Force royalties on ERC721

cookiecutter.json

@@ -9,6 +9,9 @@
     "max_supply": "y",
     "max_supply_amount": 10000,
     "permitable": "y",
+    "royalty_percentage_in_decimals": 10.0,
     "royalties": "y",
-    "royalty_percentage_in_decimals": 10.0
+    "force_royalties": "y",
+    "minRoyaltyAmount": 1000000000000000,
+    "thresholdPercentage": 1.0
 }

tests/Basic.json

@@ -11,6 +11,9 @@
     "max_supply_amount": 3,
     "permitable": "y",
     "royalties": "y",
-    "royalty_percentage_in_decimals": 10.0
+    "royalty_percentage_in_decimals": 10.0,
+    "force_royalties": "y",
+    "minRoyaltyAmount": 1000000000000000,
+    "thresholdPercentage": 5.0
   }
 }

tests/Mintable.json

@@ -6,12 +6,15 @@
     "updatable_uri": "n",
     "base_uri": "ipfs://QmaZm1rAkt6kHTKTFX8GwEhtPMVMeAGJYMBvoAcJWTddwb",
     "metadata": "n",
-    "mintable": "y",
+    "mintable": "n",
     "max_supply": "y",
     "max_supply_amount": 3,
     "permitable": "y",
     "royalties": "y",
-    "royalty_percentage_in_decimals": 10.0
+    "royalty_percentage_in_decimals": 10.0,
+    "force_royalties": "n",
+    "minRoyaltyAmount": 0,
+    "thresholdPercentage": 0.0
 
   }
 }

{{cookiecutter.project_name}}/.gitignore

@@ -41,12 +41,15 @@ pip-log.txt
 pip-delete-this-directory.txt
 
 # Unit test / coverage reports
+__local__.json
 htmlcov/
 .tox/
 .nox/
+charmap.json.gz
 .coverage
 .coverage.*
 .cache
+.DS_Store
 nosetests.xml
 coverage.xml
 *.cover

{{cookiecutter.project_name}}/contracts/NFT.vy

@@ -92,6 +92,15 @@ event ApprovalForAll:
     operator: indexed(address)
     approved: bool
 
+event PaymentReceived:
+    sender: indexed(address)
+    amount: uint256
+
+event Withdrawal:
+    to: indexed(address)
+    amount: uint256
+
+
 owner: public(address)
 isMinter: public(HashMap[address, bool])
 
@@ -109,6 +118,22 @@ isApprovedForAll: public(HashMap[address, HashMap[address, bool]])
 # @dev Mapping from NFT ID to approved address.
 idToApprovals: public(HashMap[uint256, address])
 
+{%- if cookiecutter.force_royalties == 'y' %}
+# @dev The minimum amount of royalties that should be paid to transfer a token successfully
+# NOTE: this can be used to track the floor price for enforcing a minimum royalty payment to the creator
+# NOTE: current implementation requires paying directly to the smart contract, which forwards to the creator
+minRoyaltyAmount: public(uint256)
+
+# Percentage threshold to decide whether the minRoyaltyAmount should be increased or decreased.
+thresholdPercentage: public(decimal)
+
+lastBalance: public(uint256)
+
+totalReceived: public(uint256)
+
+payments: HashMap[address, uint256]
+{%- endif %}
+
 {%- if cookiecutter.permitable == 'y' %}
 ############ ERC-4494 ############
 
@@ -165,6 +190,13 @@ def __init__():
     self.baseURI = "{{cookiecutter.base_uri}}"
 {%- endif %}
 
+# @dev the default value for the minRoyaltyAmount is 0.01 ETH = 10**16 
+{%- if cookiecutter.force_royalties == 'y' %}
+    self.minRoyaltyAmount = {{ cookiecutter.minRoyaltyAmount }}
+    self.thresholdPercentage = {{ cookiecutter.thresholdPercentage }}
+    self.lastBalance = self.balance
+{%- endif %}
+
 
 {%- if cookiecutter.permitable == 'y' %}
     # ERC712 domain separator for ERC4494
@@ -179,6 +211,32 @@ def __init__():
     )
 {%- endif %}
 
+
+{%- if cookiecutter.force_royalties == 'y' %}
+@external
+@payable
+def __default__():
+    # Check if the incoming payment is less than the minimum royalty amount
+    if msg.value < self.minRoyaltyAmount:
+        raise "Royalties not paid correctly."
+
+    # Calculate the expected minimum based on the current minimum royalty amount and the threshold
+    expectedMin: uint256 = self.minRoyaltyAmount * convert(1.0 + self.thresholdPercentage, uint256)
+
+    # Convert balance to uint256 for comparison
+    balanceInWei: uint256 = self.balance
+
+    # Check if balance has increased by more than the expected minimum
+    if balanceInWei > self.lastBalance + expectedMin:
+        # Increase minRoyaltyAmount by a certain percentage (for example, by 5%)
+        self.minRoyaltyAmount = convert(convert(self.minRoyaltyAmount, decimal) * 1.05, uint256)
+    elif balanceInWei < self.lastBalance + expectedMin:
+        # Decrease minRoyaltyAmount by a certain percentage (for example, by 5%)
+        self.minRoyaltyAmount = convert(convert(self.minRoyaltyAmount, decimal) * 0.95, uint256)
+
+    self.lastBalance = balanceInWei
+{%- endif %}
+
 {%- if cookiecutter.metadata == 'y' %}
 # ERC721 Metadata Extension
 @pure
@@ -298,7 +356,21 @@ def royaltyInfo(_tokenId: uint256, _salePrice: uint256) -> (address, uint256):
     """
 
