Add an OgmiosV6 backend based on ogmios-python

This requires bumping the python version to 3.10+, because ogmios-python requires this.
I also refactored the chain backend to not have built-in kupo support but just provide it as an extension using kupo-wrappers.
This way, both OgmiosV5 and OgmiosV6 directly have support for kupo.

Author: nielstron

integration-test/test/base.py

@@ -22,7 +22,7 @@ class TestBase:
     # TODO: Bring back kupo test
     KUPO_URL = "http://localhost:1442"
 
-    chain_context = python_ogmios.OgmiosChainContext(
+    chain_context = python_ogmios.OgmiosV5ChainContext(
         host="localhost", port=1337, network=Network.TESTNET
     )
 

poetry.lock

@@ -3,4 +3,4 @@
 from .base import *
 from .blockfrost import *
 from .cardano_cli import *
-from .ogmios import *
+from .ogmios_v5 import *

pycardano/backend/__init__.py

@@ -0,0 +1,230 @@
+from typing import Dict, List, Optional, Union
+
+import requests
+from cachetools import Cache, LRUCache, TTLCache
+
+from pycardano.address import Address
+from pycardano.backend.base import (
+    ChainContext,
+    GenesisParameters,
+)
+from pycardano.backend.blockfrost import _try_fix_script
+from pycardano.hash import DatumHash
+from pycardano.network import Network
+from pycardano.plutus import ExecutionUnits, PlutusV1Script, PlutusV2Script
+from pycardano.serialization import RawCBOR
+from pycardano.transaction import (
+    Asset,
+    MultiAsset,
+    TransactionInput,
+    TransactionOutput,
+    UTxO,
+    Value,
+)
+
+__all__ = ["KupoChainContextExtension"]
+
+
+class KupoChainContextExtension(ChainContext):
+    _wrapped_backend: ChainContext
+    _kupo_url: Optional[str]
+    _utxo_cache: Cache
+    _datum_cache: Cache
+    _refetch_chain_tip_interval: int
+
+    def __init__(
+        self,
+        wrapped_backend: ChainContext,
+        kupo_url: Optional[str] = None,
+        refetch_chain_tip_interval: int = 10,
+        utxo_cache_size: int = 1000,
+        datum_cache_size: int = 1000,
+    ):
+        self._kupo_url = kupo_url
+        self._wrapped_backend = wrapped_backend
+        self._refetch_chain_tip_interval = refetch_chain_tip_interval
+        self._utxo_cache = TTLCache(
+            ttl=self._refetch_chain_tip_interval, maxsize=utxo_cache_size
+        )
+        self._datum_cache = LRUCache(maxsize=datum_cache_size)
+
+    @property
+    def genesis_param(self) -> GenesisParameters:
+        """Get chain genesis parameters"""
+
+        return self._wrapped_backend.genesis_param
+
+    @property
+    def network(self) -> Network:
+        """Get current network"""
+        return self._wrapped_backend.network
+
+    @property
+    def epoch(self) -> int:
+        """Current epoch number"""
+        return self._wrapped_backend.epoch
+
+    @property
+    def last_block_slot(self) -> int:
+        """Last block slot"""
+        return self._wrapped_backend.last_block_slot
+
+    def _utxos(self, address: str) -> List[UTxO]:
+        """Get all UTxOs associated with an address.
+
+        Args:
+            address (str): An address encoded with bech32.
+
+        Returns:
+            List[UTxO]: A list of UTxOs.
+        """
+        key = (self.last_block_slot, address)
+        if key in self._utxo_cache:
+            return self._utxo_cache[key]
+
+        if self._kupo_url:
+            utxos = self._utxos_kupo(address)
+        else:
+            utxos = self._wrapped_backend.utxos(address)
+
+        self._utxo_cache[key] = utxos
+
+        return utxos
+
+    def _get_datum_from_kupo(self, datum_hash: str) -> Optional[RawCBOR]:
+        """Get datum from Kupo.
+
+        Args:
+            datum_hash (str): A datum hash.
+
+        Returns:
+            Optional[RawCBOR]: A datum.
+        """
+        datum = self._datum_cache.get(datum_hash, None)
+
+        if datum is not None:
+            return datum
+
+        if self._kupo_url is None:
+            raise AssertionError(
+                "kupo_url object attribute has not been assigned properly."
+            )
+
+        kupo_datum_url = self._kupo_url + "/datums/" + datum_hash
+        datum_result = requests.get(kupo_datum_url).json()
+        if datum_result and datum_result["datum"] != datum_hash:
+            datum = RawCBOR(bytes.fromhex(datum_result["datum"]))
+
+        self._datum_cache[datum_hash] = datum
+        return datum
+
+    def _utxos_kupo(self, address: str) -> List[UTxO]:
