SoftUni Course Planning

function solve(arr) {
    let lessons = arr.shift().split(', ');
    for (let i = 0; i < arr.length; i++) {
        let splited = arr[i].split(':');
        let command = splited[0];
        let lessonTitle = splited[1];
        switch (command) {
            case 'Add':
                if (!lessons.includes(lessonTitle)) {
                    lessons.push(lessonTitle);
                }
                break;
            case 'Insert':
                let insertIndex = Number(splited[2]);
                if ((!lessons.includes(lessonTitle))
                 && insertIndex <= lessons.length ) {
                    lessons.splice(insertIndex,0,lessonTitle);
                }
                break;
            case 'Remove':
                if (lessons.includes(lessonTitle)
                 && lessons.includes(`${lessonTitle}-Exercise`)) {
                    let indexOfTitle = lessons.indexOf(lessonTitle);
                    lessons.splice(indexOfTitle,2);
                }
                else if(lessons.includes(lessonTitle)){
                    let indexOfTitle = lessons.indexOf(lessonTitle);
                    lessons.splice(indexOfTitle,1);
                }
                break;
            case 'Swap':
            let lessonTitle2 = splited[2];
            let indexOfTitle = lessons.indexOf(lessonTitle);
            let indexOfTitle2 = lessons.indexOf(lessonTitle2);
            if (lessons.includes(`${lessonTitle2}-Exercise`)) {
                let lessonTitle3 = lessons[indexOfTitle2+1];
                lessons.splice(indexOfTitle,1,lessonTitle2,lessonTitle3);
                lessons.splice(indexOfTitle2+1,2,lessonTitle);
            }
            else if(lessons.includes(lessonTitle) && lessons.includes(lessonTitle2)) {
                lessons.splice(indexOfTitle,1,lessonTitle2);
                lessons.splice(indexOfTitle2,1,lessonTitle)
            }
                break;
            case 'Exercise':
            let indexOfElement = lessons.indexOf(lessonTitle);
            if (lessons.includes(lessonTitle)
            && !lessonTitle.includes('-Exercise')) {
                lessons.splice(indexOfElement,0,`${lessonTitle}-Exercise`)
            }
            else{
                lessons.push(lessonTitle)
                lessons.push(`${lessonTitle}-Exercise`)
            }
                break;
                case 'course start':
                for (let j = 0; j < lessons.length; j++) {
                    console.log(`${j+1}.${lessons[j]}`);
                }
                break;
            default:
                break;
        }
    }
}