module Exercise1.Observers where

import Initial.Cash
import Initial.Scripts

import DA.Assert
import DA.Foldable (forA_)
import Daml.Script

template AdditionalRules
  with
    bank : Party
    bankReader : Party
  where
    signatory bank
    observer bankReader

    nonconsuming choice Set_Observers : ContractId Position
      with
        owner : Party
        positionCid : ContractId Position
        new_obs : [Party]
      controller owner
      do
        position <- fetch positionCid
        owner === position.owner
        bank === position.issuer

        archive positionCid
        create position with obs = new_obs

test_set_obs : Script ()
test_set_obs = script do
  (tps@TestParties{..}, tus@TestUsers{..}) <- init_cash

  -- Create a reader party and give access to Alice and Bob
  pBankReader <- allocateParty "BankReader"
  grantUserRights uAlice [CanReadAs pBankReader]
  grantUserRights uBob [CanReadAs pBankReader]

  -- Bank Issues the new rule
  rules <- submitUser uBank do
    createCmd AdditionalRules with
      bank = pBank
      bankReader = pBankReader

  -- Alice can make Bob observer on all her positions
  alicePositions <- query @Position pAlice
  forA_ (alicePositions) (\(cid, _) -> do
    submitUser uAlice do
      exerciseCmd rules Set_Observers with 
        owner = pAlice
        positionCid = cid
        new_obs = [pBob]
    )