const ssPairBtn = document.getElementById("ss-pairs")
const displayPairsEl = document.getElementById("display-pairs")

const people = ["Alice", "Bob", "Carly", "Dan", "Ed", "Ferdinand", "Ginny"]

ssPairBtn.addEventListener('click', function(){
    const secretSantaPairs = generateSecretSantaPairs(people)
    let list = ""
    Object.entries(secretSantaPairs).forEach(([name, pair])=>{
        list += `<li>${name} = ${pair}</li>`
    })
    displayPairsEl.innerHTML = list
})

function generateSecretSantaPairs(arr) {
    const secretSantaPairs={}
    const peopleCopy = [...arr]
    const shuffledArray = shuffle(peopleCopy)
    for(let i=0; i<arr.length; i++){
        if(arr[i] !== shuffledArray[i]){
            secretSantaPairs[arr[i]] = shuffledArray[i]
        } else {
            const temp = shuffledArray[i];
            shuffledArray[i] = shuffledArray[(i + 1) % arr.length];
            shuffledArray[(i + 1) % arr.length] = temp;
            secretSantaPairs[arr[i]] = shuffledArray[i];
        }
    }
    return secretSantaPairs
}

function shuffle(arr){
    return arr.sort(() => Math.random() - 0.5);
}