import java.awt.Color;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Hashtable;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfContentByte;
import com.lowagie.text.pdf.PdfGState;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfStamper;
import com.lowagie.text.pdf.PdfWriter;
import com.zeus.ZXTMServlet.ZXTMHttpServletResponse;

public class PdfWatermark extends HttpServlet {
	private static final long serialVersionUID = 1L;

	Hashtable<String, String> defaults = new Hashtable<String, String>();

	public void init(ServletConfig config) throws ServletException {
		super.init(config);

		// Initialize defaults.  These are 'commands' that are run before any commands
		// passed in to the extension through the args list
		defaults.put("x", "30");
		defaults.put("y", "30");
		defaults.put("textAngle", "auto");
		defaults.put("textAlign", "L");
		defaults.put("textAlpha", "75");
		defaults.put("textSize", "20");
		defaults.put("textColor", "0xAAAAAA");

		// Read any values defined in the ZXTM configuration for this class
		// to override the defaults
		Enumeration<String> e = defaults.keys();
		while (e.hasMoreElements()) {
			String k = e.nextElement();
			String v = config.getInitParameter(k);
			if (v != null)
				defaults.put(k, v);
		}
	}

	public void doGet(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		try {
			ZXTMHttpServletResponse zres = (ZXTMHttpServletResponse) res;

			String ct = zres.getHeader("Content-Type");
			if (ct == null || !ct.startsWith("application/pdf"))
				return;

			// process args
			String[] args = (String[]) req.getAttribute("args");
			if (args == null)
				throw new Exception("Missing argument list");
			if (args.length % 2 != 0)
				throw new Exception(
						"Malformed argument list (expected even number of args)");

			ArrayList<String[]> actions = new ArrayList<String[]>();

			Enumeration<String> e = defaults.keys();
			while (e.hasMoreElements()) {
				String k = e.nextElement();
				actions.add(new String[] { k, defaults.get(k) });
			}
			for (int i = 0; i < args.length; i += 2) {
				actions.add(new String[] { args[i], args[i + 1] });
			}

			InputStream is = zres.getInputStream();
			OutputStream os = zres.getOutputStream();

			PdfReader reader = new PdfReader(is);

			int n = reader.getNumberOfPages();

			PdfStamper stamp = new PdfStamper(reader, os);
			stamp.setEncryption(
					PdfWriter.STANDARD_ENCRYPTION_128 | PdfWriter.DO_NOT_ENCRYPT_METADATA, 
					null, null,
					PdfWriter.ALLOW_PRINTING | PdfWriter.ALLOW_COPY
						| PdfWriter.ALLOW_FILL_IN | PdfWriter.ALLOW_SCREENREADERS
						| PdfWriter.ALLOW_DEGRADED_PRINTING);

			for (int i = 1; i <= n; i++) {
				PdfContentByte pageContent = stamp.getOverContent(i);
				com.lowagie.text.Rectangle pageSize = reader
						.getPageSizeWithRotation(i);

				watermarkPage(pageContent, actions, pageSize.getWidth(),
						pageSize.getHeight());
			}

			stamp.close();

		} catch (Exception e) {
			log(req.getRequestURI() + ": " + e.toString());
			e.printStackTrace();
		}
	}

	public void doPost(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		doGet(req, res);
	}

	private void watermarkPage(PdfContentByte pageContent,
			ArrayList<String[]> actions, float width, float height)
			throws Exception {
		float x = 0;
		float y = 0;
		double textAngle = 0;
		int textAlign = PdfContentByte.ALIGN_CENTER;
		int fontSize = 14;

		pageContent.beginText();

		for (int i = 0; i < actions.size(); i++) {
			String action = actions.get(i)[0];
			String value = actions.get(i)[1];

			if (action.equals("x")) {
				x = Float.parseFloat(value) / 100 * width;
				continue;
			}

			if (action.equals("y")) {
				y = Float.parseFloat(value) / 100 * height;
				continue;
			}

			if (action.equals("textColor")) {
				pageContent.setColorFill(Color.decode(value));
				continue;
			}

			if (action.equals("textAlpha")) {
				PdfGState gs1 = new PdfGState();
				gs1.setFillOpacity(Float.parseFloat(value) / 100f);
				pageContent.setGState(gs1);
				continue;
			}

			if (action.equals("textAngle")) {
				if (value.equals("auto")) {
					textAngle = (float) Math.atan2(height, width);
				} else {
					textAngle = Math.toRadians( Double.parseDouble(value) );
				}
				continue;
			}

			if (action.equals("textAlign")) {
				if (value.equals("L"))
					textAlign = PdfContentByte.ALIGN_LEFT;
				else if (value.equals("R"))
					textAlign = PdfContentByte.ALIGN_RIGHT;
				else
					textAlign = PdfContentByte.ALIGN_CENTER;
				continue;
			}

			if (action.equals("textSize")) {
				fontSize = Integer.parseInt(value);
				pageContent.setFontAndSize(BaseFont
						.createFont(BaseFont.HELVETICA, BaseFont.WINANSI,
								BaseFont.EMBEDDED), fontSize);
				continue;
			}

			// x,y is top left/center/right of text, so that when we move the
			// cursor at the end of a line, we can cater for subsequent fontSize 
			// changes
			if (action.equals("drawText")) {
				pageContent.showTextAligned(textAlign, value,
						(float) (x + fontSize * Math.sin(textAngle)),
						(float) (y - fontSize * Math.cos(textAngle)),
						(float) Math.toDegrees(textAngle));

				x += fontSize * 1.2 * Math.sin(textAngle);
				y -= fontSize * 1.2 * Math.cos(textAngle);
				continue;
			}

			throw new Exception("Unknown command '" + action + "'");
		}

		pageContent.endText();
	}
}