import type { Ingredient } from '$lib/types';

const UNITS = new Set([
  'g',
  'kg',
  'ml',
  'l',
  'cl',
  'dl',
  'TL',
  'EL',
  'Prise',
  'Pck.',
  'Pkg',
  'Becher',
  'Stk',
  'Stück',
  'Bund',
  'Tasse',
  'Dose'
]);

const FRACTION_MAP: Record<string, number> = {
  '1/2': 0.5,
  '1/3': 1 / 3,
  '2/3': 2 / 3,
  '1/4': 0.25,
  '3/4': 0.75
};

function parseQuantity(raw: string): number | null {
  const trimmed = raw.trim();
  if (FRACTION_MAP[trimmed] !== undefined) return FRACTION_MAP[trimmed];
  const rangeMatch = /^(\d+[.,]?\d*)\s*[-–]\s*\d+[.,]?\d*$/.exec(trimmed);
  if (rangeMatch) {
    return parseFloat(rangeMatch[1].replace(',', '.'));
  }
  const num = parseFloat(trimmed.replace(',', '.'));
  return Number.isFinite(num) ? num : null;
}

export function parseIngredient(raw: string, position = 0): Ingredient {
  const rawText = raw.trim();
  let working = rawText;
  let note: string | null = null;
  const noteMatch = /\(([^)]+)\)/.exec(working);
  if (noteMatch) {
    note = noteMatch[1].trim();
    working = (
      working.slice(0, noteMatch.index) + working.slice(noteMatch.index + noteMatch[0].length)
    ).trim();
  }

  const qtyPattern = /^((?:\d+[.,]?\d*(?:\s*[-–]\s*\d+[.,]?\d*)?)|(?:\d+\/\d+))\s+(.+)$/;
  const qtyMatch = qtyPattern.exec(working);
  if (!qtyMatch) {
    return { position, quantity: null, unit: null, name: working, note, raw_text: rawText };
  }
  const quantity = parseQuantity(qtyMatch[1]);
  let rest = qtyMatch[2].trim();
  let unit: string | null = null;
  const firstTokenMatch = /^(\S+)\s+(.+)$/.exec(rest);
  if (firstTokenMatch && UNITS.has(firstTokenMatch[1])) {
    unit = firstTokenMatch[1];
    rest = firstTokenMatch[2].trim();
  }
  return { position, quantity, unit, name: rest, note, raw_text: rawText };
}