/*! © SpryMedia Ltd - datatables.net/license */

/**
 * This feature is for use with a DataTable when multi-column sorting. It will
 * show an icon above each column that is being used for the current sort,
 * indicating the position of that column in the sort sequence.
 *
 * @name        OrderNumbers
 * @summary     Display ordering sequence along side the header cell
 * @author      SpryMedia Ltd
 * @copyright   Copyright SpryMedia Ltd.
 * @license     MIT - http://datatables.net/license/mit
 *
 * @example
 *   // Allow a display start point and search string to be specified
 *   new DataTable('#myTable', {
 *     orderNumbers: true
 *   );
 *
 * @example
 *   // As above, but with a default search
 *   new DataTable('#myTable', {
 *     orderNumbers: {
 *       className: 'my-ordering-class'
 *     }
 *   );
 */

import DataTable, { Api, Dom, InstSelector } from 'datatables.net';

import { OrderNumbers } from './types';

declare module 'datatables.net' {
	interface Defaults {
		orderNumbers: true | OrderNumbers;
	}
}

/**
 * Add event listeners to apply orderNumbers to a table
 *
 * @param src An element, selector, or DataTables API or settings object
 */
function orderNumbers(src: InstSelector, opts: OrderNumbers) {
	let table = new DataTable.Api(src);

	table.on('draw.orderNumbers', function () {
		remove(table, opts);
		draw(table, opts);
	});

	table.on('destroy', function () {
		remove(table, opts);
		table.off('draw.orderNumbers');
	});

	// Initial draw
	draw(table, opts);
}

/** Remove all existing indicators */
function remove(table: Api, opts: OrderNumbers) {
	Dom.s(table.table().header()).find('span.' + opts.className).remove();
}

/** Draw in new indicators for the currently applied order */
function draw(table: Api, opts: OrderNumbers) {
	var order = table.order();

	if (order.length > 1) {
		for (var i = 0; i < order.length; i++) {
			var col = table.column(order[i][0]);
			var cell = col.header();

			if (!col.visible()) {
				continue;
			}

			Dom.c('span')
				.classAdd(opts.className)
				.text((i + 1).toString())
				.appendTo(cell);
		}
	}
}

function applyOptions(
	optsOut: OrderNumbers,
	optsIn: Partial<OrderNumbers> | boolean | undefined
) {
	if (optsIn) {
		if (typeof optsIn === 'boolean') {
			optsOut.enable = optsIn;
		}
		else if (typeof optsIn === 'object') {
			Object.assign(optsOut, optsIn);

			// If `enable` is not given, but the object is, then we assume that
			// the feature should be enabled. Use `enable: false` if you want to
			// disable it.
			if (! optsIn.enable) {
				optsOut.enable = true;
			}
		}
	}
}

// Listen for DataTable's initialisation's so we can check if the plug-in should
// be automatically activated or not.
Dom.s(document).on('init.dt', function (e, settings) {
	if (e.namespace !== 'dt') {
		return;
	}

	let opts = Object.assign({}, orderNumbers.defaults);
	applyOptions(opts, DataTable.defaults.orderNumbers);
	applyOptions(opts, settings.init.orderNumbers);

	if (opts.enable) {
		orderNumbers(settings, opts);
	}
});

orderNumbers.defaults = {
	enable: false,
	className: 'dt-order-number',
};

DataTable.orderNumbers = orderNumbers;