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

    }

    addCar(carModel, carNumber) {

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

    removeCar(carNumber) {
        let car = this.vehicles.find(x => x.carNumber == carNumber);

        if (!car) {
            throw new Error(`The car, you're looking for, is not found.`);
        }
        if (car.payed === false) {
            throw new Error(`${carNumber} needs to pay before leaving the parking lot.`);
        }
        this.vehicles = this.vehicles.filter(x => x.carNumber !== carNumber);
        return `${carNumber} left the parking lot.`;

    }

    pay(carNumber) {
        let car = this.vehicles.find(x => x.carNumber == carNumber);

        if (!car) {
            throw new Error(`${carNumber} is not in the parking lot.`);
        }
        if (car.payed ) {
            throw new Error(`${carNumber}'s driver has already payed his ticket.`)
        }else {

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

    getStatistics(carNumber) {
        let output = '';
        let car = this.vehicles.find(x=>x.carNumber === carNumber);
        if (carNumber === undefined) {
            output = `The Parking Lot has ${this.capacity - this.vehicles.length} empty spots left.\n`;

            this.vehicles = this.vehicles.sort((a, b) => {
                return a.carModel.localeCompare(b.carModel);

            })
            for (const car of this.vehicles) {
                let payment = car.payed ? `Has payed` : `Not payed`;
                output += `${car.carModel} == ${car.carNumber} - ${payment}\n`;
            }
            return output.trim();
        } else {
            let payment = car.payed ? `Has payed` : `Not payed`;
            return `${car.carModel} == ${car.carNumber} - ${payment}`;
        }
    }
}