import { getAccessToken, getRefreshToken, setSession, clearSession } from './auth'

const API_BASE_URL =
  import.meta.env.VITE_API_BASE_URL ?? 'http://localhost:3100/api/v1'

export class ApiError extends Error {
  status: number

  constructor(status: number, message: string) {
    super(message)
    this.name = 'ApiError'
    this.status = status
  }
}

type RequestOptions = {
  method?: string
  body?: unknown
  auth?: boolean
  /** Skip refresh retry (used by refresh itself). */
  skipRefresh?: boolean
}

let refreshInFlight: Promise<boolean> | null = null

function parseErrorMessage(payload: unknown, fallback: string) {
  if (!payload || typeof payload !== 'object') return fallback
  const message = (payload as { message?: unknown }).message
  if (typeof message === 'string' && message.trim()) return message
  if (Array.isArray(message)) {
    const parts = message.filter((item) => typeof item === 'string')
    if (parts.length > 0) return parts.join('، ')
  }
  return fallback
}

async function tryRefreshSession(): Promise<boolean> {
  if (refreshInFlight) return refreshInFlight

  refreshInFlight = (async () => {
    const refreshToken = getRefreshToken()
    if (!refreshToken) {
      clearSession()
      return false
    }

    try {
      const response = await fetch(`${API_BASE_URL}/auth/refresh`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ refreshToken }),
      })

      const payload = await response.json().catch(() => null)
      if (!response.ok) {
        clearSession()
        return false
      }

      setSession({
        accessToken: payload.accessToken,
        refreshToken: payload.refreshToken,
        user: payload.user,
      })
      return true
    } catch {
      clearSession()
      return false
    } finally {
      refreshInFlight = null
    }
  })()

  return refreshInFlight
}

export async function apiRequest<T>(
  path: string,
  options: RequestOptions = {},
): Promise<T> {
  const { method = 'GET', body, auth = true, skipRefresh = false } = options

  const headers: Record<string, string> = {}
  if (body !== undefined) {
    headers['Content-Type'] = 'application/json'
  }
  if (auth) {
    const token = getAccessToken()
    if (token) headers.Authorization = `Bearer ${token}`
  }

  const response = await fetch(`${API_BASE_URL}${path}`, {
    method,
    headers,
    body: body !== undefined ? JSON.stringify(body) : undefined,
  })

  if (response.status === 401 && auth && !skipRefresh) {
    const refreshed = await tryRefreshSession()
    if (refreshed) {
      return apiRequest<T>(path, { ...options, skipRefresh: true })
    }
  }

  if (response.status === 204) {
    return undefined as T
  }

  const payload = await response.json().catch(() => null)

  if (!response.ok) {
    throw new ApiError(
      response.status,
      parseErrorMessage(payload, 'خطایی رخ داد'),
    )
  }

  return payload as T
}