/**
 * Open Food Facts Barcode API integration
 * Extracts product name, brand, package quantity & unit, image, and category.
 * Intentionally omits macro nutrients to keep interface clean & fast.
 */

function parseQuantityString(quantityStr) {
  if (!quantityStr || typeof quantityStr !== 'string') {
    return { quantity: 1, unit: 'pcs' };
  }

  const clean = quantityStr.trim().toLowerCase();

  // Pattern: e.g. "250g", "250 g", "1.5 kg", "1,5kg", "500 ml", "1 l", "1.5l", "6x100g", "4 x 125 g"
  // Multi-pack: e.g. 6 x 100 g -> 600 g or total 6 pcs
  const multiMatch = clean.match(/^(\d+)\s*[xX*]\s*([\d.,]+)\s*([a-zA-Z%]+)?/);
  if (multiMatch) {
    const count = parseInt(multiMatch[1], 10);
    const itemQty = parseFloat(multiMatch[2].replace(',', '.'));
    const itemUnit = multiMatch[3] ? normalizeUnit(multiMatch[3]) : 'g';
    if (!isNaN(count) && !isNaN(itemQty)) {
      return {
        quantity: Math.round(count * itemQty),
        unit: itemUnit,
        raw: quantityStr
      };
    }
  }

  // Single quantity: e.g. "250 g", "500ml", "1kg", "0.75 l"
  const singleMatch = clean.match(/^([\d.,]+)\s*([a-zA-Z%]+)?/);
  if (singleMatch) {
    let num = parseFloat(singleMatch[1].replace(',', '.'));
    let unit = singleMatch[2] ? normalizeUnit(singleMatch[2]) : 'g';

    // Normalize kg to g or l to ml if preferred, or keep as is. Grams / ml are most convenient for fine adjustments!
    if (unit === 'kg') {
      num = Math.round(num * 1000);
      unit = 'g';
    } else if (unit === 'l' || unit === 'liter' || unit === 'litre') {
      num = Math.round(num * 1000);
      unit = 'ml';
    }

    if (!isNaN(num) && num > 0) {
      return {
        quantity: num,
        unit: unit,
        raw: quantityStr
      };
    }
  }

  return { quantity: 1, unit: 'pcs', raw: quantityStr };
}

function normalizeUnit(u) {
  const unit = u.toLowerCase().trim();
  if (unit === 'g' || unit === 'gr' || unit === 'gram' || unit === 'gramm' || unit === 'grams') return 'g';
  if (unit === 'kg' || unit === 'kilogram' || unit === 'kilo') return 'kg';
  if (unit === 'ml' || unit === 'milliliter') return 'ml';
  if (unit === 'l' || unit === 'liter' || unit === 'litre') return 'l';
  if (unit === 'cl' || unit === 'centiliter') return 'ml';
  if (unit === 'dl' || unit === 'deciliter') return 'ml';
  if (unit === 'oz') return 'g';
  if (unit === 'stk' || unit === 'stck' || unit === 'stueck' || unit === 'stück' || unit === 'pcs' || unit === 'pc' || unit === 'piece' || unit === 'pieces') return 'pcs';
  if (unit === 'pkg' || unit === 'pack' || unit === 'packung' || unit === 'pkt') return 'pack';
  if (unit === 'fl' || unit === 'flasche' || unit === 'bottle') return 'pcs';
  if (unit === 'dose' || unit === 'can') return 'pcs';
  return unit || 'g';
}

function inferCategory(categoriesTags = [], productName = '', categoriesStr = '') {
  const combined = [
    ...(Array.isArray(categoriesTags) ? categoriesTags : []),
    productName,
    categoriesStr
  ].join(' ').toLowerCase();

  if (/getränk|beverage|drink|saft|juice|cola|soda|wasser|water|bier|beer|wein|wine|milchshake|smoothie|tee|tea|energy|sirup/i.test(combined)) {
    return 'Beverages';
  }
  if (/milch|käse|kaese|cheese|dairy|joghurt|yogurt|butter|quark|sahne|creme|schmand|mozzarella|parmesan|gouda|cheddar|feta|camembert|pudding/i.test(combined)) {
    return 'Dairy & Cheese';
  }
  if (/fleisch|meat|wurst|sausage|schinken|ham|hähnchen|chicken|rind|beef|schwein|pork|bacon|salami|speck|fisch|fish|lachs|salmon|thunfisch|tuna|seafood|garnelen/i.test(combined)) {
    return 'Meat & Fish';
  }
  if (/sauce|soße|senf|mustard|ketchup|mayo|mayonnaise|dressing|pesto|dip|essig|vinegar|öl|oil|gewürz|spice|curry|tabasco|remoulade/i.test(combined)) {
    return 'Sauces & Condiments';
  }
  if (/gemüse|vegetable|obst|fruit|salat|salad|tomate|tomato|gurke|cucumber|apfel|apple|banane|banana|zwiebel|onion|karotte|carrot|kartoffel|potato|beeren|berry|zitrus|citrus|spinat|spinach/i.test(combined)) {
    return 'Produce';
  }
  if (/brot|bread|toast|brötchen|bun|teig|dough|hefe|yeast|croissant|tortilla|wrap/i.test(combined)) {
    return 'Bakery';
  }
  if (/snack|schokolade|chocolate|chips|keks|cookie|süß|sweet|candy|nuss|nut|eis|ice cream/i.test(combined)) {
    return 'Snacks & Sweets';
  }
  if (/reste|leftover|fertiggericht|meal|pizza|suppen|soup|pasta|nudeln|noodle/i.test(combined)) {
    return 'Prepared & Leftovers';
  }

  return 'General';
}

async function lookupBarcode(barcode) {
  if (!barcode || typeof barcode !== 'string') return null;
  const cleanBarcode = barcode.trim();
  if (!cleanBarcode) return null;

  try {
    const url = `https://world.openfoodfacts.org/api/v2/product/${encodeURIComponent(cleanBarcode)}.json?fields=product_name,product_name_de,product_name_en,brands,quantity,categories_tags,categories,image_front_small_url,image_url,image_front_url`;
    
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), 6000); // 6s timeout

    const res = await fetch(url, {
      headers: {
        'User-Agent': 'Fridger - Fridge Inventory Manager (https://gitea.eibl.tech/me0nline/Fridger)'
      },
      signal: controller.signal
    });
    clearTimeout(timeout);

    if (!res.ok) {
      return null;
    }

    const data = await res.json();
    if (data.status !== 1 || !data.product) {
      return null;
    }

    const p = data.product;
    const name = p.product_name_de || p.product_name || p.product_name_en || '';
    const brand = p.brands || '';
    const parsedQty = parseQuantityString(p.quantity);
    const category = inferCategory(p.categories_tags, name, p.categories);
    const imageUrl = p.image_front_small_url || p.image_front_url || p.image_url || '';

    return {
      found: true,
      barcode: cleanBarcode,
      name: name.trim() || 'Unknown Product',
      brand: brand.trim(),
      quantity: parsedQty.quantity,
      initial_quantity: parsedQty.quantity,
      unit: parsedQty.unit,
      category: category,
      image_url: imageUrl,
      raw_quantity: p.quantity || ''
    };
  } catch (err) {
    console.warn(`Barcode lookup error for ${cleanBarcode}:`, err.message);
    return null;
  }
}

module.exports = {
  lookupBarcode,
  parseQuantityString,
  inferCategory
};