CIP102 implementation

Author: SamDelaney

pycardano/cip/__init__.py

@@ -4,3 +4,4 @@
 from .cip14 import *
 from .cip67 import *
 from .cip68 import *
+from .cip102 import *

pycardano/cip/cip102.py

@@ -0,0 +1,299 @@
+from dataclasses import dataclass
+from typing import Any, List, Optional, Union
+
+from cbor2 import CBORTag
+
+from pycardano.cip.cip67 import CIP67TokenName, InvalidCIP67Token
+from pycardano.hash import ScriptHash, VerificationKeyHash
+from pycardano.plutus import PlutusData, Unit, Primitive
+from pycardano.serialization import IndefiniteList
+from pycardano.transaction import AssetName
+
+
+ROYALTY_TOKEN_LABEL = 500
+ROYALTY_TOKEN_PAYLOAD = b"Royalty"
+
+
+class InvalidCIP102Token(Exception):
+    pass
+
+
+class CIP102RoyaltyTokenName(CIP67TokenName):
+    """Generates a CIP-102 royalty token name from an input postfix.
+
+    The royalty token name is a CIP-67 encoded token name with label ``500`` and
+    payload ``"Royalty"`` followed by an optional integer postfix.
+
+    For more information on CIP-102:
+    https://github.com/cardano-foundation/CIPs/tree/master/CIP-0102
+
+    Args:
+        data: The token name as bytes, str, or AssetName
+    """
+
+    def __init__(self, data: Union[bytes, str, AssetName]):
+        super().__init__(data)
+
+        if self.label != ROYALTY_TOKEN_LABEL:
+            raise InvalidCIP102Token(
+                f"Royalty token must have label {ROYALTY_TOKEN_LABEL}, "
+                f"got {self.label}."
+            )
+
+        if not self.payload[4:].startswith(ROYALTY_TOKEN_PAYLOAD):
+            raise InvalidCIP102Token(
+                f"Royalty token payload must start with 'Royalty', "
+                f"got {self.payload[4:]}."
+            )
+
+    @classmethod
+    def from_postfix(cls, postfix: Optional[int] = None) -> "CIP102RoyaltyTokenName":
+        """Create a royalty token name with an optional integer postfix.
+
+        Args:
+            postfix: Optional integer postfix to distinguish multiple royalty tokens
+                under the same policy ID (version 2). If ``None``, creates the
+                base ``(500)Royalty`` token for version 1.
+
+        Returns:
+            CIP102RoyaltyTokenName: The constructed royalty token name.
+
+        Example:
+            CIP102RoyaltyTokenName.from_postfix()        # (500)Royalty
+            CIP102RoyaltyTokenName.from_postfix(1)       # (500)Royalty1
+            CIP102RoyaltyTokenName.from_postfix(2)       # (500)Royalty2
+        """
+        from crc8 import crc8
+
+        label = ROYALTY_TOKEN_LABEL
+        # CIP-67 stores the label in the upper 12 bits of the first 3 bytes.
+        # data[1:5] (nibbles 1-4) are the CRC8 input, matching the validator.
+        label_bytes = (label << 4).to_bytes(3, "big")  # 3 bytes with label in upper 12 bits
+        label_nibbles_for_crc = label_bytes.hex()[1:5]  # e.g. "01f4" for label 500
+        checksum = crc8(bytes.fromhex(label_nibbles_for_crc)).hexdigest()
+        prefix = "0" + label_nibbles_for_crc + checksum + "0"  # 8 hex chars = 4 bytes
+
+        payload = ROYALTY_TOKEN_PAYLOAD
+        if postfix is not None:
+            payload = payload + str(postfix).encode()
+
+        token_hex = prefix + payload.hex()
+        return cls(token_hex)
+
+    @property
+    def postfix(self) -> Optional[int]:
+        """Return the integer postfix of this royalty token, or ``None`` if absent."""
+        suffix = self.payload[4 + len(ROYALTY_TOKEN_PAYLOAD) :]
+        if not suffix:
+            return None
+        try:
+            return int(suffix.decode())
+        except (ValueError, UnicodeDecodeError):
+            return None
+
+
+@dataclass
+class RoyaltyRecipientSomeMinFee(PlutusData):
+    """Plutus representation of ``optional_big_int`` when a value is present (``#6.121([big_int])``)."""
+
+    CONSTR_ID = 0
+    value: int
+
+
+@dataclass
+class RoyaltyRecipientNoMinFee(PlutusData):
+    """Plutus representation of ``optional_big_int`` when no value is present (``#6.122([])``).
+
+    Maps to constructor 1 in Plutus alternate constructor encoding.
+    """
+
+    CONSTR_ID = 1
+
+
+def _make_optional_big_int(value: Optional[int]) -> PlutusData:
+    """Build the ``optional_big_int`` Plutus representation.
+
+    Args:
+        value: An integer value, or ``None`` for the empty case.
+
+    Returns:
+        ``RoyaltyRecipientSomeMinFee(value)`` if value is set,
+        ``RoyaltyRecipientNoMinFee()`` if ``None``.
+    """
+    if value is not None:
+        return RoyaltyRecipientSomeMinFee(value)
+    return RoyaltyRecipientNoMinFee()
+
+
+@dataclass
+class RoyaltyRecipient(PlutusData):
+    """A single royalty recipient as specified in the CIP-102 datum.
+
+    Encodes as ``#6.121([address, fee, min_fee, max_fee])`` in CBOR/Plutus.
+
+    The ``address`` field stores the raw Plutus address bytes as produced by
+    :meth:`pycardano.address.Address.to_primitive`, matching the Plutus ledger
+    address definition.
+
+    Args:
+        address: Plutus address bytes (payment credential + optional staking credential).
