Ej 1 DS FINAL

package DateUtilities;

public class DateUtilities {
    /**
     * Indicates whether a year is a leap year . A leap year is divisible by 4,
     * unless it is divisible by 100 , in which case it must be divisible by 400
     * in order to be considered a leap year (e.g., 1900 is not a leap year ,
     * but 2000 is) = > See the JUnit seminar for an example .
     * @param year the given year
     * @return True if the given year is a leap year , false otherwise .
     */
    public static boolean isLeap ( int year ) {
        return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
    }
    /**
     * Indicates the number of days of a given month . As the number of days in
     * the month of February depends on the year , it is also necessary to pass
     * the year as an argument .
     * @param month The given month
     * @param year The given year
     * @return The number of days of that month in that year .
     * @throws IllegalArgumentException if the month is not valid .
     */
    public static int numberOfDays ( int month , int year ) throws IllegalArgumentException{

        if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12){
            return 31;
        }
        else if((month == 4 || month == 6 || month == 9 || month == 11)){
            return 30;
        }
        else if(month==2){
            if(isLeap(year))
                return 29;
            else
                return 28;
        }else{
            throw new IllegalArgumentException("Incorrecto");
        }
    }
    /**
     * The ISO date format is a standard format that displays the dates
     * starting with the year , followed by the month and the day , i.e. ,
     * "YYYY -MM -DD ". For example , in that format the text " July 28 , 2006"
     * would be represented as "2006 -07 -28".
     * The " convertToISO " method converts a date in the " Month DD , AAAA "
     * format to its ISO representation . For simplicity , let us assume that
     * the values are correctly formatted even if the date is invalid
     * (e.g., " February 31 , 2006" is correctly formatted but it is not a valid date )
     *
     * @param dateText Date in textual format ( USA style ).
     * @return A string with the given date in ISO format .
     */
    public static String convertToISODate ( String dateText ) {
        String dia, mes, year;

        String[] partes = dateText.split(" ");


        dia = partes[1].substring(0,partes[1].length()-1);
        mes = ConvierteMes(partes[0]);
        year = partes[2];

        return String.join("-", year, mes, dia);
    }

    public static String ConvierteMes(String mes){
        if (mes.equals("January")) return "01";
        if (mes.equals("February")) return "02";
        if (mes.equals("March")) return "03";
        if (mes.equals("April")) return "04";
        if (mes.equals("May")) return "05";
        if (mes.equals("June")) return "06";
        if (mes.equals("July")) return "07";
        if (mes.equals("August")) return "08";
        if (mes.equals("September")) return "09";
        if (mes.equals("October")) return "10";
        if (mes.equals("November")) return "11";
        if (mes.equals("December")) return "12";
        else{
            return "error";
        }
    }
    /**
     * Given a String representing an ISO - formatted date , the methods checks
     * its validity . This includes checking for non - valid characters , erroneous
     * string lengths , and the validity of the date itself (i.e. , checking the
     * number of days of the month ).
     * @param ISODate A date in ISO format
     * @return True if the ISO - formatted date is a valid date , False otherwise .
     */
    public static boolean checkISODate ( String ISODate ) {
        String[] partes = ISODate.split("-");
        int year, mes, dia;

        //Comprobamos si el año no contiene caracteres inválidos
        try {
            year = Integer.parseInt(partes[0]);
        }
        catch (Exception e){
            return false;
        }
        //Comprobamos si el mes no contiene caracteres invalidos
        try {
            mes = Integer.parseInt(partes[1]);
        }
        catch (Exception e){
            return false;
        }
        //Comprobamos si el día tiene caracteres invalidos
        try {
            dia = Integer.parseInt(partes[2]);
        }
        catch (Exception e){
            return false;
        }

        //Comprobar si tiene guiones
        if(ISODate.equals(partes[0])){
            return false;
        }
        //Comprobar si la longitud es correcta
        if(ISODate.length()!=10){
            return false;
        }
        //Comprobar si el año es menor que 0
        else if(year<0){
            return false;
        }
        //Comprobar si el mes es correcto
        else if(mes<1 || mes>12){
            return false;
        }

        else if(dia<1 || dia>31){
            return false;
        }
        else if((mes == 4 || mes == 6 || mes == 9 || mes == 11) && dia>30){
            return false;
        }
        else if(mes == 2 && dia == 28){
            if (isLeap(year)){
                return false;
            }else
                return true;
        }
        else if(mes == 2 && dia == 29){
            if (isLeap(year)){
                return true;
            }else
                return false;
        }

        else return true;
    }
}