import request from '@/utils/http'
import { useUserStore } from '@/store/modules/user'

const DEFAULT_PROMPT_CODE = 'home.default'

function buildRuntimeParams(promptCode = DEFAULT_PROMPT_CODE, sessionId = null, aiParamId = null) {
  return {
    promptCode,
    ...(sessionId ? { sessionId } : {}),
    ...(aiParamId !== null && aiParamId !== undefined ? { aiParamId } : {})
  }
}

function fetchGetAiRuntime(promptCode = DEFAULT_PROMPT_CODE, sessionId = null, aiParamId = null) {
  return request.get({
    url: '/ai/chat/runtime',
    params: buildRuntimeParams(promptCode, sessionId, aiParamId),
    showErrorMessage: false
  })
}

function fetchGetAiSessions(promptCode = DEFAULT_PROMPT_CODE, keyword = '') {
  return request.get({
    url: '/ai/chat/sessions',
    params: {
      promptCode,
      ...(keyword ? { keyword } : {})
    },
    showErrorMessage: false
  })
}

function fetchRemoveAiSession(sessionId) {
  return request.post({
    url: `/ai/chat/session/remove/${sessionId}`,
    showErrorMessage: false
  })
}

function fetchRenameAiSession(sessionId, title) {
  return request.post({
    url: `/ai/chat/session/rename/${sessionId}`,
    params: { title },
    showErrorMessage: false
  })
}

function fetchPinAiSession(sessionId, pinned) {
  return request.post({
    url: `/ai/chat/session/pin/${sessionId}`,
    params: { pinned },
    showErrorMessage: false
  })
}

function fetchClearAiSessionMemory(sessionId) {
  return request.post({
    url: `/ai/chat/session/memory/clear/${sessionId}`,
    showErrorMessage: false
  })
}

function fetchRetainAiSessionLatestRound(sessionId) {
  return request.post({
    url: `/ai/chat/session/memory/retain-latest/${sessionId}`,
    showErrorMessage: false
  })
}

async function fetchStreamAiChat(payload, { signal, onEvent } = {}) {
  const { VITE_API_URL } = import.meta.env
  const { accessToken } = useUserStore()
  const response = await fetch(`${VITE_API_URL}/ai/chat/stream`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Accept: 'text/event-stream',
      ...(accessToken ? { Authorization: accessToken } : {})
    },
    body: JSON.stringify(payload),
    signal
  })

  if (!response.ok) {
    throw new Error(`AI 请求失败 (${response.status})`)
  }

  if (!response.body) {
    throw new Error('AI 响应流不可用')
  }

  const reader = response.body.getReader()
  const decoder = new TextDecoder('utf-8')
  let buffer = ''

  while (true) {
    const { done, value } = await reader.read()
    if (done) {
      break
    }
    buffer += decoder.decode(value, { stream: true })
    const events = buffer.split(/\r?\n\r?\n/)
    buffer = events.pop() || ''
    events.forEach((item) => dispatchSseEvent(item, onEvent))
  }

  if (buffer.trim()) {
    dispatchSseEvent(buffer, onEvent)
  }
}

function dispatchSseEvent(rawEvent, onEvent) {
  if (!onEvent) {
    return
  }

  const lines = rawEvent.split(/\r?\n/)
  let eventName = 'message'
  const dataLines = []

  lines.forEach((line) => {
    if (line.startsWith('event:')) {
      eventName = line.slice(6).trim()
    }
    if (line.startsWith('data:')) {
      dataLines.push(line.slice(5).trim())
    }
  })

  if (!dataLines.length) {
    return
  }

  const rawData = dataLines.join('\n')
  let payload = rawData
  try {
    payload = JSON.parse(rawData)
  } catch {
  }
  onEvent(eventName, payload)
}

export {
  DEFAULT_PROMPT_CODE,
  fetchClearAiSessionMemory,
  fetchGetAiRuntime,
  fetchGetAiSessions,
  fetchPinAiSession,
  fetchRemoveAiSession,
  fetchRenameAiSession,
  fetchRetainAiSessionLatestRound,
  fetchStreamAiChat
}