/**
 * i-net software provides programming examples for illustration only, without warranty
 * either expressed or implied, including, but not limited to, the implied warranties
 * of merchantability and/or fitness for a particular purpose. This programming example
 * assumes that you are familiar with the programming language being demonstrated and
 * the tools used to create and debug procedures. i-net software support professionals
 * can help explain the functionality of a particular procedure, but they will not modify
 * these examples to provide added functionality or construct procedures to meet your
 * specific needs.
 *
 * Copyright © 1999-2025 i-net software GmbH, Berlin, Germany.
**/
package com.inet.samples.formula;

import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Properties;
import java.util.regex.Pattern;

import javax.imageio.ImageIO;

import com.inet.report.Engine;
import com.inet.report.formula.UserDefinedFunction;

/**
 * This class shows the usage of user defined Java methods in formulas of an i-net Clear Reports report.<br>
 * <br>
 * You can find more information about user defined formulas in the section "Programming" of the i-net Clear Reports
 * documentation.<br>
 * <br>
 * i-net Clear Reports adds the methods of this class to the functions, that can be used in a formula, if you set the
 * fully qualified class name (e.g. samples.userdefined_formula.FormulaSample) of this class in the property
 * "Formula Expander Class". You can find it in the dialog "Customization" of the Configuration Manager.<br>
 * <br>
 * Also, it is necessary to add this class file to the classpath. You can do this, for example, by creating a jar file
 * containing this class and all help files (with command
 * "jar cf formula-sample.jar samples/userdefined_formula/FormulaSample.class samples/userdefined_formula/*.html") and
 * copying this jar file into the "lib" directory that is included in the installation directory of i-net Clear Reports
 * or i-net Designer.<br>
 * <br>
 * Since version 13 it is possible to use one or more of the following hidden parameters as method parameter in the
 * formula expander class: "Engine", "HTTPSession" and "HTTPServletRequest". This can be useful, for example, to use the
 * Engine API to get user defined parameters from the report engine.
 */
public class FormulaSample implements UserDefinedFunction {

    /**
     * Calendar for date operations. You can see this user defined constant in the list of constants in the formula
     * editor.
     */
    public static final GregorianCalendar GREGCALENDAR = new GregorianCalendar();

    /**
     * Returns an array of length n containing the first even natural numbers, starting with 0. firstEvens(5) will
     * return [0,2,4,6,8].
     * @param n length of returned list of even numbers.
     * @return Number[] containing the first even natural numbers
     */
    public static Number[] firstEvens( Number n ) {
        int n_ = n.intValue();
        Integer[] evens = new Integer[n_];
        for( int i = 0; i < n_; i++ ) {
            evens[i] = 2 * i;
        }
        return evens;
    }

    /**
     * Returns an array of length n containing the first odd natural numbers, starting with 1. firstOdds(5) will return
     * [1,3,5,7,9].
     * @param n length of returned list of odd numbers.
     * @return Number[] containing the first odd natural numbers
     */
    public static Number[] firstOdds( Number n ) {
        int n_ = n.intValue();
        Integer[] odds = new Integer[n_];
        for( int i = 0; i < n_; i++ ) {
            odds[i] = 2 * i + 1;
        }
        return odds;
    }

    /**
     * Returns the factorial of n. Parameter n have to be less than 21.
     * @param n number to return factorial for
     * @return factorial of n
     * @throws IllegalArgumentException if n is 21 or greater
     */
    public static Number factorial( Number n ) {
        if( !(n.intValue() <= 20) ) {
            throw new IllegalArgumentException();
        }
        return Long.valueOf( factorial( n.intValue() ) );
    }

    /**
     * Computes factorial of n.
     * @param n number to compute factorial for
     * @return factorial of n
     */
    private static long factorial( int n ) {
        if( n == 0 ) {
            return 1;
        }
        return n * factorial( n - 1 );
    }

