feat: erc1155 example w/ ownable/pausable (vyperlang#2807)

* Created ERC1155 ownable example/template

* Applied most of proposed changes

* Applied more of the feedback.

* ERC165 fix

* Applied @view/@pure, updated test to accomodate

* Moved tests into the correct folder

* added interface ERC1155.py

* refactor: clean up built-in interface

* rewrote tests to use eth-tester

* cleaned up brownie tests in favor of eth-tester

* Update examples/tokens/ERC1155ownable.vy

Co-authored-by: El De-dog-lo <3859395+fubuloubu@users.noreply.github.com>

* applied proposed changes in contract and tests

* interface fix / callback bytes constant

* Ownership test assertion to ZERO_ADDRESS

* reworked uri part, simplified tests

* Fixed all testscript issues

* refactor: apply suggestions from code review

* Update examples/tokens/ERC1155ownable.vy

Co-authored-by: El De-dog-lo <3859395+fubuloubu@users.noreply.github.com>

* Update examples/tokens/ERC1155ownable.vy

Co-authored-by: El De-dog-lo <3859395+fubuloubu@users.noreply.github.com>

* applied codebase shrink tips, adjusted tests

* cleaning up commented out code

* refactor: flip orientation of `balanceOf`

* test: update tests for switch of args to `balanceOf`

* pull, isort, black, push

* Resolved linter issues

* Linter fixes for ERC1155 test script

* Fixed ownership check in safeTransferFrom

* Fixed setURI permissions, updated to docstrings

* Minor test update

Co-authored-by: El De-dog-lo <3859395+fubuloubu@users.noreply.github.com>

examples/tokens/ERC1155ownable.vy

@@ -0,0 +1,367 @@
+# @version >=0.3.3
+"""
+@dev Implementation of ERC-1155 non-fungible token standard ownable, with approval, OPENSEA compatible (name, symbol)
+@author Dr. Pixel (github: @Doc-Pixel)
+"""
+############### imports ###############
+from vyper.interfaces import ERC165
+
+############### variables ###############
+# maximum items in a batch call. Set to 128, to be determined what the practical limits are.
+BATCH_SIZE: constant(uint256) = 128             
+
+# callback number of bytes
+CALLBACK_NUMBYTES: constant(uint256) = 4096
+
+# URI length set to 1024. 
+MAX_URI_LENGTH: constant(uint256) = 1024        
+
+# the contract owner
+# not part of the core spec but a common feature for NFT projects
+owner: public(address)                          
+
+# pause status True / False
+# not part of the core spec but a common feature for NFT projects
+paused: public(bool)                            
+
+# the contracts URI to find the metadata
+_uri: String[MAX_URI_LENGTH]
+
+# NFT marketplace compatibility
+name: public(String[128])
+symbol: public(String[16])
+
+# Interface IDs
+ERC165_INTERFACE_ID: constant(bytes4)  = 0x01ffc9a7
+ERC1155_INTERFACE_ID: constant(bytes4) = 0xd9b67a26
+ERC1155_INTERFACE_ID_METADATA: constant(bytes4) = 0x0e89341c
+
+# mappings
+
+# Mapping from token ID to account balances
+balanceOf: public(HashMap[address, HashMap[uint256, uint256]])
+
+# Mapping from account to operator approvals
+isApprovedForAll: public( HashMap[address, HashMap[address, bool]])
+
+############### events ###############
+event Paused:
+    # Emits a pause event with the address that paused the contract
+    account: address
+
+event unPaused:
+    # Emits an unpause event with the address that paused the contract
+    account: address
+
+event OwnershipTransferred:
+    # Emits smart contract ownership transfer from current to new owner
+    previouwOwner: address 
+    newOwner: address
+
+event TransferSingle:
+    # Emits on transfer of a single token
+    operator:   indexed(address)
+    fromAddress: indexed(address)
+    to: indexed(address)
+    id: uint256
+    value: uint256
+
+event TransferBatch:
+    # Emits on batch transfer of tokens. the ids array correspond with the values array by their position
+    operator: indexed(address) # indexed
+    fromAddress: indexed(address)
+    to: indexed(address)
+    ids: DynArray[uint256, BATCH_SIZE]
