/**
 * API Client for QQuiz Backend
 */
import axios from 'axios'
import toast from 'react-hot-toast'

export const API_BASE_URL = import.meta.env.VITE_API_URL || '/api'
export const AUTH_TOKEN_STORAGE_KEY = 'access_token'

const AUTH_USER_STORAGE_KEY = 'user'
const PUBLIC_REQUEST_PATHS = ['/auth/login', '/auth/register']

const getRequestPath = (config) => {
  const url = config?.url || ''

  if (!url) return ''

  if (url.startsWith('http://') || url.startsWith('https://')) {
    try {
      return new URL(url).pathname
    } catch (error) {
      return url
    }
  }

  return url.startsWith('/') ? url : `/${url}`
}

const isPublicRequest = (config) => {
  if (config?.skipAuthHandling === true) {
    return true
  }

  const path = getRequestPath(config)
  return PUBLIC_REQUEST_PATHS.some((publicPath) => path.endsWith(publicPath))
}

export const buildApiUrl = (path) => {
  const base = API_BASE_URL.endsWith('/') ? API_BASE_URL.slice(0, -1) : API_BASE_URL
  const normalizedPath = path.startsWith('/') ? path : `/${path}`
  return `${base}${normalizedPath}`
}

export const getAccessToken = () => localStorage.getItem(AUTH_TOKEN_STORAGE_KEY)

export const clearAuthStorage = () => {
  localStorage.removeItem(AUTH_TOKEN_STORAGE_KEY)
  localStorage.removeItem(AUTH_USER_STORAGE_KEY)
}

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

// Request interceptor - Add auth token
api.interceptors.request.use(
  (config) => {
    const token = getAccessToken()
    if (token && !isPublicRequest(config)) {
      config.headers = config.headers || {}
      config.headers.Authorization = `Bearer ${token}`
    }
    return config
  },
  (error) => {
    return Promise.reject(error)
  }
)

// Response interceptor - Handle errors
api.interceptors.response.use(
  (response) => response,
  (error) => {
    const status = error.response?.status
    const message = error.response?.data?.detail || 'An error occurred'
    const requestConfig = error.config || {}
    const hasAuthHeader = Boolean(
      requestConfig.headers?.Authorization || requestConfig.headers?.authorization
    )

    if (status === 401 && !isPublicRequest(requestConfig) && hasAuthHeader) {
      clearAuthStorage()
      if (window.location.pathname !== '/login') {
        window.location.href = '/login'
      }
      toast.error('Session expired. Please login again.')
    } else if (status === 401) {
      toast.error(message)
    } else if (status === 403) {
      toast.error('Permission denied')
    } else if (status === 429) {
      toast.error(message)
    } else if (status >= 500) {
      toast.error('Server error. Please try again later.')
    } else {
      toast.error(message)
    }

    return Promise.reject(error)
  }
)

// ============ Auth APIs ============
export const authAPI = {
  register: (username, password) =>
    api.post('/auth/register', { username, password }, { skipAuthHandling: true }),

  login: (username, password) =>
    api.post('/auth/login', { username, password }, { skipAuthHandling: true }),

  getCurrentUser: () =>
    api.get('/auth/me'),

  changePassword: (oldPassword, newPassword) =>
    api.post('/auth/change-password', null, {
      params: { old_password: oldPassword, new_password: newPassword }
    })
}

// ============ Exam APIs ============
export const examAPI = {
  // Create exam with first document
  create: (title, file, isRandom = false) => {
    const formData = new FormData()
    formData.append('title', title)
    formData.append('file', file)
    formData.append('is_random', isRandom)
    return api.post('/exams/create', formData, {
      headers: { 'Content-Type': 'multipart/form-data' }
    })
  },

  // Append document to existing exam
  appendDocument: (examId, file) => {
    const formData = new FormData()
    formData.append('file', file)
    return api.post(`/exams/${examId}/append`, formData, {
      headers: { 'Content-Type': 'multipart/form-data' }
    })
  },

  // Get user's exam list
  getList: (skip = 0, limit = 20) =>
    api.get('/exams/', { params: { skip, limit } }),

  // Get exam detail
  getDetail: (examId) =>
    api.get(`/exams/${examId}`),

  // Delete exam
  delete: (examId) =>
    api.delete(`/exams/${examId}`),

  // Update quiz progress
  updateProgress: (examId, currentIndex) =>
    api.put(`/exams/${examId}/progress`, { current_index: currentIndex })
}

// ============ Question APIs ============
export const questionAPI = {
  // Get all questions (Question Bank)
  getAll: (skip = 0, limit = 50, examId = null) => {
    const params = { skip, limit }
    if (examId) params.exam_id = examId
    return api.get('/questions/', { params })
  },

  // Get all questions for an exam
  getExamQuestions: (examId, skip = 0, limit = 50) =>
    api.get(`/questions/exam/${examId}/questions`, { params: { skip, limit } }),

  // Get current question (based on exam's current_index)
  getCurrentQuestion: (examId) =>
    api.get(`/questions/exam/${examId}/current`),

  // Get question by ID
  getById: (questionId) =>
    api.get(`/questions/${questionId}`),

  // Check answer
  checkAnswer: (questionId, userAnswer) =>
    api.post('/questions/check', {
      question_id: questionId,
      user_answer: userAnswer
    })
}

// ============ Mistake APIs ============
export const mistakeAPI = {
  // Get user's mistake book
  getList: (skip = 0, limit = 50, examId = null) => {
    const params = { skip, limit }
    if (examId) params.exam_id = examId
    return api.get('/mistakes/', { params })
  },

  // Add to mistake book
  add: (questionId) =>
    api.post('/mistakes/add', { question_id: questionId }),

  // Remove from mistake book by mistake ID
  remove: (mistakeId) =>
    api.delete(`/mistakes/${mistakeId}`),

  // Remove from mistake book by question ID
  removeByQuestionId: (questionId) =>
    api.delete(`/mistakes/question/${questionId}`)
}

// ============ Admin APIs ============
export const adminAPI = {
  // Config
  getConfig: () => api.get('/admin/config'),
  updateConfig: (config) => api.put('/admin/config', config),

  // Users
  getUsers: (skip = 0, limit = 50, search = null) =>
    api.get('/admin/users', { params: { skip, limit, search } }),
  createUser: (username, password, is_admin = false) =>
    api.post('/admin/users', { username, password, is_admin }),
  updateUser: (userId, data) =>
    api.put(`/admin/users/${userId}`, data),
  deleteUser: (userId) =>
    api.delete(`/admin/users/${userId}`),

  // Statistics
  getStatistics: () => api.get('/admin/statistics'),
  getHealth: () => api.get('/admin/health'),

  // Export
  exportUsers: () => api.get('/admin/export/users', { responseType: 'blob' }),
  exportStatistics: () => api.get('/admin/export/statistics', { responseType: 'blob' })
}

export default api