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

export interface XMLDecl {
  version: string;
  encoding?: string;
  standalone?: boolean;
}

/**
 * The XML declaration.
 * See https://www.w3.org/TR/xml/#NT-XMLDecl
 */
class XMLDeclParser implements Parser<XMLDecl> {
  private readonly versionInfoParser: VersionInfoParser;

  private readonly encodingDeclParser: EncodingDeclParser;

  private readonly sdDeclParser: SdDeclParser;

  private rule: Rule<
    [string, string, string | undefined, boolean | undefined, undefined, string]
  >;

  public constructor() {
    const prefixRule = new LiteralRule('<?xml'); // '<?xml'
    this.versionInfoParser = new VersionInfoParser(); // VersionInfo
    this.encodingDeclParser = new EncodingDeclParser(); // EncodingDecl
    const maybeEncodingDeclRule = new MaybeRule(this.encodingDeclParser); // EncodingDecl?
    this.sdDeclParser = new SdDeclParser(); // SDDecl
    const maybeSdDeclRule = new MaybeRule(this.sdDeclParser); // SDDecl?
    const anySRule = new SRule('*'); // S?
    const suffixRule = new LiteralRule('?>'); // '?>'
    this.rule = new AndRule([
      prefixRule,
      this.versionInfoParser,
      maybeEncodingDeclRule,
      maybeSdDeclRule,
      anySRule,
      suffixRule,
    ]); // '<?xml' VersionInfo EncodingDecl? SDDecl? S? '?>'
  }

  public test(ref: DataRef, pos: number): RuleTestResponse<XMLDecl> {
    const [isValid, nextPos, res] = this.rule.test(ref, pos);
    if (!isValid || res === undefined) return [false, nextPos];
    const [, version, encoding, standalone] = res;
    const xmlDecl: XMLDecl = { version };
    if (encoding !== undefined) xmlDecl.encoding = encoding;
    if (standalone !== undefined) xmlDecl.standalone = standalone;
    return [true, nextPos, xmlDecl];
  }

  public build(data: XMLDecl) {
    const { version, encoding, standalone } = data;
    const versionInfo = this.versionInfoParser.build(version);
    const encodingDecl = encoding
      ? this.encodingDeclParser.build(encoding)
      : '';
    const sdDecl = standalone ? this.sdDeclParser.build(standalone) : '';
    return `<?xml${versionInfo}${encodingDecl}${sdDecl}?>`;
  }
}

export default XMLDeclParser;