module Main where

import Prelude

import Effect (Effect)
import Effect.Aff (Aff, launchAff)
import Effect.Class (liftEffect)
import Effect.Console (log)
import Fetch (fetch)
import Data.Binary.Base64 (decode)
import Data.Either (Either, hush, note)
import Data.Maybe (Maybe(..))
import Data.ArrayBuffer.Types (ArrayBuffer, Uint8Array)
import Data.String (drop, indexOf', indexOf, splitAt)
import Data.String.Pattern (Pattern(..))

import Crypto.Subtle.Constants.AES (aesGCM)
import Crypto.Subtle.Key.Import (aes)
import Crypto.Subtle.Key.Import (importKey) as SC
import Crypto.Subtle.Key.Types (CryptoKey, decrypt, raw)

data AviaryError
    = MalformedKey
    | MalformedUrl

instance showAviaryError :: Show AviaryError where
    show MalformedKey = "Malformed key!!"
    show MalformedUrl = "Malformed url!!"

type UrlInfo =
    { server :: String
    , fileId :: String
    , key :: String
    }

parseUrl :: String -> Either AviaryError UrlInfo
parseUrl url = note MalformedUrl do
    slashIndex <- indexOf' (Pattern "/") 8 url
    let { after, before: server } = splitAt (1 + slashIndex) url
    poundIndex <- indexOf (Pattern "#") after
    let { after: key, before: fileId } = splitAt poundIndex after
    Just { server, fileId, key: drop 1 key }

decodeKey :: String -> Either AviaryError Uint8Array
decodeKey key = note MalformedKey $ hush $ decode key

importKey :: ArrayBuffer -> Aff CryptoKey
importKey key =
    SC.importKey raw key (aes aesGCM) false [decrypt]

main_aff :: Aff Unit
main_aff = do
    { status, text } <- fetch "https://envs.sh/Q_V.txt" {}
    responseText <- text
    liftEffect $ log responseText

main :: Effect Unit
main = launchAff main_aff $> unit