// Fisher-Yates Shuffle Algorithm
function shuffle(array) {
    var currentIndex = array.length, temporaryValue, randomIndex;
    while (0 !== currentIndex) {
        randomIndex = Math.floor(Math.random() * currentIndex);
        currentIndex -= 1;
        temporaryValue = array[currentIndex];
        array[currentIndex] = array[randomIndex];
        array[randomIndex] = temporaryValue;
    }
    return array;
}

// Check for duplicate names
function checkDuplicates(names) {
    var nameSet = new Set(names);
    if (nameSet.size !== names.length) {
        alert('Duplicate entries found. Duplicates will be ignored.');
        return Array.from(nameSet);
    }
    return names;
}

// Reset the form
function resetForm() {
    document.getElementById('names').value = '';
    document.getElementById('numWinners').value = '2';
    document.getElementById('winners').innerText = '';
}

// Main function to pick winners
function pickWinners() {
    // Get the text from the textarea
    var text = document.getElementById('names').value.trim();
    
    // Validate input
    if (text === '') {
        alert('Please enter some names.');
        return;
    }
    
    // Split the text into an array of names
    var names = text.split('\n').filter(name => name.trim() !== '');
    
    // Check for duplicates
    names = checkDuplicates(names);
    
    // Get the number of winners from the input field
    var numWinners = parseInt(document.getElementById('numWinners').value);
    
    // Ensure the number of winners is valid
    if (isNaN(numWinners) || numWinners <= 0 || numWinners > names.length) {
        alert('Please enter a valid number of winners.');
        return;
    }
    
    // Display loading spinner (assuming you have a div with id 'loading')
    document.getElementById('loading').style.display = 'block';
    
    // Shuffle the array
    var shuffledNames = shuffle(names);
    
    // Pick the winners from the shuffled array
    var winners = shuffledNames.slice(0, numWinners);
    
    // Hide loading spinner
    document.getElementById('loading').style.display = 'none';
    
    // Display the winners
    document.getElementById('winners').innerText = 'Winners: ' + winners.join(', ');
}