r'\bfactura\b', r'\bmeses\b', r'\bmsi\b', r'\bbarato\b',
        r'\bpago\b', r'\bcuotas?\b',
    ]),
    ('shipping', [
        r'env[íi]o', r'env[íi]an', r'\benvias?\b', r'\bmandan\b', r'\bllega\b',
        r'\bentrega\b', r'paqueter[íi]a', r'\bgu[íi]a\b', r'mensajer[íi]a',
        r'\benvio\b',
    ]),
    ('availability', [
        r'\btienes\b', r'\btiene[n]?\b', r'\bhay\b', r'disponib', r'\bstock\b',
        r'existencia', r'inventario', r'cu[áa]ntas? (piezas|unidades|tienes)',
        r'tienen en',
    ]),
]

_YEAR_RE = re.compile(r'\b(19[89]\d|20[0-3]\d)\b')


def classify_intent(text):
    """Rule-based intent classifier. Returns (intent, confidence)."""
    if not text:
        return 'other', 0.0
    low = str(text).lower()

    for intent, patterns in _INTENT_PATTERNS:
        for pat in patterns:
            if re.search(pat, low):
                return intent, 0.85

    # A bare model-year usually means "does it fit?".
    if _YEAR_RE.search(low):
        return 'compatibility', 0.6

    return 'other', 0.35


# ─── data helpers ───────────────────────────────────────────────────────────

def _inventory_row(conn, inventory_id):
    """Return a small dict for the inventory item backing a listing."""
    if not inventory_id:
        return None
    cur = conn.cursor()
    try:
        cur.execute("""
            SELECT i.id, i.part_number, i.name, i.brand, i.price_1, i.condition, c.name
            FROM inventory i
            LEFT JOIN part_categories c ON c.id = i.category_id
            WHERE i.id = %s
        """, (inventory_id,))
        row = cur.fetchone()
    except Exception:
        return None
    finally:
        cur.close()
    if not row:
        return None
    return {
        'id': row[0], 'part_number': row[1] or '', 'name': row[2] or '',
        'brand': row[3] or '', 'price': float(row[4] or 0), 'condition': row[5] or '',
        'category': row[6] or '',
    }


def _compat_summary(conn, inventory_id, limit=6):
    """Human-readable fitment list from inventory_vehicle_compat (text rows)."""
    cur = conn.cursor()
    try:
        cur.execute("""
            SELECT make, model, year
            FROM inventory_vehicle_compat
            WHERE inventory_id = %s AND (make IS NOT NULL OR model IS NOT NULL)
            GROUP BY make, model, year
            ORDER BY make, model, year
            LIMIT %s
        """, (inventory_id, limit))
        rows = cur.fetchall()
    except Exception:
        return [], 0
    finally:
        cur.close()

    lines = []
    for make, model, year in rows:
        parts = [str(p).strip() for p in (make, model) if p]
        label = ' '.join(parts)
        if year:
            label = f"{label} {year}".strip()
        if label:
            lines.append(label)
    return lines, len(lines)


def _trailing_confirm():
    return ("Si tu vehículo no aparece, compárteme marca, modelo y año "
            "(o los últimos 8 dígitos de tu VIN) y te confirmo la compatibilidad.")


def _config_value(conn, key, default=None):
    cur = conn.cursor()
    try:
        cur.execute("SELECT value FROM tenant_config WHERE key = %s", (key,))
        row = cur.fetchone()
        return row[0] if row and row[0] else default
    except Exception:
        return default
    finally:
        cur.close()


def _stock(conn, inventory_id):
    try:
        from services.inventory_engine import get_stock
        return get_stock(conn, inventory_id)
    except Exception:
        return None


# ai_chat returns these generic strings when every backend fails. They are not
# real answers, so a question must fall back to the template instead.
_LLM_ERROR_PREFIXES = (
    'El asistente está ocupado',
    'El asistente esta ocupado',
    'El asistente tardó mucho',
    'El asistente tardo mucho',
    'El asistente no está disponible',
    'El asistente no esta disponible',
)


def _llm_answer(tenant_conn, question_text, item):
    """Free-text answer via ai_chat. Returns (text, error)."""
    try:
        from services import ai_chat
    except Exception as e:
        return None, f'ai_chat import: {e}'

    context = None
    if item:
        context = (f"Producto publicado: {item['name']} (marca {item['brand'] or 'N/D'}, "
                   f"código {item['part_number'] or 'N/D'}). Precio ${item['price']:.2f} MXN.")
    prompt = ("Eres un vendedor de autopartes que responde preguntas de compradores "
              f"en MercadoLibre. Responde breve (máximo 3 líneas), en español y con tono "
              f"amable. Nunca inventes compatibilidad que no puedas confirmar.\n\nPregunta: {question_text}")
    try:
        res = ai_chat.chat(prompt, inventory_context=context)
    except Exception as e:
        return None, str(e)
    if isinstance(res, dict):
        msg = (res.get('message') or '').strip()
        if msg and not msg.startswith(_LLM_ERROR_PREFIXES):
            return msg, None
        if msg:
            return None, f'backend sin respuesta: {msg}'
    return None, 'sin respuesta del modelo'


# ─── answer builder ─────────────────────────────────────────────────────────

def suggest_answer(tenant_conn, question_text, inventory_id=None, listing_id=None,
                   master_conn=None, use_llm=True):
    """Classify a question and build a suggested answer.

