content: {-# LANGUAGE GeneralizedNewtypeDeriving #-}
  {-# LANGUAGE StrictData #-}
  
  -- 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 CargoHold.CloudFront
    ( CloudFront,
      Domain (..),
      KeyPairId (..),
      initCloudFront,
      signedURL,
    )
  where
  
  import Control.AutoUpdate
  import qualified Data.ByteString.Base64 as B64
  import Data.ByteString.Builder
  import qualified Data.ByteString.Char8 as C8
  import Data.ByteString.Conversion
  import Data.ByteString.Lazy (toStrict)
  import Data.Text.Encoding (encodeUtf8)
  import Data.Time.Clock.POSIX
  import Data.Yaml (FromJSON)
  import Imports
  import OpenSSL.EVP.Digest (getDigestByName)
  import qualified OpenSSL.EVP.Sign as SSL
  import OpenSSL.PEM (PemPasswordSupply (PwNone), readPrivateKey)
  import URI.ByteString
  
  newtype KeyPairId = KeyPairId Text
    deriving (Eq, Show, ToByteString, Generic, FromJSON)
  
  newtype Domain = Domain Text
    deriving (Eq, Show, ToByteString, Generic, FromJSON)
  
  data CloudFront = CloudFront
    { _baseUrl :: URI,
      _keyPairId :: KeyPairId,
      _ttl :: Word,
      _clock :: IO POSIXTime,
      _func :: ByteString -> IO ByteString
    }
  
  initCloudFront :: (MonadIO m) => FilePath -> KeyPairId -> Word -> Domain -> m CloudFront
  initCloudFront kfp kid ttl (Domain dom) =
    liftIO $
      CloudFront baseUrl kid ttl <$> mkPOSIXClock <*> sha1Rsa kfp
    where
      baseUrl =
        URI
          { uriScheme = Scheme "https",
            uriAuthority = Just (Authority Nothing (Host (encodeUtf8 dom)) Nothing),
            uriPath = "/",
            uriQuery = Query [],
            uriFragment = Nothing
          }
  
  signedURL :: (MonadIO m, ToByteString p) => CloudFront -> p -> m URI
  signedURL (CloudFront base kid ttl clock sign) path = liftIO $ do
    time <- (+ ttl) . round <$> clock
    sig <- sign (toStrict (toLazyByteString (policy url time)))
    pure $!
      url
        { uriQuery =
            Query
              [ ("Expires", toByteString' time),
                ("Signature", b64 sig),
                ("Key-Pair-Id", toByteString' kid)
              ]
        }
    where
      url = base {uriPath = "/" <> toByteString' path}
      policy r t =
        "{\"Statement\":[{\"Resource\":\""
          <> serializeURIRef r
          <> "\",\
             \\"Condition\":{\
             \\"DateLessThan\":{\
             \\"AWS:EpochTime\":"
          <> wordDec t
          <> "}}}]}"
      b64 = C8.map f . B64.encode
        where
          f '+' = '-'
          f '=' = '_'
          f '/' = '~'
          f c = c
  
  sha1Rsa :: FilePath -> IO (ByteString -> IO ByteString)
  sha1Rsa fp = do
    sha1 <-
      liftIO $
        getDigestByName "SHA1"
          >>= maybe (error "OpenSSL: SHA1 not found") pure
    kbs <- readFile fp
    key <- readPrivateKey kbs PwNone
    pure (SSL.signBS sha1 key)
  
  mkPOSIXClock :: IO (IO POSIXTime)
  mkPOSIXClock =
    mkAutoUpdate
      defaultUpdateSettings
        { updateAction = getPOSIXTime
        }
  