Stream Server-Sent Events and JSON Lines

import type { Options, StreamResult, SuccessOf, TypedEvent } from '../../../client'
import type { StreamChatOptions, StreamChatResponses } from '../../types/StreamChat'
import { client } from '../../../client'

export function streamChat<ThrowOnError extends boolean = true>(
  options: Options<StreamChatOptions, ThrowOnError> = {},
): Promise<StreamResult<StreamChatResponses, ThrowOnError, TypedEvent<SuccessOf<StreamChatResponses>>>> {
  const { client: apiClient = client, ...config } = options

  return apiClient.stream<StreamChatResponses, ThrowOnError, TypedEvent<SuccessOf<StreamChatResponses>>>({
    method: 'POST',
    url: '/chat',
    contentType: { response: 'text/event-stream' },
    eventShape: 'event',
    rawData: true,
    ...config,
    throwOnError: config.throwOnError ?? true,
  })
}

export type SuccessOf<TResponses> = TResponses[Extract<keyof TResponses, '200' | '201' | '202' | '203' | '204' | '205' | '206' | '207' | '208' | '226' | '2xx'>]

export type ServerSentEvent<TData = unknown> = { data: TData; event: string; id?: string; retry?: number }

export type TypedEvent<TEvent> = TEvent & Pick<ServerSentEvent, 'id' | 'retry'>

export type StreamResult<TResponses, ThrowOnError extends boolean = true, TEvent = ServerSentEvent<SuccessOf<TResponses>>> = {
  stream: AsyncGenerator<TEvent>
  response: Response
}

client.stream = async <TResponses, ThrowOnError extends boolean = true, TEvent = ServerSentEvent<SuccessOf<TResponses>>>(
  config: RequestConfig,
): Promise<StreamResult<TResponses, ThrowOnError, TEvent>> => {
  // send the request, then parse the body into TEvent values
}