Fix parsing format in date calculation

packages/nodes-base/nodes/DateTime.node.ts

@@ -1,7 +1,8 @@
-import * as moment from 'moment-timezone';
-import { set } from 'lodash';
 
-import { IExecuteFunctions } from 'n8n-core';
+import {
+	IExecuteFunctions,
+} from 'n8n-core';
+
 import {
 	IDataObject,
 	ILoadOptionsFunctions,
@@ -12,6 +13,11 @@ import {
 	NodeOperationError,
 } from 'n8n-workflow';
 
+import {
+	set,
+} from 'lodash';
+
+import * as moment from 'moment-timezone';
 
 export class DateTime implements INodeType {
 	description: INodeTypeDescription = {
@@ -21,6 +27,7 @@ export class DateTime implements INodeType {
 		group: ['transform'],
 		version: 1,
 		description: 'Allows you to manipulate date and time values',
+		subtitle: '={{$parameter["action"]}}',
 		defaults: {
 			name: 'Date & Time',
 			color: '#408000',
@@ -33,6 +40,11 @@ export class DateTime implements INodeType {
 				name: 'action',
 				type: 'options',
 				options: [
+					{
+						name: 'Calculate a Date',
+						description: 'Add or subtract time from a date',
+						value: 'calculate',
+					},
 					{
 						name: 'Format a Date',
 						description: 'Convert a date to a different format',
@@ -76,7 +88,7 @@ export class DateTime implements INodeType {
 				name: 'custom',
 				displayOptions: {
 					show: {
-						action:[
+						action: [
 							'format',
 						],
 					},
@@ -90,7 +102,7 @@ export class DateTime implements INodeType {
 				name: 'toFormat',
 				displayOptions: {
 					show: {
-						action:[
+						action: [
 							'format',
 						],
 						custom: [
@@ -109,10 +121,10 @@ export class DateTime implements INodeType {
 				type: 'options',
 				displayOptions: {
 					show: {
-						action:[
+						action: [
 							'format',
 						],
-						custom:[
+						custom: [
 							false,
 						],
 					},
@@ -162,7 +174,7 @@ export class DateTime implements INodeType {
 				name: 'options',
 				displayOptions: {
 					show: {
-						action:[
+						action: [
 							'format',
 						],
 					},
@@ -200,6 +212,156 @@ export class DateTime implements INodeType {
 					},
 				],
 			},
+			{
+				displayName: 'Date Value',
+				name: 'value',
+				displayOptions: {
+					show: {
+						action: [
+							'calculate',
+						],
+					},
+				},
+				type: 'string',
+				default: '',
+				description: 'The date string or timestamp from which you want to add/subtract time.',
+				required: true,
+			},
+			{
+				displayName: 'Operation',
+				name: 'operation',
+				displayOptions: {
+					show: {
+						action: [
+							'calculate',
+						],
+					},
+				},
+				type: 'options',
+				options: [
+					{
+						name: 'Add',
+						value: 'add',
+						description: 'Add time to Date Value',
+					},
+					{
+						name: 'Subtract',
+						value: 'subtract',
+						description: 'Subtract time from Date Value',
+					},
+				],
+				default: 'add',
+				required: true,
+			},
+			{
+				displayName: 'Duration',
+				name: 'duration',
+				displayOptions: {
+					show: {
+						action: [
+							'calculate',
+						],
+					},
+				},
+				type: 'number',
+				typeOptions: {
+					minValue: 0,
+				},
+				default: 0,
+				required: true,
+				description: 'E.g. enter “10” then select “Days” if you want to add 10 days to Date Value.',
+			},
+			{
+				displayName: 'Time Unit',
+				name: 'timeUnit',
+				description: 'Time unit for Duration parameter above.',
+				displayOptions: {
+					show: {
+						action: [
+							'calculate',
+						],
+					},
+				},
+				type: 'options',
+				options: [
+					{
+						name: 'Quarters',
+						value: 'quarters',
+					},
+					{
+						name: 'Years',
+						value: 'years',
+					},
+					{
+						name: 'Months',
+						value: 'months',
+					},
+					{
+						name: 'Weeks',
+						value: 'weeks',
+					},
+					{
+						name: 'Days',
+						value: 'days',
+					},
+					{
+						name: 'Hours',
+						value: 'hours',
+					},
+					{
+						name: 'Minutes',
+						value: 'minutes',
+					},
+					{
+						name: 'Seconds',
+						value: 'seconds',
+					},
+					{
+						name: 'Milliseconds',
+						value: 'milliseconds',
+					},
+				],
+				default: 'days',
+				required: true,
+			},
+			{
+				displayName: 'Property Name',
+				name: 'dataPropertyName',
+				type: 'string',
+				default: 'data',
+				required: true,
+				displayOptions: {
+					show: {
+						action: [
+							'calculate',
+						],
+					},
+				},
+				description: 'Name of the output property to which to write the converted date.',
+			},
+			{
+				displayName: 'Options',
+				name: 'options',
+				type: 'collection',
+				placeholder: 'Add Option',
+				default: {},
+				displayOptions: {
+					show: {
+						action: [
+							'calculate',
+						],
+					},
+				},
+				options: [
+					{
+						displayName: 'From Format',
+						name: 'fromFormat',
+						type: 'string',
+						default: '',
+						description: 'Format for parsing the value as a date. If unrecognized, specify the <a href="https://docs.n8n.io/nodes/n8n-nodes-base.dateTime/#faqs">format</a> for the value.',
+					},
+				],
+			},
 		],
 	};
 
