import axios from 'axios'

// 创建 axios 实例
const api = axios.create({
  baseURL: '/api',
  timeout: 30000,
  headers: {
    'Content-Type': 'application/json'
  }
})

// 请求拦截器：添加认证 token
api.interceptors.request.use(
  (config) => {
    const token = localStorage.getItem('access_token')
    if (token) {
      config.headers.Authorization = `Bearer ${token}`
    }
    return config
  },
  (error) => {
    return Promise.reject(error)
  }
)

// 响应拦截器：处理通用错误
api.interceptors.response.use(
  (response) => response.data,
  (error) => {
    if (error.response?.status === 401) {
      localStorage.removeItem('access_token')
      localStorage.removeItem('user')
      window.location.href = '/auth'
    }
    return Promise.reject(error.response?.data || error.message)
  }
)

/**
 * SSE 流式请求处理器
 * @param {string} url - API URL (不含 baseURL 前缀)
 * @param {object} body - 请求体
 * @param {object} callbacks - 事件回调: { onProcessStep, onDone, onError }
 * @returns {{ abort: () => void }}
 */
export function createSSEStream(url, body, { onProcessStep, onDone, onError }) {
  const token = localStorage.getItem('access_token')
  const controller = new AbortController()

  const promise = (async () => {
    try {
      const res = await fetch(`/api${url}`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'Authorization': `Bearer ${token}`
        },
        body: JSON.stringify(body),
        signal: controller.signal
      })

      if (!res.ok) {
        const err = await res.json().catch(() => ({}))
        throw new Error(err.message || `HTTP ${res.status}`)
      }

      const reader = res.body.getReader()
      const decoder = new TextDecoder()
      let buffer = ''
      let completed = false

      while (true) {
        const { done, value } = await reader.read()
        if (done) break

        buffer += decoder.decode(value, { stream: true })
        const lines = buffer.split('\n')
        buffer = lines.pop() || ''

        let currentEvent = ''
        for (const line of lines) {
          if (line.startsWith('event: ')) {
            currentEvent = line.slice(7).trim()
          } else if (line.startsWith('data: ')) {
            const data = JSON.parse(line.slice(6))
            if (currentEvent === 'process_step' && onProcessStep) {
              onProcessStep(data.step)
            } else if (currentEvent === 'done' && onDone) {
              completed = true
              onDone(data)
            } else if (currentEvent === 'error' && onError) {
              onError(data.content)
            }
          }
        }
      }

      if (!completed && onError) {
        onError('stream ended unexpectedly')
      }
    } catch (e) {
      if (e.name !== 'AbortError' && onError) {
        onError(e.message)
      }
    }
  })()

  promise.abort = () => controller.abort()
  return promise
}

// ============ 认证接口 ============

export const authAPI = {
  login: (data) => api.post('/auth/login', data),
  register: (data) => api.post('/auth/register', data),
  logout: () => api.post('/auth/logout'),
  getMe: () => api.get('/auth/me')
}

// ============ 会话接口 ============

export const conversationsAPI = {
  list: (params) => api.get('/conversations/', { params }),
  create: (data) => api.post('/conversations/', data),
  get: (id) => api.get(`/conversations/${id}`),
  update: (id, data) => api.put(`/conversations/${id}`, data),
  delete: (id) => api.delete(`/conversations/${id}`)
}

// ============ 消息接口 ============

export const messagesAPI = {
  list: (conversationId, params) => api.get('/messages/', { params: { conversation_id: conversationId, ...params } }),
  send: (data) => api.post('/messages/', data),
  
  // 发送消息（流式）
  sendStream: (data, callbacks) => {
    return createSSEStream('/messages/stream', {
      conversation_id: data.conversation_id,
      content: data.content,
      tools_enabled: callbacks.toolsEnabled !== false
    }, callbacks)
  },
  
  delete: (id) => api.delete(`/messages/${id}`)
}

// ============ 工具接口 ============

export const toolsAPI = {
  list: (params) => api.get('/tools/', { params }),
  get: (name) => api.get(`/tools/${name}`),
  execute: (name, data) => api.post(`/tools/${name}/execute`, data)
}

// ============ LLM Provider 接口 ============

export const providersAPI = {
  list: () => api.get('/providers/'),
  create: (data) => api.post('/providers/', data),
  get: (id) => api.get(`/providers/${id}`),
  update: (id, data) => api.put(`/providers/${id}`, data),
  delete: (id) => api.delete(`/providers/${id}`),
  test: (id) => api.post(`/providers/${id}/test`)
}

export default api