+    values: DynArray[uint256, BATCH_SIZE]
+
+event ApprovalForAll:
+    # This emits when an operator is enabled or disabled for an owner. The operator manages all tokens for an owner
+    account: indexed(address)
+    operator: indexed(address)
+    approved: bool
+
+event URI:
+    # This emits when the URI gets changed
+    value: String[MAX_URI_LENGTH]
+    id: uint256
+
+
+############### interfaces ###############
+implements: ERC165
+
+interface IERC1155Receiver:
+    def onERC1155Received(
+       operator: address,
+       sender: address,
+       id: uint256,
+       amount: uint256,
+       data: Bytes[CALLBACK_NUMBYTES],
+   ) -> bytes32: payable
+    def onERC1155BatchReceived(
+        operator: address,
+        sender: address,
+        ids: DynArray[uint256, BATCH_SIZE],
+        amounts: DynArray[uint256, BATCH_SIZE],
+        data: Bytes[CALLBACK_NUMBYTES],
+    ) -> bytes4: payable
+
+interface IERC1155MetadataURI:
+    def uri(id: uint256) -> String[MAX_URI_LENGTH]: view
+
+############### functions ###############
+
+@external
+def __init__(name: String[128], symbol: String[16], uri: String[1024]):
+    """
+    @dev contract initialization on deployment
+    @dev will set name and symbol, interfaces, owner and URI
+    @dev self.paused will default to false
+    @param name the smart contract name
+    @param symbol the smart contract symbol
+    @param uri the new uri for the contract
+    """
+    self.name = name
+    self.symbol = symbol
+    self.owner = msg.sender
+    self._uri = uri
+
+## contract status ##
+@external
+def pause():
+    """
+    @dev Pause the contract, checks if the caller is the owner and if the contract is paused already
+    @dev emits a pause event 
+    @dev not part of the core spec but a common feature for NFT projects
+    """
+    assert self.owner == msg.sender, "Ownable: caller is not the owner"
+    assert not self.paused, "the contract is already paused"
+    self.paused = True
+    log Paused(msg.sender)
+
+@external
+def unpause():
+    """
+    @dev Unpause the contract, checks if the caller is the owner and if the contract is paused already
+    @dev emits an unpause event 
+    @dev not part of the core spec but a common feature for NFT projects
+    """
+    assert self.owner == msg.sender, "Ownable: caller is not the owner"
+    assert self.paused, "the contract is not paused"
+    self.paused = False
+    log unPaused(msg.sender)
+
+## ownership ##
+@external
+def transferOwnership(newOwner: address):
+    """
+    @dev Transfer the ownership. Checks for contract pause status, current owner and prevent transferring to
+    @dev zero address
+    @dev emits an OwnershipTransferred event with the old and new owner addresses
+    @param newOwner The address of the new owner.
+    """
+    assert not self.paused, "The contract has been paused"
+    assert self.owner == msg.sender, "Ownable: caller is not the owner"
+    assert newOwner != self.owner, "This account already owns the contract"
+    assert newOwner != ZERO_ADDRESS, "Transfer to ZERO_ADDRESS not allowed. Use renounceOwnership() instead."
+    oldOwner: address = self.owner
+    self.owner = newOwner
+    log OwnershipTransferred(oldOwner, newOwner)
+
+@external
+def renounceOwnership():
+    """
+    @dev Transfer the ownership to ZERO_ADDRESS, this will lock the contract
+    @dev emits an OwnershipTransferred event with the old and new ZERO_ADDRESS owner addresses
+    """
+    assert not self.paused, "The contract has been paused"
+    assert self.owner == msg.sender, "Ownable: caller is not the owner"
+    oldOwner: address = self.owner
+    self.owner = ZERO_ADDRESS
+    log OwnershipTransferred(oldOwner, ZERO_ADDRESS)
+
+@external
+@view
+def balanceOfBatch(accounts: DynArray[address, BATCH_SIZE], ids: DynArray[uint256, BATCH_SIZE]) -> DynArray[uint256,BATCH_SIZE]:  # uint256[BATCH_SIZE]:
+    """
