✨ Add LinkedIn Integration (#942)

* 🚧 node logic, request logic, authentication, logo, descriptions

* 🚧 Posting image, article and text finished.

* 🚧 Posting image, article and text in post finished

* ⚡ Post creation (image, articles, text)

* ⚡ Added post creation by organization, fixed up descriptions, credentials, indentation

* ⚡ Fix issues on LinkedIn-Node

Co-authored-by: Jan Oberhauser <jan.oberhauser@gmail.com>
Co-authored-by: Jan <janober@users.noreply.github.com>

packages/nodes-base/nodes/LinkedIn/GenericFunctions.ts

@@ -0,0 +1,52 @@
+import {
+	OptionsWithUrl,
+} from 'request';
+
+import {
+	IExecuteFunctions,
+	IHookFunctions,
+	ILoadOptionsFunctions,
+} from 'n8n-core';
+
+export async function linkedInApiRequest(this: IHookFunctions | IExecuteFunctions | ILoadOptionsFunctions, method: string, endpoint: string, body: any = {}, binary?: boolean, headers?: object): Promise<any> { // tslint:disable-line:no-any
+	const options: OptionsWithUrl = {
+		headers: {
+			'Accept': 'application/json',
+			'X-Restli-Protocol-Version': '2.0.0'
+		},
+		method,
+		body,
+		url: binary ? endpoint : `https://api.linkedin.com/v2${endpoint}`,
+		json: true,
+	};
+
+	// If uploading binary data
+	if (binary) {
+		delete options.json;
+		options.encoding = null;
+	}
+
+	if (Object.keys(body).length === 0) {
+		delete options.body;
+	}
+
+	try {
+		return await this.helpers.requestOAuth2!.call(this, 'linkedInOAuth2Api', options, { tokenType: 'Bearer' });
+	} catch (error) {
+		if (error.respose && error.response.body && error.response.body.detail) {
+			throw new Error(`Linkedin Error response [${error.statusCode}]: ${error.response.body.detail}`);
+		}
+		throw error;
+	}
+}
+
+
+export function validateJSON(json: string | undefined): any { // tslint:disable-line:no-any
+	let result;
+	try {
+		result = JSON.parse(json!);
+	} catch (exception) {
+		result = '';
+	}
+	return result;
+}