implement loan example

[aleeusgr]

https://github.com/Vortecsmaster/EA_PlutusExamples/tree/master/PlutusApps/V2_110/LendingPlatform

https://github.com/input-output-hk/plutus-use-cases

[aleeusgr]

data LoanActions = RequestLoan | CancelLoan deriving Eq
data LoanBond = LB { borrower :: PubKeyHash
                   , request  :: Ledger.Value
                   , duration :: POSIXTime
                   , collateral :: Ledger.Value
                   }

https://github.com/Vortecsmaster/EA_PlutusExamples/blob/f66688a3eecd803eed4582a3de279c844a427505/PlutusApps/V2_110/LendingPlatform/src/RequestLoan.hs#L48-L53

[aleeusgr]

{-# INLINABLE loanRequest #-} 
loanRequest :: LoanBond -> LoanActions -> PlutusV2.ScriptContext -> Bool   
loanRequest datum action sContext 
  | action == RequestLoan      = requestLoan 
  | action == CancelLoan       = cancelLoan  
  | otherwise                  = False
  where


    info :: LedgerV2.TxInfo
    info = LedgerV2.scriptContextTxInfo sContext


    timeoutReached :: Bool
    timeoutReached = contains (from $ duration datum) (LedgerV2.txInfoValidRange info)   
 
    requestLoan :: Bool
    requestLoan = timeoutReached  


    cancelLoan :: Bool
    cancelLoan = if (length (txInfoOutputs info) == 1) then (pubKeyHashAddress $ borrower datum) == txOutAddress $ head ((txInfoOutputs info))

https://github.com/Vortecsmaster/EA_PlutusExamples/blob/f66688a3eecd803eed4582a3de279c844a427505/PlutusApps/V2_110/LendingPlatform/src/UsingSCvalidator.hs#L70-L76