itextpdf-master/itext/src/main/java/com/itextpdf/text/factories/RomanNumberFactory.java
/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2022 iText Group NV
 * Authors: Bruno Lowagie, Paulo Soares, et al.
 *
 * This program is free software; you can redistribute it and/or modify
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package com.itextpdf.text.factories;
/**
 * This class can produce String combinations representing a roman number.
 */
public class RomanNumberFactory {
	/**
	 * Helper class for Roman Digits
	 */
	private static class RomanDigit {

		/** part of a roman number */
		public char digit;

		/** value of the roman digit */
		public int value;

		/** can the digit be used as a prefix */
		public boolean pre;

		/**
		 * Constructs a roman digit
		 * @param digit the roman digit
		 * @param value the value
		 * @param pre can it be used as a prefix
		 */
		RomanDigit(final char digit, final int value, final boolean pre) {
			this.digit = digit;
			this.value = value;
			this.pre = pre;
		}
	}

	/**
	 * Array with Roman digits.
	 */
	private static final RomanDigit[] roman = {
		new RomanDigit('m', 1000, false),
		new RomanDigit('d', 500, false),
		new RomanDigit('c', 100, true),
		new RomanDigit('l', 50, false),
		new RomanDigit('x', 10, true),
		new RomanDigit('v', 5, false),
		new RomanDigit('i', 1, true)
	};

	/**
	 * Changes an int into a lower case roman number.
	 * @param index the original number
	 * @return the roman number (lower case)
	 */
	public static final String getString(int index) {
		StringBuffer buf = new StringBuffer();

		// lower than 0 ? Add minus
		if (index < 0) {
			buf.append('-');
			index = -index;
		}

		// greater than 3000
		if (index > 3000) {
			buf.append('|');
			buf.append(getString(index / 1000));
			buf.append('|');
			// remainder
			index = index - (index / 1000) * 1000;
		}

		// number between 1 and 3000
		int pos = 0;
		while (true) {
			// loop over the array with values for m-d-c-l-x-v-i
			RomanDigit dig = roman[pos];
			// adding as many digits as we can
			while (index >= dig.value) {
				buf.append(dig.digit);
				index -= dig.value;
			}
			// we have the complete number
			if (index <= 0) {
				break;
			}
			// look for the next digit that can be used in a special way
			int j = pos;
			while (!roman[++j].pre);

			// does the special notation apply?
			if (index + roman[j].value >= dig.value) {
				buf.append(roman[j].digit).append(dig.digit);
				index -= dig.value - roman[j].value;
			}
			pos++;
		}
		return buf.toString();
	}

	/**
	 * Changes an int into a lower case roman number.
	 * @param index the original number
	 * @return the roman number (lower case)
	 */
	public static final String getLowerCaseString(final int index) {
		return getString(index);
	}

	/**
	 * Changes an int into an upper case roman number.
	 * @param index the original number
	 * @return the roman number (lower case)
	 */
	public static final String getUpperCaseString(final int index) {
		return getString(index).toUpperCase();
	}

	/**
	 * Changes an int into a roman number.
	 * @param index the original number
	 * @param lowercase true for lowercase, false otherwise
	 * @return the roman number (lower case)
	 */
	public static final String getString(final int index, final boolean lowercase) {
		if (lowercase) {
			return getLowerCaseString(index);
		}
		else {
			return getUpperCaseString(index);
		}
	}
}
