/**
 * I took inspiration in few stack exchange posts
 * and Tencent vConsole library (MIT)
 * by wrapping the XMLHttpRequest object in a Proxy
 * we can intercept the network requests
 * in not-so-hacky way
 * */
import NetworkMessage from './networkMessage'
import { RequestState, INetworkMessage, RequestResponseData } from './types';
import { formatByteSize, genStringBody, getStringResponseByType, getURL } from './utils'

export class ResponseProxyHandler<T extends Response> implements ProxyHandler<T> {
  public resp: Response
  public item: NetworkMessage

  constructor(resp: T, item: NetworkMessage) {
    this.resp = resp
    this.item = item
    this.mockReader()
  }

  public set(target: T, key: string, value: (args: any[]) => any) {
    return Reflect.set(target, key, value)
  }

  public get(target: T, key: string) {
    const value = Reflect.get(target, key)
    switch (key) {
      case 'arrayBuffer':
      case 'blob':
      case 'formData':
      case 'json':
      case 'text':
        return () => {
          this.item.responseType = <any>key.toLowerCase()
          // @ts-ignore
          return value.apply(target).then((resp: any) => {
            this.item.response = getStringResponseByType(this.item.responseType, resp)
            return resp
          })
        }
    }
    if (typeof value === 'function') {
      return value.bind(target)
    } else {
      return value
    }
  }

  protected mockReader() {
    let readerReceivedValue: Uint8Array
    if (!this.resp.body) {
      // some browsers do not return `body` in some cases, like `OPTIONS` method
      return
    }
    if (typeof this.resp.body.getReader !== 'function') {
      return
    }
    const clonedResp = this.resp.clone();
    const _getReader = clonedResp.body.getReader
    // @ts-ignore
    clonedResp.body.getReader = () => {
      const reader = <ReturnType<typeof _getReader>>_getReader.apply(this.resp.body)

      // when readyState is already 4,
      // it's not a chunked stream, or it had already been read.
      // so should not update status.
      if (this.item.readyState === RequestState.DONE) {
        return reader
      }

      const _read = reader.read
      const _cancel = reader.cancel
      this.item.responseType = 'arraybuffer'

      // @ts-ignore
      reader.read = () => {
        return (<ReturnType<typeof _read>>_read.apply(reader)).then(
          (result: ReadableStreamReadResult<Uint8Array>) => {
            if (!readerReceivedValue) {
              // @ts-ignore
              readerReceivedValue = new Uint8Array(result.value)
            } else {
              // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
              const newValue = new Uint8Array(readerReceivedValue.length + result.value!.length)
              newValue.set(readerReceivedValue)
              // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
              newValue.set(result.value!, readerReceivedValue.length)
              readerReceivedValue = newValue
            }
            this.item.endTime = performance.now()
            this.item.duration = this.item.endTime - (this.item.startTime || this.item.endTime)
            this.item.readyState = result.done ? 4 : 3
            this.item.statusText = result.done ? String(this.item.status) : 'Loading'
            this.item.responseSize = readerReceivedValue.length
            this.item.responseSizeText = formatByteSize(this.item.responseSize)
            if (result.done) {
              this.item.response = getStringResponseByType(
                this.item.responseType,
                readerReceivedValue,
              )
            }
            return result
          },
        )
      }

      reader.cancel = (...args) => {
        this.item.cancelState = 2
        this.item.statusText = 'Cancel'
        this.item.endTime = performance.now()
        this.item.duration = this.item.endTime - (this.item.startTime || this.item.endTime)
        this.item.response = getStringResponseByType(this.item.responseType, readerReceivedValue)
        return _cancel.apply(reader, args)
      }
      return reader
    }
  }
}

export class FetchProxyHandler<T extends typeof fetch> implements ProxyHandler<T> {
  constructor(
    private readonly ignoredHeaders: boolean | string[],
    private readonly setSessionTokenHeader: (cb: (name: string, value: string) => void) => void,
    private readonly sanitize: (data: RequestResponseData) => RequestResponseData | null,
    private readonly sendMessage: (item: INetworkMessage) => void,
    private readonly isServiceUrl: (url: string) => boolean,
    private readonly tokenUrlMatcher?: (url: string) => boolean,
  ) {}

  public apply(target: T, _: typeof window, argsList: [RequestInfo | URL, RequestInit]) {
    const input = argsList[0]
    const init = argsList[1]
    if (
      !input ||
      // @ts-ignore
      (typeof input !== 'string' && !input?.url)
    ) {
      return <ReturnType<T>>target.apply(window, argsList)
    }

    const isORUrl =
      input instanceof URL || typeof input === 'string'
        ? this.isServiceUrl(String(input))
        : this.isServiceUrl(String(input.url))

    if (isORUrl) {
      return target.apply(window, argsList)
    }

    const item = new NetworkMessage(this.ignoredHeaders, this.setSessionTokenHeader, this.sanitize)
    this.beforeFetch(item, input as RequestInfo, init)

