TF-EssentialsX/Essentials/src/com/earth2me/essentials/textreader/BookPager.java

package com.earth2me.essentials.textreader;

import static com.earth2me.essentials.I18n.tl;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.Map;


public class BookPager
{
	private final transient IText text;
	final double pageMax = 254;
	final double charMax = 18.5;
	final int lineMax = 12;

	public BookPager(final IText text)
	{
		this.text = text;
	}

	public List<String> getPages(final String pageStr) throws Exception
	{
		List<String> lines = text.getLines();
		List<String> chapters = text.getChapters();
		List<String> pageLines = new ArrayList<String>();
		Map<String, Integer> bookmarks = text.getBookmarks();

		//This checks to see if we have the chapter in the index
		if (!bookmarks.containsKey(pageStr.toLowerCase(Locale.ENGLISH)))
		{
			throw new Exception(tl("infoUnknownChapter"));
		}

		//Since we have a valid chapter, count the number of lines in the chapter
		final int chapterstart = bookmarks.get(pageStr.toLowerCase(Locale.ENGLISH)) + 1;
		int chapterend;
		for (chapterend = chapterstart; chapterend < lines.size(); chapterend++)
		{
			final String line = lines.get(chapterend);
			if (line.length() > 0 && line.charAt(0) == '#')
			{
				break;
			}
		}

		List<String> pages = new ArrayList<String>();
		double pageLength = 0;

		for (int lineNo = chapterstart; lineNo < chapterend; lineNo += 1)
		{
			String pageLine = lines.get(lineNo);
			String tempLine;

			final int lineLength = pageLine.length();
			double length = 0;
			int pointer = 0;
			int start = 0;
			double weight = 1;
			boolean forcePageEnd = false;

			while (pointer < lineLength)
			{
				Character letter = pageLine.charAt(pointer);

				if (pageLine.charAt(start) == ' ')
				{
					start++;
					pointer++;
					continue;
				}

				if (pageLength >= pageMax)
				{
					length = charMax;
					pageLength = 0;
					forcePageEnd = true;
				}

				if (length >= charMax || (letter == '\u00a7' && length + 1 >= charMax))
				{
					int pos = pointer;
					int rollback = 0;
					while (pos > start && pageLine.charAt(pos) != ' ' && pageLine.charAt(pos) != "\n".charAt(0))
					{
						rollback++;
						pos--;
					}
					if (pos != start)
					{
						pointer = pos;
						pageLength -= rollback;
					}

					tempLine = pageLine.substring(start, pointer);
					pageLines.add(tempLine);
					if (buildPage(pages, pageLines, forcePageEnd))
					{
						pageLength = 0;
					}
					forcePageEnd = false;

					start = pointer;
					length = 0;
					pageLength += 1;
				}

				pageLength++;

				if (letter == '\u00a7' && pointer + 1 < lineLength)
				{
					Character nextLetter = pageLine.charAt(pointer + 1);
					if (nextLetter == 'l' || nextLetter == 'L')
					{
						weight = 1.25;
					}
					else
					{
						weight = 1;
					}
					pointer++;
				}
				else if (letter == 'i' || letter == '.' || letter == ',' || letter == '!' || letter == ':' || letter == ';' || letter == '|')
				{
					length += (0.34 * weight);
				}
				else if (letter == 'l' || letter == '\'' || letter == '`')
				{
					length += (0.53 * weight);
				}
				else if (letter == ' ' || letter == 't' || letter == 'I' || letter == '[' || letter == ']')
				{
					length += (0.69 * weight);
				}
				else if (letter == 'f' || letter == 'k' || letter == '"' || letter == '*'
						 || letter == '(' || letter == ')' || letter == '{' || letter == '}' || letter == '<' || letter == '>')
				{
					length += (0.85 * weight);
				}
				else if (letter == '@' || letter == '~')
				{
					length += (1.2 * weight);
				}
				else
				{
					length += weight;
				}
				pointer++;
			}

			if (length > 0)
			{
				tempLine = pageLine.substring(start, lineLength);
				pageLines.add(tempLine);
				if (buildPage(pages, pageLines, false))
				{
					pageLength = 0;
				}
			}
		}

		buildPage(pages, pageLines, true);
		return pages;
	}

	boolean buildPage(List<String> pages, List<String> lines, boolean override)
	{
		if (override || lines.size() > lineMax)
		{
			StringBuilder newPage = new StringBuilder();
			for (String aline : lines)
			{
				newPage.append(aline).append("\n");
			}
			pages.add(newPage.toString());
			lines.clear();
			return true;
		}
		return false;
	}
}