Username

function solve(input){
    let username = input.shift();

    for(let  i = 0; i < input.length; i++){
        let [command, firstArg, secondArg] = input[i].split(' ');
        // console.log(command);
        switch(command){
            case "Case":
                if(firstArg === "lower"){
                   username = username.toLowerCase();
                   console.log(username);
                } else if(firstArg === "upper"){
                    username = username.toUpperCase();
                    console.log(username);
                }
                break;
            case "Reverse":
                indexStart = Number(firstArg);
                indexEnd = Number(secondArg);
                if(indexStart>= 0 && indexStart < username.length && indexEnd >= 0 && indexEnd < username.length){
                    let str = username.substring(indexStart, indexEnd + 1)
                    .split('')
                    .reverse()
                    .join('');
                   console.log(str);
                }
                break;
            case "Cut":
                if(username.includes(firstArg)){
                   username = username.replace(firstArg, '');
                        console.log(username);
                } else {
                    console.log(`The word ${username.toLowerCase()} doesn't contain ${firstArg}.`);
                }
                break;
            case "Replace":
                for(let i = 0; i < username.length; i++){
                    if(username.includes(firstArg)){
                    username = username.replace(firstArg, '*');
                    }
                }
                console.log(username);
                break;
            case "Check":
                if(username.includes(firstArg)){
                    console.log("Valid");
                } else {
                    console.log(`Your username must contain ${firstArg}.`);

                }
                break;
            default:
                break;
        }

    }
}