viarno reshenie activation keys - final exam

function activation(input) {
    let rawKeys = input.shift();
    let line = input.shift();

    while (line !== "Generate") {
        let tokens = line.split(">>>");

        let command = tokens[0];

        switch (command) {
            case "Contains": {
                let subString = tokens[1];

                if (rawKeys.includes(subString)) {
                    console.log(`${rawKeys} contains ${subString}`);
                } else {
                    console.log(`Substring not found!`);
                }

                break;
            }
            case "Flip": {
                let currentCommand = tokens[1];
                let startIndex = Number(tokens[2]);
                let endIndex = Number(tokens[3]);

                let subString = rawKeys.slice(startIndex, endIndex);

                if (currentCommand === "Upper") {
                    rawKeys = rawKeys.replace(subString, subString.toUpperCase());
                } else {
                    rawKeys = rawKeys.replace(subString, subString.toLowerCase());
                }

                console.log(rawKeys);

                break;
            }
            case "Slice": {
                let startIndex = Number(tokens[1]);
                let endIndex = Number(tokens[2]);

                let cut = rawKeys.substring(startIndex, endIndex);
                rawKeys = rawKeys.split(cut).join("");

                console.log(rawKeys);

                break;
            }

        }

        line = input.shift();
    }

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