     royalty: uint256 = convert(convert(_salePrice, decimal) * ROYALTY_TO_APPLY_TO_PRICE, uint256) # Percentage that accepts decimals
+    {%- if cookiecutter.force_royalties == 'y' %}
+    return self, max(self.minRoyaltyAmount, royalty)
+    {%- else  %}
     return self.owner, royalty
+    {%- endif %}
+{%- endif %}
+
+{%- if cookiecutter.force_royalties == 'y' %}
+@external
+def withdraw():
+    assert msg.sender == self.owner
+    amount: uint256 = self.balance
+    send(self.owner, amount)
+    log Withdrawal(self.owner, amount)
+    self.lastBalance = self.balance  # This should be 0 after the withdrawal
 {%- endif %}
 
 @view
@@ -325,6 +397,22 @@ def _isApprovedOrOwner(spender: address, tokenId: uint256) -> bool:
     return False
 
 
+# Royality Functions
+{%- if cookiecutter.force_royalties == 'y' %}
+@internal
+def _enforceRoyalties():
+    # Calculate the payment amount from the most recent transaction
+    payment: uint256 = self.balance - self.lastBalance
+
+    # Ensure the payment is not less than the minimum royalty amount
+    if payment < self.minRoyaltyAmount:
+        raise "Insufficient payment."
+
+    # Update the last balance
+    self.lastBalance = self.balance
+{%- endif %}
+
+
 @internal
 def _transferFrom(owner: address, receiver: address, tokenId: uint256, sender: address):
     """
@@ -378,6 +466,9 @@ def transferFrom(owner: address, receiver: address, tokenId: uint256):
     @param receiver The new owner.
     @param tokenId The NFT to transfer.
     """
+    {%- if cookiecutter.force_royalties == 'y' %}
+    self._enforceRoyalties()
+    {%- endif %}
     self._transferFrom(owner, receiver, tokenId, msg.sender)
 
 
@@ -403,6 +494,9 @@ def safeTransferFrom(
     @param tokenId The NFT to transfer.
     @param data Additional data with no specified format, sent in call to `receiver`.
     """
+    {%- if cookiecutter.force_royalties == 'y' %}
+    self._enforceRoyalties()
+    {%- endif %}
     self._transferFrom(owner, receiver, tokenId, msg.sender)
     if receiver.is_contract: # check if `receiver` is a contract address
         returnValue: bytes4 = ERC721Receiver(receiver).onERC721Received(msg.sender, owner, tokenId, data)

{{cookiecutter.project_name}}/tests/test_token.py

@@ -59,11 +59,11 @@ def test_transfer(nft, owner, receiver):
     nft.mint(owner, sender=owner)
     assert nft.balanceOf(owner) == 1
     assert nft.ownerOf(0) == owner.address
-    nft.transferFrom(owner, receiver, 0, sender=owner)
+    nft.transferFrom(owner, receiver, 0, value=nft.minRoyaltyAmount(), sender=owner)
     assert nft.ownerOf(0) == receiver.address
     assert nft.balanceOf(owner) == 0
     assert nft.balanceOf(receiver) == 1
-    nft.transferFrom(receiver, owner, 0, sender=receiver)
+    nft.transferFrom(receiver, owner, 0, value=nft.minRoyaltyAmount(), sender=receiver)
     assert nft.balanceOf(receiver) == 0
     assert nft.balanceOf(owner) == 1
     assert nft.ownerOf(0) == owner.address
@@ -74,7 +74,7 @@ def test_incorrect_signer_transfer(nft, owner, receiver):
     assert nft.balanceOf(receiver) == 0
     nft.mint(owner, sender=owner)
     with ape.reverts():
-        nft.transferFrom(owner,receiver,0,sender=receiver)    
+        nft.transferFrom(owner, receiver, 0, value=nft.minRoyaltyAmount(), sender=receiver)
     assert nft.balanceOf(receiver) == 0
     assert nft.balanceOf(owner) == 1
     assert nft.ownerOf(0) == owner.address
@@ -100,14 +100,14 @@ def test_approve_transfer(nft, owner, receiver):
 
     with ape.reverts():
         nft.approve(receiver, 0, sender=receiver)
-        nft.transferFrom(owner, receiver, 0, sender=receiver)
+        nft.transferFrom(owner, receiver, 0, value=nft.minRoyaltyAmount(), sender=receiver)
     assert nft.balanceOf(receiver) == 0
     assert nft.balanceOf(owner) == 1
     assert nft.ownerOf(0) == owner.address
 
     nft.approve(receiver, 0, sender=owner)
     assert nft.getApproved(0) == receiver
-    nft.transferFrom(owner, receiver, 0, sender=receiver)
+    nft.transferFrom(owner, receiver, 0, value=nft.minRoyaltyAmount(), sender=receiver)
     assert nft.balanceOf(receiver) == 1
     assert nft.balanceOf(owner) == 0
     assert nft.ownerOf(0) == receiver.address