✨ Add PostHog Node (#1440)

* ✨ PostHog Node

* ⚡ Minor improvements to PostHog Node

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

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

@@ -0,0 +1,80 @@
+import {
+	OptionsWithUrl,
+} from 'request';
+
+import {
+	IExecuteFunctions,
+	ILoadOptionsFunctions,
+} from 'n8n-core';
+
+import {
+	IDataObject,
+} from 'n8n-workflow';
+
+export async function posthogApiRequest(this: IExecuteFunctions | ILoadOptionsFunctions, method: string, path: string, body: any = {}, qs: IDataObject = {}, option = {}): Promise<any> { // tslint:disable-line:no-any
+
+	const credentials = this.getCredentials('postHogApi') as IDataObject;
+
+	const base = credentials.url as string;
+
+	body.api_key = credentials.apiKey as string;
+
+	const options: OptionsWithUrl = {
+		headers: {
+			'Content-Type': 'application/json',
+		},
+		method,
+		body,
+		qs,
+		url: `${base}${path}`,
+		json: true,
+	};
+
+	try {
+		if (Object.keys(body).length === 0) {
+			delete options.body;
+		}
+		return await this.helpers.request!(options);
+	} catch (error) {
+		if (error.response && error.response.body && error.response.body.message) {
+
+			const message = error.response.body.message;
+			// Try to return the error prettier
+			throw new Error(
+				`PosHog error response [${error.statusCode}]: ${message}`,
+			);
+		}
+		throw error;
+	}
+}
+
+export interface IEvent {
+	event: string;
+	properties: { [key: string]: any }; // tslint:disable-line:no-any
+}
+
+export interface IAlias {
+	type: string;
+	event: string;
+	properties: { [key: string]: any }; // tslint:disable-line:no-any
+	context: { [key: string]: any }; // tslint:disable-line:no-any
+}
+
+export interface ITrack {
+	type: string;
+	event: string;
+	name: string;
+	messageId?: string;
+	distinct_id: string;
+	category?: string;
+	properties: { [key: string]: any }; // tslint:disable-line:no-any
+	context: { [key: string]: any }; // tslint:disable-line:no-any
+}
+
+
+export interface IIdentity {
+	event: string;
+	messageId?: string;
+	distinct_id: string;
+	properties: { [key: string]: any }; // tslint:disable-line:no-any
+}