+    @dev check the balance for an array of specific IDs and addresses
+    @dev will return an array of balances
+    @dev Can also be used to check ownership of an ID
+    @param accounts a dynamic array of the addresses to check the balance for
+    @param ids a dynamic array of the token IDs to check the balance
+    """
+    assert len(accounts) == len(ids), "ERC1155: accounts and ids length mismatch"
+    batchBalances: DynArray[uint256, BATCH_SIZE] = []
+    j: uint256 = 0
+    for i in ids:
+        batchBalances.append(self.balanceOf[accounts[j]][i])
+        j += 1
+    return batchBalances
+
+## mint ##
+@external
+def mint(receiver: address, id: uint256, amount:uint256, data:bytes32):
+    """
+    @dev mint one new token with a certain ID
+    @dev this can be a new token or "topping up" the balance of a non-fungible token ID
+    @param receiver the account that will receive the minted token
+    @param id the ID of the token
+    @param amount of tokens for this ID
+    @param data the data associated with this mint. Usually stays empty
+    """
+    assert not self.paused, "The contract has been paused"
+    assert self.owner == msg.sender, "Only the contract owner can mint"
+    assert receiver != ZERO_ADDRESS, "Can not mint to ZERO ADDRESS"
+    operator: address = msg.sender
+    self.balanceOf[receiver][id] += amount
+    log TransferSingle(operator, ZERO_ADDRESS, receiver, id, amount)
+
+
+@external
+def mintBatch(receiver: address, ids: DynArray[uint256, BATCH_SIZE], amounts: DynArray[uint256, BATCH_SIZE], data: bytes32):
+    """
+    @dev mint a batch of new tokens with the passed IDs
+    @dev this can be new tokens or "topping up" the balance of existing non-fungible token IDs in the contract
+    @param receiver the account that will receive the minted token
+    @param ids array of ids for the tokens
+    @param amounts amounts of tokens for each ID in the ids array
+    @param data the data associated with this mint. Usually stays empty
+    """
+    assert not self.paused, "The contract has been paused"
+    assert self.owner == msg.sender, "Only the contract owner can mint"
+    assert receiver != ZERO_ADDRESS, "Can not mint to ZERO ADDRESS"
+    assert len(ids) == len(amounts), "ERC1155: ids and amounts length mismatch"
+    operator: address = msg.sender
+
+    for i in range(BATCH_SIZE):
+        if i >= len(ids):
+            break
+        self.balanceOf[receiver][ids[i]] += amounts[i]
+
+    log TransferBatch(operator, ZERO_ADDRESS, receiver, ids, amounts)
+
+## burn ##
+@external
+def burn(id: uint256, amount: uint256):
+    """
+    @dev burn one or more token with a certain ID
+    @dev the amount of tokens will be deducted from the holder's balance
+    @param receiver the account that will receive the minted token
+    @param id the ID of the token to burn
+    @param amount of tokens to burnfor this ID
+    """
+    assert not self.paused, "The contract has been paused"
+    assert self.balanceOf[msg.sender][id] > 0 , "caller does not own this ID"
+    self.balanceOf[msg.sender][id] -= amount
+    log TransferSingle(msg.sender, msg.sender, ZERO_ADDRESS, id, amount)
+
+@external
+def burnBatch(ids: DynArray[uint256, BATCH_SIZE], amounts: DynArray[uint256, BATCH_SIZE]):
+    """
+    @dev burn a batch of tokens with the passed IDs
+    @dev this can be burning non fungible tokens or reducing the balance of existing non-fungible token IDs in the contract
+    @dev inside the loop ownership will be checked for each token. We can not burn tokens we do not own
+    @param ids array of ids for the tokens to burn
+    @param amounts array of amounts of tokens for each ID in the ids array
+    """
+    assert not self.paused, "The contract has been paused"
+    assert len(ids) == len(amounts), "ERC1155: ids and amounts length mismatch"
+    operator: address = msg.sender 
+
+    for i in range(BATCH_SIZE):
+        if i >= len(ids):
