/**
 * @param {RegExpMatchArray & {
 *   indices: {
 *     groups: {
 *       [key: string]: [number, number]
 *     }
 *   }
 *   groups: {[key: string]: string}
 * }} match An inline tag regexp match.
 * @returns {'pipe' | 'plain' | 'prefix' | 'space'}
 */
function determineFormat (match) {
  const {separator, text} = match.groups;
  const [, textEnd] = match.indices.groups.text;
  const [tagStart] = match.indices.groups.tag;
  if (!text) {
    return 'plain';
  } else if (separator === '|') {
    return 'pipe';
  } else if (textEnd < tagStart) {
    return 'prefix';
  }
  return 'space';
}

/**
 * Extracts inline tags from a description.
 * @param {string} description
 * @returns {import('.').InlineTag[]} Array of inline tags from the description.
 */
function parseDescription (description) {
  /** @type {import('.').InlineTag[]} */
  const result = [];

  // This could have been expressed in a single pattern,
  // but having two avoids a potentially exponential time regex.

  const prefixedTextPattern = new RegExp(/(?:\[(?<text>[^\]]+)\])\{@(?<tag>[^}\s]+)\s?(?<namepathOrURL>[^}\s|]*)\}/gu, 'gud');
  // The pattern used to match for text after tag uses a negative lookbehind
  // on the ']' char to avoid matching the prefixed case too.
  const suffixedAfterPattern = new RegExp(/(?<!\])\{@(?<tag>[^}\s]+)\s?(?<namepathOrURL>[^}\s|]*)\s*(?<separator>[\s|])?\s*(?<text>[^}]*)\}/gu, 'gud');

  const matches = [
    ...description.matchAll(prefixedTextPattern),
    ...description.matchAll(suffixedAfterPattern)
  ];

  for (const mtch of matches) {
    const match = /**
      * @type {RegExpMatchArray & {
      *   indices: {
      *     groups: {
      *       [key: string]: [number, number]
      *     }
      *   }
      *   groups: {[key: string]: string}
      * }}
      */ (
        mtch
      );
    const {tag, namepathOrURL, text} = match.groups;
    const [start, end] = match.indices[0];
    const format = determineFormat(match);

    result.push({
      tag,
      namepathOrURL,
      text,
      format,
      start,
      end
    });
  }

  return result;
}

/**
 * Splits the `{@ prefix}` from remaining `Spec.lines[].token.description`
 * into the `inlineTags` tokens, and populates `spec.inlineTags`
 * @param {import('comment-parser').Block} block
 * @returns {import('.').JsdocBlockWithInline}
 */
export function parseInlineTags (block) {
  const inlineTags =
    /**
     * @type {(import('./commentParserToESTree').JsdocInlineTagNoType & {
     *   line?: import('./commentParserToESTree').Integer
     * })[]}
     */ (
      parseDescription(block.description)
    );

  /** @type {import('.').JsdocBlockWithInline} */ (
    block
  ).inlineTags = inlineTags;

  for (const tag of block.tags) {
    /**
     * @type {import('.').JsdocTagWithInline}
     */ (tag).inlineTags = parseDescription(tag.description);
  }
  return (
    /**
     * @type {import('.').JsdocBlockWithInline}
     */ (block)
  );
}
