import type OpenAI from 'openai'
import { SSE } from 'sse.js'

import { type Message } from './utils'
import { BASE_PATH } from '../shared/constants'

/**
 * Perform a one-off query to AI based on a snapshot of messages
 */
export function queryAi(messages: Message[], timeout = 0) {
  return new Promise<string>((resolve, reject) => {
    const eventSource = new SSE(`${BASE_PATH}/api/ai/docs`, {
      headers: {
        apikey: process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY ?? '',
        Authorization: `Bearer ${process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY}`,
        'Content-Type': 'application/json',
      },
      payload: JSON.stringify({
        messages: messages.map(({ role, content }) => ({ role, content })),
      }),
    })

    let timeoutId: number | undefined

    function handleError<T>(err: T) {
      if (timeoutId) {
        clearTimeout(timeoutId)
      }
      console.error(err)
      reject(err)
    }

    if (timeout > 0) {
      timeoutId = window.setTimeout(() => {
        handleError(new Error('AI query timed out'))
      }, timeout)
    }

    let answer = ''

    eventSource.addEventListener('error', handleError)
    eventSource.addEventListener('message', (e: MessageEvent) => {
      try {
        if (e.data === '[DONE]') {
          if (timeoutId) {
            clearTimeout(timeoutId)
          }
          resolve(answer)
          return
        }

        const completionChunk: OpenAI.Chat.Completions.ChatCompletionChunk = JSON.parse(e.data)
        const [
          {
            delta: { content },
          },
        ] = completionChunk.choices

        if (content) {
          answer += content
        }
      } catch (err) {
        handleError(err)
      }
    })

    eventSource.stream()
  })
}