import API from '@/api/config.js'
import config from '@/utils/config.js'
import { getClient, getNonce, getVersion, guid } from '@/utils/util.js'

let BASE_URL = config.BASE_URL
// #ifdef H5
BASE_URL = '/api'
// #endif

function buildRequestData(params = {}) {
  const token = uni.getStorageSync('token')
  const uid = uni.getStorageSync('open_id')
  let mac = uni.getStorageSync('mac')
  if (!mac) {
    mac = uni.getSystemInfoSync().deviceId || guid()
    uni.setStorageSync('mac', mac)
  }
  const { version, version_code } = getVersion()
  const data = {
    token,
    uid,
    mac,
    base_timestamp: parseInt(Date.now() / 1000),
    client: getClient(),
    source: uni.getStorageSync('source') || '',
    client_ios: uni.getSystemInfoSync().platform === 'ios' ? 1 : 0,
    version,
    version_code,
    ...params,
    stream: 1
  }
  Object.keys(data).forEach((key) => {
    if (data[key] === '') delete data[key]
  })
  return data
}

function buildHeader() {
  const token = uni.getStorageSync('token')
  const { timeStr, nonce } = getNonce()
  const header = {
    'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8',
    Accept: 'text/event-stream',
    timestr: timeStr,
    nonce
  }
  if (token) header.token = token
  return header
}

function mergeBytes(pending, bytes) {
  if (!pending || !pending.length) return bytes
  const merged = new Uint8Array(pending.length + bytes.length)
  merged.set(pending, 0)
  merged.set(bytes, pending.length)
  return merged
}

function appendCodePoint(text, codePoint) {
  if (codePoint <= 0xffff) return text + String.fromCharCode(codePoint)
  const value = codePoint - 0x10000
  return text + String.fromCharCode(0xd800 + (value >> 10), 0xdc00 + (value & 0x3ff))
}

function isContinuationByte(byte) {
  return (byte & 0xc0) === 0x80
}

function decodeUtf8Fallback(bytes, state, flush = false) {
  const input = mergeBytes(state.utf8Pending, bytes)
  let output = ''
  let i = 0

  while (i < input.length) {
    const first = input[i]
    if (first < 0x80) {
      output += String.fromCharCode(first)
      i += 1
      continue
    }

    let needed = 0
    let codePoint = 0
    if (first >= 0xc2 && first <= 0xdf) {
      needed = 2
      codePoint = first & 0x1f
    } else if (first >= 0xe0 && first <= 0xef) {
      needed = 3
      codePoint = first & 0x0f
    } else if (first >= 0xf0 && first <= 0xf4) {
      needed = 4
      codePoint = first & 0x07
    } else {
      output += '\uFFFD'
      i += 1
      continue
    }

    if (i + needed > input.length) break

    let valid = true
    for (let j = 1; j < needed; j += 1) {
      const next = input[i + j]
      if (!isContinuationByte(next)) {
        valid = false
        break
      }
      codePoint = (codePoint << 6) | (next & 0x3f)
    }

    const second = input[i + 1]
    if (
      !valid ||
      (needed === 3 && ((first === 0xe0 && second < 0xa0) || (first === 0xed && second >= 0xa0))) ||
      (needed === 4 && ((first === 0xf0 && second < 0x90) || (first === 0xf4 && second >= 0x90)))
    ) {
      output += '\uFFFD'
      i += 1
      continue
    }

    output = appendCodePoint(output, codePoint)
    i += needed
  }

  const pending = Array.prototype.slice.call(input, i)
  state.utf8Pending = flush ? [] : pending
  if (flush && pending.length) output += '\uFFFD'
  return output
}

function arrayBufferToString(buffer, state, flush = false) {
  const bytes = buffer ? new Uint8Array(buffer) : new Uint8Array(0)
  if (!state.disableTextDecoder && typeof TextDecoder !== 'undefined') {
    try {
      if (!state.decoder) state.decoder = new TextDecoder('utf-8')
      return state.decoder.decode(bytes, { stream: !flush })
    } catch (e) {
      state.disableTextDecoder = true
    }
  }
  return decodeUtf8Fallback(bytes, state, flush)
}

function consumeSse(bufferState, chunk, callbacks) {
  bufferState.text += String(chunk || '').replace(/\r\n/g, '\n')
  const parts = bufferState.text.split(/\n\n+/)
  bufferState.text = parts.pop() || ''
  parts.forEach((part) => {
    const lines = part.split('\n')
    let event = 'message'
    let dataText = ''
    lines.forEach((line) => {
      if (line.indexOf('event:') === 0) event = line.replace(/^event:\s*/, '').trim()
      if (line.indexOf('data:') === 0) dataText += line.replace(/^data:\s*/, '')
    })
    if (!dataText) return
    let data = {}
    try {
      data = JSON.parse(dataText)
    } catch (e) {
      data = { content: dataText }
    }
    if (event === 'start') callbacks.onStart && callbacks.onStart(data)
    else if (event === 'message') callbacks.onMessage && callbacks.onMessage(data)
    else if (event === 'done') callbacks.onDone && callbacks.onDone(data)
    else if (event === 'error') callbacks.onError && callbacks.onError(data)
  })
}

function flushSse(bufferState, callbacks) {
  const tail = arrayBufferToString(null, bufferState, true)
  if (tail) consumeSse(bufferState, tail, callbacks)
  if (bufferState.text && bufferState.text.trim()) {
    consumeSse(bufferState, '\n\n', callbacks)
  }
}

export function requestNameStream(params, callbacks = {}) {
  // #ifdef MP-WEIXIN
  const bufferState = { text: '', utf8Pending: [] }
  const task = wx.request({
    url: `${BASE_URL}${API.INTERFACE_AINAME_POST_SEND}`,
    method: 'POST',
    header: buildHeader(),
    data: buildRequestData(params),
    enableChunked: true,
    success: (res) => {
      flushSse(bufferState, callbacks)
      if (res.statusCode >= 400) {
        callbacks.onError && callbacks.onError({ msg: `网络异常 (${res.statusCode})` })
      }
    },
    fail: (e) => {
      callbacks.onError && callbacks.onError({ msg: e.errMsg || '生成失败' })
    }
  })
  task.onChunkReceived((res) => {
    consumeSse(bufferState, arrayBufferToString(res.data, bufferState), callbacks)
  })
  return task
  // #endif

  // #ifndef MP-WEIXIN
  callbacks.onError && callbacks.onError({ msg: '当前端暂不支持流式生成' })
  return null
  // #endif
}