static DateTime _parseCookieDate()

in packages/devtools_app/lib/src/http/_http_date.dart [275:407]
116 lines of code
65 McCabe index (conditional complexity)

  static DateTime _parseCookieDate(String date) {
    const List monthsLowerCase = const [
      "jan",
      "feb",
      "mar",
      "apr",
      "may",
      "jun",
      "jul",
      "aug",
      "sep",
      "oct",
      "nov",
      "dec"
    ];

    int position = 0;

    void error() {
      throw new HttpException("Invalid cookie date $date");
    }

    bool isEnd() => position == date.length;

    bool isDelimiter(String s) {
      int char = s.codeUnitAt(0);
      if (char == 0x09) return true;
      if (char >= 0x20 && char <= 0x2F) return true;
      if (char >= 0x3B && char <= 0x40) return true;
      if (char >= 0x5B && char <= 0x60) return true;
      if (char >= 0x7B && char <= 0x7E) return true;
      return false;
    }

    bool isNonDelimiter(String s) {
      int char = s.codeUnitAt(0);
      if (char >= 0x00 && char <= 0x08) return true;
      if (char >= 0x0A && char <= 0x1F) return true;
      if (char >= 0x30 && char <= 0x39) return true; // Digit
      if (char == 0x3A) return true; // ':'
      if (char >= 0x41 && char <= 0x5A) return true; // Alpha
      if (char >= 0x61 && char <= 0x7A) return true; // Alpha
      if (char >= 0x7F && char <= 0xFF) return true; // Alpha
      return false;
    }

    bool isDigit(String s) {
      int char = s.codeUnitAt(0);
      if (char > 0x2F && char < 0x3A) return true;
      return false;
    }

    int getMonth(String month) {
      if (month.length < 3) return -1;
      return monthsLowerCase.indexOf(month.substring(0, 3));
    }

    int toInt(String s) {
      int index = 0;
      for (; index < s.length && isDigit(s[index]); index++) {
        ;
      }
      return int.parse(s.substring(0, index));
    }

    var tokens = [];
    while (!isEnd()) {
      while (!isEnd() && isDelimiter(date[position])) {
        position++;
      }
      int start = position;
      while (!isEnd() && isNonDelimiter(date[position])) {
        position++;
      }
      tokens.add(date.substring(start, position).toLowerCase());
      while (!isEnd() && isDelimiter(date[position])) {
        position++;
      }
    }

    String timeStr;
    String dayOfMonthStr;
    String monthStr;
    String yearStr;

    for (var token in tokens) {
      if (token.length < 1) continue;
      if (timeStr == null &&
          token.length >= 5 &&
          isDigit(token[0]) &&
          (token[1] == ":" || (isDigit(token[1]) && token[2] == ":"))) {
        timeStr = token;
      } else if (dayOfMonthStr == null && isDigit(token[0])) {
        dayOfMonthStr = token;
      } else if (monthStr == null && getMonth(token) >= 0) {
        monthStr = token;
      } else if (yearStr == null &&
          token.length >= 2 &&
          isDigit(token[0]) &&
          isDigit(token[1])) {
        yearStr = token;
      }
    }

    if (timeStr == null ||
        dayOfMonthStr == null ||
        monthStr == null ||
        yearStr == null) {
      error();
    }

    int year = toInt(yearStr);
    if (year >= 70 && year <= 99) {
      year += 1900;
    } else if (year >= 0 && year <= 69) year += 2000;
    if (year < 1601) error();

    int dayOfMonth = toInt(dayOfMonthStr);
    if (dayOfMonth < 1 || dayOfMonth > 31) error();

    int month = getMonth(monthStr) + 1;

    var timeList = timeStr.split(":");
    if (timeList.length != 3) error();
    int hour = toInt(timeList[0]);
    int minute = toInt(timeList[1]);
    int second = toInt(timeList[2]);
    if (hour > 23) error();
    if (minute > 59) error();
    if (second > 59) error();

    return new DateTime.utc(year, month, dayOfMonth, hour, minute, second);
  }