Merge pull request #497 from graphprotocol/ariel/gns-ownership

Transferrable subgraph ownership

cli/commands/migrate.ts

@@ -25,6 +25,7 @@ let allContracts = [
   'GraphCurationToken',
   'ServiceRegistry',
   'Curation',
+  'SubgraphNFTDescriptor',
   'GNS',
   'Staking',
   'RewardsManager',

contracts/base/ISubgraphNFTDescriptor.sol

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+pragma solidity ^0.7.6;
+
+import "../discovery/IGNS.sol";
+
+/// @title Describes subgraph NFT tokens via URI
+interface ISubgraphNFTDescriptor {
+    /// @notice Produces the URI describing a particular token ID for a Subgraph
+    /// @dev Note this URI may be a data: URI with the JSON contents directly inlined
+    /// @param _gns GNS contract that holds the Subgraph data
+    /// @param _subgraphID The ID of the subgraph NFT for which to produce a description, which may not be valid
+    /// @return The URI of the ERC721-compliant metadata
+    function tokenURI(IGNS _gns, uint256 _subgraphID) external view returns (string memory);
+}

contracts/base/SubgraphNFT.sol

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+pragma solidity ^0.7.6;
+
+import "@openzeppelin/contracts-upgradeable/token/ERC721/ERC721Upgradeable.sol";
+
+import "./ISubgraphNFTDescriptor.sol";
+
+abstract contract SubgraphNFT is ERC721Upgradeable {
+    ISubgraphNFTDescriptor public tokenDescriptor;
+
+    // -- Events --
+
+    event TokenDescriptorUpdated(address tokenDescriptor);
+
+    // -- Functions --
+
+    /**
+     * @dev Initializes the contract by setting a `name`, `symbol` and `descriptor` to the token collection.
+     */
+    function __SubgraphNFT_init(address _tokenDescriptor) internal initializer {
+        __ERC721_init("Subgraph", "SG");
+        _setTokenDescriptor(address(_tokenDescriptor));
+    }
+
+    /**
+     * @dev Set the token descriptor contract used to create the ERC-721 metadata URI
+     * @param _tokenDescriptor Address of the contract that creates the NFT token URI
+     */
+    function _setTokenDescriptor(address _tokenDescriptor) internal {
+        require(
+            _tokenDescriptor != address(0) && AddressUpgradeable.isContract(_tokenDescriptor),
+            "NFT: Invalid token descriptor"
+        );
+        tokenDescriptor = ISubgraphNFTDescriptor(_tokenDescriptor);
+        emit TokenDescriptorUpdated(_tokenDescriptor);
+    }
+}

contracts/base/SubgraphNFTDescriptor.sol

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+pragma solidity ^0.7.6;
+
+import "./ISubgraphNFTDescriptor.sol";
+
+/// @title Describes subgraph NFT tokens via URI
+contract SubgraphNFTDescriptor is ISubgraphNFTDescriptor {
+    /// @inheritdoc ISubgraphNFTDescriptor
+    function tokenURI(IGNS _gns, uint256 _subgraphID)
+        external
+        view
+        override
+        returns (string memory)
+    {
+        // TODO: fancy implementation
+        // uint256 signal = _gns.subgraphSignal(_subgraphID);
+        // uint256 tokens = _gns.subgraphTokens(_subgraphID);
+        // id
+        // owner
+        return "";
+    }
+}