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

export type PI = ['PI', string] | ['PI', string, string]; // [, target, content]

/**
 * The processing instruction.
 * See https://www.w3.org/TR/xml/#NT-PI
 */
class PIParser implements Parser<PI> {
  private readonly rule: Rule<
    [string, string, [undefined, string] | undefined, string]
  >;

  public constructor() {
    const prefixRule = new LiteralRule('<?'); // '<?'
    const piTargetRule = new PITargetRule(); // PITarget
    const sRule = new SRule('+'); // S
    const charRule = new CharRule();
    const anyCharRule = new AnyCharRule(charRule, ['?>']); // Char* - (Char* '?>' Char*)
    const sAndAnyCharRule = new AndRule([sRule, anyCharRule]); // S (Char* - (Char* '?>' Char*))
    const piContentRule = new MaybeRule(sAndAnyCharRule); // (S (Char* - (Char* '?>' Char*)))?
    const suffixRule = new LiteralRule('?>'); // '?>'
    this.rule = new AndRule([
      prefixRule,
      piTargetRule,
      piContentRule,
      suffixRule,
    ]); // '<?' PITarget (S (Char* - (Char* '?>' Char*)))? '?>'
  }

  public test(ref: DataRef, pos: number): RuleTestResponse<PI> {
    const [isValid, nextPos, res] = this.rule.test(ref, pos);
    if (!isValid || res === undefined) return [false, nextPos];
    const [, target, parsedContent] = res;
    const pi: PI = ['PI', target];
    if (Array.isArray(parsedContent)) pi.push(parsedContent[1]);
    return [true, nextPos, pi];
  }

  public build(data: PI) {
    const [, target, content = ''] = data;
    if (target.toLowerCase() === 'xml') {
      throw new Error(
        'The target of the processing instruction should not be "xml"'
      );
    }
    if (content.includes('?>')) {
      throw new Error(
        'The content of the processing instruction should not contain "?>"'
      );
    }
    return `<?${target}${content ? ` ${content}` : ''}?>`;
  }
}

export default PIParser;