internals.dart

import 'package:certlogic_dart/src/evaluate.dart';
import 'package:certlogic_dart/src/typings.dart';

class CertLogicInternals {

  static bool isFalsy(dynamic value) =>
      value == false ||
      value == null ||
      (value is String && value.isEmpty) ||
      (value is num && value == 0) ||
      (value is Iterable && value.isEmpty) ||
      (value is Map && value.isEmpty);

  static bool isTruthy(dynamic value) =>
      value == true ||
      (value is String && value.isNotEmpty) ||
      (value is num && value != 0) ||
      (value is Iterable && value.isNotEmpty) ||
      (value is Map && value.isNotEmpty);

  static bool? boolsiness(dynamic value) {
    if (isTruthy(value)) {
      return true;
    }
    if (isFalsy(value)) {
      return false;
    }
    return null;
  }


  /// NOTE:
  /// Effectively, any date is always converted to the corresponding ms-precise date-time
  /// at midnight of that date. Note that that doesn't properly reflect the resolution of
  /// the input date. That effect has to be taken into account by the logic implementor.
  static DateTime dateFromString(String str) {
    DateTime? dateTime;
    if (str.length == 10) {
      // No TZ is added
      final date = DateTime.parse(str);
      dateTime = DateTime.utc(
          date.year, date.month, date.day); // Set it to midnight as per specs
    }
    final regex =
        r'(^[T,\-,:,\.0-9]{10,}[+,-])([0-9]|[0-9]{3}|[0-9]:[0-9]{2})$';
    str = str.replaceAllMapped(
        RegExp(regex), (match) => '${match.group(1)}0${match.group(2)}');
    dateTime ??= DateTime.parse(str);
    return DateTime.utc(
      dateTime.year,
      dateTime.month,
      dateTime.day,
      dateTime.hour,
      dateTime.minute,
      dateTime.second,
      dateTime.millisecond,
    );
  }


  static final yyyyRegExp = new RegExp(r'^\d{4}$');
  static final yyyymmRegExp = new RegExp(r'^\d{4}-\d{2}$');
  static final yyyymmddRegExp = new RegExp(r'^\d{4}-\d{2}-\d{2}$');

  static DateTime? roundUpPartialDate(String str) {
    if (yyyyRegExp.hasMatch(str)) {
      return dateFromString('${str}-12-31');
    }
    if (yyyymmRegExp.hasMatch(str)) {
      final dateTime = dateFromString('${str}-01');
      return DateTime.utc(
          dateTime.year,
          dateTime.month + 1,
          dateTime.day - 1,
          dateTime.hour,
          dateTime.minute,
          dateTime.second,
          dateTime.millisecond);
    }
    return null;
  }


  static DateTime plusTime(
      String dateTimeLikeStr, int amount, CertLogicTimeUnit unit) {
    final dateTime = roundUpPartialDate(dateTimeLikeStr) ?? dateFromString(dateTimeLikeStr);
    switch (unit) {
      case CertLogicTimeUnit.HOUR:
        return DateTime.utc(
          dateTime.year,
          dateTime.month,
          dateTime.day,
          dateTime.hour + amount,
          dateTime.minute,
          dateTime.second,
          dateTime.millisecond,
        );
      case CertLogicTimeUnit.DAY:
        return DateTime.utc(
          dateTime.year,
          dateTime.month,
          dateTime.day + amount,
          dateTime.hour,
          dateTime.minute,
          dateTime.second,
          dateTime.millisecond,
        );
      case CertLogicTimeUnit.MONTH:
        return DateTime.utc(
          dateTime.year,
          dateTime.month + amount,
          dateTime.day,
          dateTime.hour,
          dateTime.minute,
          dateTime.second,
          dateTime.millisecond,
        );
      case CertLogicTimeUnit.YEAR:
        return DateTime.utc(
          dateTime.year + amount,
          dateTime.month,
          dateTime.day,
          dateTime.hour,
          dateTime.minute,
          dateTime.second,
          dateTime.millisecond,
        );
    }
  }


  /// returns A Dart [DateTime] representing the given date that may be partial (YYYY[-MM[-DD]]).
  ///   See [the CertLogic specification](https://github.com/ehn-dcc-development/dgc-business-rules/blob/main/certlogic/specification/README.md) for details.
  static DateTime dccDateOfBirth(String str) {
    final forPartialDate = roundUpPartialDate(str);
    if (forPartialDate != null) {
      return forPartialDate;
    }
    if (yyyymmddRegExp.hasMatch(str)) {
      return dateFromString(str);
    }
    throw CertLogicException(
        'can\'t parse "${str}" as an EU DCC date-of-birth');
  }


  static const optionalPrefix = "URN:UVCI:";

  /// returns The fragment with given index from the UVCI string
  ///  (see Annex 2 in the [UVCI specification](https://ec.europa.eu/health/sites/default/files/ehealth/docs/vaccination-proof_interoperability-guidelines_en.pdf)),
  ///  or `null` when that fragment doesn't exist.
  static String? extractFromUVCI(String? uvci, int index) {
    if (uvci == null || index < 0) {
      return null;
    }
    final prefixlessUvci = uvci.startsWith(optionalPrefix)
        ? uvci.substring(optionalPrefix.length)
        : uvci;
    final fragments = prefixlessUvci.split(RegExp(r'[/#:]'));
    return index < fragments.length ? fragments[index] : null;
  }


  static dynamic access(dynamic data, String path) {
    if (path == '') return data;
    var returnData = data;
    path.split('.').forEach((fragment) {
      if (returnData == null) return;
      if (returnData is Iterable) {
        try {
          final index = int.parse(fragment);
          if (index < 0 || index > (returnData as Iterable).length - 1) {
            returnData = null;
            return;
          }
          returnData = returnData[index];
          return;
        } catch (e) {
          return;
        }
      }
      if (returnData is Map) {
        returnData = returnData[fragment];
        return;
      }
      returnData = null;
    });
    return returnData;
  }

}