package com.corejsf;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

import javax.faces.component.NamingContainer;
import javax.faces.component.UIComponent;
import javax.faces.component.UIData;
import javax.faces.component.UIForm;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import javax.faces.el.ValueBinding;
import javax.faces.render.Renderer;

import com.linkare.commons.metainfo.Linkare;

@Linkare(author = "Paulo Zenida", comments = "Added from the book Core JSF, 1st Edition")
public class PagerRenderer extends Renderer {

    @Override
    public void encodeBegin(final FacesContext context, final UIComponent component) throws IOException {
	final String id = component.getClientId(context);
	UIComponent parent = component;
	while (!(parent instanceof UIForm))
	    parent = parent.getParent();
	final String formId = parent.getClientId(context);

	final ResponseWriter writer = context.getResponseWriter();

	final String styleClass = (String) get(context, component, "styleClass");
	final String selectedStyleClass = (String) get(context, component, "selectedStyleClass");
	final String dataTableId = (String) get(context, component, "dataTableId");
	Integer a = (Integer) get(context, component, "showpages");
	int showpages = a == null ? 0 : a.intValue();

	// find the component with the given ID

	UIData data = (UIData) findComponent(context.getViewRoot(), getId(dataTableId, id), context);

	if (null == data)
	    return;

	int first = data.getFirst();
	int itemcount = data.getRowCount();
	int pagesize = data.getRows();
	if (pagesize <= 0)
	    pagesize = itemcount;

	int pages = itemcount / pagesize;
	if (itemcount % pagesize != 0) {
	    pages++;
	}

	int currentPage = first / pagesize;
	if (first >= itemcount - pagesize) {
	    currentPage = pages - 1;
	}
	int startPage = 0;
	int endPage = pages;
	if (showpages > 0) {
	    startPage = (currentPage / showpages) * showpages;
	    endPage = Math.min(startPage + showpages, pages);
	}

	if (currentPage > 0) {
	    writeLink(writer, component, formId, id, "<", styleClass);
	}

	if (startPage > 0) {
	    writeLink(writer, component, formId, id, "<<", styleClass);
	}

	for (int i = startPage; i < endPage; i++) {
	    writeLink(writer, component, formId, id, "" + (i + 1), i == currentPage ? selectedStyleClass : styleClass);
	}

	if (endPage < pages) {
	    writeLink(writer, component, formId, id, ">>", styleClass);
	}

	if (first < itemcount - pagesize) {
	    writeLink(writer, component, formId, id, ">", styleClass);
	}

	// hidden field to hold result
	writeHiddenField(writer, component, id);
    }

    private void writeLink(ResponseWriter writer, UIComponent component, String formId, String id, String value, String styleClass)
	    throws IOException {
	writer.writeText(" ", null);
	writer.startElement("a", component);
	writer.writeAttribute("href", "#", null);
	writer.writeAttribute("onclick", onclickCode(formId, id, value), null);
	if (styleClass != null)
	    writer.writeAttribute("class", styleClass, "styleClass");
	writer.writeText(value, null);
	writer.endElement("a");
    }

    private String onclickCode(String formId, String id, String value) {
	StringBuffer buffer = new StringBuffer();
	buffer.append("document.forms[");
	buffer.append("'");
	buffer.append(formId);
	buffer.append("'");
	buffer.append("]['");
	buffer.append(id);
	buffer.append("'].value='");
	buffer.append(value);
	buffer.append("';");
	buffer.append(" document.forms[");
	buffer.append("'");
	buffer.append(formId);
	buffer.append("'");
	buffer.append("].submit()");
	buffer.append("; return false;");
	return buffer.toString();
    }

    private void writeHiddenField(ResponseWriter writer, UIComponent component, String id) throws IOException {
	writer.startElement("input", component);
	writer.writeAttribute("type", "hidden", null);
	writer.writeAttribute("name", id, null);
	writer.endElement("input");
    }

    public void decode(FacesContext context, UIComponent component) {
	String id = component.getClientId(context);
	Map parameters = context.getExternalContext().getRequestParameterMap();
	String response = (String) parameters.get(id);

	String dataTableId = (String) get(context, component, "dataTableId");
	Integer a = (Integer) get(context, component, "showpages");
	int showpages = a == null ? 0 : a.intValue();

	UIData data = (UIData) findComponent(context.getViewRoot(), getId(dataTableId, id), context);

	int first = data.getFirst();
	int itemcount = data.getRowCount();
	int pagesize = data.getRows();
	if (pagesize <= 0)
	    pagesize = itemcount;

	if (response.equals("<")) {
	    first -= pagesize;
	} else if (response.equals(">")) {
	    first += pagesize;
	} else if (response.equals("<<")) {
	    first -= pagesize * showpages;
	} else if (response.equals(">>")) {
	    first += pagesize * showpages;
	} else {
	    int page = Integer.parseInt(response);
	    first = (page - 1) * pagesize;
	}
	if (first + pagesize > itemcount) {
	    first = itemcount - pagesize;
	}
	if (first < 0) {
	    first = 0;
	}
	data.setFirst(first);
    }

    private static Object get(FacesContext context, UIComponent component, String name) {
	ValueBinding binding = component.getValueBinding(name);
	if (binding != null) {
	    return binding.getValue(context);
	} else {
	    return component.getAttributes().get(name);
	}
    }

    @SuppressWarnings("unchecked")
    private static UIComponent findComponent(UIComponent component, String id, FacesContext context) {
	String componentId = component.getClientId(context);
	if (componentId.equals(id))
	    return component;
	Iterator<UIComponent> kids = component.getChildren().iterator();
	while (kids.hasNext()) {
	    UIComponent kid = kids.next();
	    UIComponent found = findComponent(kid, id, context);
	    if (found != null) {
		return found;
	    }
	}
	return null;
    }

    private static String getId(String id, String baseId) {
	String separator = "" + NamingContainer.SEPARATOR_CHAR;
	String[] idSplit = id.split(separator);
	String[] baseIdSplit = baseId.split(separator);
	StringBuffer buffer = new StringBuffer();
	for (int i = 0; i < baseIdSplit.length - idSplit.length; i++) {
	    buffer.append(baseIdSplit[i]);
	    buffer.append(separator);
	}
	buffer.append(id);
	return buffer.toString();
    }
}