frontend/src/lib/api.ts

import axios, { AxiosError, InternalAxiosRequestConfig } from 'axios'

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

// Flag to prevent multiple refresh attempts
let isRefreshing = false
let failedQueue: Array<{
  resolve: (value?: unknown) => void
  reject: (reason?: unknown) => void
}> = []

const processQueue = (error: Error | null, token: string | null = null) => {
  failedQueue.forEach((prom) => {
    if (error) {
      prom.reject(error)
    } else {
      prom.resolve(token)
    }
  })
  failedQueue = []
}

// Helper to get tokens from storage
const getStoredTokens = () => {
  const stored = localStorage.getItem('auth-storage')
  if (stored) {
    try {
      const { state } = JSON.parse(stored)
      return {
        accessToken: state?.token,
        refreshToken: state?.refreshToken,
      }
    } catch {
      return { accessToken: null, refreshToken: null }
    }
  }
  return { accessToken: null, refreshToken: null }
}

// Helper to update stored tokens
const updateStoredTokens = (accessToken: string, refreshToken: string) => {
  const stored = localStorage.getItem('auth-storage')
  if (stored) {
    try {
      const data = JSON.parse(stored)
      data.state.token = accessToken
      data.state.refreshToken = refreshToken
      localStorage.setItem('auth-storage', JSON.stringify(data))
    } catch {
      // Ignore parse errors
    }
  }
}

// Add auth token to requests
api.interceptors.request.use((config) => {
  const { accessToken } = getStoredTokens()
  if (accessToken) {
    config.headers.Authorization = `Bearer ${accessToken}`
  }
  return config
})

// Handle auth errors with automatic refresh
api.interceptors.response.use(
  (response) => response,
  async (error: AxiosError) => {
    const originalRequest = error.config as InternalAxiosRequestConfig & { _retry?: boolean }

    // If 401 and we haven't retried yet
    if (error.response?.status === 401 && !originalRequest._retry) {
      // Don't try to refresh if this was the refresh endpoint itself
      if (originalRequest.url === '/api/auth/refresh') {
        localStorage.removeItem('auth-storage')
        window.location.href = '/login'
        return Promise.reject(error)
      }

      if (isRefreshing) {
        // If already refreshing, queue this request
        return new Promise((resolve, reject) => {
          failedQueue.push({ resolve, reject })
        })
          .then((token) => {
            originalRequest.headers.Authorization = `Bearer ${token}`
            return api(originalRequest)
          })
          .catch((err) => Promise.reject(err))
      }

      originalRequest._retry = true
      isRefreshing = true

      const { refreshToken } = getStoredTokens()

      if (!refreshToken) {
        localStorage.removeItem('auth-storage')
        window.location.href = '/login'
        return Promise.reject(error)
      }

      try {
        // Call refresh endpoint
        const response = await axios.post('/api/auth/refresh', {
          refresh_token: refreshToken,
        })

        const { access_token, refresh_token: newRefreshToken } = response.data

        // Update stored tokens
        updateStoredTokens(access_token, newRefreshToken)

        // Update auth header for retry
        originalRequest.headers.Authorization = `Bearer ${access_token}`

        // Process queued requests
        processQueue(null, access_token)

        // Retry original request
        return api(originalRequest)
      } catch (refreshError) {
        // Refresh failed - logout
        processQueue(refreshError as Error, null)
        localStorage.removeItem('auth-storage')
        window.location.href = '/login'
        return Promise.reject(refreshError)
      } finally {
        isRefreshing = false
      }
    }

    return Promise.reject(error)
  }
)

export default api