class Company {
    constructor() {
        this.departments = [];
    }

    addEmployee(username, salary, position, department) {
        for (let arg of [username, salary, position, department]) {
            this.validate(arg);
        }

        if (!this.departments[department]) {
            this.departments[department] = [];
        }

        this.departments[department].push({ username, salary, position });

        return `New employee is hired. Name: ${username}. Position: ${position}`;
    }

    bestDepartment() {
        //department - avg salary
        let departments = {};
        Object.entries(this.departments).forEach(([department, employees]) => {
            let totalSalary = employees
                .map((e) => e.salary)
                .reduce((acc, curr) => (acc += curr));

            departments[department] = totalSalary / employees.length;
        });

        let maxSalary = 0;
        let bestDepartment;
        Object.entries(departments).forEach(([department, avgSalary]) => {
            if (avgSalary > maxSalary) {
                maxSalary = avgSalary;
                bestDepartment = department;
            }
        });

        let output = `Best Department is: ${bestDepartment}\nAverage salary: ${departments[
            bestDepartment
            ].toFixed(2)}\n`;

        this.departments[bestDepartment]
            .sort(
                (a, b) => b.salary - a.salary || a.username.localeCompare(b.username)
            )
            .forEach((e) => {
                output += `${e.username} ${e.salary} ${e.position}\n`;
            });

        return output.trim();
    }

    validate(value) {
        if (!value || value < 0) {
            throw new Error("Invalid input!");
        }
    }
}