const ASSIGNMENT = 'assignment';
const ANSWER = 'answer';
const ALGORITHM_CHECKBOX = 'algorithm';
const NEWLINE_CHARACTER = '\n';
const TOP_1 = 1;
const TOP_N = 3;

/**
 * Main function
 */
window.onload = function() {
    document.getElementById(ASSIGNMENT).addEventListener("input", calculateAnswer);
    document.getElementById(ALGORITHM_CHECKBOX).addEventListener("click", calculateAnswer);
}

/**
 * Listener function for input in assignment field.
 * @param event the onInput event 
 */
function calculateAnswer(event) {
  console.info("Calculating answer for input...");
  let assignment = document.getElementById(ASSIGNMENT).value;
  let top3 = document.getElementById(ALGORITHM_CHECKBOX).checked;
  let answer = algorithm(assignment, (top3)? TOP_N: 1);

  document.getElementById(ANSWER).innerText = answer;
}

/**
 * Calculate the answer to assignment1 with 2 variables, count and highest.
 * @param assignment the input from the assignment.
 * @param topn the
 * @return string the elf with the highest calory count
 */
function algorithm(assignment, topn) {
    let currentCalorieScore = 0;
    let highestCalorieScores = Array.from({length: topn}, () => (0));
    let currentElf = 1;

    let lines = assignment.trim().split(NEWLINE_CHARACTER);
    console.info("Linecount:" + lines.length);

    for(var i = 0; i < lines.length; i++){
        let line = lines[i];

        if(!line && currentCalorieScore > 0) { // Check for empty line and skip subsequent emptylines
            console.debug("Calculated score for elf " + currentElf + ": " + currentCalorieScore);

            for(let j=0; j < highestCalorieScores.length; j++) {
                if(currentCalorieScore > highestCalorieScores[j]) {
                    console.debug("New highest #"+(j+1) + " elf found, with score:" + currentCalorieScore);
                    let oldHighestCalorieScore = highestCalorieScores[j];
                    highestCalorieScores[j] = currentCalorieScore;
                    currentCalorieScore = oldHighestCalorieScore;
                }
            }

            // Reset values
            currentCalorieScore = 0;
            currentElf++;
            continue;
        }
            
        let calorieScore = parseInt(line);
        currentCalorieScore += calorieScore;
    }

    console.debug(highestCalorieScores);
    return "The highest of sum of calorie amount: " + highestCalorieScores.reduce(function(a, b) { return a + b; }, 0);
}