/**
 * Client-side bulk import of the shop `artikeltabelle.csv` export format.
 *
 * The CSV is semicolon-separated (often wrapped in `="…"` from Excel export)
 * with columns:
 *   ArtNr; Name; Preis; USt; Pfand; Hersteller; Kategorie; Barcode; V/K
 *
 * All work is done through the existing dashback API:
 *   - categories  → POST /api/category
 *   - brands      → PUT /api/brand
 *   - articles    → POST /api/article (+ price / brand / ean / categories PUTs)
 */

/** Parse one `="value"` / `"value"` / plain Excel-style CSV cell. */
export function stripCell(value) {
  if (value == null) return '';
  let text = String(value).trim();
  if (text.startsWith('=')) text = text.slice(1);
  text = text.trim();
  if (
    text.length >= 2 &&
    text.startsWith('"') &&
    text.endsWith('"')
  ) {
    text = text.slice(1, -1).replace(/""/g, '"');
  }
  return text.trim();
}

/**
 * Split a semicolon CSV line into cells, honoring double-quoted fields.
 * (Cell values are still raw; use `stripCell` for the Excel `="…"` wrapper.)
 */
export function splitCsvLine(line) {
  const cells = [];
  let cur = '';
  let inQuotes = false;
  for (let i = 0; i < line.length; i++) {
    const ch = line[i];
    if (inQuotes) {
      if (ch === '"') {
        if (line[i + 1] === '"') {
          cur += '"';
          i++;
        } else {
          inQuotes = false;
        }
      } else {
        cur += ch;
      }
    } else if (ch === '"') {
      inQuotes = true;
    } else if (ch === ';') {
      cells.push(cur);
      cur = '';
    } else {
      cur += ch;
    }
  }
  cells.push(cur);
  return cells.map((c) => stripCell(c));
}

/**
 * Parse a CSV string into row objects keyed by the header names.
 * Skips blank lines and the optional `sep=;` hint line.
 */
export function parseArtikelCsv(csvText) {
  const lines = String(csvText ?? '')
    .replace(/\r\n/g, '\n')
    .split('\n')
    .map((l) => l.trim())
    .filter((l) => l !== '' && l !== 'sep=;');

  if (lines.length === 0) return [];

  const headers = splitCsvLine(lines[0]);
  const rows = [];
  for (let i = 1; i < lines.length; i++) {
    const cells = splitCsvLine(lines[i]);
    const row = {};
    headers.forEach((header, idx) => {
      row[header] = cells[idx] ?? '';
    });
    if (row.Name) rows.push(row);
  }
  return rows;
}

/**
 * Resolve a de-DE (or plain) number from a CSV field.
 * Accepts `2,00`, `1.234,56`, and plain `2.00`.
 */
export function parseCsvNumber(value) {
  const text = String(value ?? '').trim();
  if (text === '') return null;
  let normalized = text.replace(/\s/g, '');
  if (normalized.includes(',')) {
    normalized = normalized.replace(/\./g, '').replace(',', '.');
  }
  const parsed = Number(normalized);
  return Number.isFinite(parsed) && parsed >= 0 ? parsed : null;
}

/** EAN from a CSV cell (digits only), or null. */
export function parseCsvEan(value) {
  const digits = String(value ?? '').replace(/\D/g, '');
  return digits || null;
}

/**
 * Split a `Kategorie` path (`Haupt | Grow | Erde`) into trimmed segments.
 * Empty / falsy path → [].
 */
export function parseCategoryPath(value) {
  return String(value ?? '')
    .split('|')
    .map((s) => s.trim())
    .filter(Boolean);
}

/**
 * Column index → name. Uses a forgiving match so the exact header text
 * (with or without `="` wrapper, case) doesn't matter.
 */
function headerName(name) {
  return stripCell(name).toLowerCase().trim();
}

export const COLUMNS = {
  artNr: 'artnr',
  name: 'name',
  price: 'preis',
  tax: 'ust',
  deposit: 'pfand',
  brand: 'hersteller',
  category: 'kategorie',
  ean: 'barcode',
  vk: 'v/k',
};

/**
 * Normalize one raw CSV row object into the typed import record.
 * Unknown/missing columns become null/[] so downstream code can skip them.
 */
export function normalizeRow(row, headers = []) {
  const byName = new Map();
  (headers.length ? headers : Object.keys(row)).forEach((h) => {
    byName.set(headerName(h), row[h] ?? row[stripCell(h)] ?? '');
  });
  const get = (key) => byName.get(COLUMNS[key]) ?? byName.get(key) ?? '';

  const artNr = get('artNr');
  const name = get('name');
  const price = parseCsvNumber(get('price'));
  const tax = parseCsvNumber(get('tax'));
  const brand = get('brand');
  const categoryPath = parseCategoryPath(get('category'));
  const ean = parseCsvEan(get('ean'));
  const vk = get('vk');

  return {
    artNr,
    name,
    price,
    tax,
    deposit: parseCsvNumber(get('deposit')),
    brand,
    categoryPath,
    ean,
    vk,
  };
}

/**
 * Parse a full CSV string into typed import records.
 * @param {string} csvText
 * @returns {Array<ReturnType<typeof normalizeRow>>}
 */
export function parseImportCsv(csvText) {
  const rawRows = parseArtikelCsv(csvText);
  const headers = rawRows.length ? Object.keys(rawRows[0]) : [];
  return rawRows.map((row) => normalizeRow(row, headers));
}