/**
 * Extract a JAV product code from a filename.
 * Handles common patterns: "SSIS-001.jpg", "[ABC] DEF-123.png", "ssis001 cover.jpg",
 * "abp-456_cover.jpeg", and pre-fixes like "FHD-MIDV-123.jpg".
 *
 * Returns the canonical "PREFIX-NUMBER" form (uppercased), or null if no match.
 */

// Prefix must start with a letter and may contain digits (e.g. "T28", "ABP",
// "MIAA"). Total prefix length 2-6 alphanumerics. The numeric tail is 3-5
// digits, with an optional single-letter suffix for variant releases —
// "IBW-610z" (z-version / re-cut), "ABP-456a" (part-a), etc. Suffix is
// preserved in the canonical form so e.g. IBW-610 and IBW-610Z stay
// distinct (they're different versions of the same release).
const CODE_RE = /\b([A-Za-z][A-Za-z0-9]{1,5})[-_ ]?(\d{3,5})([a-zA-Z])?\b/;
const QUALITY_PREFIXES = new Set(["fhd", "hd", "sd", "uhd", "4k", "1080p", "720p", "480p", "hevc", "x265", "x264"]);

/**
 * Canonicalise an already-known code to "PREFIX-NUMBER" with the number
 * left-padded to a minimum of 3 digits and the prefix uppercased. Inputs
 * coming from NFO `<id>` tags can arrive in any of "MIAA-291", "miaa291",
 * "MIAA-00291", etc.; we want them all to compare equal so the collision
 * detector isn't fooled by formatting drift.
 */
export function normalizeCode(raw: string | null | undefined): string | null {
  if (!raw) return null;
  const m = raw.trim().match(CODE_RE);
  if (!m) return null;
  const suffix = (m[3] ?? "").toUpperCase();
  return `${m[1].toUpperCase()}-${m[2].padStart(3, "0")}${suffix}`;
}

export function extractCode(filename: string): string | null {
  const base = filename.replace(/\.[^.]+$/, "");
  // Walk left-to-right, skipping quality prefixes that look like codes (e.g. "FHD-").
  let cursor = 0;
  while (cursor < base.length) {
    const m = base.slice(cursor).match(CODE_RE);
    if (!m) return null;
    const prefix = m[1];
    const num = m[2];
    const suffix = (m[3] ?? "").toUpperCase();
    if (QUALITY_PREFIXES.has(prefix.toLowerCase())) {
      cursor += (m.index ?? 0) + m[0].length;
      continue;
    }
    return `${prefix.toUpperCase()}-${num.padStart(3, "0")}${suffix}`;
  }
  return null;
}