import type { ISeoRedirectSource } from '../../service/seo/seo.interface';

/**
 * What a source will catch that its author may not expect, or empty.
 *
 * @param {ISeoRedirectSource} source - The source as typed.
 * @returns {string} The hint.
 */
export const sourceHint = (source: ISeoRedirectSource): string => {
  const pattern = source.pattern.trim();
  if (pattern === '') {
    return '';
  }
  if (source.comparison === 'regex') {
    return /^\^?\//.test(pattern)
      ? 'The first slash is optional: the address is matched without it, so this reads the same as without the slash.'
      : '';
  }
  if (source.comparison !== 'exact' && pattern.includes('?')) {
    return 'Only an exact source can hold a query string; this one is refused on save.';
  }
  const word = pattern.replace(/^\/+|\/+$/g, '');
  if (
    source.comparison === 'contains' &&
    !(pattern.startsWith('/') && pattern.endsWith('/'))
  ) {
    return `Catches “${word}” inside longer words too, such as /my-${word}s/. Type /${word}/ to catch that whole segment only.`;
  }
  if (source.comparison === 'starts' && !pattern.endsWith('/')) {
    return `Also catches addresses that only begin like it, such as /${word}s/. Type /${word}/ to catch that segment and what is under it only.`;
  }
  if (source.comparison === 'ends' && !pattern.startsWith('/')) {
    return `Also catches addresses that only end like it, such as /my-${word}/. Type /${word} to catch that last segment only.`;
  }
  return '';
};

/**
 * The sources of a saved rule as the form shows them: an exact address
 * with its first slash, the way it was typed, though the rule keeps it
 * without.
 *
 * @param {ISeoRedirectSource[]} sources - As the rule keeps them.
 * @returns {ISeoRedirectSource[]}
 */
export const editableSources = (
  sources: ISeoRedirectSource[]
): ISeoRedirectSource[] =>
  sources.map(source =>
    source.comparison === 'exact' &&
    !source.pattern.startsWith('/') &&
    !/^https?:\/\//i.test(source.pattern)
      ? { ...source, pattern: `/${source.pattern}` }
      : source
  );