fa12.ligo

fa12.ligo

function transfer (const addressFrom : address; const addressTo : address; const value : nat; var store : store) : return is
  block {
    if addressFrom = addressTo then skip;
    else block {
      case isAllowed(addressFrom, addressTo, value, store) of 
      | False -> block {
          failwith ("NotEnoughAllowance");
        }
      | True -> skip
      end;

      const addressFromAccount: account = getAccount(addressFrom, store.accounts);
      if value > addressFromAccount.balance
      then failwith ("NotEnoughBalance");
      else skip;

      // Update balances
      const newFromBalance :nat = abs(addressFromAccount.balance - value);  // ensure non negative
      patch addressFromAccount with record [balance = newFromBalance];
      store.accounts[addressFrom] := addressFromAccount;

      const addressToAccount: account = getAccount(addressTo, store.accounts);
      const newToBalance :nat = addressToAccount.balance + value;  // ensure non negative
      patch addressToAccount with record [balance = newToBalance];
      store.accounts[addressTo] := addressToAccount;

      // Update allowances
      case store.accounts[addressFrom] of
        | None -> skip
        | Some(account) -> block {
            case account.allowances[addressTo] of
              | None -> skip
              | Some(allowanceAmount) -> block {
                  account.allowances[addressTo] :=  abs(allowanceAmount - value);
                  store.accounts[addressFrom] := record balance = addressFromAccount.balance; allowances = account.allowances; end;
                }
            end;
          }
      end;
    }
  } with (emptyOps, store);