//
// Copyright © 2024 Hardcore Engineering Inc.
//
// Licensed under the Eclipse Public License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License. You may
// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//
// See the License for the specific language governing permissions and
// limitations under the License.
//

import { Token, decodeToken } from '@hcengineering/server-token'
import cors from 'cors'
import express, { type Express, type NextFunction, type Request, type Response } from 'express'
import { IncomingHttpHeaders, type Server } from 'http'
import { MeasureContext } from '@hcengineering/core'
import { Telegraf } from 'telegraf'
import telegram, { TelegramNotificationRecord } from '@hcengineering/telegram'
import { translate } from '@hcengineering/platform'

import { ApiError } from './error'
import { PlatformWorker } from './worker'
import { Limiter } from './limiter'
import config from './config'
import { toTelegramHtml } from './utils'

const extractCookieToken = (cookie?: string): Token | null => {
  if (cookie === undefined || cookie === null) {
    return null
  }

  const cookies = cookie.split(';')
  const tokenCookie = cookies.find((cookie) => cookie.toLocaleLowerCase().includes('token'))
  if (tokenCookie === undefined) {
    return null
  }

  const encodedToken = tokenCookie.split('=')[1]
  if (encodedToken === undefined) {
    return null
  }

  return decodeToken(encodedToken)
}

const extractAuthorizationToken = (authorization?: string): Token | null => {
  if (authorization === undefined || authorization === null) {
    return null
  }
  const encodedToken = authorization.split(' ')[1]

  if (encodedToken === undefined) {
    return null
  }

  return decodeToken(encodedToken)
}

const extractToken = (headers: IncomingHttpHeaders): Token => {
  try {
    const token = extractCookieToken(headers.cookie) ?? extractAuthorizationToken(headers.authorization)

    if (token === null) {
      throw new ApiError(401)
    }

    return token
  } catch {
    throw new ApiError(401)
  }
}

type AsyncRequestHandler = (req: Request, res: Response, token: Token, next: NextFunction) => Promise<void>

const handleRequest = async (
  fn: AsyncRequestHandler,
  req: Request,
  res: Response,
  next: NextFunction
): Promise<void> => {
  try {
    const token = extractToken(req.headers)
    await fn(req, res, token, next)
  } catch (err: unknown) {
    console.error('Error during extract token', err)
    next(err)
  }
}

const wrapRequest = (fn: AsyncRequestHandler) => (req: Request, res: Response, next: NextFunction) => {
  void handleRequest(fn, req, res, next)
}

export function createServer (bot: Telegraf, worker: PlatformWorker, ctx: MeasureContext): Express {
  const limiter = new Limiter()
  const app = express()

  app.use(cors())
  app.use(express.json())

  app.post(
    '/test',
    wrapRequest(async (_, res, token) => {
      const record = await worker.getUserRecordByEmail(token.email)
      if (record === undefined) {
        throw new ApiError(404)
      }

      await limiter.add(record.telegramId, async () => {
        const testMessage = await translate(telegram.string.TestMessage, { app: config.App })
        await bot.telegram.sendMessage(record.telegramId, testMessage)
      })

      res.status(200)
      res.json({})
    })
  )

  app.post(
    '/auth',
    wrapRequest(async (req, res, token) => {
      if (req.body == null || typeof req.body !== 'object') {
        throw new ApiError(400)
      }

      const { code } = req.body

      if (code == null || code === '' || typeof code !== 'string') {
        throw new ApiError(400)
      }

      const record = await worker.getUserRecordByEmail(token.email)

      if (record !== undefined) {
        throw new ApiError(409, 'User already authorized')
      }

      const newRecord = await worker.authorizeUser(code, token.email)

      if (newRecord === undefined) {
        throw new ApiError(500)
      }

      void limiter.add(newRecord.telegramId, async () => {
        const message = await translate(telegram.string.AccountConnectedHtml, { app: config.App, email: token.email })
        await bot.telegram.sendMessage(newRecord.telegramId, message, { parse_mode: 'HTML' })
      })

      res.status(200)
      res.json({})
    })
  )

  app.get(
    '/info',
    wrapRequest(async (_, res, token) => {
      const me = await bot.telegram.getMe()
      const profilePhotos = await bot.telegram.getUserProfilePhotos(me.id)
      const photoId = profilePhotos.photos[0]?.[0]?.file_id

      let photoUrl = ''

      if (photoId !== undefined) {
        photoUrl = (await bot.telegram.getFileLink(photoId)).toString()
      }
      res.status(200)
      res.json({ username: me.username, name: me.first_name, photoUrl })
    })
  )

  app.post(
    '/notify',
    wrapRequest(async (req, res, token) => {
      ctx.info('Received notification', { email: token.email })
      if (req.body == null || !Array.isArray(req.body)) {
        ctx.error('Invalid request body', { body: req.body, email: token.email })
        throw new ApiError(400)
      }
      const notificationRecords = req.body as TelegramNotificationRecord[]
      const userRecord = await worker.getUserRecordByEmail(token.email)

      if (userRecord === undefined) {
        ctx.error('User not found', { email: token.email })
        throw new ApiError(404)
      }

      for (const notificationRecord of notificationRecords) {
        void limiter.add(userRecord.telegramId, async () => {
          const formattedMessage = toTelegramHtml(notificationRecord)
          const message = await bot.telegram.sendMessage(userRecord.telegramId, formattedMessage, {
            parse_mode: 'HTML'
          })
          await worker.addNotificationRecord({
            notificationId: notificationRecord.notificationId,
            email: userRecord.email,
            workspace: notificationRecord.workspace,
            telegramId: message.message_id
          })
        })
      }

      res.status(200)
      res.json({})
    })
  )

  app.use((err: any, _req: any, res: any, _next: any) => {
    if (err instanceof ApiError) {
      res.status(err.code).send({ code: err.code, message: err.message })
      return
    }

    res.status(500).send(err.message?.length > 0 ? { message: err.message } : err)
  })

  return app
}

export function listen (e: Express, ctx: MeasureContext, port: number, host?: string): Server {
  const cb = (): void => {
    ctx.info(`Telegram bot service has been started at ${host ?? '*'}:${port}`)
  }

  return host !== undefined ? e.listen(port, host, cb) : e.listen(port, cb)
}