employees

function solve() {
    class Developer {
        constructor(firstName, lastName) {
            this.firstName = firstName;
            this.lastName = lastName;
            this.baseSalary = 1000;
            this.tasks = [];
            this.experience = 0;
        }

        addTask(id, taskName, priority) {
            if (priority === 'high') {
                this.tasks.unshift({ id, taskName, priority });
            } else {
                this.tasks.push({ id, taskName, priority });
            }

            return `Task id ${id}, with ${priority} priority, has been added.`
        }

        doTask() {
            if (this.tasks.length === 0) {
                return `${this.firstName}, you have finished all your tasks. You can rest now.`
            } else {
                let task = this.tasks.shift();
                return task.taskName;
            }
        }


        getSalary() {
            return `${this.firstName} ${this.lastName} has a salary of: ${this.baseSalary}`
        }

        reviewTasks() {
            let result = ["Tasks, that need to be completed:"];

            while (this.tasks.length > 0) {
                let r = this.tasks.shift();
                result.push(`${r.id}: ${r.taskName} - ${r.priority}`)
            }

            return result.join('\n')
        }
    }


    class Junior extends Developer {
        constructor(firstName, lastName, bonus, experience) {
            super(firstName, lastName);
            this.baseSalary = 1000 + bonus;
            this.tasks = [];
            this.experience = experience;
        }

        learn(years) {
            this.experience += years;
        }


    }

    class Senior extends Developer {
        constructor(firstName, lastName, bonus, experience) {
            super(firstName, lastName);
            this.baseSalary = 1000 + bonus;
            this.tasks = [];
            this.experience = experience + 5;
        }

        changeTaskPriority(taskId) {
            let find = this.tasks.find((o) => { return o.id === taskId });

            if (find.priority === 'high') {
                find.priority = 'low';
                let i = this.tasks.indexOf(find);
                this.tasks.push(find);
                this.tasks.splice(i, 1);
                return 'low';
            } else {
                find.priority = 'high';
                let i = this.tasks.indexOf(find);
                this.tasks.unshift(find);
                this.tasks.splice(i, 1);
                return 'high';

            }

        }
    }

    return {
        Developer,
        Junior,
        Senior
    }
}