✨ Add AWS Textract node (#2330)

* ✨ AWS Textract node

* ⚡ Fix issue with types

* ⚡ Small change to labels

* ⚡ Improvements

* ⚡ Improve error message

* ⚡ Improve description

Co-authored-by: Jan Oberhauser <jan.oberhauser@gmail.com>

packages/nodes-base/nodes/Aws/Textract/GenericFunctions.ts

@@ -0,0 +1,156 @@
+import {
+	URL,
+} from 'url';
+
+import {
+	Request,
+	sign,
+} from 'aws4';
+
+import {
+	OptionsWithUri,
+} from 'request';
+
+import {
+	parseString,
+} from 'xml2js';
+
+import {
+	IExecuteFunctions,
+	IHookFunctions,
+	ILoadOptionsFunctions,
+	IWebhookFunctions,
+} from 'n8n-core';
+
+import {
+	ICredentialDataDecryptedObject,
+	ICredentialTestFunctions,
+	NodeApiError,
+	NodeOperationError,
+} from 'n8n-workflow';
+
+function getEndpointForService(service: string, credentials: ICredentialDataDecryptedObject): string {
+	let endpoint;
+	if (service === 'lambda' && credentials.lambdaEndpoint) {
+		endpoint = credentials.lambdaEndpoint;
+	} else if (service === 'sns' && credentials.snsEndpoint) {
+		endpoint = credentials.snsEndpoint;
+	} else {
+		endpoint = `https://${service}.${credentials.region}.amazonaws.com`;
+	}
+	return (endpoint as string).replace('{region}', credentials.region as string);
+}
+
+export async function awsApiRequest(this: IHookFunctions | IExecuteFunctions | ILoadOptionsFunctions | IWebhookFunctions, service: string, method: string, path: string, body?: string, headers?: object): Promise<any> { // tslint:disable-line:no-any
+	const credentials = await this.getCredentials('aws');
+	if (credentials === undefined) {
+		throw new NodeOperationError(this.getNode(), 'No credentials got returned!');
+	}
+
+	// Concatenate path and instantiate URL object so it parses correctly query strings
+	const endpoint = new URL(getEndpointForService(service, credentials) + path);
+
+	// Sign AWS API request with the user credentials
+	const signOpts = { headers: headers || {}, host: endpoint.host, method, path, body } as Request;
+	sign(signOpts, { accessKeyId: `${credentials.accessKeyId}`.trim(), secretAccessKey: `${credentials.secretAccessKey}`.trim() });
+
+
+	const options: OptionsWithUri = {
+		headers: signOpts.headers,
+		method,
+		uri: endpoint.href,
+		body: signOpts.body,
+	};
+
+	try {
+		return await this.helpers.request!(options);
+	} catch (error) {
+		if (error?.response?.data || error?.response?.body) {
+			const errorMessage = error?.response?.data || error?.response?.body;
+			if (errorMessage.includes('AccessDeniedException')) {
+				const user = JSON.parse(errorMessage).Message.split(' ')[1];
+				throw new NodeApiError(this.getNode(), error, { 
+					message: 'Unauthorized — please check your AWS policy configuration',
+					description: `Make sure an identity-based policy allows user ${user} to perform textract:AnalyzeExpense` });
+			}
+		}
+
+		throw new NodeApiError(this.getNode(), error); // no XML parsing needed
+	}
+}
+
+export async function awsApiRequestREST(this: IHookFunctions | IExecuteFunctions | ILoadOptionsFunctions, service: string, method: string, path: string, body?: string, headers?: object): Promise<any> { // tslint:disable-line:no-any
+	const response = await awsApiRequest.call(this, service, method, path, body, headers);
+	try {
+		return JSON.parse(response);
+	} catch (error) {
+		return response;
+	}
+}
+
+export async function awsApiRequestSOAP(this: IHookFunctions | IExecuteFunctions | ILoadOptionsFunctions | IWebhookFunctions, service: string, method: string, path: string, body?: string, headers?: object): Promise<any> { // tslint:disable-line:no-any
+	const response = await awsApiRequest.call(this, service, method, path, body, headers);
+	try {
+		return await new Promise((resolve, reject) => {
+			parseString(response, { explicitArray: false }, (err, data) => {
+				if (err) {
+					return reject(err);
+				}
+				resolve(data);
+			});
+		});
+	} catch (error) {
+		return response;
+	}
+}
+
+export function simplify(data: IExpenseDocument) {
+	const result: { [key: string]: string } = {};
+	for (const document of data.ExpenseDocuments) {
+		for (const field of document.SummaryFields) {
+			result[field?.Type?.Text || field?.LabelDetection?.Text] = field.ValueDetection.Text;
+		}
+	}
+	return result;
+}
+
+export interface IExpenseDocument {
+	ExpenseDocuments: [
+		{
+			SummaryFields: [
+				{
+					LabelDetection: { Text: string },
+					ValueDetection: { Text: string },
+					Type: { Text: string }
+				}]
+		}];
+}
+
+export async function validateCrendetials(this: ICredentialTestFunctions, decryptedCredentials: ICredentialDataDecryptedObject, service: string): Promise<any> { // tslint:disable-line:no-any
+	const credentials = decryptedCredentials;
+
+	// Concatenate path and instantiate URL object so it parses correctly query strings
+	const endpoint = new URL(getEndpointForService(service, credentials) + `?Action=GetCallerIdentity&Version=2011-06-15`);
+
+	// Sign AWS API request with the user credentials
+	const signOpts = { host: endpoint.host, method: 'POST', path: '?Action=GetCallerIdentity&Version=2011-06-15' } as Request;
+	sign(signOpts, { accessKeyId: `${credentials.accessKeyId}`.trim(), secretAccessKey: `${credentials.secretAccessKey}`.trim() });
+
+	const options: OptionsWithUri = {
+		headers: signOpts.headers,
+		method: 'POST',
+		uri: endpoint.href,
+		body: signOpts.body,
+	};
+
+	const response = await this.helpers.request!(options);
+
+	return await new Promise((resolve, reject) => {
+		parseString(response, { explicitArray: false }, (err, data) => {
+			if (err) {
+				return reject(err);
+			}
+			resolve(data);
+		});
+	});
+}