/*
 * File: TextAnalyzer.java
 * Author: Java, Java, Java
 */

import java.io.*;

public abstract class TextAnalyzer {

    /**
     * englishFrequency array gives the relative frequencies of the characters 'a' to 'z'.
     *  For example, the letter 'e' has frequency 0.111, which means approximately 11.1% of characters in 
     *  English text are 'e'. The text used for these data was Tom Sawyer by Mark Twain.
     */
    protected final double englishFrequency[] = { 
	0.073,                              // a = 97   i.e., 73 occurences out of 1000, roughly 7.3
	0.016, 0.019, 0.049, 0.111,         // b,c,d,e = 11.1%
	0.021, 0.017, 0.067, 0.062, 	    // f,g,h,i
	0.002, 0.013, 0.040, 0.032,         // j,k,l,m
	0.066, 0.091, 0.017, 0.001,         // n,o,p,q = 0.1% i.e., 1 per 1000
	0.053, 0.061, 0.099, 0.032,         // r,s,t,u
	0.009, 0.025, 0.001, 0.025, 0.0001};  // v,w,x,y,z

    /**
     * Reads the named text file and returns its contents as a string.
     * @param fName is a string giving the files name (full path)
     * @return the contents of fName as a String
     */
    public String readFile(String fName) {
	String msg="";
	try {
	    File theFile = new File(fName);
	    InputStreamReader iStream = new InputStreamReader( new FileInputStream(theFile));
	    int length = (int)theFile.length();
	    char input[] = new char[length];
	    iStream.read(input);
	    msg = new String(input);
	} catch (IOException e) {
	    e.printStackTrace();
	} // catch
	return msg;
    }


    // Complete the implementation and documentation of this method
    protected double chiSquare(double[] exp, double[] obs) {
	return 0.0;
    }


    // Complete the implementation and documentation of this method
    protected double applyChiSquare(String text) {
	return 0.0;
    }

    // Here are the abstract method definitions. These should be implemented
    //  in the FrequencyAnalyzer subclass

    /**
     * Calculates the relative letter frequencies in text storing them in freqs array.
     * @param text is the text to be counted
     * @param freqs is an array of the resulting relative frequency counts
     */
    protected abstract void calcFreqs(String text, double freqs[]);

    /**
     * Analyzes the text parameter and returns a String result.
     * @param text is the text to be analyzed
     * @return a String reporting the result
     */
    public abstract String analyze(String text);

} // TextAnalyzer