+        """Get all UTxOs associated with an address with Kupo.
+        Since UTxO querying will be deprecated from Ogmios in next
+        major release: https://ogmios.dev/mini-protocols/local-state-query/.
+
+        Args:
+            address (str): An address encoded with bech32.
+
+        Returns:
+            List[UTxO]: A list of UTxOs.
+        """
+        if self._kupo_url is None:
+            raise AssertionError(
+                "kupo_url object attribute has not been assigned properly."
+            )
+
+        kupo_utxo_url = self._kupo_url + "/matches/" + address + "?unspent"
+        results = requests.get(kupo_utxo_url).json()
+
+        utxos = []
+
+        for result in results:
+            tx_id = result["transaction_id"]
+            index = result["output_index"]
+
+            if result["spent_at"] is None:
+                tx_in = TransactionInput.from_primitive([tx_id, index])
+
+                lovelace_amount = result["value"]["coins"]
+
+                script = None
+                script_hash = result.get("script_hash", None)
+                if script_hash:
+                    kupo_script_url = self._kupo_url + "/scripts/" + script_hash
+                    script = requests.get(kupo_script_url).json()
+                    if script["language"] == "plutus:v2":
+                        script = PlutusV2Script(bytes.fromhex(script["script"]))
+                        script = _try_fix_script(script_hash, script)
+                    elif script["language"] == "plutus:v1":
+                        script = PlutusV1Script(bytes.fromhex(script["script"]))
+                        script = _try_fix_script(script_hash, script)
+                    else:
+                        raise ValueError("Unknown plutus script type")
+
+                datum = None
+                datum_hash = (
+                    DatumHash.from_primitive(result["datum_hash"])
+                    if result["datum_hash"]
+                    else None
+                )
+                if datum_hash and result.get("datum_type", "inline"):
+                    datum = self._get_datum_from_kupo(result["datum_hash"])
+
+                if not result["value"]["assets"]:
+                    tx_out = TransactionOutput(
+                        Address.from_primitive(address),
+                        amount=lovelace_amount,
+                        datum_hash=datum_hash,
+                        datum=datum,
+                        script=script,
+                    )
+                else:
+                    multi_assets = MultiAsset()
+
+                    for asset, quantity in result["value"]["assets"].items():
+                        policy_hex, policy, asset_name_hex = self._extract_asset_info(
+                            asset
+                        )
+                        multi_assets.setdefault(policy, Asset())[
+                            asset_name_hex
+                        ] = quantity
+
+                    tx_out = TransactionOutput(
+                        Address.from_primitive(address),
+                        amount=Value(lovelace_amount, multi_assets),
+                        datum_hash=datum_hash,
+                        datum=datum,
+                        script=script,
+                    )
+                utxos.append(UTxO(tx_in, tx_out))
+            else:
+                continue
+
+        return utxos
+
+    def submit_tx_cbor(self, cbor: Union[bytes, str]):
+        """Submit a transaction to the blockchain.
+
+        Args:
+            cbor (Union[bytes, str]): The transaction to be submitted.
+
+        Raises:
+            :class:`InvalidArgumentException`: When the transaction is invalid.
+            :class:`TransactionFailedException`: When fails to submit the transaction to blockchain.
+        """
+        return self._wrapped_backend.submit_tx_cbor(cbor)
+
+    def evaluate_tx_cbor(self, cbor: Union[bytes, str]) -> Dict[str, ExecutionUnits]:
+        """Evaluate execution units of a transaction.
+
+        Args:
+            cbor (Union[bytes, str]): The serialized transaction to be evaluated.
+
+        Returns:
+            Dict[str, ExecutionUnits]: A list of execution units calculated for each of the transaction's redeemers
+
+        Raises:
+            :class:`TransactionFailedException`: When fails to evaluate the transaction.
+        """
+        return self._wrapped_backend.evaluate_tx_cbor(cbor)