import * as builder from "botbuilder";
import * as express from "express";
import * as crypto from "crypto";
import { OutgoingWebhookDeclaration, IOutgoingWebhook } from "express-msteams-host";

/**
 * Implementation for <%= customBotTitle %>
 */
@OutgoingWebhookDeclaration("/api/webhook")
export class <%= customBotClassName %> implements IOutgoingWebhook {

    /**
     * Implement your outgoing webhook logic here
     * @param req the Request
     * @param res the Response
     * @param next
     */
    public requestHandler(req: express.Request, res: express.Response, next: express.NextFunction) {
        // parse the incoming message
        const incoming = req.body as builder.Activity;

        // create the response, any Teams compatible responses can be used
        const message: Partial<builder.Activity> = {
            type: builder.ActivityTypes.Message
        };

        const securityToken = process.env.SECURITY_TOKEN;
        if (securityToken && securityToken.length > 0) {
            // There is a configured security token
            const auth = req.headers.authorization;
            const msgBuf = Buffer.from((req as any).rawBody, "utf8");
            const msgHash = "HMAC " + crypto
                .createHmac("sha256", Buffer.from(securityToken as string, "base64"))
                .update(msgBuf)
                .digest("base64");

            if (msgHash === auth) {
                // Message was ok and verified
                message.text = `Echo ${incoming.text}`;
            } else {
                // Message could not be verified
                message.text = "Error: message sender cannot be verified";
            }
        } else {
            // There is no configured security token
            message.text = "Error: outgoing webhook is not configured with a security token";
        }

        // send the message
        res.send(JSON.stringify(message));
    }
}