import {
  AndRule,
  type DataRef,
  OrRule,
  type Rule,
  type RuleTestResponse,
} from '@os-team/lexical-rules';
import type { Parser } from './Parser.js';
import ChoiceParser, { type Choice } from './ChoiceParser.js';
import SeqParser, { type Seq } from './SeqParser.js';
import QuantifierRule, { type Quantifier } from '../rules/QuantifierRule.js';

type ChildrenContent = Choice | Seq;
export type Children = ChildrenContent | [ChildrenContent, '?' | '*' | '+'];

/**
 * The custom content of an element.
 * See https://www.w3.org/TR/xml/#NT-children
 */
class ChildrenParser implements Parser<Children> {
  private readonly choiceParser: ChoiceParser;

  private readonly seqParser: SeqParser;

  private readonly rule: Rule<[Choice | Seq, Quantifier]>;

  public constructor() {
    this.choiceParser = new ChoiceParser(); // choice
    this.seqParser = new SeqParser(); // seq
    const choiceOrSeqRule = new OrRule([this.choiceParser, this.seqParser]); // choice | seq
    const quantifierRule = new QuantifierRule(); // ('?' | '*' | '+')?
    this.rule = new AndRule([choiceOrSeqRule, quantifierRule]); // (choice | seq) ('?' | '*' | '+')?
  }

  public test(ref: DataRef, pos: number): RuleTestResponse<Children> {
    const [isValid, nextPos, res] = this.rule.test(ref, pos);
    if (!isValid || res === undefined) return [false, nextPos];

    const [content, quantifier] = res;
    const children: Children = quantifier ? [content, quantifier] : content;

    return [true, nextPos, children];
  }

  public build(data: Children) {
    const [content, quantifier = ''] = Array.isArray(data) ? data : [data];

    const strContent =
      content.type === 'CHOICE'
        ? this.choiceParser.build(content)
        : this.seqParser.build(content);

    return `${strContent}${quantifier}`;
  }
}

export default ChildrenParser;