using System;

using Quartz;

using NCrontab;

using System.Linq;

public class Program

{

    public static void Main()

    {

        string[] cronExpressions = {

            "0 0 12 ? * MON-FRI *",  // Valid Quartz cron

            "0 0 * * *",            // Valid Unix cron

            "0 0 0 ? * * *",        // Valid Quartz cron

            "0 15 10 * * ?",        // Valid Quartz cron

            "0 15 10 * * *",        // Invalid (should be Unix but has 6 fields)

            "0 15 * * * *",          // Invalid Unix cron (6 fields)

            "* * * 06 *",

            "99 0 0 ? * * *"

        };

​

        foreach (var cron in cronExpressions)

        {

            Console.WriteLine($"Cron: {cron} -> {ValidateCron(cron)}");

        }

    }

    static string ValidateCron(string cron)

    {

        int fieldCount = cron.Split(' ').Length;

​

        if (fieldCount == 5)

        {

            return ValidateUnixCron(cron) ? "✅ Valid Unix Cron" : "❌ Invalid Unix Cron";

        }

        else if (fieldCount == 6 || fieldCount == 7)

        {

            return ValidateQuartzCron(cron) ? "✅ Valid Quartz Cron" : "❌ Invalid Quartz Cron";

        }

        return "❌ Invalid Cron Expression";

    }

​

    static bool ValidateUnixCron(string cron)

    {

        try

        {

            _ = CrontabSchedule.Parse(cron);

            return true;

        }

        catch

        {

            return false;

        }

    }

​

    static bool ValidateQuartzCron(string cron)

    {

        if (!CronExpression.IsValidExpression(cron))

            return false;

​

        string[] fields = cron.Split(' ');

​

        // Field Ranges (Quartz 7-field cron: second, minute, hour, dayOfMonth, month, dayOfWeek, year)

        int[][] validRanges = {

            new int[] { 0, 59 },  // Seconds (0-59)

            new int[] { 0, 59 },  // Minutes (0-59)

            new int[] { 0, 23 },  // Hours (0-23)

            new int[] { 1, 31 },  // Day of Month (1-31) or '?'

            new int[] { 1, 12 },  // Month (1-12 or JAN-DEC)

            new int[] { 0, 6 },   // Day of Week (0-6 or SUN-SAT) or '?'

            new int[] { 1970, 2099 } // Year (optional)

        };

​

        for (int i = 0; i < validRanges.Length && i < fields.Length; i++)

        {

            if (!IsValidCronField(fields[i], validRanges[i]))

                return false;

        }

​

        return true;

    }

​

    static bool IsValidCronField(string field, int[] range)

    {

        Console.WriteLine(field);

        if (field == "?" || field == "*" || field.Contains("-"))

            return true;

​

        if (field.All(char.IsDigit))

        {

            if (int.TryParse(field, out int num))

                return num >= range[0] && num <= range[1];

        }

        return false;

    }

}