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

    addCar(carModel, carNumber) {
        if (this.capacity <= 0) {
            throw new Error('Not enough parking space.')
        }
        this.vehicles.push({carModel, carNumber, payed: false})
        this.capacity--
        return `The ${carModel}, with a registration number ${carNumber}, parked.`
    }

    removeCar(carNumber) {
        // found index of the object
        let index = this.vehicles.map(function (car) {return car.carNumber;}).indexOf(carNumber);
        // get the object
        let foundCar = this.vehicles[index]
        if (!foundCar) {
            throw new Error(`The car, you're looking for, is not found.`)
        }
        if (foundCar.payed === false) {
            throw new Error(`${carNumber} needs to pay before leaving the parking lot.`)
        }
        // remove the object from array
        this.vehicles = this.vehicles.splice(index, 1);
        this.capacity++
        return `${carNumber} left the parking lot.`
    }

    pay(carNumber) {
        // found index of the object
        let index = this.vehicles.map(function (car) {return car.carNumber;}).indexOf(carNumber);
        // get the object
        let foundCar = this.vehicles[index];
        if(!foundCar){
            throw new Error(`${carNumber} is not in the parking lot.`)
        }
        if(foundCar.payed === true){
            throw new Error(`${carNumber}'s driver has already payed his ticket.`)
        }
        this.vehicles[index].payed = true;
        return`${carNumber}'s driver successfully payed for his stay.`
    }
    getStatistics(carNumber){
        if(carNumber === undefined){
           let result = `The Parking Lot has ${this.capacity} empty spots left.`
            this.vehicles.sort((a,b)=> a.carModel.localeCompare(b.carModel));
            for (let i = 0; i < this.vehicles.length; i++) {
                let currentCar = this.vehicles[i];
                result += `\n${currentCar.carModel} == ${currentCar.carNumber} - ${currentCar.payed === false ? 'Not payed' : 'Has payed'}`
            }
            return result.trim();
        } else {
            // found index of the object
            let index = this.vehicles.map(function (car) {return car.carNumber;}).indexOf(carNumber);
            // get the object
            let foundCar = this.vehicles[index];
            return `${foundCar.carModel} == ${foundCar.carNumber} - ${foundCar.payed === false ? 'Not payed' : 'Has payed'}`
        }
    }

}