+        fee: Variable fee as integer denominator. The royalty percentage is
+            ``10 / fee`` (e.g., fee=625 → 1.6%).
+        min_fee: Optional minimum royalty fee in lovelace.
+        max_fee: Optional maximum royalty fee in lovelace.
+
+    For fee calculations see :mod:`pycardano.cip.cip102` module-level helpers.
+    """
+
+    CONSTR_ID = 0
+
+    address: bytes
+    fee: int
+    min_fee: Union[RoyaltyRecipientSomeMinFee, RoyaltyRecipientNoMinFee]
+    max_fee: Union[RoyaltyRecipientSomeMinFee, RoyaltyRecipientNoMinFee]
+
+    @classmethod
+    def new(
+        cls,
+        address: bytes,
+        fee: int,
+        min_fee: Optional[int] = None,
+        max_fee: Optional[int] = None,
+    ) -> "RoyaltyRecipient":
+        """Construct a royalty recipient with optional min/max fee.
+
+        Args:
+            address: Plutus address bytes.
+            fee: On-chain fee denominator (``floor(10 / pct)``).
+            min_fee: Minimum royalty in lovelace, or ``None``.
+            max_fee: Maximum royalty in lovelace, or ``None``.
+
+        Returns:
+            RoyaltyRecipient: The constructed recipient.
+        """
+        return cls(
+            address=address,
+            fee=fee,
+            min_fee=_make_optional_big_int(min_fee),
+            max_fee=_make_optional_big_int(max_fee),
+        )
+
+
+@dataclass
+class RoyaltyInfo(PlutusData):
+    """The CIP-102 royalty datum.
+
+    Encodes as ``#6.121([royalty_recipients, version, extra])`` in CBOR/Plutus,
+    suitable for use as an inline datum on the royalty token UTxO.
+
+    For more information on CIP-102:
+    https://github.com/cardano-foundation/CIPs/tree/master/CIP-0102
+
+    Args:
+        recipients: List of :class:`RoyaltyRecipient` objects.
+        version: Datum version. Use ``1`` for a single ``(500)Royalty`` token;
+            use ``2`` when postfixed royalty tokens are involved.
+        extra: Required extra field. Pass :class:`pycardano.plutus.Unit` for empty.
+
+    Example:
+        from pycardano.plutus import Unit
+        recipient = RoyaltyRecipient.new(address=bytes(29), fee=625)
+        datum = RoyaltyInfo(recipients=[recipient], version=1, extra=Unit())
+        cbor_hex = datum.to_cbor_hex()
+    """
+
+    CONSTR_ID = 0
+
+    recipients: List[RoyaltyRecipient]
+    version: int
+    extra: Any
+
+    def __post_init__(self):
+        # Deliberately does not call super().__post_init__() to allow Any-typed
+        # extra field (same pattern as CIP68Datum).
+        pass
+
+    def to_shallow_primitive(self) -> CBORTag:
+        """Serialize to CBOR, wrapping the ``extra`` field appropriately."""
+        primitives: Primitive = super().to_shallow_primitive()
+        if isinstance(primitives, CBORTag):
+            value = primitives.value
+            if value:
+                extra = value[2]
+                if isinstance(extra, Unit):
+                    extra = CBORTag(121, IndefiniteList([]))
+                elif isinstance(extra, CBORTag):
+                    extra = CBORTag(extra.tag, IndefiniteList(extra.value))
+                recipients = value[0]
+                value = [recipients, value[1], extra]
+        return CBORTag(121, value)
+
+
+def fee_to_chain(pct: float) -> int:
+    """Convert a royalty percentage to the on-chain integer denominator.
+
+    The on-chain fee is stored as ``floor(10 / pct)`` (integer division with
+    precision 10), so that ``pct = 10 / fee``.
+
+    Args:
+        pct: Royalty percentage as a decimal (e.g., ``0.016`` for 1.6%).
+
+    Returns:
+        int: The on-chain fee denominator.
+
+    Example:
+        >>> fee_to_chain(0.016)
+        625
+    """
+    import math
+
+    return math.floor(10 / pct)
+
+
+def fee_from_chain(chain_fee: int) -> float:
+    """Convert an on-chain fee denominator back to a royalty percentage.
+
+    Args:
+        chain_fee: The on-chain integer denominator stored in the royalty datum.
+
+    Returns:
+        float: The royalty percentage (e.g., ``0.016`` for 1.6%).
+
+    Example:
+        >>> fee_from_chain(625)
+        0.016
+    """
+    return 10 / chain_fee
+
+
+def calculate_royalty(
+    chain_fee: int,
+    sale_price: int,
+    min_fee: Optional[int] = None,
+    max_fee: Optional[int] = None,
+) -> int:
+    """Calculate the royalty amount for a given sale price.
+
+    Applies the CIP-102 formula::
+
+        max(min_fee, min(max_fee, (10 * sale_price) // chain_fee))
+
+    Args:
+        chain_fee: On-chain fee denominator from the royalty datum.
+        sale_price: Sale price in the same monetary unit as the royalty.
+        min_fee: Optional minimum fee. If ``None``, no lower bound is applied.
+        max_fee: Optional maximum fee. If ``None``, no upper bound is applied.
+
+    Returns:
+        int: Calculated royalty amount.
+
+    Example:
+        >>> calculate_royalty(625, 100_000_000)  # 1.6% of 100 ADA
+        1600000
+    """
+    amount = (10 * sale_price) // chain_fee
+    if max_fee is not None:
+        amount = min(amount, max_fee)
+    if min_fee is not None:
+        amount = max(amount, min_fee)
+    return amount