// The final quest
function final(input) {

    let sentence = input.shift().split(" ");

    for (let i = 0; i < input.length; i++) {
        let cmd = input[i].split(" ")[0];
        let wordOne = input[i].split(" ")[1];
        let wordTwo = input[i].split(" ")[2];
        if (cmd === "Delete") {
            //Delete {index} – removes the word after the given index if it is valid.
            if (typeof sentence[wordOne] !== "undefined") {
                let index = +wordOne + 1;
                sentence.splice(index, 1);
            }
        } else if (cmd === "Swap") {
            //Swap {word1} {word2} – find the given words in the collections if they exist and swap their places.
            if(sentence.includes(wordOne) && sentence.includes(wordTwo)) {
               let indexOfWordOne = sentence.indexOf(wordOne);
               let indexOfWordTwo = sentence.indexOf(wordTwo);
               sentence.splice(indexOfWordOne, 1, wordTwo);
               sentence.splice(indexOfWordTwo, 1, wordOne);
            }
        } else if (cmd === "Put") {
            //Put {word} {index} – add a word at the previous place {index} before the given one, if it exists.
            if (typeof sentence[wordTwo] !== "undefined") {
               let index = +wordTwo - 1;
               sentence.splice(index, 0, wordOne);
            }
        } else if (cmd === "Sort") {
            //Sort – you must sort the words in descending order
            sentence.sort(function(a, b) {
                return b.localeCompare(a)
            });
        } else if (cmd === "Replace") {
            //Replace {word1} {word2} – find the second word {word2} in the collection (if it exists) and replace it with the first word – {word1}.
            if(sentence.includes(wordTwo)) {
                sentence.splice(sentence.indexOf(wordTwo), 1, wordOne);
            }
        } else {
           break;
        }
    }
    return(sentence.join(" "));
}
console.log(final([`Congratulations! You last also through the have challenge!`,
    `Swap have last`,
    `Replace made have`,
    `Delete 2`,
    `Put it 4`,
    `Stop`]));