feat: Add Asset.contract_id() for calculating the id of the asset c…

…ontract. (#901)

CHANGELOG.md

@@ -4,6 +4,7 @@ Release History
 ### Pending
 #### Update
 - chore: throw an exception when the API does not provide streaming support. ([#878](https://github.com/StellarCN/py-stellar-base/pull/878))
+- feat: Add `Asset.contract_id()` for calculating the id of the asset contract. ([#901](https://github.com/StellarCN/py-stellar-base/pull/901))
 
 ### Version 9.2.0
 

stellar_sdk/asset.py

@@ -4,7 +4,9 @@
 from . import xdr as stellar_xdr
 from .exceptions import AssetCodeInvalidError, AssetIssuerInvalidError
 from .keypair import Keypair
+from .network import Network
 from .strkey import StrKey
+from .utils import sha256
 
 __all__ = ["Asset"]
 
@@ -82,6 +84,26 @@ def type(self) -> str:
     def type(self, v) -> None:
         raise AttributeError("Asset type is immutable.")
 
+    def contract_id(self, network_passphrase: str) -> str:
+        """Return the contract Id for the asset contract.
+
+        :param network_passphrase: The network where the asset is located.
+        :return: The contract Id for the asset contract.
+        """
+        network_id_hash = stellar_xdr.Hash(Network(network_passphrase).network_id())
+        preimage = stellar_xdr.HashIDPreimage(
+            stellar_xdr.EnvelopeType.ENVELOPE_TYPE_CONTRACT_ID,
+            contract_id=stellar_xdr.HashIDPreimageContractID(
+                network_id=network_id_hash,
+                contract_id_preimage=stellar_xdr.ContractIDPreimage(
+                    stellar_xdr.ContractIDPreimageType.CONTRACT_ID_PREIMAGE_FROM_ASSET,
+                    from_asset=self.to_xdr_object(),
+                ),
+            ),
+        )
+        contract_id = sha256(preimage.to_xdr_bytes())
+        return StrKey.encode_contract(contract_id)
+
     def guess_asset_type(self) -> str:
         """Return the type of the asset, Can be one of
         following types: ``native``, ``credit_alphanum4`` or ``credit_alphanum12``.

stellar_sdk/utils.py

@@ -1,16 +1,19 @@
 """This file contains constants, functions and classes used internally by this SDK.
 They may change at any time, so please do not use them directly.
 """
+
 import hashlib
 import re
 from decimal import ROUND_FLOOR, Context, Decimal, Inexact
-from typing import Dict, Optional, Sequence, Union
+from typing import TYPE_CHECKING, Dict, Optional, Sequence, Union
 from urllib.parse import urljoin, urlsplit, urlunsplit
 
-from .asset import Asset
 from .exceptions import Ed25519PublicKeyInvalidError, NoApproximationError
 from .strkey import StrKey
 
+if TYPE_CHECKING:
+    from .asset import Asset
+
 MUXED_ACCOUNT_STARTING_LETTER: str = "M"
 ED25519_PUBLIC_KEY_STARTING_LETTER: str = "G"
 _LOWER_LIMIT = "0"
@@ -55,7 +58,7 @@ def hex_to_bytes(hex_string: Union[str, bytes]) -> bytes:
     return hex_string
 
 
-def convert_assets_to_horizon_param(assets: Sequence[Asset]) -> str:
+def convert_assets_to_horizon_param(assets: Sequence["Asset"]) -> str:
     assets_string = []
     for asset in assets:
         if asset.is_native():

tests/test_asset.py

@@ -1,5 +1,6 @@
 import pytest
 
+from stellar_sdk import Network
 from stellar_sdk.asset import Asset
 from stellar_sdk.exceptions import AssetCodeInvalidError, AssetIssuerInvalidError
 
@@ -180,3 +181,39 @@ def test_to_xdr_change_trust_xdr_asset_object(self, asset, xdr):
         xdr_object = asset.to_change_trust_asset_xdr_object()
         assert xdr_object.to_xdr() == xdr
         assert Asset.from_xdr_object(xdr_object) == asset
+
+    @pytest.mark.parametrize(
+        "asset, network_passphrase, contract_id",
+        [
+            pytest.param(
+                Asset.native(),
+                Network.PUBLIC_NETWORK_PASSPHRASE,
+                "CAS3J7GYLGXMF6TDJBBYYSE3HQ6BBSMLNUQ34T6TZMYMW2EVH34XOWMA",
+                id="native_public",
+            ),
+            pytest.param(
+                Asset.native(),
+                Network.TESTNET_NETWORK_PASSPHRASE,
+                "CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC",
+                id="native_testnet",
+            ),
+            pytest.param(
+                Asset(
+                    "USDC", "GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN"
+                ),
+                Network.PUBLIC_NETWORK_PASSPHRASE,
+                "CCW67TSZV3SSS2HXMBQ5JFGCKJNXKZM7UQUWUZPUTHXSTZLEO7SJMI75",
+                id="alphanum4_public",
+            ),
+            pytest.param(
+                Asset(
+                    "yUSDC", "GDGTVWSM4MGS4T7Z6W4RPWOCHE2I6RDFCIFZGS3DOA63LWQTRNZNTTFF"
+                ),
+                Network.PUBLIC_NETWORK_PASSPHRASE,
+                "CDOFW7HNKLUZRLFZST4EW7V3AV4JI5IHMT6BPXXSY2IEFZ4NE5TWU2P4",
+                id="alphanum12_public",
+            ),
+        ],
+    )
+    def test_contract_id(self, asset, network_passphrase, contract_id):
+        assert asset.contract_id(network_passphrase) == contract_id