import java.util.*;
public class StringArrayUtils {
    /**
     * @param array array of String objects
     * @return first element of specified array
     */ // TODO
    public static String getFirstElement(String[] array) {

        return array[0];
    }

    /**
     * @param array array of String objects
     * @return second element in specified array
     */
    public static String getSecondElement(String[] array) {
        return array[1];
    }

    /**
     * @param array array of String objects
     * @return last element in specified array
     */ // TODO
    public static String getLastElement(String[] array) {
        return array[array.length - 1];
    }

    /**
     * @param array array of String objects
     * @return second to last element in specified array
     */ // TODO
    public static String getSecondToLastElement(String[] array) {
        return array[array.length - 2];
    }

    /**
     * @param array array of String objects
     * @param value value to check array for
     * @return true if the array contains the specified `value`
     */ // TODO
    public static boolean contains(String[] array, String value) {
        for(int i=0; i<array.length; i++){
            if(array[i]==value){
                return true;
            }
        }
        return false;
    }

    /**
     * @param array of String objects
     * @return an array with identical contents in reverse order
     */ // TODO
    public static String[] reverse(String[] array) {
        String[] arr = new String[array.length];
        int j = 0;
        for(int i=array.length-1; i>=0; i--){
            arr [j] = array[i]; 
            j++;
        }
        return arr;
    }

    /**
     * @param array array of String objects
     * @return true if the order of the array is the same backwards and forwards
     */ // TODO
    public static boolean isPalindromic(String[] array) {
        String[] reversedArr = new String[array.length];
        reversedArr = reverse(array);
        boolean flag = true;
        for(int i=0; i<reversedArr.length; i++){
            if(!array[i].equalsIgnoreCase(reversedArr[i])){
                flag = false;
                break;
            }
        }
        System.out.println(reversedArr);

        return flag;
    }

    /**
     * @param array array of String objects
     * @return true if each letter in the alphabet has been used in the array
     */ // TODO
    public static boolean isPangramic(String[] array) {
        String s = "";
        for(String element: array){
            s += element;
        }
        int NO_OF_LETTERS_OF_ALPHABET = 26;
        if(s.length() < NO_OF_LETTERS_OF_ALPHABET){
            return false;
        }
        for (char ch = 'A'; ch <= 'Z'; ch++) {
            if (s.indexOf(ch) < 0
            && s.indexOf((char) (ch + 32)) < 0) {
                return false;
            }
        }
        return true;
    }

    /**
     * @param array array of String objects
     * @param value value to check array for
     * @return number of occurrences the specified `value` has occurred
     */ // TODO
    public static int getNumberOfOccurrences(String[] array, String value) {
        int count = 0;
        for(int i=0; i<array.length;i++){
            if(value.equalsIgnoreCase(array[i].toString())){
                count++;
            }
        }
        return count;
    }

    /**
     * @param array         array of String objects
     * @param valueToRemove value to remove from array
     * @return array with identical contents excluding values of `value`
     */ // TODO
    public static String[] removeValue(String[] array, String valueToRemove) {
        int k = 0;
        int n = getNumberOfOccurrences(array, valueToRemove);
        String[] str = new String[array.length - n];
        for(int i=0; i<array.length; i++)
        {
            if(!array[i].equals(valueToRemove))
            {
                str[k] = array[i];
                k++;
            }
           
        }
        
        return str; 
    }


    /**
     * @param array array of chars
     * @return array of Strings with consecutive duplicates removes
     */ // TODO
    public static String[] removeConsecutiveDuplicates(String[] array) {
        ArrayList<String> removedList = new ArrayList<String>();
        removedList.add(array[0]);
        for(int i=1; i<array.length; i++){
            if(!array[i-1].equalsIgnoreCase(array[i])){
                removedList.add(array[i]);
            }
        }
        String[] finalArray = removedList.toArray(new String[removedList.size()]);

        return finalArray;
    }

    /**
     * @param array array of chars
     * @return array of Strings with each consecutive duplicate occurrence concatenated as a single string in an array of Strings
     */ // TODO
    public static String[] packConsecutiveDuplicates(String[] array) {
        ArrayList<String> list = new ArrayList<>();
        list.add(array[0]);
        int k=0;

        for(int i = 1 ; i < array.length ; i++) {

            if(array[i-1].equalsIgnoreCase(array[i])){

                String lastElement = list.get(list.size()-1);

                lastElement = lastElement.concat(array[i]);

                list.set(list.size()-1,lastElement);
            }
            else{
                list.add(array[i]);
            }
        }

        String[] newArray = list.toArray(new String[list.size()]);
        return newArray;
    }

}