import {
  AndRule,
  type DataRef,
  LiteralRule,
  MaybeRule,
  OrRule,
  type Rule,
  type RuleTestResponse,
} from '@os-team/lexical-rules';
import AttValueRule from '../rules/AttValueRule.js';
import SRule from '../rules/SRule.js';
import type { Parser } from './Parser.js';

export interface RequiredDefaultDecl {
  type: 'REQUIRED';
}

export interface ImpliedDefaultDecl {
  type: 'IMPLIED';
}

export interface FixedDefaultDecl {
  type: 'FIXED';
  attValue: string;
}

export type DefaultDecl =
  | RequiredDefaultDecl
  | ImpliedDefaultDecl
  | FixedDefaultDecl;

/**
 * The attribute default declaration.
 * See https://www.w3.org/TR/xml/#NT-DefaultDecl
 */
class DefaultDeclParser implements Parser<DefaultDecl> {
  private readonly rule: Rule<
    string | [[string, undefined] | undefined, string]
  >;

  public constructor() {
    const requiredRule = new LiteralRule('#REQUIRED'); // '#REQUIRED'
    const impliedRule = new LiteralRule('#IMPLIED'); // '#IMPLIED'
    const fixedRule = new LiteralRule('#FIXED'); // '#FIXED'
    const sRule = new SRule('+'); // S
    const fixedWithSRule = new AndRule([fixedRule, sRule]); // '#FIXED' S
    const maybeFixedWithSRule = new MaybeRule(fixedWithSRule); // ('#FIXED' S)?
    const attValueRule = new AttValueRule(); // AttValue
    const fixedAttValueRule = new AndRule([maybeFixedWithSRule, attValueRule]); // ('#FIXED' S)? AttValue
    this.rule = new OrRule([requiredRule, impliedRule, fixedAttValueRule]); // '#REQUIRED' | '#IMPLIED' | (('#FIXED' S)? AttValue)
  }

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

    const defaultDecl: DefaultDecl = Array.isArray(res)
      ? { type: 'FIXED', attValue: res[1] }
      : { type: res === '#REQUIRED' ? 'REQUIRED' : 'IMPLIED' };

    return [true, nextPos, defaultDecl];
  }

  public build(data: DefaultDecl) {
    return `#${data.type}${
      data.type === 'FIXED' ? ` "${data.attValue.replaceAll('"', "'")}"` : ''
    }`;
  }
}

export default DefaultDeclParser;