/*----------------------------------------------------------
 *				HTBLA-Leonding / Class: 2IHIF
 * ---------------------------------------------------------
 * Exercise Number: 09
 * Title:			Tower of Hanoi Disk ADT Implemenation
 * Author:			Marc Tismonar
 * ----------------------------------------------------------
 * Description:
 * Implementation of toh_disk.h.
 * ----------------------------------------------------------
 */

#include "toh_disk.h"
#include "config.h"
#include <stdlib.h>

struct DiskData {
   unsigned short size;
};

/**
 * Provides the instance of the disk with the given size.
 * Valid disk sizes are from 1 to MAX_DISKS.
 * 
 * @param size The size of the desired disk.
 * @return The disk of the given size or 0, 
 *         if no such disk is available.
 */
Disk td_get_disk(unsigned short size) {
    if(size < 1 || size > MAX_DISKS) {
        return 0;
    }

    Disk disk = (Disk)calloc(sizeof(struct DiskData), 1);
    disk->size = size;
    return disk;
}

/**
 * Determines whether or not the given disk is valid.
 * It is valid if it is not 0 and has a size between 1 and MAX_DISKS.
 * 
 * @param disk The disk in focus of this ADT.
 * @return True if the disk is valid, false otherwise.
 */
bool td_is_valid(Disk disk) {
    if (disk == 0 || disk->size < 1 || disk->size > MAX_DISKS) {
        return false;
    }

    return true;
}

/**
 * Provides the size of the given disk.
 * 
 * @param disk The disk in focus of this ADT.
 * @return The size of the disk, if it is valid or 0 otherwise.
 */
unsigned short td_get_size(Disk disk) {
    if (!td_is_valid(disk)) {
        return 0;
    }

    return disk->size;
}

/**
 * Compares the size of the candidate disk with size of the given disk.
 * 
 * @param disk The disk in focus of this ADT.
 * @param smaller_candidate The disk to evaluate.
 * @return True if the 'smaller_candidate' disk is smaller than the 
 * given disk of this ADT and both disks are valid, false otherwise.
 */
bool td_is_smaller(Disk disk, Disk smaller_candidate) {
    if (!td_is_valid(disk) || !td_is_valid(smaller_candidate)) {
        return false;
    }

    return disk->size > smaller_candidate->size;
}