activation keys - final exam - fundamentals

function activation(input) {
    let rawKeys = input.shift();
    //console.log(rawKeys);
    let line = input.shift();
    rawKeys = String(rawKeys);
    while (line !== "Generate") {
        let [command, mode, firstArgument, secondArgument] = line.split(">>>");
        switch (command) {
            case "Contains":
                let substring = mode;
                if (rawKeys.includes(substring)) {
                    console.log(`${rawKeys} contains ${substring}`);

                } else {
                    console.log(`Substring not found!`);
                }
                break;
            case "Flip": {
                let startIndex = Number(firstArgument);
                let endIndex = Number(secondArgument);
                if (mode === "Upper")
                let substring = rawKeys.slice(startIndex, endIndex);
                rawKeys = rawKeys.replace(substring.substring.toUpperCase());
                console.log(rawKeys);

            } else {
                let substr = rawKeys.slice(startIndex, endIndex);
                rawKeys = rawKeys.replace(substr.substr.toLowerCase());
                console.log(rawKeys);
            }

            break;

        }
            case "Slice": {
                let startIndex = Number(firstArgument);
                let endIndex = Number(secondArgument);
                let cut = rawKeys.substring(startIndex, endIndex);
                rawKeys = rawKeys.replace(cut, "");
                console.log(rawKeys);
                break;
            }

    }
        line = input.shift();
    console.log(`Your activation key is: ${rawKeys}`);
}

activation((["abcdefghijklmnopqrstuvwxyz",
"Slice>>>2>>>6",
"Flip>>>Upper>>>3>>>14",
"Flip>>>Lower>>>5>>>7",
"Contains>>>def",
"Contains>>>deF",
"Generate"])
);