import { ref, computed } from 'vue'

interface LoginRequest {
  username: string
  password: string
  role?: string
}

interface LoginResponse {
  accessToken: string
  expiresIn: number
  tokenType: string
}

interface AuthState {
  token: string | null
  expiresAt: number | null
  isAuthenticated: boolean
}

const API_BASE = '/api'
const TOKEN_STORAGE_KEY = 'kartsell_auth_token'
const EXPIRES_AT_KEY = 'kartsell_expires_at'

// Initialize from localStorage
function loadStoredAuth(): AuthState {
  if (typeof window === 'undefined') {
    return { token: null, expiresAt: null, isAuthenticated: false }
  }

  const token = localStorage.getItem(TOKEN_STORAGE_KEY)
  const expiresAtStr = localStorage.getItem(EXPIRES_AT_KEY)
  const expiresAt = expiresAtStr ? parseInt(expiresAtStr, 10) : null

  return {
    token,
    expiresAt,
    isAuthenticated: !!(token && expiresAt && expiresAt > Date.now()),
  }
}

export function useAuthApi() {
  const loading = ref(false)
  const error = ref<string | null>(null)

  const authState = ref<AuthState>(loadStoredAuth())

  const login = async (username: string, password: string, role?: string): Promise<boolean> => {
    loading.value = true
    error.value = null

    try {
      const response = await fetch(`${API_BASE}/auth/login`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({
          username,
          password,
          role: role || 'User',
        } as LoginRequest),
      })

      if (!response.ok) {
        const errorData = await response.json().catch(() => ({ message: 'Login failed' }))
        throw new Error(errorData.message || `HTTP ${response.status}`)
      }

      const data = await response.json() as LoginResponse

      // Store token and expiration
      const expiresAt = Date.now() + data.expiresIn * 1000
      localStorage.setItem(TOKEN_STORAGE_KEY, data.accessToken)
      localStorage.setItem(EXPIRES_AT_KEY, expiresAt.toString())

      authState.value = {
        token: data.accessToken,
        expiresAt,
        isAuthenticated: true,
      }

      return true
    } catch (err) {
      error.value = err instanceof Error ? err.message : 'Login failed'
      console.error('Login error:', err)
      return false
    } finally {
      loading.value = false
    }
  }

  const logout = (): void => {
    localStorage.removeItem(TOKEN_STORAGE_KEY)
    localStorage.removeItem(EXPIRES_AT_KEY)
    authState.value = {
      token: null,
      expiresAt: null,
      isAuthenticated: false,
    }
  }

  const getToken = (): string | null => {
    // Check if token is still valid
    const expiresAt = authState.value.expiresAt
    if (!authState.value.token || !expiresAt || expiresAt < Date.now()) {
      logout()
      return null
    }
    return authState.value.token
  }

  const refreshAuthState = (): void => {
    authState.value = loadStoredAuth()
  }

  return {
    // State
    loading,
    error,
    authState: computed(() => authState.value),

    // Computed
    isAuthenticated: computed(() => authState.value.isAuthenticated),
    hasError: computed(() => error.value !== null),

    // Methods
    login,
    logout,
    getToken,
    refreshAuthState,
  }
}

// Global API interceptor - inject auth token into all requests
export function setupAuthInterceptor() {
  const originalFetch = window.fetch

  window.fetch = function (
    input: RequestInfo | URL,
    init?: RequestInit
  ): Promise<Response> {
    // Load token from localStorage
    const token = localStorage.getItem(TOKEN_STORAGE_KEY)
    const expiresAtStr = localStorage.getItem(EXPIRES_AT_KEY)
    const expiresAt = expiresAtStr ? parseInt(expiresAtStr, 10) : null

    // Only add auth header if token is valid
    if (token && expiresAt && expiresAt > Date.now()) {
      const headers = new Headers(init?.headers || {})
      headers.set('Authorization', `Bearer ${token}`)

      return originalFetch(input, {
        ...init,
        headers,
      })
    }

    return originalFetch(input, init)
  }
}

export type { LoginRequest, LoginResponse }