/* Solution to Chapter 19, Exercise 1 in Teach Yourself Java in 21 Days (Eighth
   Edition) by Rogers Cadenhead. */
package com.java21days;

import java.io.*;
import nu.xom.*;

public class BookFilter {
    
    public BookFilter() {
    	// no initialization needed
    }
    
    public void read() {    	
        try {
            Builder bob = new Builder();
            File xmlFile = new File("books.xml");
            Document doc = bob.build(xmlFile);

            // Get the file's root elements
            Element root = doc.getRootElement();

            // Get all of the <book> elements and loop through them
            Elements books = root.getChildElements("Book");
            for (int i = 0; i < books.size(); i++) {
                // Get an <book> element
                Element book = books.get(i);
                
                // Look for an <author> element inside it
                Element author = book.getFirstChildElement("Author");
                
                // If found, look for its contents
                if (author != null) {
                    Text authorText = (Text) author.getChild(0);
                    String authorName = authorText.getValue();
                    
                    if (authorName.equals("Naomi Novik")) {
                        System.out.println("\nAuthor: " + authorName);
                        // Display the other elements
                        Element title = book.getFirstChildElement("Title");
                        display("Title", title);
                        Element pubDate = book.getFirstChildElement("PubDate");
                        display("Publication Date", pubDate);
                        Attribute edition = pubDate.getAttribute("edition");
                        displayAttribute("Edition", edition);
                        Element publisher = book.getFirstChildElement("Publisher");
                        display("Publisher", publisher);
                        Element subject = book.getFirstChildElement("Subject");
                        display("Subject", subject);
                        Element review = book.getFirstChildElement("Review");
                        display("Review", review);
                    }
                }
            }
        } catch (ParsingException | IOException exc) {
            System.out.println("Error: " + exc.getMessage());
            exc.printStackTrace();
        }
    }
    
    // display the text inside an element (if it exists)
    void display(String label, Element element) {
    	if (element != null) {
            Text elementText = (Text) element.getChild(0);
            String elementString = elementText.getValue();
            System.out.println(label + ": " + elementString);
    	}
    }    		
    
    // display an attribute's value (if it exists)
    void displayAttribute(String label, Attribute attribute) {
    	if (attribute != null) {
            String attributeString = attribute.getValue();
            System.out.println(label + ": " + attributeString);
    	}
    }
    
    public static void main(String[] arguments) {
        BookFilter bf = new BookFilter();
        bf.read();
    }
}