export function assertIsNode(e: EventTarget | null): asserts e is Node {
  if (!e || !('nodeType' in e)) {
    throw new Error('Node expected');
  }
}

/**
 * Wrapper class for generalized text matching.
 * 
 * If possible create regexp, otherwise use symbol matching.
*/
export class TextMatcher {
  protected query: RegExp | string
  
  constructor(query: string, isPlainText?: boolean, isCaseSensitive?: boolean) {
    if (isPlainText) {
      query = query.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&');
    }
    try {
      this.query = new RegExp(query, isCaseSensitive ? '' : 'i');
    } catch(exception: unknown) {
      this.query = query;
    }
  }

  test(text: string): boolean {
    if (typeof this.query === 'string') {
      return text.indexOf(this.query) !== -1;
    } else {
      return !!text.match(this.query);
    }
  }
}

/**
 * Text substitution guided by mapping and regular explression.
*/
export function applyPattern(text: string, mapping: { [key: string]: string }, pattern: RegExp): string {
  if (text === '' || pattern === null) {
    return text;
  }
  let posInput = 0;
  let output = '';
  const patternMatches = text.matchAll(pattern);
  for (const segment of patternMatches) {
    const entity = segment[0];
    const start = segment.index!;
    if (entity in mapping) {
      output += text.substring(posInput, start);
      output += mapping[entity];
      posInput = start + segment[0].length;
    }
  }
  output += text.substring(posInput);
  return output;
}