oauthServer.ts

import fetch from 'node-fetch'
import express, { Request, Response } from 'express'
import * as dotenv from 'dotenv'
import bodyParser from 'body-parser'


dotenv.config()

const redirectUri = 'http://localhost:5010/oauth/linearCallback'
const AuthorizationHost = 'https://linear.app'
const TokenHost = 'https://api.linear.app'
const AuthorizePath = '/oauth/authorize'
const TokenPath = '/oauth/token'
const params = {
  response_type: 'code',
  client_id: process.env.LINEAR_CLIENT_API_KEY!,
  actor: 'application', // https://developers.linear.app/docs/oauth/oauth-actor-authorization
  redirect_uri: redirectUri,
  scope: 'read,write,issues:create,comments:create',
}
const url = new URL(AuthorizationHost)
url.pathname = AuthorizePath
url.search = new URLSearchParams(params).toString()
const authorizationUri = url.href

const app = express()
app.set('port', (process.env.PORT || 5010))
app.listen(app.get('port'), () => {
  console.info('Node app is running on port', app.get('port'))
})
app.use(bodyParser.json())


app.get('/oauth/linear', (req, res) => {
  res.redirect(authorizationUri)
})

app.get('/oauth/linearCallback', async (req: Request, res: Response) => {
  const { code } = req.query

  const params = {
    code: typeof code === 'string' ? code : '',
    redirect_uri: redirectUri,
    client_id: process.env.LINEAR_CLIENT_API_KEY!,
    client_secret: process.env.LINEAR_CLIENT_SECRET!,
    grant_type: 'authorization_code',
  }

  try {
    const url = new URL(TokenHost)
    url.pathname = TokenPath
    const response = await fetch(url.href, {
      method: 'POST',
      body: new URLSearchParams(params).toString(),
      headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    })
    if (!response.ok) throw new Error(response.status.toString())
    const payload = await response.json()
    res.json(payload)
  } catch (error) {
    console.error('Access Token Error', error)
    res.status(500).json('Authentication failed')
  }
})