/**
 * Orders Specialist - Extracción de productos y cantidades
 * 
 * El specialist más importante: maneja add_to_cart, remove_from_cart,
 * view_cart, confirm_order con soporte para multi-items.
 */

import OpenAI from "openai";
import { loadPrompt } from "../promptLoader.js";
import { validateOrders, getValidationErrors, createEmptyNlu } from "../schemas.js";

let _client = null;

function getClient() {
  const apiKey = process.env.OPENAI_API_KEY || process.env.OPENAI_APIKEY;
  if (!apiKey) {
    throw new Error("OPENAI_API_KEY is not set");
  }
  if (!_client) {
    _client = new OpenAI({ apiKey });
  }
  return _client;
}

function extractJson(text) {
  const s = String(text || "");
  const i = s.indexOf("{");
  const j = s.lastIndexOf("}");
  if (i >= 0 && j > i) {
    try {
      return JSON.parse(s.slice(i, j + 1));
    } catch {
      return null;
    }
  }
  return null;
}

/**
 * Normaliza unidades a formato estándar
 */
function normalizeUnit(unit) {
  if (!unit) return null;
  const u = String(unit).toLowerCase().trim();
  if (["kg", "kilo", "kilos", "kilogramo", "kilogramos"].includes(u)) return "kg";
  if (["g", "gr", "gramo", "gramos"].includes(u)) return "g";
  if (["unidad", "unidades", "u", "un"].includes(u)) return "unidad";
  return null;
}

/**
 * Normaliza items extraídos
 */
function normalizeItems(items) {
  if (!Array.isArray(items) || items.length === 0) return null;
  
  return items
    .filter(item => item && item.product_query)
    .map(item => ({
      product_query: String(item.product_query || "").trim(),
      quantity: typeof item.quantity === "number" ? item.quantity : null,
      unit: normalizeUnit(item.unit),
    }))
    .filter(item => item.product_query.length > 0);
}

/**
 * Procesa un mensaje de pedido
 * 
 * @param {Object} params
 * @param {number} params.tenantId - ID del tenant
 * @param {string} params.text - Mensaje del usuario
 * @param {Object} params.storeConfig - Config de la tienda
 * @returns {Object} NLU unificado
 */
export async function ordersNlu({ tenantId, text, storeConfig = {} }) {
  const openai = getClient();
  
  // Cargar prompt de orders
  const { content: systemPrompt, model } = await loadPrompt({
    tenantId,
    promptKey: "orders",
    variables: storeConfig,
  });
  
  // Hacer la llamada al LLM
  const response = await openai.chat.completions.create({
    model: model || "gpt-4-turbo",
    temperature: 0.1, // Baja temperatura para extracción precisa
    max_tokens: 500,
    response_format: { type: "json_object" },
    messages: [
      { role: "system", content: systemPrompt },
      { role: "user", content: text },
    ],
  });
  
  const rawText = response?.choices?.[0]?.message?.content || "";
  let parsed = extractJson(rawText);
  
  // Intentar validar
  let validationOk = false;
  if (parsed && validateOrders(parsed)) {
    validationOk = true;
  } else if (parsed) {
    // Intentar normalizar respuesta parcialmente válida
    parsed = {
      intent: parsed.intent || "add_to_cart",
      confidence: parsed.confidence || 0.8,
      items: parsed.items || null,
      product_query: parsed.product_query || null,
      quantity: parsed.quantity || null,
      unit: parsed.unit || null,
    };
    validationOk = true;
  } else {
    // Fallback total
    parsed = {
      intent: "add_to_cart",
      confidence: 0.5,
      items: null,
      product_query: text.length < 50 ? text : null,
      quantity: null,
      unit: null,
    };
  }
  
  // Normalizar items - SIEMPRE convertir a array
  let normalizedItems = normalizeItems(parsed.items);
  
  // Si no hay items pero hay product_query en raíz, convertir a array
  if ((!normalizedItems || normalizedItems.length === 0) && parsed.product_query) {
    normalizedItems = [{
      product_query: String(parsed.product_query).trim(),
      quantity: typeof parsed.quantity === "number" ? parsed.quantity : null,
      unit: normalizeUnit(parsed.unit),
    }];
  }
  
  // Convertir a formato NLU unificado
  const nlu = createEmptyNlu();
  nlu.intent = parsed.intent || "add_to_cart";
  nlu.confidence = parsed.confidence || 0.8;
  
  // Entities - siempre usar items[], nunca campos individuales
  nlu.entities.items = normalizedItems || [];
  nlu.entities.product_query = null; // Deprecado, usar items[]
  nlu.entities.quantity = null;
  nlu.entities.unit = null;
  
  // Needs
  nlu.needs.catalog_lookup = ["add_to_cart", "remove_from_cart"].includes(nlu.intent);
  nlu.needs.knowledge_lookup = false;
  
  return {
    nlu,
    raw_text: rawText,
    model,
    usage: response?.usage || null,
    validation: { ok: validationOk, errors: validationOk ? [] : getValidationErrors(validateOrders) },
  };
}