// Kyle Thayer, CSE 142
// Some examples of using ArrayLists

import java.util.*;

// Translation from array to ArrayList:
//      String[]             ArrayList<String>
//      new String[n]        new ArrayList<String>()
//      int[]                ArrayList<Integer>
//      list[i]              list.get(i)
//      list[i] = val        list.set(i, val);
//      list.length          list.size()
// New operations:
//      list.add(val)        appends val to list
//      list.add(i, val)     inserts val at index i shifting subsequent values to the right
//      list.remove(i)       removes and returns the value at i
//      list.clear()         clears the entire ArrayList


public class ArrayListExamples {
   public static void main(String[] args) {
      // create an ArrayList of Strings. It starts out empty
      ArrayList<String> list = new ArrayList<String>();
      
      // add a bunch of words to the list
      list.add("it's");
      list.add("friday");
      list.add("friday");
      list.add("gotta");
      list.add("get");
      list.add("down");
      list.add("on");
      list.add("thursday"); 
      

  
      //if we are just replacing a value, this is the easiest way
      // to do so:
      list.set(7, "friday");
      
      //we can alternately remove the old value and add the new one:
      // list.remove(7);
      // list.add("friday");
      
      list.remove(3);
      list.add(3, "got to");
      
      // find the length of the longest string
      System.out.println("length of the longest is " + maxLength(list));
      
      //To create an ArrayList of ints, we need to use the wrapper
      // class "Integer"
      ArrayList<Integer> numbers = new ArrayList<Integer>();
      
      numbers.add(42);
      numbers.add(17);
      numbers.add(99);
      numbers.add(-2);
      
      // move the smallest number to the front
      minToFront(numbers);
      
      System.out.println("numbers = " + numbers);
      
      // remove all strings that have an even length
      removeEvenLength(list);
      
      System.out.println("list = " + list);
      
      list.add("down");
      list.add("on");
      list.add("friday"); 
      
      // double each element in the list
      stretch(list);
      
      System.out.println("list = " + list);
   }
   
    
   // Returns the length of the longest String in the given list
   public static int maxLength(ArrayList<String> list) {
      int longestLen = 0; // longest length found so far, starts at 0
      
      // loop over the ArrayList
      for(int i = 0; i < list.size(); i++){
         // get the i'th element of the list
         String thisString = list.get(i);
         // if it is longer than the previous longest length, update the longest length
         if(thisString.length() > longestLen){
            longestLen = thisString.length();
         }
      }
      return longestLen;
   }
   
   // Moves the minimum value to the front of the given list, otherwise
   // preserving the order of the elements
   public static void minToFront(ArrayList<Integer> list) {
      // find the index where the minimum element is located
      int smallestIndex = 0; // start out assuming it's index 0
      
      // see if any other element in the list is smaller
      for(int i = 1; i < list.size(); i++){
         int currentNum = list.get(i);
         // if the current number is smaller, update the smallestIndex
         if(currentNum < list.get(smallestIndex)){
            smallestIndex = i;
         }
      }
      
      // move it to the front
      // NOTE: This code doesn't handle the case where the list
      // is of length 0
      int temp = list.remove(smallestIndex);
      list.add(0, temp);
   }

   // Removes from the list all strings of even length
   public static void removeEvenLength(ArrayList<String> list) {
      // go over the list to find and remove even strings
      for(int i = 0; i < list.size(); i++){
         // get the current string at index i
         String current = list.get(i);
         // see if the current string has an even length
         if(current.length() % 2 == 0){
            // remove the string
            list.remove(i);
            // since removing the string shifted all the indexes after it
            // by -1, do i-- to keep i lined up with the list how we want
            i--;
         }
      }
   }
 
   // Duplicates every value in the list
   // Note: We didn't do this in class but this method can be a bit tricky too!
   public static void stretch(ArrayList<String> list) {
      // Make sure we do i+= 2 since we are adding one to the list each time,
      // otherwise you'll get an infinite loop (Try running it through the debugger)
      for (int i = 0; i < list.size(); i += 2) {
         // get the current string
         String val = list.get(i);
         // add the current string to the current location, so there are
         // two of them there. This adds one the the indexes of everything after it.
         list.add(i, val);
      }
      
      // Alternate solution: Go over the list backward, so we never look back at the 
      // part of the list where the indexes changed
      /*
      for(int i = list.size() - 1; i >= 0; i--){
         String val = list.get(i);
         list.add(i, val);
      }
      */
   }
}