class Errors {
	/**
	 * Create a new Errors instance.
	 */
	constructor() {
		this.errors = {};
	}

	/**
	 * Determine if an errors exists for the given field.
	 *
	 * @param {string} field
	 */
	has(field) {
		return this.errors.hasOwnProperty(field);
	}

	/**
	 * Determine if we have any errors.
	 */
	any() {
		return Object.keys(this.errors).length > 0;
	}

	/**
	 * Retrieve the error message for a field.
	 *
	 * @param {string} field
	 */
	get(field) {
		if (this.errors[field]) {
			return this.errors[field][0];
		}
	}

	/**
	 * Record the new errors.
	 *
	 * @param {object} errors
	 */
	record(errors) {
		this.errors = errors;
	}

	/**
	 * Clear one or all error fields.
	 *
	 * @param {string|null} field
	 */
	clear(field) {
		if (field) {
			delete this.errors[field];
			return;
		}
		this.errors = {};
	}
}

	class Form {
	/**
	 * Create a new Form instance.
	 *
	 * @param {object} data
	 */
	constructor(data) {
		this.originalData = data;
		for (let field in data) {
			this[field] = data[field];
		}
		this.errors = new Errors();
	}

	/**
	 * Fetch all relevant data for the form.
	 */
	data() {
		let data = {};
		for (let property in this.originalData) {
			data[property] = this[property];
		}
		return data;
	}

	/**
	 * Reset the form fields.
	 */
	reset() {
		for (let field in this.originalData) {
			this[field] = '';
		}
		this.errors.clear();
	}

	/**
	 * Send a POST request to the given URL.
	 * .
	 * @param {string} url
	 */
	post(url) {
		return this.submit('post', url);
	}

	/**
	 * Send a PUT request to the given URL.
	 * .
	 * @param {string} url
	 */
	put(url) {
		return this.submit('put', url);
	}

	/**
	 * Send a PATCH request to the given URL.
	 * .
	 * @param {string} url
	 */
	patch(url) {
		return this.submit('patch', url);
	}

	/**
	 * Send a DELETE request to the given URL.
	 * .
	 * @param {string} url
	 */
	delete(url) {
		return this.submit('delete', url);
	}

	/**
	 * Submit the form.
	 *
	 * @param {string} requestType
	 * @param {string} url
	 */
	submit(requestType, url) {
		return new Promise((resolve, reject) => {
			window.axios[requestType](url, this.data())
				.then(response => {
					this.onSuccess(response.data);
					resolve(response.data);
				})
				.catch(error => {
					this.onFail(error.response.data);
					reject(error.response.data);
				});
		});
	}

	/**
	 * Handle a successful form submission.
	 *
	 * @param {object} data
	 */
	onSuccess(data) {
		// in Laravel controller do
		// return ['message' => 'success'];
		// alert(data.message);
		this.reset();
	}

	/**
	 * Handle a failed form submission.
	 *
	 * @param {object} errors
	 */
	onFail(errors) {
		this.errors.record(errors);
	}
}

export default Form;

// HOW TO USE IN VUE COMPONENT:
// data : {
// 	form : new Form({
// 		name        : '',
// 		description : '',
// 	}),
// },

// methods : {
// 	onSubmit() {
// 		this.form.post('/projects')
// 			.then(response => alert('Wahoo!'));
// 	}
// }