org.verapdf.tools.PageLabels Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of parser Show documentation
veraPDF tools for parsing, modifying and creating PDF documents.
There is a newer version: 1.26.1
package org.verapdf.tools;

import org.verapdf.as.ASAtom;
import org.verapdf.cos.COSArray;
import org.verapdf.cos.COSDictionary;
import org.verapdf.cos.COSObjType;
import org.verapdf.cos.COSObject;

import java.util.Map;
import java.util.TreeMap;

/**
 * @author Maksim Bezrukov
 */
public class PageLabels {

	private final TreeMap labelsMap;

	public PageLabels(COSDictionary numbTree) {
		if (numbTree == null) {
			throw new IllegalArgumentException("Number tree base element can not be null");
		}
		labelsMap = new TreeMap<>();
		parseTree(numbTree);
	}

	private void parseTree(COSDictionary numbTree) {
		COSObject nums = numbTree.getKey(ASAtom.NUMS);
		if (nums != null && !nums.empty() && nums.getType() == COSObjType.COS_ARRAY) {
			addLabelsFromArray((COSArray) nums.getDirectBase());
		}

		COSObject kids = numbTree.getKey(ASAtom.KIDS);
		if (kids != null && !kids.empty() && kids.getType() == COSObjType.COS_ARRAY) {
			for (COSObject kid : (COSArray) kids.getDirectBase()) {
				if (kid != null && !kid.empty() && kid.getType() == COSObjType.COS_DICT) {
					parseTree((COSDictionary) kid.getDirectBase());
				}
			}
		}
	}

	private void addLabelsFromArray(COSArray nums) {
		for (int i = 0; i < nums.size(); i+=2) {
			COSObject cosKey = nums.at(i);
			Long key = cosKey == null ? null : cosKey.getInteger();
			COSObject cosValue = nums.at(i+1);
			if (key != null && cosValue != null && !cosValue.empty() && cosValue.getType() == COSObjType.COS_DICT) {
				PageLabelDictionary pageLabelDictionary = new PageLabelDictionary((COSDictionary) cosValue.getDirectBase(), key.intValue());
				this.labelsMap.put(key.intValue(), pageLabelDictionary);
			}
		}
	}

	public String getLabel(int pageIndex) {
		Map.Entry pageLabelDictionaryEntry = labelsMap.floorEntry(pageIndex);
		if (pageLabelDictionaryEntry != null) {
			return pageLabelDictionaryEntry.getValue().getLabel(pageIndex);
		}
		return null;
	}

	private static class PageLabelDictionary {

		private final static TreeMap MAP = new TreeMap<>();

		static {
			MAP.put(1000, "M");
			MAP.put(900, "CM");
			MAP.put(500, "D");
			MAP.put(400, "CD");
			MAP.put(100, "C");
			MAP.put(90, "XC");
			MAP.put(50, "L");
			MAP.put(40, "XL");
			MAP.put(10, "X");
			MAP.put(9, "IX");
			MAP.put(5, "V");
			MAP.put(4, "IV");
			MAP.put(1, "I");
		}

		private final ASAtom type;
		private final String prefix;
		private final int firstRangePortion;
		private final int rangeStartIndex;

		public PageLabelDictionary(COSDictionary dict, int rangeStartIndex) {
			this.type = dict.getNameKey(ASAtom.S);
			String prefixValue = dict.getStringKey(ASAtom.P);
			this.prefix = prefixValue == null ? "" : prefixValue;
			Long integerKey = dict.getIntegerKey(ASAtom.ST);
			this.firstRangePortion = integerKey == null ? 1 : integerKey.intValue();
			this.rangeStartIndex = rangeStartIndex;
		}

		public String getLabel(int pageIndex) {
			if (pageIndex < rangeStartIndex) {
				throw new IllegalArgumentException("Page index can not be less than range start index");
			}
			int pageNumber = getLabelNumber(pageIndex);
			String number = getTypedNumber(pageNumber);
			return this.prefix + number;
		}

		private String getTypedNumber(int pageNumber) {
			if (ASAtom.D == this.type) {
				return String.valueOf(pageNumber);
			} else if (ASAtom.R == this.type) {
				return getRoman(pageNumber);
			} else if (ASAtom.R_LOWERCASE == this.type) {
				return getRoman(pageNumber).toLowerCase();
			} else if (ASAtom.A == this.type) {
				return getLetters(pageNumber);
			} else if (ASAtom.A_LOWERCASE == this.type) {
				return getLetters(pageNumber).toLowerCase();
			} else {
				return "";
			}
		}

		private static String getLetters(int pageNumber) {
			int numb = pageNumber - 1;
			int remainder = numb % 26;
			char letter = (char) ('A' + remainder);
			int numberOfLetters = numb / 26 + 1;
			StringBuilder builder = new StringBuilder();
			for (int i = 0; i < numberOfLetters; ++i) {
				builder.append(letter);
			}
			return builder.toString();
		}

		private static String getRoman(int pageNumber) {
			int curr = pageNumber;
			StringBuilder builder = new StringBuilder();
			while (curr > 0) {
				int floor =  MAP.floorKey(curr);
				builder.append(MAP.get(floor));
				curr -= floor;
			}
			return builder.toString();
		}

		private int getLabelNumber(int pageIndex) {
			return pageIndex - rangeStartIndex + firstRangePortion;
		}
	}
}