package ora.jwsnut.chapter6.headerbookservice;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.InputStreamReader;
import java.io.InputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.StringTokenizer;

/**
 * A class that loads the data for the header book service 
 */
class HeaderBookServiceServantData {

    /**
     * The author data in the form of a HashMap, created when it is
     * first requested.
     */
    private static HashMap bookAuthorMap;
    
    /**
     * List of book titles.
     */
    private static String[] bookTitles;
    
    /**
     * Buffer used when reading image data
     */
    private static byte[] buffer;
    
    /**
     * Stream used when reading image data
     */
    private static ByteArrayOutputStream os;
    
    /**
     * Gets a list of all known books.
     */
    public static String[] getBookTitles() {
        loadData();
        return bookTitles;
    }
    
    /**
     * Gets the author name for a book with a given title.
     */
    public static String getBookAuthor(String title) {
        loadData();
        return (String)bookAuthorMap.get(title.trim().toUpperCase());
    }
    
    /**
     * Loads the book data from information contained
     * in the booklist.txt file.
     */
    private static void loadData() {
        if (bookAuthorMap == null) {
            
            // First request - create the data
            bookAuthorMap = new HashMap();
            ArrayList list = new ArrayList();

            try {
                buffer = new byte[1024];
                os = new ByteArrayOutputStream();                
                InputStream is = 
                    HeaderBookServiceServantData.class.getResourceAsStream("booklist.txt");
                BufferedReader reader = new BufferedReader(new InputStreamReader(is));
                String line;
                while ((line = reader.readLine()) != null) {
                    StringTokenizer st = new StringTokenizer(line, "!");
                    if (st.countTokens() == 2) {
                        String title = st.nextToken();
                        String canonicalTitle = title.trim().toUpperCase();
                        String author = st.nextToken();
                        
                        // Store the author name
                        bookAuthorMap.put(canonicalTitle, author);
                        
                        // Add a new book title
                        list.add(title);
                    }
                }
                
                bookTitles = new String[list.size()];
                list.toArray(bookTitles);
            } catch (Exception ex) {
                // Just return an empty or partial list                
                ex.printStackTrace();
            }
        }
    }  
}