    ``tenant_conn`` is an open tenant connection (not committed). The function
    never raises for backend/data failures: it degrades to a template answer.
    """
    intent, conf = classify_intent(question_text)
    item = _inventory_row(tenant_conn, inventory_id) if inventory_id else None

    out = {
        'intent': intent,
        'suggested_answer': '',
        'confidence': conf,
        'source': 'rules',
        'auto_ok': False,
        'evidence': {},
        'listing_id': listing_id,
        'inventory_id': inventory_id,
    }
    if item:
        out['evidence']['item'] = {
            'part_number': item['part_number'], 'name': item['name'],
            'brand': item['brand'], 'price': item['price'],
        }

    if intent == 'compatibility' and inventory_id:
        lines, n = _compat_summary(tenant_conn, inventory_id)
        out['evidence']['compat_count'] = n
        if lines:
            out['suggested_answer'] = (
                "¡Sí! Esta pieza es compatible con: " + ", ".join(lines) + ". " + _trailing_confirm()
            )
            out['confidence'] = 0.9
            out['source'] = 'compat_db'
            # Fitment can still be model/trim specific -> human review, no auto-send.
            out['auto_ok'] = False
            return out

    elif intent == 'price' and item and item['price'] > 0:
        out['suggested_answer'] = (
            f"El precio es ${item['price']:,.2f} MXN. "
            "El envío se calcula al finalizar la compra según tu código postal. ¿Te ayudo con algo más?"
        )
        out['confidence'] = 0.9
        out['source'] = 'inventory'
        out['auto_ok'] = True
        return out

    elif intent == 'availability' and inventory_id:
        stock = _stock(tenant_conn, inventory_id)
        out['evidence']['stock'] = stock
        if stock is not None:
            if stock > 0:
                out['suggested_answer'] = (
                    f"Sí, tenemos {stock} {'pieza' if stock == 1 else 'piezas'} disponibles. "
                    "Puedes comprar directo desde la publicación."
                )
                out['confidence'] = 0.9
            else:
                out['suggested_answer'] = (
                    "Por el momento no tenemos existencia de esta pieza. "
                    "Déjame tu pregunta y te aviso en cuanto llegue."
                )
                out['confidence'] = 0.8
            out['source'] = 'inventory'
            out['auto_ok'] = True
            return out

    elif intent == 'shipping':
        mode = _config_value(tenant_conn, 'meli_shipping_mode', '')
        extra = f" Modalidad: {mode}." if mode else ''
        out['suggested_answer'] = (
            "El costo y tiempo de envío se muestran al ingresar tu código postal en MercadoLibre." + extra +
            " Si estás en la ciudad, también puedes pasar a recogerlo a la tienda."
        )
        out['confidence'] = 0.75
        out['source'] = 'template'
        out['auto_ok'] = out['confidence'] >= 0.8
        return out

    # Fallback: free text for "other", or when the data needed was missing.
    if use_llm:
        text, err = _llm_answer(tenant_conn, question_text, item)
        if text:
            out['suggested_answer'] = text
            out['source'] = 'llm'
            out['confidence'] = max(out['confidence'], 0.6)
            out['auto_ok'] = False
            return out
        out['evidence']['llm_error'] = err

    if not out['suggested_answer']:
        if intent == 'compatibility':
            out['suggested_answer'] = ("Con gusto te confirmo la compatibilidad. " + _trailing_confirm())
        else:
            out['suggested_answer'] = (
                "¡Hola! Gracias por tu pregunta; en un momento te atendemos con el detalle."
            )
        out['source'] = 'template'
        out['confidence'] = min(out['confidence'], 0.5)
        out['auto_ok'] = False
    return out


def get_question_suggestion(tenant_conn, question_id, master_conn=None, use_llm=True):
    """Resolve a local marketplace question then build its suggested answer."""
    cur = tenant_conn.cursor()
    try:
        cur.execute("""
            SELECT q.question_text, q.listing_id, l.inventory_id
            FROM marketplace_questions q
            LEFT JOIN marketplace_listings l ON l.id = q.listing_id
            WHERE q.id = %s
        """, (question_id,))
        row = cur.fetchone()
    finally:
        cur.close()
    if not row:
        raise ValueError('Question not found')

    q_text, listing_id, inventory_id = row
    return suggest_answer(
        tenant_conn, q_text or '', inventory_id=inventory_id,
        listing_id=listing_id, master_conn=master_conn, use_llm=use_llm,
    )