Simple ICalendar Parser to JS Objects

ICalendarParser.ts

/**
 * @copyright bartosz.bobin
 */
export class ICalendarParser {
  skipNotStandardKeys = true;

  parse(text: string) {
    const lines = text.replace(/\n /g, '').split(/\n/);

    let obj = {vcalendar: undefined};
    this.analyseCalendar(lines, obj);

    return obj.vcalendar;
  }

  private analyseCalendar(lines, obj) {
    const path = [obj];

    for (let line of lines) {
      line = line.trim();
      let currentPathItem = path[path.length - 1];

      if (line.indexOf('BEGIN:') === 0) {
        this.createNewPathItem(line, currentPathItem, path);
        continue;
      }

      if (line.indexOf(`END:`) === 0) {
        path.pop();
        continue;
      }

      if (line.indexOf(`X-`) === 0 && this.skipNotStandardKeys) {
        continue;
      }

      this.analyseProperty(line, currentPathItem);
    }
  }

  private analyseProperty(line, current) {
    const keyValueSeparatorIndex = line.indexOf(':');
    let key = line.substr(0, keyValueSeparatorIndex);

    const keyPropertySeparatorIndex = key.indexOf(';');

    let value = {
      data: line.substr(keyValueSeparatorIndex + 1)
    };

    if (keyPropertySeparatorIndex > -1) {
      const properties = key.split(/;/g);
      key = properties.shift();

      for (const prop of properties) {
        const t = prop.split('=');
        value[ICalendarParser.toCamelCase(t.shift())] = t.join('=');
      }
    }

    current[ICalendarParser.toCamelCase(key)] = value;
  }

  private createNewPathItem(line, currentPathItem, path) {
    const keyName = ICalendarParser.toCamelCase(line.substr(6));
    const item = this.keyToObjectMapper(keyName);

    if (typeof currentPathItem[keyName] === 'object') {
      if (!Array.isArray(currentPathItem[keyName])) {
        currentPathItem[keyName] = [currentPathItem[keyName]];
      }

      currentPathItem[keyName].push(item);
    } else {
      currentPathItem[keyName] = item;
    }

    path.push(item);
  }

  private keyToObjectMapper(key) {
    switch (key.toLowerCase()) {
      case "vcalendar": return new VCalendar();
      case "vevent": return new VEvent();
      case "vtodo": return new VTodo();
      case "vjournal": return new VJournal();
      case "vfreebusy": return new VFreeBusy();
      case "vtimezone": return new VTimezone();
      default:return {};
    }
  }

  static toCamelCase(str) {
    return str.toLowerCase();
  }
}

export class VCalendar {}
export class VEvent {}
export class VTodo {}
export class VJournal {}
export class VFreeBusy {}
export class VTimezone {}