# Webhooks lib

Integration with external services can be possible with webhooks notifications. This lib generate url for webhooks.

## Example bot

See [example bot](https://t.me/BBWebhookBot)

{% hint style="info" %}
From [wikipedia](https://en.wikipedia.org/wiki/Webhook): a **webhook** is a method of augmenting or altering the behavior of bot, with custom [callbacks](https://en.wikipedia.org/wiki/Callback_\(computer_programming\)).

These callbacks may be maintained, modified, and managed by third-party users and developers who may not necessarily be affiliated with the originating website or application.

 The term "webhook" was coined by Jeff Lindsay in 2007 from the computer programming term [hook](https://en.wikipedia.org/wiki/Hooking).
{% endhint %}

Webhooks is more simple way for integration. Other libs also use webhooks notifications already: CoinPayments, FreeKassa.

{% hint style="success" %}
Webhook link have public\_user\_token - it is public secret.

User can't modify user\_id, command because it is protected with public\_user\_token.
{% endhint %}

## Get Webhook Url

```javascript
// user's webhook
let webhookUrl = Libs.Webhooks.getUrlFor({
  // this command will be runned on webhook
  command: "/onWebhook",
  // this text will be passed to command
  content: "Did you see the cat?",
  // execute for this (current) user
  user_id: user.id,
  // redirect to page with cat after calling webhook
  // you need remove this for external service
  redirect_to: "https://cataas.com/cat"
})

Bot.inspect(webhookUrl);
```

This code will generate Webhook url. 

After loading page via this url:

* web page with cat will be loaded (Thank for cat to [https://cataas.com](https://cataas.com/cat))
* command `/onWebhook` will be execute on Bot for user with user.id
* content "Did you see the cat?" will be passed for command `/onWebhook`

###  

## Receive webhook for user

As a rule, the webhook URL must be set from the admin panel on the external service. So we can not set it for just one user: 

```javascript
// global bot webhook
let webhookUrl = Libs.Webhooks.getUrlFor({
  // this command will be runned on webhook
  command: "/onWebhook",
  user_id: user.id
})
```

{% hint style="warning" %}
Webhooks can be with GET and POST methods only. All passed data contains on content variable
{% endhint %}

On command `/onWebhook` we can get posted content from external service

```javascript
// for user's webhook
Bot.sendMessage(inspect(content))
// also you can read data with Bot.getProperty - you need store it before
```

As a rule, external service must pass useful data on webhook. For example info about payments: order\_id, user\_id. Use it!

## Receive global webhook for bot

On command `/onWebhook` for bot's webhook we do not have user:

```javascript
// for bot's webhook

// this is not worked - because no current user on bot's webhook
// Bot.sendMessage(inspect(content))

// make any not specific user code
// ...

// We can pass user_id in content (it is depend from external service)
Bot.run({
   command: "/userCommand",
   user_id: JSON.parse(content).user_id
})

// in /userCommand we can now use Bot.sendMessage function

```

## Call options

You can use options on BJS on webhook request

`/onWebhook` command:

```javascript
Bot.sendMessage(
  JSON.stringify(options)
);
```

| Key               | Value                                                                  |
| ----------------- | ---------------------------------------------------------------------- |
| `options.url`     | webhook url                                                            |
| `options.method`  | request method ("GET" or "POST")                                       |
| `options.params`  | request params                                                         |
| `options.headers` | headers for this request like Ip,  User-Agent, Accept-Language and etc |
| `options.ip`      | client IP                                                              |

## Webhook response

### 1. Content response with bot answer

```javascript
// call user's webhook
// first message sending appears on bot
Bot.sendMessage("This answer will be in bot");

//...
// last message sending
// will be on bot and on web page
// you can open this web page on your browser via webhook url

Bot.sendMessage("Hello in browser!");

// in web page you will have:
// { answer: "Hello in browser!" }
```

### 2. Content response without bot answer

You can use [WebApp](https://help.bots.business/bjs/web-app) render - it is not produce message from bot.

```javascript
// render this command in web
WebApp.render({ content: "Hello from bot " + bot.name });
```

### Code response

Webhook response can be:

* 200 - BJS is runned, no errors
* 503 - we have errors in BJS

you can throw error in BJS:

`throw new Error("Error on webhook")`

## Possible issues

In the case of a large number of requests from an external web service, such a web service may be subject to ban filters.

Please provide an external IP address and we will add it to the White List.