3_parking js advanced exam

class Parking {
    constructor(capacity) {
        this.capacity = capacity;
        this.vehicles = [];
    }


    addCar(carModel, carNumber) {
        if (this.capacity === this.vehicles.length) {
            throw Error("Not enough parking space.")
        } else {
            this.vehicles.push({ carModel, carNumber, payed: false });
            return `The ${carModel}, with a registration number ${carNumber}, parked.`
        }
    }

    removeCar(carNumber) {
        let find = this.vehicles.find((o) => { return o.carNumber === carNumber });

        if (!find) {
            throw Error("The car, you're looking for, is not found.")
        }

        if (!find.payed) {
            throw Error(`${carNumber} needs to pay before leaving the parking lot.`)
        }

        let i = this.vehicles.indexOf(find);
        this.vehicles.splice(i, 1);

        return `${carNumber} left the parking lot.`
    }

    pay(carNumber) {
        let c = this.vehicles.find((o) => { return o.carNumber === carNumber });

        if (!c) {
            throw Error(`${carNumber} is not in the parking lot.`)
        }

        if (c.payed) {
            throw Error(`${carNumber}'s driver has already payed his ticket.`);
        }

        c.payed = true;
        return `${carNumber}'s driver successfully payed for his stay.`
    }

    getStatistics(carNumber) {
        if (!carNumber) {
            let result = [`The Parking Lot has ${this.capacity - this.vehicles.length} empty spots left.`,]
            let sorted = this.vehicles.sort((a, b) => a.carModel.localeCompare(b.carModel));

            for (const s of sorted) {
                if (s.payed) {
                    result.push(`${s.carModel} == ${s.carNumber} - Has payed`)
                } else {
                    result.push(`${s.carModel} == ${s.carNumber} - Not payed`)
                }
            }
            return result.join('\n')
        } else {
            let x = this.vehicles.find((o) => { return o.carNumber === carNumber });

            if (x.payed) {
                return `${x.carModel} == ${carNumber} - Has payed`;
            } else {
                return `${x.carModel} == ${carNumber} - Not payed`;
            }
        }
    }
}