    this.setSessionTokenHeader((name, value) => {
      if (this.tokenUrlMatcher !== undefined) {
        if (!this.tokenUrlMatcher(item.url)) {
          return
        }
      }
      if (argsList[1] === undefined && argsList[0] instanceof Request) {
        return argsList[0].headers.append(name, value)
      } else {
        if (!argsList[1]) argsList[1] = {}
        if (argsList[1].headers === undefined) {
          argsList[1] = { ...argsList[1], headers: {} }
        }
        if (argsList[1].headers instanceof Headers) {
          argsList[1].headers.append(name, value)
        } else if (Array.isArray(argsList[1].headers)) {
          argsList[1].headers.push([name, value])
        } else {
          // @ts-ignore
          argsList[1].headers[name] = value
        }
      }
    })
    return (<ReturnType<T>>target.apply(window, argsList))
      .then(this.afterFetch(item))
      .catch((e) => {
        // mock finally
        item.endTime = performance.now()
        item.duration = item.endTime - (item.startTime || item.endTime)
        throw e
      })
  }

  protected beforeFetch(item: NetworkMessage, input: RequestInfo | string, init?: RequestInit) {
    let url: URL,
      method = 'GET',
      requestHeader: HeadersInit = {}

    // handle `input` content
    if (typeof input === 'string') {
      // when `input` is a string
      method = init?.method || 'GET'
      url = getURL(input)
      requestHeader = init?.headers || {}
    } else {
      // when `input` is a `Request` object
      method = input.method || 'GET'
      url = getURL(input.url)
      requestHeader = input.headers
    }

    item.method = <NetworkMessage['method']>method
    item.requestType = 'fetch'
    item.requestHeader = requestHeader
    item.url = url.toString()
    item.name = (url.pathname.split('/').pop() || '') + url.search
    item.status = 0
    item.statusText = 'Pending'
    item.readyState = 1
    if (!item.startTime) {
      // UNSENT
      item.startTime = performance.now()
    }

    if (Object.prototype.toString.call(requestHeader) === '[object Headers]') {
      item.requestHeader = {}
      for (const [key, value] of <Headers>requestHeader) {
        item.requestHeader[key] = value
      }
    } else {
      item.requestHeader = requestHeader
    }

    // save GET data
    if (url.search && url.searchParams) {
      item.getData = {}
      for (const [key, value] of url.searchParams) {
        item.getData[key] = value
      }
    }

    // save POST data
    if (init?.body) {
      item.requestData = genStringBody(init.body)
    }
  }

  protected afterFetch(item: NetworkMessage) {
    return (resp: Response) => {
      item.endTime = performance.now()
      item.duration = item.endTime - (item.startTime || item.endTime)
      item.status = resp.status
      item.statusText = String(resp.status)

      let isChunked = false
      item.header = {}
      for (const [key, value] of resp.headers) {
        item.header[key] = value
        isChunked = value.toLowerCase().indexOf('chunked') > -1 ? true : isChunked
      }

      if (isChunked) {
        // when `transfer-encoding` is chunked, the response is a stream which is under loading,
        // so the `readyState` should be 3 (Loading),
        // and the response should NOT be `clone()` which will affect stream reading.
        item.readyState = 3
      } else {
        // Otherwise, not chunked, the response is not a stream,
        // so it's completed and can be cloned for `text()` calling.
        item.readyState = 4

        this.handleResponseBody(resp.clone(), item)
          .then((responseValue: string | ArrayBuffer) => {
            item.responseSize =
              typeof responseValue === 'string' ? responseValue.length : responseValue.byteLength
            item.responseSizeText = formatByteSize(item.responseSize)
            item.response = getStringResponseByType(item.responseType, responseValue)

            const msg = item.getMessage()
            if (msg) {
              this.sendMessage(msg)
            }
          })
          .catch((e) => {
            if (e.name !== 'AbortError') {
              throw e
            } else {
              // ignore AbortError
            }
          })
      }

      return new Proxy(resp, new ResponseProxyHandler(resp, item))
    }
  }

  protected handleResponseBody(resp: Response, item: NetworkMessage) {
    // parse response body by Content-Type
    const contentType = resp.headers.get('content-type')
    if (contentType && contentType.includes('application/json')) {
      item.responseType = 'json'
      return resp.text()
    } else if (
      contentType &&
      (contentType.includes('text/html') || contentType.includes('text/plain'))
    ) {
      item.responseType = 'text'
      return resp.text()
    } else {
      item.responseType = 'arraybuffer'
      return resp.arrayBuffer()
    }
  }
}

export default class FetchProxy {
  public static create(
    ignoredHeaders: boolean | string[],
    setSessionTokenHeader: (cb: (name: string, value: string) => void) => void,
    sanitize: (data: RequestResponseData) => RequestResponseData | null,
    sendMessage: (item: INetworkMessage) => void,
    isServiceUrl: (url: string) => boolean,
    tokenUrlMatcher?: (url: string) => boolean,
  ) {
    return new Proxy(
      fetch,
      new FetchProxyHandler(
        ignoredHeaders,
        setSessionTokenHeader,
        sanitize,
        sendMessage,
        isServiceUrl,
        tokenUrlMatcher,
      ),
    )
  }
}