Homework1.hs

{-# LANGUAGE DataKinds           #-}
{-# LANGUAGE DeriveAnyClass      #-}
{-# LANGUAGE DeriveGeneric       #-}
{-# LANGUAGE FlexibleContexts    #-}
{-# LANGUAGE NoImplicitPrelude   #-}
{-# LANGUAGE OverloadedStrings   #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell     #-}
{-# LANGUAGE TypeApplications    #-}
{-# LANGUAGE TypeFamilies        #-}
{-# LANGUAGE TypeOperators       #-}

module Week03.Homework1 where

import           Control.Monad        hiding (fmap)
import           Data.Aeson           (ToJSON, FromJSON, Value (Bool))
import           Data.Map             as Map
import           Data.Text            (Text)
import           Data.Void            (Void)
import           GHC.Generics         (Generic)
import           Plutus.Contract      hiding (when)
import qualified PlutusTx
import           PlutusTx.Prelude     hiding (unless)
import           Ledger               hiding (singleton)
import           Ledger.Constraints   as Constraints
import qualified Ledger.Typed.Scripts as Scripts
import           Ledger.Ada           as Ada
import           Playground.Contract  (printJson, printSchemas, ensureKnownCurrencies, stage, ToSchema)
import           Playground.TH        (mkKnownCurrencies, mkSchemaDefinitions)
import           Playground.Types     (KnownCurrency (..))
import qualified Prelude              as P
import           Text.Printf          (printf)

data VestingDatum = VestingDatum
    { beneficiary1 :: PubKeyHash
    , beneficiary2 :: PubKeyHash
    , deadline     :: Slot
    } deriving Show

PlutusTx.unstableMakeIsData ''VestingDatum

{-# INLINABLE mkValidator #-}
-- This should validate if either beneficiary1 has signed the transaction and the current slot is before or at the deadline
-- or if beneficiary2 has signed the transaction and the deadline has passed.
mkValidator :: VestingDatum -> () -> ScriptContext -> Bool
mkValidator dat () ctx =
    traceIfFalse "Beneficiary missing" checkGen
  where
    info :: TxInfo
    info = scriptContextTxInfo ctx
    
    checkGen :: Bool
    checkGen = if checkDeadline then beneficiary2 dat `elem` txInfoSignatories info else beneficiary1 dat `elem` txInfoSignatories info

    checkDeadline :: Bool
    checkDeadline = from (deadline dat) `contains` txInfoValidRange info

data Vesting
instance Scripts.ScriptType Vesting where
    type instance DatumType Vesting = VestingDatum
    type instance RedeemerType Vesting = ()

inst :: Scripts.ScriptInstance Vesting
inst = Scripts.validator @Vesting
    $$(PlutusTx.compile [|| mkValidator ||])
    $$(PlutusTx.compile [|| wrap ||])
  where
    wrap = Scripts.wrapValidator @VestingDatum @()

validator :: Validator
validator = Scripts.validatorScript inst

scrAddress :: Ledger.Address
scrAddress = scriptAddress validator

data GiveParams = GiveParams
    { gpBeneficiary :: !PubKeyHash
    , gpDeadline    :: !Slot
    , gpAmount      :: !Integer
    } deriving (Generic, ToJSON, FromJSON, ToSchema)

type VestingSchema =
    BlockchainActions
        .\/ Endpoint "give" GiveParams
        .\/ Endpoint "grab" ()

give :: (HasBlockchainActions s, AsContractError e) => GiveParams -> Contract w s e ()
give gp = do
    pkh <- pubKeyHash <$> ownPubKey
    let dat = VestingDatum
                { beneficiary1 = gpBeneficiary gp
                , beneficiary2 = pkh
                , deadline     = gpDeadline gp
                }
        tx  = mustPayToTheScript dat $ Ada.lovelaceValueOf $ gpAmount gp
    ledgerTx <- submitTxConstraints inst tx
    void $ awaitTxConfirmed $ txId ledgerTx
    logInfo @String $ printf "made a gift of %d lovelace to %s with deadline %s"
        (gpAmount gp)
        (show $ gpBeneficiary gp)
        (show $ gpDeadline gp)

grab :: forall w s e. (HasBlockchainActions s, AsContractError e) => Contract w s e ()
grab = do
    now    <- currentSlot
    pkh    <- pubKeyHash <$> ownPubKey
    utxos  <- utxoAt scrAddress
    let utxos1 = Map.filter (isSuitable $ \dat -> beneficiary1 dat == pkh && now <= deadline dat) utxos
        utxos2 = Map.filter (isSuitable $ \dat -> beneficiary2 dat == pkh && now >  deadline dat) utxos
    logInfo @String $ printf "found %d gift(s) to grab" (Map.size utxos1 P.+ Map.size utxos2)
    unless (Map.null utxos1) $ do
        let orefs   = fst <$> Map.toList utxos1
            lookups = Constraints.unspentOutputs utxos1 P.<>
                      Constraints.otherScript validator
            tx :: TxConstraints Void Void
            tx      = mconcat [mustSpendScriptOutput oref $ Redeemer $ PlutusTx.toData () | oref <- orefs] P.<>
                      mustValidateIn (to now)
        void $ submitTxConstraintsWith @Void lookups tx
    unless (Map.null utxos2) $ do
        let orefs   = fst <$> Map.toList utxos2
            lookups = Constraints.unspentOutputs utxos2 P.<>
                      Constraints.otherScript validator
            tx :: TxConstraints Void Void
            tx      = mconcat [mustSpendScriptOutput oref $ Redeemer $ PlutusTx.toData () | oref <- orefs] P.<>
                      mustValidateIn (from now)
        void $ submitTxConstraintsWith @Void lookups tx
  where
    isSuitable :: (VestingDatum -> Bool) -> TxOutTx -> Bool
    isSuitable p o = case txOutDatumHash $ txOutTxOut o of
        Nothing -> False
        Just h  -> case Map.lookup h $ txData $ txOutTxTx o of
            Nothing        -> False
            Just (Datum e) -> maybe False p $ PlutusTx.fromData e

endpoints :: Contract () VestingSchema Text ()
endpoints = (give' `select` grab') >> endpoints
  where
    give' = endpoint @"give" >>= give
    grab' = endpoint @"grab" >>  grab

mkSchemaDefinitions ''VestingSchema

mkKnownCurrencies []