/* ============================================================================
 * File: Fibonacci.java
 * ----------------------------------------------------------------------------
 *
 * This file is part of the Microsoft Supplemental UI Library for Visual J# .NET
 * Code Samples.
 *
 * Copyright (C)  2003  Microsoft Corporation. All rights reserved.
 *
 * THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
 * WHETHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
 * ============================================================================
 */

package RecursionDemo;

/**
 * This class implements RecursiveFunction interface to demonstrate calculation of
 * Fibonacci numbers as recursive funtion.
 * Refer Factorial.java also.
 */
public class Fibonacci implements RecursiveFunction {
    private RecursionStack stack;

    public String getName() {
        return "Fibonacci Function";
    }
    
    public String getDescription() {
        return "This function generates Fibonacci numbers." +
            "  Fibonacci numbers are 0, 1, 1, 2, 3, 5, 8, 13, ..." +
            " i.e. the next number is sum of previous two numbers.";
    }

    public String getCode() {
        return "public int fibonacci(int n) {\n" +
            "    if (n <= 1)\n" +
            "        return 0;\n" +
            "    else if (n == 2)\n" +
            "        return 1;\n" +
            "    else\n" +
            "        return (fibonacci(n - 1) + fibonacci(n - 2));\n" +
            "}";
    }

    public int doRecursion(int n) {
        stack.push(n);

        int retVal;
        if (n <= 1) {
            retVal = 0;
        }
        else if (n == 2) {
            retVal = 1;
        }
        else {
            retVal = doRecursion(n - 2) + doRecursion(n - 1);
        }

        stack.pop(retVal);

        return retVal;
    }

    public void setRecursionStack(RecursionStack s) {
        stack = s;
    }
}