{-# LANGUAGE DataKinds         #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell   #-}
{-# OPTIONS_GHC -fplugin PlutusTx.Plugin #-}
{-# OPTIONS_GHC -fplugin-opt PlutusTx.Plugin:defer-errors #-}

-- | Verify-gate validator (Plutus V3).
--
--   A minimal spending validator whose ONLY job is to run the real
--   commitment-aware Groth16 verifier ('groth16VerifyCommitted') against:
--
--     * a verifying key @vk@ (672 B) and public input @pub@ (32 B) baked in at
--       deploy time as the applied parameter, and
--     * a proof @p@ (336 B) supplied at spend time as the redeemer.
--
--   The UTxO at this script's address is spendable iff the proof verifies under
--   the baked-in (vk, pub). The node runs the pairing check as phase-2
--   validation: a valid proof => the spend succeeds; a tampered proof => a
--   BLS12-381 builtin errors => the script fails => no spend (collateral
--   forfeit).
--
--   Parameter encoding (applied at deploy time):
--     paramsData = toBuiltinData ((vk, pub) :: (BuiltinByteString, BuiltinByteString))
--                = Constr 0 [B vk, B pub]
--   Redeemer encoding (supplied at spend time):
--     redeemer   = B p           -- the raw 336-byte proof bytes, as a Data bytestring
module Gate (mkGate, compiledGate) where

import PlutusTx
import PlutusTx.Prelude
import qualified PlutusTx.Builtins as B
import PlutusTx.Builtins.Internal (BuiltinUnit)
import PlutusLedgerApi.V3 (ScriptContext (..), Redeemer (..))
import Recovery.Types (VerifyingKey (..), Proof (..), Scalar (..))
import Recovery.Verify (groth16VerifyCommitted)

-- | V3 validator. First argument is the Data-encoded (vk, pub) parameter
--   (applied at deploy time); second is the ScriptContext supplied by the
--   ledger. The proof is read from the spending redeemer (a Data bytestring).
{-# INLINABLE mkGate #-}
mkGate :: BuiltinData -> BuiltinData -> BuiltinUnit
mkGate paramsData ctxData =
  let (vk, pub) = unsafeFromBuiltinData paramsData :: (BuiltinByteString, BuiltinByteString)
      ctx       = unsafeFromBuiltinData ctxData    :: ScriptContext
      proofData = getRedeemer (scriptContextRedeemer ctx)
      proof     = B.unsafeDataAsB proofData
  in  check (groth16VerifyCommitted (VerifyingKey vk) (Proof proof) (Scalar pub))

-- | PlutusTx-compiled UPLC validator. Apply 'compiledGate' to the Data-encoded
--   (vk, pub) parameter to obtain the deployable @BuiltinData -> BuiltinUnit@.
compiledGate :: CompiledCode (BuiltinData -> BuiltinData -> BuiltinUnit)
compiledGate = $$(compile [|| mkGate ||])