import { API_PREFIX } from '@/config'
import Toast from '@/app/components/base/toast'

const TIME_OUT = 100000

const ContentType = {
  json: 'application/json',
  stream: 'text/event-stream',
  form: 'application/x-www-form-urlencoded; charset=UTF-8',
  download: 'application/octet-stream', // for download
}

const baseOptions = {
  method: 'GET',
  mode: 'cors',
  credentials: 'include', // always send cookies、HTTP Basic authentication.
  headers: new Headers({
    'Content-Type': ContentType.json,
  }),
  redirect: 'follow',
}

export type IOnDataMoreInfo = {
  conversationId: string | undefined
  messageId: string
  errorMessage?: string
}

export type IOnData = (message: string, isFirstMessage: boolean, moreInfo: IOnDataMoreInfo) => void
export type IOnCompleted = () => void
export type IOnError = (msg: string) => void

type IOtherOptions = {
  needAllResponseContent?: boolean
  onData?: IOnData // for stream
  onError?: IOnError
  onCompleted?: IOnCompleted // for stream
}

function unicodeToChar(text: string) {
  return text.replace(/\\u[0-9a-f]{4}/g, (_match, p1) => {
    return String.fromCharCode(parseInt(p1, 16))
  })
}

const handleStream = (response: any, onData: IOnData, onCompleted?: IOnCompleted) => {
  if (!response.ok)
    throw new Error('Network response was not ok')

  const reader = response.body.getReader()
  const decoder = new TextDecoder('utf-8')
  let buffer = ''
  let bufferObj: any
  let isFirstMessage = true
  function read() {
    reader.read().then((result: any) => {
      if (result.done) {
        onCompleted && onCompleted()
        return
      }
      buffer += decoder.decode(result.value, { stream: true })
      const lines = buffer.split('\n')
      try {
        lines.forEach((message) => {
          if (!message)
            return
          bufferObj = JSON.parse(message) // remove data: and parse as json
          onData(unicodeToChar(bufferObj.answer), isFirstMessage, {
            conversationId: bufferObj.conversation_id,
            messageId: bufferObj.id,
          })
          isFirstMessage = false
        })
        buffer = lines[lines.length - 1]
      }
      catch (e) {
        onData('', false, {
          conversationId: undefined,
          messageId: '',
          errorMessage: `${e}`,
        })
        return
      }

      read()
    })
  }
  read()
}

const baseFetch = (url: string, fetchOptions: any, { needAllResponseContent }: IOtherOptions) => {
  const options = Object.assign({}, baseOptions, fetchOptions)

  const urlPrefix = API_PREFIX

  let urlWithPrefix = `${urlPrefix}${url.startsWith('/') ? url : `/${url}`}`

  const { method, params, body } = options
  // handle query
  if (method === 'GET' && params) {
    const paramsArray: string[] = []
    Object.keys(params).forEach(key =>
      paramsArray.push(`${key}=${encodeURIComponent(params[key])}`),
    )
    if (urlWithPrefix.search(/\?/) === -1)
      urlWithPrefix += `?${paramsArray.join('&')}`

    else
      urlWithPrefix += `&${paramsArray.join('&')}`

    delete options.params
  }

  if (body)
    options.body = JSON.stringify(body)

  // Handle timeout
  return Promise.race([
    new Promise((resolve, reject) => {
      setTimeout(() => {
        reject(new Error('request timeout'))
      }, TIME_OUT)
    }),
    new Promise((resolve, reject) => {
      globalThis.fetch(urlWithPrefix, options)
        .then((res: any) => {
          const resClone = res.clone()
          // Error handler
          if (!/^(2|3)\d{2}$/.test(res.status)) {
            try {
              const bodyJson = res.json()
              switch (res.status) {
                case 401: {
                  Toast.notify({ type: 'error', message: 'Invalid token' })
                  return
                }
                default:
                  // eslint-disable-next-line no-new
                  new Promise(() => {
                    bodyJson.then((data: any) => {
                      Toast.notify({ type: 'error', message: data.message })
                    })
                  })
              }
            }
            catch (e) {
              Toast.notify({ type: 'error', message: `${e}` })
            }

            return Promise.reject(resClone)
          }

          // handle delete api. Delete api not return content.
          if (res.status === 204) {
            resolve({ result: 'success' })
            return
          }

          // return data
          const data = options.headers.get('Content-type') === ContentType.download ? res.blob() : res.json()

          resolve(needAllResponseContent ? resClone : data)
        })
        .catch((err) => {
          Toast.notify({ type: 'error', message: err })
          reject(err)
        })
    }),
  ])
}

export const ssePost = (url: string, fetchOptions: any, { onData, onCompleted, onError }: IOtherOptions) => {
  const options = Object.assign({}, baseOptions, {
    method: 'POST',
  }, fetchOptions)

  const urlPrefix = API_PREFIX
  const urlWithPrefix = `${urlPrefix}${url.startsWith('/') ? url : `/${url}`}`

  const { body } = options
  if (body)
    options.body = JSON.stringify(body)

  globalThis.fetch(urlWithPrefix, options)
    .then((res: any) => {
      if (!/^(2|3)\d{2}$/.test(res.status)) {
        // eslint-disable-next-line no-new
        new Promise(() => {
          res.json().then((data: any) => {
            Toast.notify({ type: 'error', message: data.message || 'Server Error' })
          })
        })
        onError?.('Server Error')
        return
      }
      return handleStream(res, (str: string, isFirstMessage: boolean, moreInfo: IOnDataMoreInfo) => {
        if (moreInfo.errorMessage) {
          Toast.notify({ type: 'error', message: moreInfo.errorMessage })
          return
        }
        onData?.(str, isFirstMessage, moreInfo)
      }, () => {
        onCompleted?.()
      })
    }).catch((e) => {
      Toast.notify({ type: 'error', message: e })
      onError?.(e)
    })
}

export const request = (url: string, options = {}, otherOptions?: IOtherOptions) => {
  return baseFetch(url, options, otherOptions || {})
}

export const get = (url: string, options = {}, otherOptions?: IOtherOptions) => {
  return request(url, Object.assign({}, options, { method: 'GET' }), otherOptions)
}

export const post = (url: string, options = {}, otherOptions?: IOtherOptions) => {
  return request(url, Object.assign({}, options, { method: 'POST' }), otherOptions)
}

export const put = (url: string, options = {}, otherOptions?: IOtherOptions) => {
  return request(url, Object.assign({}, options, { method: 'PUT' }), otherOptions)
}

export const del = (url: string, options = {}, otherOptions?: IOtherOptions) => {
  return request(url, Object.assign({}, options, { method: 'DELETE' }), otherOptions)
}