Plutus pioneer program week04 homework solution

homework.hs

{-# LANGUAGE DataKinds         #-}
{-# LANGUAGE DeriveAnyClass    #-}
{-# LANGUAGE DeriveGeneric     #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeApplications  #-}
{-# LANGUAGE TypeOperators     #-}

module Week04.Homework where

import Data.Aeson            (FromJSON, ToJSON)
import Data.Functor          (void)
import Data.Text             (Text, unpack)
import GHC.Generics          (Generic)
import Ledger
import Ledger.Ada            as Ada
import Ledger.Constraints    as Constraints
import Plutus.Contract       as Contract
import Plutus.Trace.Emulator as Emulator
import Wallet.Emulator.Wallet

data PayParams = PayParams
    { ppRecipient :: PubKeyHash
    , ppLovelace  :: Integer
    } deriving (Show, Generic, FromJSON, ToJSON)

type PaySchema = Endpoint "pay" PayParams

payContract :: Contract () PaySchema Text ()
payContract = do
    params <- endpoint @"pay"
    let recipient = ppRecipient params
    let amount = lovelaceValueOf $ ppLovelace params
    let tx = mustPayToPubKey recipient amount
    Contract.handleError
        (\err -> Contract.logError $ "caught: " ++ unpack err)
        $ void $ submitTx tx
    payContract

-- A trace that invokes the pay endpoint of payContract on Wallet 1 twice, each time with Wallet 2 as
-- recipient, but with amounts given by the two arguments. There should be a delay of one slot
-- after each endpoint call.
payTrace :: Integer -> Integer -> EmulatorTrace ()
payTrace amount1 amount2 = do
    h1 <- activateContractWallet (Wallet 1) payContract
    let pkh = pubKeyHash $ walletPubKey $ Wallet 2
    callEndpoint @"pay" h1 $ PayParams { ppRecipient = pkh, ppLovelace = amount1 }
    void $ Emulator.waitNSlots 1
    callEndpoint @"pay" h1 $ PayParams { ppRecipient = pkh, ppLovelace = amount2 }

payTest1 :: IO ()
payTest1 = runEmulatorTraceIO $ payTrace 1000000 2000000

payTest2 :: IO ()
payTest2 = runEmulatorTraceIO $ payTrace 1000000000 2000000