purchase.js

class Purchase {
    constructor(totalPrice, isInternetConnection, phoneLines, selectedCellPhones) {
        this.totalPrice = totalPrice;
        this.isInternetConnection = isInternetConnection;
        this.phoneLines = phoneLines;
        this.selectedCellPhones = selectedCellPhones;
    }

    internetConnection(isInternetConnectionChecked) {
        const internetConnectionPrice = 200;

        if (typeof isInternetConnectionChecked !== 'boolean') {
            throw new Error('isInternetConnectionChecked must be a boolean.');
        }
        this.isInternetConnection = isInternetConnectionChecked; // assign value to class attribute
        if (this.isInternetConnection) {
            this.totalPrice += internetConnectionPrice;
        } else if (!this.isInternetConnection && this.totalPrice > 0) {
            this.totalPrice -= internetConnectionPrice;
        }
        return this.totalPrice;
    }

    addPhoneLines() {
        const phoneLinePrice = 150;
        // non numerical and decimal numbers
        if (typeof this.phoneLines !== 'number' || !Number.isInteger(this.phoneLines)) {
            throw new Error('phoneLines must be an integer between 0 and 8.');
        }
        if (this.phoneLines < 0) {
            throw new Error('The minimum number of phone lines that can be hired is 0.');
        }
        // covers cases between 0 and 7
        if(this.phoneLines < 8) {
            this.phoneLines++;
            this.totalPrice += phoneLinePrice;
        } else {
            // > 8
            throw new Error('The maximum number of phone lines that can be hired is 8.');
        }
        return this.totalPrice;
    }

    removePhoneLines() {
        const phoneLinePrice = 150;
        // non numerical and decimal numbers
        if (typeof this.phoneLines !== 'number' || !Number.isInteger(this.phoneLines)) {
            throw new Error('phoneLines must be an integer between 0 and 8.');
        }
        if (this.phoneLines > 8) {
            throw new Error('The maximum number of phone lines that can be hired is 8.');
        }
        // covers cases between 0 and 8
        if(this.phoneLines > 0) {
            this.phoneLines--;
            this.totalPrice -= phoneLinePrice;
        } else {
            // < 0
            throw new Error('The minimum number of phone lines that can be hired is 0.');
        }
        return this.totalPrice;
    }

    selectCellPhone(modelName) {
        const cellPhoneNames = ["Motorola G99", "iPhone 99", 'Samsung Galaxy 99', "Sony Xperia 99", "Huawei 99"];
        const cellPhonePrices = [800, 6000, 1000, 900, 900];  // frequency array

        // if the parameter received is not a string, then throw an error
        if (typeof modelName !== 'string') {
            throw new Error('The parameter modelName must be a string.');
        }

        // if the parameter received is not included in the array of Available Phones (cellPhoneNames), then throw an error
        if(!cellPhoneNames.includes(modelName)) {
            throw new Error('The Model Name must be one of the 5 available Models!');
        }

        // iterate through the cellPhoneNames array
        // if we find an element in the array with the same name as the newly selected phone,
        // then add the newly selected phone name in the array of selectedCellPhones
        // increase the total price with the corresponding cost of the selected phone
        for (let i = 0; i < cellPhoneNames.length; i ++) {
            if (modelName === cellPhoneNames[i]) {
                this.selectedCellPhones.push(modelName);
                this.totalPrice += cellPhonePrices[i];
                break;
            }
        }
        return this.totalPrice;
    }

    unselectCellPhone(modelName) {
        const cellPhoneNames = ["Motorola G99", "iPhone 99", 'Samsung Galaxy 99', "Sony Xperia 99", "Huawei 99"];
        const cellPhonePrices = [800, 6000, 1000, 900, 900];  // frequency array

        // if the parameter received is not a string, then throw an error
        if (typeof modelName !== 'string') {
            throw new Error('The parameter modelName must be a string.');
        }

        // if the parameter received is not included in the array of Available Phones (cellPhoneNames), then throw an error
        if(!cellPhoneNames.includes(modelName)) {
            throw new Error('The Model Name must be one of the 5 available Models!');
        }

        // iterate through the selectedCellPhones array
        // if we find an element in the array with the same name as the newly selected phone,
        // then delete the newly selected phone name in the array of selectedCellPhones
        for (let i = 0; i < this.selectedCellPhones.length; i ++) {
            if (modelName === this.selectedCellPhones[i]) {
                this.selectedCellPhones.splice(i, 1); // delete an element from array at index i
                break;
            }
        }

        // iterate through the cellPhoneNames array
        // if we find an element in the array with the same name as the newly selected phone,
        // decrease the total price with the corresponding cost of the selected phone
        for (let i = 0; i < cellPhoneNames.length; i ++) {
            if (modelName === cellPhoneNames[i]) {
                this.totalPrice -= cellPhonePrices[i];
                break;
            }
        }
        return this.totalPrice;
    }

    showBuyingReceipt() {
        let receiptMessage = "";
        if (this.isInternetConnection) {
            receiptMessage += 'Internet Connection: ' + this.isInternetConnection + '\n';
        }
        if (this.phoneLines > 0) {
            receiptMessage += 'Number of Phone Lines: ' + this.phoneLines + '\n';
        }
        if (this.selectedCellPhones.length > 0) {
            receiptMessage += 'Cell Phones: ' + this.selectedCellPhones + '\n';
        }
        if (this.totalPrice !== 0) {
            receiptMessage += 'Total Price: ' + this.totalPrice + ' DKK';
            return receiptMessage;
        }
        receiptMessage += "Nothing is selected! Please select an item!";
        return receiptMessage;
    }

}

module.exports = Purchase;