import $ from '../../shared/jquery.js';
import { AjaxReq, fetchHeaders } from './OMGUtils';

const EDIT_ACTION = 'edit';
const EDITABLE_COLUMN_ATTRIBUTE = 'aria-editable';
const EDIT_ACTIVE_CLASS = 'shadow rounded bg-dark text-light';
const EDIT_ACTIVE_ROW_CLASS = 'bg-info';
const FORM_CONTENT_TYPE = 'application/x-www-form-urlencoded';
const NON_EDITABLE_VALUE = 'false';

let tableSelector = null;
let controllerUrl = '';

/**
 * Returns the editable table column names.
 *
 * @returns {string[]} Column names.
 * @sideEffects Reads the document.
 */
function getTableFieldNames() {
	return $(`${tableSelector} thead th`).map(function () {
		return this.innerText;
	}).get();
}

/**
 * Returns an attribute from a table column definition.
 *
 * @param {number} columnIndex Column index.
 * @param {string} attributeName Attribute name.
 * @returns {string|undefined} Attribute value.
 * @sideEffects Reads the document.
 */
function getColumnAttribute(columnIndex, attributeName) {
	return $(`${tableSelector} thead th`).eq(columnIndex).attr(attributeName);
}

/**
 * Cancels the edit of a table cell and restores its previous value.
 *
 * @param {HTMLElement} cell Table cell.
 * @returns {void}
 * @sideEffects Updates the edited table cell.
 */
function cancelEdit(cell) {
	cell.innerText = $(cell).data('oldvalue');
	$(cell).parent('tr').removeClass(`dt-editing-cell ${EDIT_ACTIVE_ROW_CLASS}`);
	$(cell).removeClass(EDIT_ACTIVE_CLASS);
	$('body').focus();
	cell.contentEditable = 'false';
}

/**
 * Shows a request error without discarding diagnostic context.
 *
 * @param {unknown} error Request failure.
 * @returns {void}
 * @sideEffects Logs the failure and displays an alert.
 */
function showRequestError(error) {
	console.error('Editable table request failed.', error);
	alert('Unable to save the table changes.');
}

/**
 * Runs a table command using form-urlencoded data.
 *
 * @param {string} action Server action.
 * @returns {void}
 * @sideEffects Performs a network request and displays an alert.
 */
function executeTableAction(action) {
	AjaxReq(controllerUrl, {
		headers: { ...fetchHeaders, 'Content-Type': FORM_CONTENT_TYPE },
		method: 'POST',
		body: `action=${action}`,
	}).fetchPromise()
		.then(response => alert(`${response.code} - ${response.err}`))
		.catch(showRequestError);
}

/**
 * Sends the currently edited row to the server.
 *
 * @param {HTMLElement} cell Edited cell.
 * @returns {void}
 * @sideEffects Performs a network request and refreshes the DataTable.
 */
function saveEdit(cell) {
	const formData = new FormData();
	const fields = getTableFieldNames();

	$('.dt-editing-cell td').each(function (index) {
		formData.append(fields[index], this.innerText);
	});
	formData.append('action', EDIT_ACTION);

	AjaxReq(controllerUrl, { method: 'POST', body: formData }).fetchPromise()
		.then(response => {
			$(tableSelector).DataTable().ajax.reload();
			alert(`${response.code} - ${response.err}`);
		})
		.catch(showRequestError)
		.finally(() => {
			cell.contentEditable = 'false';
		});
}

/**
 * Initializes an editable DataTable.
 *
 * @param {string} tableReference DataTable selector.
 * @param {string} controllerUrlReference Server endpoint.
 * @returns {void}
 * @sideEffects Initializes the table and registers DOM event handlers.
 */
function initializeEditableTable(tableReference, controllerUrlReference) {
	tableSelector = tableReference;
	controllerUrl = controllerUrlReference;
	const tableBody = $(`${tableSelector} tbody`);

	$(tableSelector).DataTable({
		ajax: {
			url: controllerUrl,
			type: 'POST',
			data: { action: 'getData' },
			dataSrc(data) {
				$(tableSelector).closest('.dt-container').parent().removeClass('d-none');
				return data;
			},
		},
		lengthChange: false,
		dom: 'frtBip',
		order: [[0, 'asc']],
		buttons: [
			{ text: 'Completa lista', action: () => executeTableAction('closelist') },
			{ text: 'Annulla lista', action: () => executeTableAction('cancellist') },
		],
	});

	tableBody.on('click', 'td', function () {
		if (getColumnAttribute(this.cellIndex, EDITABLE_COLUMN_ATTRIBUTE) === NON_EDITABLE_VALUE) {
			return;
		}

		this.contentEditable = 'true';
		$(this).data('oldvalue', this.innerText);
		$(this).parent('tr').addClass(`dt-editing-cell ${EDIT_ACTIVE_ROW_CLASS}`);
		$(this).addClass(EDIT_ACTIVE_CLASS);
		this.focus();
	});

	tableBody.on('blur', 'td', function () {
		cancelEdit(this);
	});

	tableBody.on('keydown', 'td', function (event) {
		if (event.code === 'Escape' || event.code === 'Tab') {
			cancelEdit(this);
			return false;
		}

		if (event.code === 'Enter') {
			$(this).data('oldvalue', this.innerText);
			saveEdit(this);
			return false;
		}
	});
}

export default initializeEditableTable;