-- This should be its own package!

module Exercise3.Solutions.Currency.Bonus.Swap where

import Exercise3.Solutions.Currency.Bonus.Interfaces

import DA.Assert

-- This module is not really needed as part of the solution.
-- It demonstrates how to also upgrade in such a way that
-- "Cash" becomes "USD" and "Cash_V2 CHF" becomes merely "CHF".

template AssetSwapProposal
  with
    requester : Party
    receiver : Party
    -- Triples of issuer, assetType, quantity
    offerSpec : (Party, Text, Decimal)
    offerCid : ContractId IAsset
    requestedSpec : (Party, Text, Decimal)
  where
    signatory requester
    observer receiver

    choice Settle : ()
      with
        requestedCid : ContractId IAsset
      controller receiver
      do
        actualOffer <- fetch offerCid
        actualRequested <- fetch requestedCid
        let
          vo = view actualOffer
          vr = view actualRequested

        -- Check signatories. Needed for safety!
        assertMsg "Offer Asset not signed by issuer!" (vo.issuer `elem` signatory actualOffer)
        assertMsg "Requested Asset not signed by issuer!" (vr.issuer `elem` signatory actualRequested)

        -- Check against spec
        (vo.issuer, vo.assetType, vo.quantity) === offerSpec
        (vr.issuer, vr.assetType, vr.quantity) === requestedSpec

        -- Transfer
        exercise offerCid Transfer with newOwner = receiver
        exercise requestedCid Transfer with newOwner = requester
        
        return ()