import {
  AndRule,
  CharRule,
  type DataRef,
  LiteralRule,
  OrRule,
  RepetitionRule,
  type Rule,
  type RuleTestResponse,
} from '@os-team/lexical-rules';
import NumberRule from './NumberRule.js';

/**
 * See https://www.w3.org/TR/xml/#NT-CharRef
 */
class CharRefRule implements Rule<string> {
  private readonly rule: Rule<
    [string, number, string] | [string, string[], string]
  >;

  public constructor() {
    const numCharRefPrefixRule = new LiteralRule('&#'); // '&#'
    const numCharRefCodeRule = new NumberRule(); // [0-9]+
    const charRefSuffixRule = new LiteralRule(';'); // ';'
    const numCharRefRule = new AndRule([
      numCharRefPrefixRule,
      numCharRefCodeRule,
      charRefSuffixRule,
    ]); // '&#' [0-9]+ ';'
    const hexCharRefPrefixRule = new LiteralRule('&#x'); // '&#x'
    const hexCharRule = new CharRule({
      allowed: [
        ['0', '9'],
        ['a', 'f'],
        ['A', 'F'],
      ],
    }); // [0-9a-fA-F]
    const hexCharRefCodeRule = new RepetitionRule(hexCharRule, 1); // [0-9a-fA-F]+
    const hexCharRefRule = new AndRule([
      hexCharRefPrefixRule,
      hexCharRefCodeRule,
      charRefSuffixRule,
    ]); // '&#x' [0-9a-fA-F]+ ';'
    this.rule = new OrRule([numCharRefRule, hexCharRefRule]); // ('&#' [0-9]+ ';') | ('&#x' [0-9a-fA-F]+ ';')
  }

  public test(ref: DataRef, pos: number): RuleTestResponse<string> {
    const [isValid, nextPos, res] = this.rule.test(ref, pos);
    if (!isValid || res === undefined) return [false, nextPos];
    const [prefix, code, suffix] = res;
    const str = Array.isArray(code)
      ? `${prefix}${code.join('')}${suffix}`
      : `${prefix}${code}${suffix}`;
    return [true, nextPos, str];
  }
}

export default CharRefRule;