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

/**
 * A button that can be used to trigger a server-side action, typically a
 * download of a file generated by the server. If server-side processing
 * is enabled in the host table it will automatically add the last parameters
 * used for a table draw allowing the script to output a file with the same
 * order / search applied as the main table.
 *
 * This is particularly useful when using server-side processing and wishing
 * to allow user export of the data in a table. The default Buttons package
 * will only export the data available on the client-side, while this button
 * can be used to let the server generate the required file and then download
 * it to the client-side.
 *
 * @name        Download Button
 * @summary     A button that can be configured to trigger a server-side action.
 * @author      SpryMedia Ltd (www.datatables.net)
 * @copyright   Copyright SpryMedia Ltd.
 * @requires    DataTables 3+
 * @license     MIT - http://datatables.net/license/mit
 *
 * @example
 *   // Download button
 *   const table = new DataTable('#example', {
 *     layout: {
 *      topStart: {
 *        buttons: [{
 *          extend: 'download',
 *          url: '/api/download'
 *        }]
 *      }
 *    }
 *   });
 */

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

function flattenJson(data: any, name?: any, flattened?: any) {
	if (!flattened) {
		flattened = {};
	}

	if (!name) {
		name = '';
	}

	if (util.is.plainObject(data))
		util.object.each(data, function (idx, val) {
			if (name === '') {
				flattenJson(val, idx, flattened);
			}
			else {
				flattenJson(val, name + '[' + idx.toString() + ']', flattened);
			}
		});
	else if (Array.isArray(data)) {
		for (let i = 0; i < data.length; i++) {
			if (name === '') {
				flattenJson(data[i], i, flattened);
			}
			else {
				flattenJson(
					data[i],
					name + '[' + i.toString() + ']',
					flattened
				);
			}
		}
	}
	else {
		flattened[name] = data;
	}

	return flattened;
}

DataTable.ext.buttons.download = {
	text: 'Download',
	action: function (e: Event, dt: Api, node: Node, config: any) {
		// Gather information to be submitted
		var data = {};

		if (dt.page.info().serverSide) {
			Object.assign(data, dt.ajax.params());
		}

		if (typeof config.data === 'function') {
			config.data(data);
		}
		else if (typeof config.data === 'object') {
			Object.assign(data, config.data);
		}

		// Convert data to a flat structure for submission
		var flattened = flattenJson(data);

		// Create an iframe
		var iframe = document.createElement('iframe');
		iframe.style.border = 'none';
		iframe.style.height = '0';
		iframe.style.width = '0';
		document.body.appendChild(iframe);

		var contentDoc = iframe.contentWindow!.document;
		contentDoc.open();
		contentDoc.close();

		var form = contentDoc.createElement('form');
		form.method = config.type;
		form.action = config.url;
		contentDoc.appendChild(form);

		util.object.each(flattened, function (name, val) {
			let input = contentDoc.createElement('input');
			input.type = 'text';
			input.name = name.toString();
			input.value = val as string;
			input.autocomplete = 'no' as any;
			form.appendChild(input);
		});

		form.submit();
	},
	url: '',
	type: 'POST',
	data: {}
};