intent identifier params should be optional

changed to allow optional currency and amount params in intent identifier

examples/vasp/wallet.py

@@ -107,11 +107,14 @@ def pay(
         """make payment from given user account to intent_id"""
 
         intent = identifier.decode_intent(intent_id, self.hrp)
+        if not intent.amount or not intent.currency_code:
+            raise ValueError("should provide currency_code and amount")
+
         command = offchain.PaymentCommand.init(
             self.gen_user_account_id(user_name),
             self.users[user_name].kyc_data(),
             intent.account_id,
-            intent.amount,
+            intent.amount,  # pyre-ignore
             intent.currency_code,
             original_payment_reference_id=original_payment_reference_id,
             description=desc,

src/diem/identifier/__init__.py

@@ -40,15 +40,15 @@ class Intent:
 
     account_address: diem_types.AccountAddress
     sub_address: typing.Optional[bytes]
-    currency_code: str
-    amount: int
+    currency_code: typing.Optional[str]
+    amount: typing.Optional[int]
 
     def __init__(
         self,
         account_address: diem_types.AccountAddress,
         sub_address: typing.Optional[bytes],
-        currency_code: str,
-        amount: int,
+        currency_code: typing.Optional[str],
+        amount: typing.Optional[int],
         hrp: str,
     ) -> None:
         self.account_address = account_address
@@ -66,13 +66,22 @@ def account_id(self) -> str:
         return encode_account(self.account_address, self.sub_address, self.hrp)
 
 
-def encode_intent(encoded_account_identifier: str, currency_code: str, amount: int) -> str:
+def encode_intent(
+    encoded_account_identifier: str, currency_code: typing.Optional[str] = None, amount: typing.Optional[int] = None
+) -> str:
     """
     Encode account identifier string(encoded), currency code and amount into
     Diem intent identifier (https://dip.diem.com/dip-5/)
     """
 
-    return "diem://%s?c=%s&am=%d" % (encoded_account_identifier, currency_code, amount)
+    params = []
+    if currency_code:
+        params.append("c=%s" % currency_code)
+    if amount is not None and amount > 0:
+        params.append("am=%s" % amount)
+    if params:
+        return "diem://%s?%s" % (encoded_account_identifier, "&".join(params))
+    return "diem://%s" % encoded_account_identifier
 
 
 def decode_intent(encoded_intent_identifier: str, hrp: str) -> Intent:
@@ -113,7 +122,7 @@ def decode_intent(encoded_intent_identifier: str, hrp: str) -> Intent:
 
 def _decode_param(name, params, field, convert):  # pyre-ignore
     if field not in params:
-        raise InvalidIntentIdentifierError(f"Can't decode {name}: not found in params {params}")
+        return None
 
     if not isinstance(params[field], list):
         raise InvalidIntentIdentifierError(f"Can't decode {name}: unknown type {params}")

tests/test_identifier.py

@@ -154,6 +154,22 @@ def test_intent_identifier(hrp_addresses):
     assert account_id == intent.account_id
 
 
+def test_intent_identifier_without_params(hrp_addresses):
+    hrp, enocded_addr_with_none_subaddr, enocded_addr_with_subaddr = hrp_addresses
+    account_id = identifier.encode_account(test_onchain_address, None, hrp)
+    intent_id = identifier.encode_intent(account_id)
+    assert intent_id == "diem://%s" % enocded_addr_with_none_subaddr
+
+    intent = identifier.decode_intent(intent_id, hrp)
+    assert intent.account_address == utils.account_address(test_onchain_address)
+    assert intent.account_address_bytes.hex() == test_onchain_address
+    assert intent.sub_address is None
+    assert intent.currency_code is None
+    assert intent.amount is None
+
+    assert account_id == intent.account_id
+
+
 def test_intent_identifier_with_sub_address(hrp_addresses):
     hrp, enocded_addr_with_none_subaddr, enocded_addr_with_subaddr = hrp_addresses
     account_id = identifier.encode_account(test_onchain_address, test_sub_address, hrp)
@@ -167,28 +183,30 @@ def test_intent_identifier_with_sub_address(hrp_addresses):
     assert intent.amount == 123
 
 
+def test_intent_identifier_with_one_param():
+    account_id = "dm1p7ujcndcl7nudzwt8fglhx6wxnvqqqqqqqqqqqqqd8p9cq"
+    intent_id = identifier.encode_intent(account_id, currency_code="XUS")
+    assert intent_id == "diem://%s?c=%s" % (account_id, "XUS")
+    intent_id = identifier.encode_intent(account_id, currency_code="")
+    assert intent_id == "diem://%s" % account_id
+    intent_id = identifier.encode_intent(account_id, amount=122)
+    assert intent_id == "diem://%s?am=%s" % (account_id, 122)
+    intent_id = identifier.encode_intent(account_id, amount=0)
+    assert intent_id == "diem://%s" % account_id
+    intent_id = identifier.encode_intent(account_id, amount=-1)
+    assert intent_id == "diem://%s" % account_id
+
+
 def test_intent_identifier_decode_errors(hrp_addresses):
     hrp, enocded_addr_with_none_subaddr, enocded_addr_with_subaddr = hrp_addresses
     # amount is not int
     with pytest.raises(identifier.InvalidIntentIdentifierError):
         identifier.decode_intent("diem://%s?c=XUS&am=str" % (enocded_addr_with_none_subaddr), hrp)
 
-    # amount not exist
-    with pytest.raises(identifier.InvalidIntentIdentifierError):
-        identifier.decode_intent("diem://%s?c=XUS" % (enocded_addr_with_none_subaddr), hrp)
-
     # too many amount
     with pytest.raises(identifier.InvalidIntentIdentifierError):
         identifier.decode_intent("diem://%s?c=XUS&am=2&am=3" % (enocded_addr_with_none_subaddr), hrp)
 
-    # amount is none
-    with pytest.raises(identifier.InvalidIntentIdentifierError):
-        identifier.decode_intent("diem://%s?c=XUS&am=" % (enocded_addr_with_none_subaddr), hrp)
-
-    # currency code not exist
-    with pytest.raises(identifier.InvalidIntentIdentifierError):
-        identifier.decode_intent("diem://%s?am=2" % (enocded_addr_with_none_subaddr), hrp)
-
     # scheme not match
     with pytest.raises(identifier.InvalidIntentIdentifierError):
         identifier.decode_intent("hello://%s?am=2&c=XUS" % (enocded_addr_with_none_subaddr), hrp)