package eecs2030.test2;

import java.util.ArrayList;
import java.util.List;

public class Test2H {
    /**
     * The size of the list required by the method Test2G.avg2 
     */
    public static final int AVG2_LIST_SIZE = 2;

    private Test2H() {
        // empty by design
    }
    

    /**
     * Returns true if <code>tf</code> is false, and false if
     * <code>tf</code> is true.
     * 
     * @param tf a boolean value
     * @return the opposite of tf
     */
    public static boolean not(boolean tf) {
        return !tf;
    }

    
    /**
     * Given a list containing exactly 2 integers, returns the average of the
     * two integers. The list <code>t</code> is not modified by this method. 
     * For example:
     * 
     * <pre>
     * t            Test2F.avg2(t)
     * ---------------------------
     * [-5, 9]       2
     * [3, 3]        3
     * [12, 7]       9.5
     * </pre>
     * 
     * @pre t is not null
     * 
     * @param t
     *            a list containing exactly 2 integers
     * @return   
     *            the average of the two values in t
     * @throws IllegalArgumentException
     *             if the list does not contain exactly 2 integers
     */
    public static double avg2(List<Integer> t) {
        if (t.size() != 2) {
            throw new IllegalArgumentException("list size != 2");
        }
        double t0 = t.get(0);
        double t1 = t.get(1);
        return (t0 + t1) / 2.0;
    }

    

    /**
     * Computes the sum of the values in the list <code>t</code>.
     * The list <code>t</code> is not modified by this method.
     * The sum of an empty list is zero. If the sum of the values
     * is greater than <code>Integer.MAX_VALUE</code> then
     * <code>Integer.MAX_VALUE</code> is returned.
     * If the sum of the values
     * is less than <code>Integer.MIN_VALUE</code> then
     * <code>Integer.MIN_VALUE</code> is returned.
     * 
     * @param t a list of values
     * @return the sum of the values in t
     * @pre t is not null
     */
    public static int sum(List<Integer> t) {
        long sum = 0;
        for (int i : t) {
            sum += i;
        }
        if (sum > Integer.MAX_VALUE) {
            sum = Integer.MAX_VALUE;
        }
        else if (sum < Integer.MIN_VALUE) {
            sum = Integer.MIN_VALUE;
        }
        return (int) sum;
    }

    

    /**
     * Returns a new list consisting of the individual digits of the number <code>n</code>.
     * For example:
     * 
     * <pre>
     * n                 Test2H.fromInt(n)
     * -----------------------------------
     *  0                 [0]
     * -25                [-2, 5]
     * 9876543            [9, 8, 7, 6, 5, 4, 3]
     * </pre>
     * 
     * @param n a number
     * @return a list consisting of the individual digits of the number <code>n</code>
     */
    public static List<Integer> fromInt(int n) {
        String s = "" + n;
        List<Integer> t = new ArrayList<Integer>();
        int i = 0;
        char c = s.charAt(0);
        boolean isNeg = false;
        if (c == '-') {
            i = 1;
            isNeg = true;
        }
        for (; i < s.length(); i++) {
            c = s.charAt(i);
            t.add(Integer.valueOf("" + c));
        }
        if (isNeg) {
            t.set(0, -t.get(0));
        }
        return t;
    }
    
    
    public static void main(String[] args) {
        
        // not
        boolean tf = true;
        System.out.println(
                String.format("not(%b) : ", tf) + 
                Test2H.not(tf));
        
        // negate2
        List<Integer> t = new ArrayList<Integer>();
        t.add(3);
        t.add(5);
        System.out.println(
                String.format("avg2(%s) : %s", t.toString(), Test2H.avg2(t)));
        
        // sum
        t.clear();
        t.add(4);
        t.add(5);
        t.add(6);
        t.add(7);
        t.add(8);
        System.out.println(
                String.format("sum(%s) : %d", 
                        t.toString(), Test2H.sum(t)));
        
        // fromInt
        int n = 1234;
        System.out.println(
                String.format("fromInt(%d) : %s", 
                        n, Test2H.fromInt(n)));
    }
    
}