+            break
+        self.balanceOf[msg.sender][ids[i]] -= amounts[i]
+
+    log TransferBatch(msg.sender, msg.sender, ZERO_ADDRESS, ids, amounts)
+
+## approval ##
+@external
+def setApprovalForAll(owner: address, operator: address, approved: bool):
+    """
+    @dev set an operator for a certain NFT owner address
+    @param account the NFT owner address
+    @param operator the operator address
+    """
+    assert owner == msg.sender, "You can only set operators for your own account"
+    assert not self.paused, "The contract has been paused"
+    assert owner != operator, "ERC1155: setting approval status for self"
+    self.isApprovedForAll[owner][operator] = approved
+    log ApprovalForAll(owner, operator, approved)
+
+@external
+def safeTransferFrom(sender: address, receiver: address, id: uint256, amount: uint256, bytes: bytes32):
+    """
+    @dev transfer token from one address to another.
+    @param sender the sending account (current owner)
+    @param receiver the receiving account
+    @param id the token id that will be sent
+    @param amount the amount of tokens for the specified id
+    """
+    assert not self.paused, "The contract has been paused"
+    assert receiver != ZERO_ADDRESS, "ERC1155: transfer to the zero address"
+    assert sender != receiver
+    assert sender == msg.sender or self.isApprovedForAll[sender][msg.sender], "Caller is neither owner nor approved operator for this ID"
+    assert self.balanceOf[sender][id] > 0 , "caller does not own this ID or ZERO balance"
+    operator: address = msg.sender
+    self.balanceOf[sender][id] -= amount
+    self.balanceOf[receiver][id] += amount
+    log TransferSingle(operator, sender, receiver, id, amount)
+
+@external
+def safeBatchTransferFrom(sender: address, receiver: address, ids: DynArray[uint256, BATCH_SIZE], amounts: DynArray[uint256, BATCH_SIZE], _bytes: bytes32):
+    """
+    @dev transfer tokens from one address to another.
+    @param sender the sending account
+    @param receiver the receiving account
+    @param ids a dynamic array of the token ids that will be sent
+    @param amounts a dynamic array of the amounts for the specified list of ids.
+    """
+    assert not self.paused, "The contract has been paused"
+    assert receiver != ZERO_ADDRESS, "ERC1155: transfer to the zero address"
+    assert sender != receiver
+    assert sender == msg.sender or self.isApprovedForAll[sender][msg.sender], "Caller is neither owner nor approved operator for this ID"
+    assert len(ids) == len(amounts), "ERC1155: ids and amounts length mismatch"
+    operator: address = msg.sender
+    for i in range(BATCH_SIZE):
+        if i >= len(ids):
+            break
+        id: uint256 = ids[i]
+        amount: uint256 = amounts[i]
+        self.balanceOf[sender][id] -= amount
+        self.balanceOf[receiver][id] += amount
+
+    log TransferBatch(operator, sender, receiver, ids, amounts)
+
+# URI #
+@external
+def setURI(uri: String[MAX_URI_LENGTH]):
+    """
+    @dev set the URI for the contract
+    @param uri the new uri for the contract
+    """
+    assert not self.paused, "The contract has been paused"
+    assert self._uri != uri, "new and current URI are identical"
+    assert msg.sender == self.owner, "Only the contract owner can update the URI"
+    self._uri = uri
+    log URI(uri, 0)
+
+@external
+def uri(id: uint256) -> String[MAX_URI_LENGTH]:
+    """
+    @dev retrieve the uri, this function can optionally be extended to return dynamic uris. out of scope.
+    @param id NFT ID to retrieve the uri for. 
+    """
+    return self._uri
+
+@pure
+@external
+def supportsInterface(interfaceId: bytes4) -> bool:
+    """
+    @dev Returns True if the interface is supported
+    @param interfaceID bytes4 interface identifier
+    """
+    return interfaceId in [
+        ERC165_INTERFACE_ID,
+        ERC1155_INTERFACE_ID,
+        ERC1155_INTERFACE_ID_METADATA, 
+    ]