const TOKEN_KEY = 'fabric-admin-token'

export function getApiBaseUrl(): string {
  return (import.meta.env.VITE_API_BASE_URL as string | undefined)?.replace(/\/$/, '')
    || 'https://parche.montest.ir/server/api'
}

export function getAccessToken(): string | null {
  return localStorage.getItem(TOKEN_KEY) ?? sessionStorage.getItem(TOKEN_KEY)
}

export function setAccessToken(token: string | null, remember = true): void {
  localStorage.removeItem(TOKEN_KEY)
  sessionStorage.removeItem(TOKEN_KEY)
  if (!token) return
  if (remember) localStorage.setItem(TOKEN_KEY, token)
  else sessionStorage.setItem(TOKEN_KEY, token)
}

export class ApiError extends Error {
  status: number
  constructor(status: number, message: string) {
    super(message)
    this.status = status
  }
}

type RequestOptions = {
  method?: string
  body?: unknown
  auth?: boolean
  query?: Record<string, string | number | boolean | undefined | null>
}

function buildUrl(path: string, query?: RequestOptions['query']): string {
  const base = getApiBaseUrl()
  const joined = path.startsWith('http')
    ? path
    : `${base.replace(/\/$/, '')}/${path.replace(/^\//, '')}`

  const url = joined.startsWith('http')
    ? new URL(joined)
    : new URL(joined, typeof window !== 'undefined' ? window.location.origin : 'http://127.0.0.1')

  if (query) {
    for (const [key, value] of Object.entries(query)) {
      if (value === undefined || value === null || value === '') continue
      url.searchParams.set(key, String(value))
    }
  }
  return url.toString()
}

function errorMessageFromBody(data: unknown, status: number): string {
  if (typeof data === 'object' && data && 'message' in data) {
    const message = (data as { message: unknown }).message
    if (Array.isArray(message)) return message.join('، ')
    return String(message)
  }
  if (typeof data === 'string') {
    if (/upstream error/i.test(data)) {
      return 'سرور API در دسترس نیست. کمی بعد دوباره تلاش کنید.'
    }
    if (data.trim() && !data.trimStart().startsWith('<')) {
      return data.trim().slice(0, 200)
    }
  }
  return `خطای سرور (${status})`
}

export async function apiRequest<T>(path: string, options: RequestOptions = {}): Promise<T> {
  const headers: Record<string, string> = {
    Accept: 'application/json',
  }
  if (options.body !== undefined) {
    headers['Content-Type'] = 'application/json'
  }
  if (options.auth !== false) {
    const token = getAccessToken()
    if (token) headers.Authorization = `Bearer ${token}`
  }

  let res: Response
  try {
    res = await fetch(buildUrl(path, options.query), {
      method: options.method ?? (options.body !== undefined ? 'POST' : 'GET'),
      headers,
      body: options.body !== undefined ? JSON.stringify(options.body) : undefined,
      signal: AbortSignal.timeout(20_000),
    })
  } catch (err) {
    const timedOut =
      (err instanceof DOMException && err.name === 'TimeoutError') ||
      (err instanceof Error && err.name === 'TimeoutError')
    throw new ApiError(
      0,
      timedOut
        ? 'پاسخ سرور طول کشید. دوباره تلاش کنید.'
        : 'اتصال به سرور برقرار نشد. اینترنت یا آدرس API را بررسی کنید.',
    )
  }

  const text = await res.text()
  let data: unknown = null
  if (text) {
    try {
      data = JSON.parse(text)
    } catch {
      data = text
    }
  }

  if (!res.ok) {
    throw new ApiError(res.status, errorMessageFromBody(data, res.status))
  }

  return data as T
}