/*******************************************************************************
 * Copyright (c) 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jst.jsp.ui.internal.taginfo;


import java.io.IOException;
import java.io.Reader;
import java.net.URL;

import org.eclipse.jst.jsp.ui.internal.Logger;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Display;


/**
 * Provides a set of convenience methods for creating HTML pages.
 * 
 * Based on org.eclipse.jdt.internal.ui.text.HTMLPrinter
 */
class HTMLPrinter {

	static RGB BG_COLOR_RGB = null;

	static {
		// try to do in advance
		getSystemBGColor();
	}

	private static RGB getSystemBGColor() {
		RGB result = null;
		if (BG_COLOR_RGB == null) {
			final Display display = Display.getCurrent();
			if (display != null && !display.isDisposed()) {

				display.asyncExec(new Runnable() {
					public void run() {
						if (display != null && !display.isDisposed()) {
							BG_COLOR_RGB = display.getSystemColor(SWT.COLOR_INFO_BACKGROUND).getRGB();
						}
					}
				});

			}
		}
		else {
			result = BG_COLOR_RGB;
		}
		return result;
	}

	private HTMLPrinter() {
		super();
	}

	private static String replace(String text, char c, String s) {

		int previous = 0;
		int current = text.indexOf(c, previous);

		if (current == -1)
			return text;

		StringBuffer buffer = new StringBuffer();
		while (current > -1) {
			buffer.append(text.substring(previous, current));
			buffer.append(s);
			previous = current + 1;
			current = text.indexOf(c, previous);
		}
		buffer.append(text.substring(previous));

		return buffer.toString();
	}

	public static String convertToHTMLContent(String content) {
		content = replace(content, '<', "&lt;"); //$NON-NLS-1$
		return replace(content, '>', "&gt;"); //$NON-NLS-1$
	}

	static String read(Reader rd) {

		StringBuffer buffer = new StringBuffer();
		char[] readBuffer = new char[2048];

		try {
			int n = rd.read(readBuffer);
			while (n > 0) {
				buffer.append(readBuffer, 0, n);
				n = rd.read(readBuffer);
			}
			return buffer.toString();
		}
		catch (IOException x) {
			// never expected
			Logger.logException(x);
		}

		return null;
	}

	public static void insertPageProlog(StringBuffer buffer, int position, RGB bgRGB, URL styleSheetURL) {

		if (bgRGB == null)
			insertPageProlog(buffer, position, styleSheetURL);
		else {
			StringBuffer pageProlog = new StringBuffer(300);

			pageProlog.append("<html>"); //$NON-NLS-1$

			appendStyleSheetLink(pageProlog, styleSheetURL);

			pageProlog.append("<body text=\"#000000\" bgcolor=\""); //$NON-NLS-1$
			appendColor(pageProlog, bgRGB);
			pageProlog.append("\"><font size=-1>"); //$NON-NLS-1$

			buffer.insert(position, pageProlog.toString());
		}
	}

	public static void insertPageProlog(StringBuffer buffer, int position, RGB bgRGB) {
		if (bgRGB == null)
			insertPageProlog(buffer, position);
		else {
			StringBuffer pageProlog = new StringBuffer(60);
			pageProlog.append("<html><body text=\"#000000\" bgcolor=\""); //$NON-NLS-1$
			appendColor(pageProlog, bgRGB);
			pageProlog.append("\"><font size=-1>"); //$NON-NLS-1$
			buffer.insert(position, pageProlog.toString());
		}
	}

	private static void appendStyleSheetLink(StringBuffer buffer, URL styleSheetURL) {
		if (styleSheetURL == null)
			return;

		buffer.append("<head>"); //$NON-NLS-1$

		buffer.append("<LINK REL=\"stylesheet\" HREF= \""); //$NON-NLS-1$
		buffer.append(styleSheetURL);
		buffer.append("\" CHARSET=\"ISO-8859-1\" TYPE=\"text/css\">"); //$NON-NLS-1$

		buffer.append("</head>"); //$NON-NLS-1$
	}

	private static void appendColor(StringBuffer buffer, RGB rgb) {
		buffer.append('#');
		buffer.append(Integer.toHexString(rgb.red));
		buffer.append(Integer.toHexString(rgb.green));
		buffer.append(Integer.toHexString(rgb.blue));
	}

	public static void insertPageProlog(StringBuffer buffer, int position) {
		insertPageProlog(buffer, position, getBgColor()); //$NON-NLS-1$
	}

	public static void insertPageProlog(StringBuffer buffer, int position, URL styleSheetURL) {
		insertPageProlog(buffer, position, getBgColor(), styleSheetURL); //$NON-NLS-1$
	}

	static RGB getBgColor() {
		RGB result = getSystemBGColor();
		if (result == null) {
			// use RGB value of default info bg color
			// on WindowsXP
			result = new RGB(255, 255, 225);
		}
		return result;

	}

	public static void addPageProlog(StringBuffer buffer) {
		insertPageProlog(buffer, buffer.length());
	}

	public static void addPageEpilog(StringBuffer buffer) {
		buffer.append("</font></body></html>"); //$NON-NLS-1$
	}

	public static void startBulletList(StringBuffer buffer) {
		buffer.append("<ul>"); //$NON-NLS-1$
	}

	public static void endBulletList(StringBuffer buffer) {
		buffer.append("</ul>"); //$NON-NLS-1$
	}

	public static void addBullet(StringBuffer buffer, String bullet) {
		if (bullet != null) {
			buffer.append("<li>"); //$NON-NLS-1$
			buffer.append(bullet);
			buffer.append("</li>"); //$NON-NLS-1$
		}
	}

	public static void addSmallHeader(StringBuffer buffer, String header) {
		if (header != null) {
			buffer.append("<h5>"); //$NON-NLS-1$
			buffer.append(header);
			buffer.append("</h5>"); //$NON-NLS-1$
		}
	}

	public static void addParagraph(StringBuffer buffer, String paragraph) {
		if (paragraph != null) {
			buffer.append("<p>"); //$NON-NLS-1$
			buffer.append(paragraph);
		}
	}

	public static void addParagraph(StringBuffer buffer, Reader paragraphReader) {
		if (paragraphReader != null)
			addParagraph(buffer, read(paragraphReader));
	}
}