import { apiRequest } from '@/lib/api'
import { timeseriesSearch, type TimeseriesRequest } from './timeseries'

const MAX_CSV_BYTES = 2 * 1024 * 1024

/** Uses the same authorization, HTTP errors and bounded request as JSON. A
 * bearer token never appears in an export URL or download filename. */
export async function fetchStatsCsv(request: TimeseriesRequest, signal?: AbortSignal): Promise<Blob> {
  const search = timeseriesSearch(request)
  const response = await apiRequest(`/api/v1/stats/timeseries.csv?${search}`, { signal, headers: { Accept: 'text/csv' } })
  if (!response.headers.get('Content-Type')?.toLowerCase().includes('text/csv')) throw new Error('Сервер не вернул CSV')
  if (Number(response.headers.get('Content-Length')) > MAX_CSV_BYTES) throw new Error('CSV превышает допустимый размер')
  const blob = await response.blob()
  if (blob.size > MAX_CSV_BYTES) throw new Error('CSV превышает допустимый размер')
  return blob
}

export function saveStatsCsv(blob: Blob, request: TimeseriesRequest) {
  const url = URL.createObjectURL(blob)
  const anchor = document.createElement('a')
  anchor.href = url
  anchor.download = `evofw-packets-${request.resolution}-${request.from.slice(0, 10)}-${request.to.slice(0, 10)}.csv`
  document.body.appendChild(anchor)
  anchor.click()
  anchor.remove()
  window.setTimeout(() => URL.revokeObjectURL(url), 1000)
}