parking kolega

class Parking {
    constructor(capacity) {
        this.capacity = capacity;
        this.vehicles = [];
        this.currentSpots = 0;
    }
    addCar(carModel, carNumber) {
        if (this.currentSpots + 1 > this.capacity) {
            throw new Error("Not enough parking space.")
        } else {
            let currCar = { carModel: carModel, carNumber: carNumber, payed: false }
            this.vehicles.push(currCar)
            this.currentSpots++;
        }
        return `The ${carModel}, with a registration number ${carNumber}, parked.`;
    }
    removeCar(carNumber) {
        if (this.vehicles.find(x => x.carNumber == carNumber) == undefined) {
            throw new Error("The car, you're looking for, is not found.")
        } else {
            let currCar = this.vehicles.find(x => x.carNumber == carNumber);
            if (currCar.payed == false) {
                throw new Error(`${carNumber} needs to pay before leaving the parking lot.`)
            } else {
                let carrIndex = this.vehicles.findIndex(x => x.carNumber == carNumber);
                this.vehicles = this.vehicles.splice(carrIndex, 1);
                this.currentSpots--;
                return `${carNumber} left the parking lot.`;
            }
        }
    }
    pay(carNumber) {
        if (this.vehicles.find(x => x.carNumber == carNumber) == undefined) {
            throw new Error(`${carNumber} is not in the parking lot.`);
        } else {
            let currCar = this.vehicles.find(x => x.carNumber == carNumber);
            if (currCar.payed == false) {
                currCar.payed = true;
                return `${carNumber}'s driver successfully payed for his stay.`
            } else {
                throw new Error(`${carNumber}'s driver has already payed his ticket.`)
            }
        }
    }

    getStatistics() {
        if (arguments.length > 0) {
            let carNumber = arguments[0];
            let currCarr = this.vehicles.find(x => x.carNumber == carNumber);
            let payedRes;
            if (currCarr.payed) {
                payedRes = 'Has payed';
            } else {
                payedRes = 'Not payed'
            }
            return `${currCarr.carModel} == ${currCarr.carNumber} - ${payedRes}`;
        } else {
            let res = [];
            res.push(`The Parking Lot has ${this.capacity - this.currentSpots} empty spots left.`)
            let sorted = this.vehicles.sort(function (a, b) {
                if (a.carModel > b.carModel) {
                    return 1;
                }
                if (b.carModel < b.carModel) {
                    return -1;
                }
            });
            sorted.forEach(x => {
                let payedRes;
                if (x.payed) {
                    payedRes = 'Has payed';
                } else {
                    payedRes = 'Not payed';
                }
                res.push(`${x.carModel} == ${x.carNumber} - ${payedRes}`);
            })
            return res.join('\n');
        }
    }

}