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webhook.ts
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webhook.ts
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// deno-lint-ignore-file no-explicit-any
import { Bot } from '../bot.ts'
import { debug as d, Update } from '../platform.ts'
import { WebhookReplyEnvelope } from '../core/client.ts'
import { Context } from '../context.ts'
const debugErr = d('grammy:error')
/**
* HTTP Web frameworks for which grammY provides compatible callback out of the
* box.
*/
type SupportedFrameworks =
| 'express'
| 'http'
| 'https'
| 'koa'
| 'oak'
| 'fastify'
| 'worktop'
/**
* Abstraction over a request-response cycle, provding access to the update, as
* well as a mechanism for responding to the request and to end it.
*/
interface ReqResHandler {
/**
* The update object sent from Telegram, usually resolves the request's JSON
* body
*/
update: Promise<Update>
/**
* Ends the request immediately without body, called after every request
* unless a webhook reply was performed
*/
end?: () => void
/**
* Sends the specified JSON as a payload in the body, used for webhook
* replies
*/
respond: (json: string) => unknown
}
/**
* Middleware for a web framework. Creates a request-response handler for a
* request. The handler will be used to integrate with the compatible framework.
*/
type FrameworkAdapter = (...args: any[]) => ReqResHandler
const standard: FrameworkAdapter = (req, res) => ({
update: Promise.resolve(req.body),
end: () => res.end(),
respond: json => res.send(json),
})
// Integrations with popular frameworks
const frameworkAdapters: Record<SupportedFrameworks, FrameworkAdapter> = {
express: standard,
http: standard,
https: standard,
koa: ctx => ({
update: Promise.resolve(ctx.request.body),
end: () => (ctx.body = ''),
respond: json => (ctx.response.body = json),
}),
oak: ctx => ({
update: ctx.request.body({ type: 'json' }).value,
end: () => (ctx.response.status = 200),
respond: json => {
ctx.response.type = 'json'
ctx.response.body = json
},
}),
fastify: (req, reply) => ({
update: Promise.resolve(req.body),
respond: json => reply.send(json),
}),
worktop: (req, res) => ({
update: Promise.resolve(req.body.json()),
end: () => res.end(),
respond: json => res.send(200, json)
})
// please open a PR if you want to add another
}
/**
* Creates a callback function that you can pass to a web framework (such as
* express) if you want to run your bot via webhooks. Use it like this:
* ```ts
* const app = express() // or whatever you're using
* const bot = new Bot('<token>')
*
* app.use(webhookCallback(bot, 'express'))
* ```
*
* Confer the grammY
* [documentation](https://grammy.dev/guide/deployment-types.html) to read more
* about how to run your bot with webhooks.
*
* @param bot The bot for which to create a callback
* @param framework An optional string identifying the framework (default: 'express')
* @param onTimeout An optional strategy to handle timeouts (default: 'throw')
* @param timeoutMilliseconds An optional number of timeout milliseconds (default: 10_000)
*/
export function webhookCallback<C extends Context = Context>(
bot: Bot<C>,
framework: SupportedFrameworks = 'express',
onTimeout: 'throw' | 'return' | ((...args: any[]) => unknown) = 'throw',
timeoutMilliseconds = 10_000
) {
const server = frameworkAdapters[framework] ?? standard
let firstUpdate = true
let initialized = false
let initCall: Promise<void> | undefined
return async (...args: any[]) => {
const { update, respond, end } = server(...args)
let usedWebhookReply = false
const webhookReplyEnvelope: WebhookReplyEnvelope = {
send: async json => {
usedWebhookReply = true
await respond(json)
},
}
if (!initialized) {
if (firstUpdate) {
initCall = bot.init()
firstUpdate = false
}
await initCall
initialized = true
}
await timeoutIfNecessary(
bot.handleUpdate(await update, webhookReplyEnvelope),
typeof onTimeout === 'function'
? () => onTimeout(...args)
: onTimeout,
timeoutMilliseconds
)
if (end !== undefined && !usedWebhookReply) end()
}
}
function timeoutIfNecessary(
task: Promise<void>,
onTimeout: 'throw' | 'return' | (() => unknown),
timeout: number
): Promise<void> {
if (timeout === Infinity) return task
return new Promise((resolve, reject) => {
const handle = setTimeout(() => {
if (onTimeout === 'throw') {
reject(new Error(`Request timed out after ${timeout} ms`))
} else {
if (typeof onTimeout === 'function') onTimeout()
resolve()
}
const now = Date.now()
task.finally(() => {
const diff = Date.now() - now
debugErr(`Request completed ${diff} ms after timeout!`)
})
}, timeout)
task.then(resolve)
.catch(reject)
.finally(() => clearTimeout(handle))
})
}