    /**
     * Validates a alpha-numerical number string of formats ddddd-AAA-dddddd.
     * @param serialstring string to verify pattern for.
     * @return Boolean.TRUE if pattern matches, else Boolean.FALSE
     */
    public static Boolean verify( String serialstring ) {
        return Pattern.matches( "[0-9]{5}-[A-Z]{3}-[0-9]{6}", serialstring );
    }

    /**
     * Validates a string of formats regex. See Java Doc for details.
     * @param regex Regular expression to use to verify arg
     * @param arg string to verify
     * @return result of Pattern.matches(regex, arg) as Boolean
     */
    public static Boolean verify( String regex, String arg ) {
        return Pattern.matches( regex, arg );
    }

    /**
     * Returns if year is a leap year. Use for values of i-net Clear Reports type Date.
     * @param date date to check whether its year is a leap year.
     * @return whether the year of the given date is a leap year
     */
    public static Boolean leapYear( java.sql.Date date ) {
        return GREGCALENDAR.isLeapYear( Calendar.getInstance().get( Calendar.YEAR ) - 1900 );
    }

    /**
     * Returns if year is a leap year. Use for values of i-net Clear Reports type Datetime.
     * @param date date time to check whether its year is a leap year
     * @return whether the year of the given date time is a leap year
     */
    public static Boolean leapYear( java.sql.Timestamp date ) {
        return GREGCALENDAR.isLeapYear( Calendar.getInstance().get( Calendar.YEAR ) - 1900 );
    }

    /**
     * This function will roll up the hour field of the time value (in range between 0 and 23).
     * @param time time object to roll hour up for
     * @return time with hour rolled up by one
     */
    public static java.sql.Time rollHour( java.sql.Time time ) {
        GregorianCalendar gCal =
            new GregorianCalendar( 1970, 1, 1, Calendar.getInstance().get( Calendar.HOUR_OF_DAY ), Calendar.getInstance().get( Calendar.MINUTE ),
                                   Calendar.getInstance().get( Calendar.SECOND ) );
        gCal.roll( Calendar.HOUR, 1 );
        return new java.sql.Time( gCal.getTimeInMillis() );
    }

    /**
     * Returns true if parity of boolean array args is even.
     * @param args parameter expected to be a Boolean array
     * @return Boolean if Boolean array has an even parity
     * @throws IllegalArgumentException if args is not a Boolean array.
     */
    public static Boolean evenParity( Object[] args ) {
        int count = 0;
        for( int i = 0; i < args.length; i++ ) {
            if( !(args[i] instanceof Boolean) ) {
                throw new IllegalArgumentException( "Boolean expected." );
            }
            if( args[i].equals( Boolean.TRUE ) ) {
                count++;
            }
        }
        return count % 2 == 0;
    }

    /**
     * Draws a String "Demo" at Position (10,10) of the image in <code>bytes</code>. If an error occurs, the original
     * byte[] is returned.
     * @param bytes image data to draw into
     * @return the manipulated image; If manipulation fails the original image is returned.
     */
    public static byte[] drawDemoToImage( byte[] bytes ) {
        try {
            ByteArrayInputStream bais = new ByteArrayInputStream( bytes );
            BufferedImage img = ImageIO.read( bais );
            Graphics2D g2d = img.createGraphics();
            g2d.drawString( "Demo", 10, 10 );
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            ImageIO.write( img, "png", out );
            return out.toByteArray();
        } catch( Exception e ) {
            e.printStackTrace();
        }
        return bytes;
    }

    /**
     * Returns the value of a user property that has been set either with engine.setUserProperties(), checkProperties()
     * or in the report URL.
     * @param propertyKey the key of the property
     * @param engine the report engine instance
     * @return the user property value or an empty string, if it does not exists
     */
    static public String getUserProperty( String propertyKey, Engine engine ) {
        Properties properties = engine.getUserProperties();
        if( properties != null ) {
            return properties.getProperty( propertyKey, "" );
        } else {
            return "";
        }
    }
}