/* 
 * ITI 1121. Introduction to Computing II (Winter 2010). Laboratory 2. <br/>
 * ITI 1521. Introduction à l'informatique II (Hiver 2010). Laboratory 2.
 */

/**
 * This is a utility class. For now, it contains a single method,
 * called findAndReplace.
 *
 * @author Marcel Turcotte, uOttawa (turcotte@site.uottawa.ca)
 */

public class Utils {

    /**
     * Returns a copy of the array in where each word occurring in the array
     * 'what' has been replaced by the word occurring in the same position
     * in the array 'with'.
     *
     * @param in an array of Strings;
     * @param what an array of words to be replaced;
     * @param with an array of replacement words;
     * @return a new array idententical to 'in' except that all the occurrences of words
     * found in 'what' have been replaced by the corresponding word from 'with'.
     */

    public static String[] findAndReplace( String[] in, String[] what, String[] with ) {

        String[] out = null; // The new array to be returned
	boolean valid = true; // True if the pre-conditions are satistified

	// Testing pre-conditions

	if ( in == null || what == null || with == null ) {
	    valid = false;
	} else {
	    for ( int i=0; valid == true && i<in.length; i++ ) {
		if ( in[ i ] == null ) {
		    valid = false;
		}
	    }
	    if ( valid ) {
		if ( what.length != with.length ) {
		    valid = false;
		} else {
		    for ( int i=0; valid == true && i<what.length; i++ ) {
			if ( what[ i ] == null || with[ i ] == null ) {
			    valid = false;
			}
		    }
		}
	    }
	}

	if ( valid ) {
	    out = new String[ in.length ];
	    for ( int i=0; i<in.length; i++ ) {
		boolean found = false;
		for ( int j=0; ! found && j<what.length; j++ ) {
		    // if ( in[ i ] == what[ j ] ) { // incorrect answer, makes testChangeFirst2 fails
		    if ( in[ i ].equals( what[ j ] ) ) {
			out[ i ] = with[ j ];
			found = true;
		    }
		}
		if ( ! found ) {
		    out[ i ] = in[ i ];
		}
	    }
	}

        // Returning a reference to the newly created array that
        // contains the same entries as 'in' except that all the
        // occurrences of words from 'what' have been replaced by
        // their corresponding occurrence from 'with'.

        return out;
    }

}