'use strict';

const path = require('path');
const { isSpecialKey } = require('../../chapter-identity');

const RESERVED = /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i;

function cleanPart(value, max = 120) {
  let result = String(value || '')
    .normalize('NFC')
    .replace(/[<>:"/\\|?*\x00-\x1f]/g, '')
    .replace(/[\[\]]/g, '')
    .replace(/\s+/g, ' ')
    .trim()
    .replace(/[ .]+$/g, '');
  if (!result) result = 'Untitled';
  if (RESERVED.test(result)) result += '-manga';
  return result.slice(0, max).replace(/[ .]+$/g, '');
}

function chapterKey(value) {
  const raw = String(value).trim();
  if (isSpecialKey(raw)) return raw.toLowerCase();
  if (/^\d+(?:\.\d+)?$/.test(raw)) {
    const [integer, decimal = ''] = raw.split('.');
    const normalized = decimal.replace(/0+$/g, '');
    return `c${integer.padStart(4, '0')}${normalized ? `.${normalized}` : ''}`;
  }
  const extra = raw.match(/^x(\d+)$/i);
  if (extra) return `x${extra[1].padStart(2, '0')}`;
  throw new Error(`Unsupported chapter number: ${value}`);
}

function chapterFolder(chapter) {
  const parts = [chapterKey(chapter.number)];
  if (chapter.title) parts.push(cleanPart(chapter.title));
  parts.push(`[${cleanPart(chapter.source.name, 50)}]`);
  return parts.join(' ');
}

function assertInside(parent, child) {
  const root = path.resolve(parent);
  const target = path.resolve(child);
  if (target !== root && !target.startsWith(root + path.sep)) {
    throw new Error(`Path escapes library root: ${target}`);
  }
  return target;
}

module.exports = { cleanPart, chapterKey, chapterFolder, assertInside };