package com.something.eclipse.script.contentassist;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.Iterator;

import org.eclipse.swt.custom.StyleRange;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Display;

import org.eclipse.jface.text.DefaultInformationControl;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextPresentation;

public class HTMLTextPresenter implements DefaultInformationControl.IInformationPresenter
{
	private static final String LINE_DELIM = System.getProperty("line.separator","\n"); //$NON-NLS-1$ //$NON-NLS-2$
	private int fCounter;
	private boolean fEnforceUpperLineLimit;

	public HTMLTextPresenter(boolean enforceUpperLineLimit)
	{
		super();
		fEnforceUpperLineLimit = enforceUpperLineLimit;
	}

	public HTMLTextPresenter()
	{
		this(true);
	}

	protected Reader createReader(String hoverInfo, TextPresentation presentation)
	{
		return new HTML2TextReader(new StringReader(hoverInfo),presentation);
	}

	protected void adaptTextPresentation(TextPresentation presentation, int offset, int insertLength)
	{

		int yoursStart = offset;
		int yoursEnd = offset+insertLength-1;
		yoursEnd = Math.max(yoursStart,yoursEnd);

		Iterator e = presentation.getAllStyleRangeIterator();
		while(e.hasNext())
		{

			StyleRange range = (StyleRange)e.next();

			int myStart = range.start;
			int myEnd = range.start+range.length-1;
			myEnd = Math.max(myStart,myEnd);

			if(myEnd<yoursStart)
				continue;

			if(myStart<yoursStart)
				range.length += insertLength;
			else
				range.start += insertLength;
		}
	}

	private void append(StringBuffer buffer, String string, TextPresentation presentation)
	{

		int length = string.length();
		buffer.append(string);

		if(presentation!=null)
			adaptTextPresentation(presentation,fCounter,length);

		fCounter += length;
	}

	private String getIndent(String line)
	{
		int length = line.length();

		int i = 0;
		while(i<length&&Character.isWhitespace(line.charAt(i)))
			++i;

		return (i==length ? line : line.substring(0,i))+" ";
	}

	/*
	 * @see IHoverInformationPresenter#updatePresentation(Display display, String, TextPresentation, int, int)
	 */
	public String updatePresentation(Display display, String hoverInfo, TextPresentation presentation, int maxWidth, int maxHeight)
	{

		if(hoverInfo==null)
			return null;

		GC gc = new GC(display);
		try
		{

			StringBuffer buffer = new StringBuffer();
			int maxNumberOfLines = Math.round(maxHeight/gc.getFontMetrics().getHeight());

			fCounter = 0;
			LineBreakingReader reader = new LineBreakingReader(createReader(hoverInfo,presentation),gc,maxWidth);

			boolean lastLineFormatted = false;
			String lastLineIndent = null;

			String line = reader.readLine();
			boolean lineFormatted = reader.isFormattedLine();
			boolean firstLineProcessed = false;

			while(line!=null)
			{

				if(fEnforceUpperLineLimit&&maxNumberOfLines<=0)
					break;

				if(firstLineProcessed)
				{
					if(!lastLineFormatted)
						append(buffer,LINE_DELIM,null);
					else
					{
						append(buffer,LINE_DELIM,presentation);
						if(lastLineIndent!=null)
							append(buffer,lastLineIndent,presentation);
					}
				}

				append(buffer,line,null);
				firstLineProcessed = true;

				lastLineFormatted = lineFormatted;
				if(!lineFormatted)
					lastLineIndent = null;
				else if(lastLineIndent==null)
					lastLineIndent = getIndent(line);

				line = reader.readLine();
				
				lineFormatted = reader.isFormattedLine();

				maxNumberOfLines--;
			}

			if(line!=null)
			{
				append(buffer,LINE_DELIM,lineFormatted ? presentation : null);
				append(buffer,"...",presentation);
			}

			return trim(buffer,presentation);

		}
		catch(IOException e)
		{

			// ignore TODO do something else?
			return null;

		}
		finally
		{
			gc.dispose();
		}
	}

	private String trim(StringBuffer buffer, TextPresentation presentation)
	{

		int length = buffer.length();

		int end = length-1;
		while(end>=0&&Character.isWhitespace(buffer.charAt(end)))
			--end;

		if(end==-1)
			return "";

		if(end<length-1)
			buffer.delete(end+1,length);
		else
			end = length;

		int start = 0;
		while(start<end&&Character.isWhitespace(buffer.charAt(start)))
			++start;

		buffer.delete(0,start);
		presentation.setResultWindow(new Region(start,buffer.length()));
		return buffer.toString();
	}
}

