// Shared minimal CSV parsing helpers -- extracted from
// src/lib/expected-assets.ts (2026-08-21) when src/lib/assets.ts needed
// the same line-splitting logic for AssetItem import (2026-08-23). Handles
// quoted fields (incl. embedded commas/escaped double-quotes) without a
// dependency, which is enough for this app's actual import files (simple
// flat tables, not arbitrary user-supplied CSV).

/**
 * Splits one CSV line into fields. A quote only opens a quoted field when
 * it's the very first character of that field -- a stray/legitimate quote
 * mid-value (e.g. a 24" monitor size) is kept as a literal character
 * instead of wrongly starting quoted-content mode.
 */
export function splitCsvLine(line: string): string[] {
  const fields: string[] = [];
  let current = "";
  let inQuotes = false;
  for (let i = 0; i < line.length; i++) {
    const char = line[i];
    if (inQuotes) {
      if (char === '"') {
        if (line[i + 1] === '"') {
          current += '"';
          i++;
        } else {
          inQuotes = false;
        }
      } else {
        current += char;
      }
    } else if (char === '"' && current === "") {
      inQuotes = true;
    } else if (char === ",") {
      fields.push(current);
      current = "";
    } else {
      current += char;
    }
  }
  fields.push(current);
  return fields.map((f) => f.trim());
}

/** Splits raw CSV text into non-blank lines (handles \r\n, \r, \n). */
export function splitCsvLines(text: string): string[] {
  return text.split(/\r\n|\r|\n/).filter((line) => line.trim() !== "");
}

export function normalizeHeader(header: string): string {
  return header.trim().toLowerCase().replace(/[_-]+/g, " ").replace(/\s+/g, " ");
}

/** Quotes a single CSV field for output if it contains a comma, quote, or
 * newline -- doubling any embedded quotes, per RFC4180. */
export function csvField(value: string): string {
  if (/[",\n]/.test(value)) {
    return `"${value.replace(/"/g, '""')}"`;
  }
  return value;
}