content: -- This file is part of the Wire Server implementation.
  --
  -- Copyright (C) 2022 Wire Swiss GmbH <opensource@wire.com>
  --
  -- This program is free software: you can redistribute it and/or modify it under
  -- the terms of the GNU Affero General Public License as published by the Free
  -- Software Foundation, either version 3 of the License, or (at your option) any
  -- later version.
  --
  -- This program is distributed in the hope that it will be useful, but WITHOUT
  -- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  -- FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
  -- details.
  --
  -- You should have received a copy of the GNU Affero General Public License along
  -- with this program. If not, see <https://www.gnu.org/licenses/>.
  
  module Data.ZAuth.Validation
    ( Failure (..),
      check,
    )
  where
  
  import Data.ByteString.Conversion
  import Data.Time.Clock.POSIX
  import Data.Vector (Vector, (!))
  import Data.Vector qualified as Vec
  import Data.ZAuth.CryptoSign (CryptoSign, verifyWith)
  import Data.ZAuth.Token
  import Imports
  import Polysemy
  import Polysemy.Error
  import Sodium.Crypto.Sign (PublicKey)
  import Wire.Sem.FromUTC (FromUTC (fromUTCTime))
  import Wire.Sem.Now qualified as Now
  
  data Failure
    = -- | The token signature is incorrect.
      Falsified
    | -- | The token is expired.
      Expired
    | -- | Invalid token.
      Invalid
    | -- | This operation is unsupported on this token type
      Unsupported
    deriving (Eq, Show)
  
  instance Exception Failure
  
  check :: (SerializableToken t, Member CryptoSign r, Member Now.Now r) => Vector PublicKey -> Token t -> Sem r (Either Failure ())
  check pubKeys t = runError $ do
    let dat = toByteString' $ writeData t.header t.body
    let k = t.header.key
    when (k < 1 || k > Vec.length pubKeys) $
      throw Invalid
    ok <- verifyWith (pubKeys ! (k - 1)) t.signature dat
    unless ok $
      throw Falsified
    isExpired <-
      if t.header.time == -1
        then pure False
        else (t.header.time <) <$> now
    when isExpired $
      throw Expired
  
  now :: (Member Now.Now r) => Sem r Integer
  now = floor . fromUTCTime @POSIXTime <$> Now.get
  