package tree;

import java.util.Scanner;

public class Interface {

    static Scanner scan;
    
    public static void main(String[] args) {
        Node tree  = null;     
        char choice; 
            
        scan = new Scanner(System.in);
            
        printExplanatoryMessage();

        do { // until interactive user signals to quit
            choice = printMenuAndGetAction ();  // Insists on a valid response
            tree = performAction(tree, choice);    // Take an action
        } while (choice != 'Q' && choice != 'q');
            
        System.out.println();
        scan.close();
    }

    /*************  P R I N T   E X P L A N A T O R Y   M E S S A G E  ***********
    This function prints a message to the interactive user explaining briefly
    what the program is going to do.  Documented and coded by W. Knight. */

    static void printExplanatoryMessage() {
        System.out.println("\n\nThis program allows an interactive user to create, modify,");
        System.out.println("display, and destroy binary trees.  The program is menu driven.");
        System.out.println("Press the Enter key to continue.");
        scan.nextLine(); // Clear the input stream up through newline.
    } // printExplanatoryMessage()

    /********************  P E R F O R M   A C T I O N  **************************
    This function performs an action on the tree based on the reponse character. 
    Documented and coded by W. Knight and Dana Vrajitoru */

    static Node performAction(Node tree, char response) {
        switch (response) { // Response is necessarily one of the following.
        case 'B' :
        case 'b' : 
            tree = Node.buildABinaryTree (tree, null, scan);
            break;
        case 'C' :
        case 'c' : 
            System.out.println("\nThere are " + Node.countOfZeroDataValues (tree)
                               + " zero data values in the current tree.");
            break;
        case 'D' :
        case 'd' : 
            System.out.println();
            tree = null;
            System.out.println("\nThe tree should now be empty.");
            break;
        case 'H' :
        case 'h' : 
            System.out.println("\nThe height of the tree is " + Node.height(tree));
            break;
        case 'I' :
        case 'i' : 
            Node.incrementEachDatum (tree);
            System.out.println("\nEvery data value should have been incremented.");
            break;
        case 'P' : 
        case 'p' : 
            if (tree == null)
                System.out.println("\nThe tree is empty.");
            else
                tree.graphPrint();
            break;
        case 'Q' :
        case 'q' : break; // Do nothing.  The program will quit.
        case 'R' :
        case 'r' : 
            System.out.println();
            if (tree != null)
                tree.reverse();
            System.out.println("\nThe tree should now be the mirror image of what it was.");
            break;
        case 'S' :
        case 's' : 
            if (tree != null)
                System.out.println("\nThe sum of the negative data values is "
                                   + tree.sumOfNegativeData ());
            else
                System.out.println("\nThe sum of the negative data values is 0");
            break;
        }
        return tree;
    } // performAction()

    /**********  P R I N T   M E N U   A N D   G E T   A C T I O N  *************
    This function displays a menu of actions and asks an interactive user to 
    select one.  It will not return until it has read an acceptable response. 
    Documented and coded by W.Knight. */

    static char printMenuAndGetAction () {
        String response;
        System.out.println("\n");
        System.out.println("Which of the following actions do you wish to take?");
        System.out.println("   B)uild or modify the current tree interactively.");
        System.out.println("   C)ount and report number of zero data values in the tree");
        System.out.println("   D)estroy the current tree.");
        System.out.println("   H)eight of the tree -- determine it.");
        System.out.println("   I)ncrement every data value in the current tree by 1.");
        System.out.println("   P)rint the current tree on the screen.");
        System.out.println("   Q)uit.");
        System.out.println("   R)eplace the current tree by its mirror image.");
        System.out.println("   S)um the negative data values in the current tree.");
        System.out.println();
        System.out.println("Your choice:");
    
        response = scan.nextLine();
    
        while (true) { // loop will continue until user gives an appropriate response
            if (response.length() > 0 && "BbCcDdHhIiPpQqRrSs".contains(response.subSequence(0, 1))) 
                return response.charAt(0);  // EXIT FROM THE FUNCTION WITH PARAMETER HAVING OK VALUE 
            else
                System.out.println("Improper Response; Please type an appropriate letter.");
            response = scan.nextLine();
        }
    } // printMenuAndGetAction()
}