@@ -297,8 +459,69 @@ export class DateTime implements INodeType {
 
 				returnData.push(newItem);
 			}
+
+			if (action === 'calculate') {
+
+				const dateValue = this.getNodeParameter('value', i) as string;
+				const operation = this.getNodeParameter('operation', i) as 'add' | 'subtract';
+				const duration = this.getNodeParameter('duration', i) as number;
+				const timeUnit = this.getNodeParameter('timeUnit', i) as moment.DurationInputArg2;
+				const { fromFormat } = this.getNodeParameter('options', i) as { fromFormat?: string };
+				const dataPropertyName = this.getNodeParameter('dataPropertyName', i) as string;
+
+				const newDate = fromFormat
+					? parseDateByFormat(dateValue, fromFormat)
+					: parseDateByDefault(dateValue);
+
+				operation === 'add'
+					? newDate.add(duration, timeUnit).utc().format()
+					: newDate.subtract(duration, timeUnit).utc().format();
+
+				let newItem: INodeExecutionData;
+				if (dataPropertyName.includes('.')) {
+					// Uses dot notation so copy all data
+					newItem = {
+						json: JSON.parse(JSON.stringify(item.json)),
+					};
+				} else {
+					// Does not use dot notation so shallow copy is enough
+					newItem = {
+						json: { ...item.json },
+					};
+				}
+
+				if (item.binary !== undefined) {
+					newItem.binary = item.binary;
+				}
+
+				set(newItem, `json.${dataPropertyName}`, newDate);
+
+				returnData.push(newItem);
+			}
 		}
 
 		return this.prepareOutputData(returnData);
 	}
 }
+
+function parseDateByFormat(value: string, fromFormat: string) {
+	const date = moment(value, fromFormat, true);
+	if (moment(date).isValid()) return date;
+
+	throw new Error('Date input cannot be parsed. Please recheck the value and the "From Format" field.');
+}
+
+function parseDateByDefault(value: string) {
+	const isoValue = getIsoValue(value);
+	if (moment(isoValue).isValid()) return moment(isoValue);
+
+	throw new Error('Unrecognized date input. Please specify a format in the "From Format" field.');
+}
+
+function getIsoValue(value: string) {
+	try {
+		return new Date(value).toISOString(); // may throw due to unpredictable input
+	} catch (error) {
+		throw new Error('Unrecognized date input. Please specify a format in the "From Format" field.');
+	}
+}