package com.ekiras.taglib;

import java.io.Writer;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.SimpleTagSupport;

public class PaginationTaglib extends SimpleTagSupport {
 private String uri;
 private int offset;
 private int count;
 private int max = 10;
 private int steps = 10;
 private String previous = "Previous";
 private String next = "Next";

 private Writer getWriter() {
  JspWriter out = getJspContext().getOut();
  return out;
 }

 @Override
 public void doTag() throws JspException {
  Writer out = getWriter();

  try {
   out.write("<nav>");
   out.write("<ul class=\"pagination\">");
   
   if(offset<steps)
    out.write(constructLink(1, previous, "disabled", true));
   else
    out.write(constructLink(offset-steps, previous, null, false));
   
   for(int itr=0;itr<count;itr+=steps) {
    if(offset==itr)
     out.write(constructLink((itr/10+1)-1 *steps, String.valueOf(itr/10+1), "active", true));
    else
     out.write(constructLink(itr/10*steps, String.valueOf(itr/10+1), null , false));
   }

   if(offset+steps>count)
    out.write(constructLink(offset+steps, next, "disabled", true));
   else
    out.write(constructLink(offset+steps, next, null , false));
   
   
   out.write("</ul>");
   out.write("</nav>");
  } catch (java.io.IOException ex) {
   throw new JspException("Error in Paginator tag", ex);
  }
 }


 private String constructLink(int page, String text, String className, boolean disabled) {
  StringBuilder link = new StringBuilder("<li");
  if (className != null) {
   link.append(" class=\"");
   link.append(className);
   link.append("\"");
  }
  if(disabled)
   link.append(">").append("<a href=\"#\">"+text+"</a></li>");
  else
   link.append(">").append("<a href=\""+uri+"?offset="+page + "\">"+text+"</a></li>");
  return link.toString();
 }

 public String getUri() {
  return uri;
 }

 public void setUri(String uri) {
  this.uri = uri;
 }

 public int getOffset() {
  return offset;
 }

 public void setOffset(int offset) {
  this.offset = offset;
 }

 public int getCount() {
  return count;
 }

 public void setCount(int count) {
  this.count = count;
 }

 public int getMax() {
  return max;
 }

 public void setMax(int max) {
  this.max = max;
 }

 public String getPrevious() {
  return previous;
 }

 public void setPrevious(String previous) {
  this.previous = previous;
 }

 public String getNext() {
  return next;
 }

 public void setNext(String next) {
  this.next = next;
 }

 public int getSteps() {
  return steps;
 }

 public void setSteps(int steps) {
  this.steps = steps;
 }

}

<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.1" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd">
  <tlib-version>1.0</tlib-version>
  <short-name>paginator</short-name>
  <uri>/WEB-INF/taglibs/customTaglib.tld</uri>
 
  <tag>
    <name>paginate</name>
    <tag-class>com.ekiras.taglib.PaginationTaglib</tag-class>
    <body-content>empty</body-content>
    
    <attribute>
      <name>next</name>
      <rtexprvalue>true</rtexprvalue>
      <type>java.lang.String</type>
    </attribute>
    <attribute>
      <name>previous</name>
      <rtexprvalue>true</rtexprvalue>
      <type>java.lang.String</type>
    </attribute>
    <attribute>
      <name>uri</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
      <type>java.lang.String</type>
    </attribute>
    <attribute>
      <name>offset</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
      <type>int</type>
    </attribute>
    <attribute>
      <name>count</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
      <type>int</type>
    </attribute>
    <attribute>
      <name>max</name>
      <rtexprvalue>true</rtexprvalue>
      <type>int</type>
    </attribute>
  </tag>
</taglib>