import { useEffect } from 'react'
import { LOCAL_STORAGE_KEYS } from '../constants'
import { getSharedTelemetryData, getTelemetryCookieOptions } from '../telemetry-utils'

interface UseTelemetryCookieProps {
  enabled: boolean
}

/**
 * This hook saves the initial telemetry data to a cookie so we can preserve first-touch attribution
 * (e.g. `document.referrer`) until the initial pageview is emitted. If the user never
 * consents, this cookie is never used.
 */
export function useTelemetryCookie({ enabled }: UseTelemetryCookieProps) {
  const telemetryStorageKey = LOCAL_STORAGE_KEYS.TELEMETRY_DATA

  useEffect(() => {
    if (typeof window === 'undefined') return
    if (!enabled) return

    const cookies = document.cookie.split(';')
    const cookieOptions = getTelemetryCookieOptions()

    const telemetryCookie = cookies.find((cookie) =>
      cookie.trim().startsWith(`${telemetryStorageKey}=`)
    )
    if (telemetryCookie) return

    const telemetryData = getSharedTelemetryData(window.location.pathname)

    const encodedData = encodeURIComponent(JSON.stringify(telemetryData))
    document.cookie = `${telemetryStorageKey}=${encodedData}; ${cookieOptions}`
  }, [enabled, telemetryStorageKey])
}

export default useTelemetryCookie