feat: transferrable subgraphs using an NFT

- make the subgraph to use a single primary key
- major refactor of data structures
- refactor variable names and add migrate legacy subgraph
- get subgraph data depending if legacy or new subgraph
- improve validations
- refactor all subgraph checks
- update tests
- NFT burn and mint

Author: abarmat

contracts/base/SubgraphNFT.sol

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+pragma solidity ^0.7.4;
+
+import "@openzeppelin/contracts-upgradeable/token/ERC721/ERC721Upgradeable.sol";
+
+abstract contract SubgraphNFT is ERC721Upgradeable {
+    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {}
+}

contracts/discovery/GNS.sol

@@ -3,12 +3,13 @@
 pragma solidity ^0.7.6;
 pragma abicoder v2;
 
+import "../base/SubgraphNFT.sol";
 import "../governance/Managed.sol";
 
 import "./erc1056/IEthereumDIDRegistry.sol";
 import "./IGNS.sol";
 
-contract GNSV1Storage is Managed {
+abstract contract GNSV1Storage is Managed {
     // -- State --
 
     // In parts per hundred
@@ -17,17 +18,33 @@ contract GNSV1Storage is Managed {
     // Bonding curve formula
     address public bondingCurve;
 
-    // graphAccountID => subgraphNumber => subgraphDeploymentID
-    // subgraphNumber = A number associated to a graph accounts deployed subgraph. This
-    //                  is used to point to a subgraphID (graphAccountID + subgraphNumber)
-    mapping(address => mapping(uint256 => bytes32)) public subgraphs;
+    // Stores what subgraph deployment a particular legacy subgraph targets
+    // A subgraph is defined by (graphAccountID, subgraphNumber)
+    // A subgraph can target one subgraph deployment (bytes32 hash)
+    // (graphAccountID, subgraphNumber) => subgraphDeploymentID
+    mapping(address => mapping(uint256 => bytes32)) internal legacySubgraphs;
 
-    // graphAccountID => subgraph deployment counter
-    mapping(address => uint256) public graphAccountSubgraphNumbers;
+    // Every time an account creates a subgraph it increases a per-account sequence ID
+    // account => seqID
+    mapping(address => uint256) public nextAccountSeqID;
 
-    // graphAccountID => subgraphNumber => NameCurationPool
-    mapping(address => mapping(uint256 => IGNS.NameCurationPool)) public nameSignals;
+    // Stores all the signal deposited on a legacy subgraph
+    // (graphAccountID, subgraphNumber) => SubgraphData
+    mapping(address => mapping(uint256 => IGNS.SubgraphData)) public legacySubgraphData;
 
-    // ERC-1056 contract reference
-    IEthereumDIDRegistry public erc1056Registry;
+    // [DEPRECATED] ERC-1056 contract reference
+    // This contract is used for managing identities
+    IEthereumDIDRegistry private __DEPRECATED_erc1056Registry;
+}
+
+abstract contract GNSV2Storage is GNSV1Storage, SubgraphNFT {
+    // TODO: review order of storage
+
+    // Use it whenever a legacy (v1) subgraph NFT was claimed to maintain compatibility
+    // Keep a reference from subgraphID => (graphAccount, subgraphNumber)
+    mapping(uint256 => IGNS.LegacySubgraphKey) public legacySubgraphKeys;
+
+    // Store data for all NFT-based (v2) subgraphs
+    // subgraphID => SubgraphData
+    mapping(uint256 => IGNS.SubgraphData) public subgraphs;
 }

contracts/discovery/GNSStorage.sol

@@ -5,16 +5,21 @@ pragma solidity ^0.7.6;
 interface IGNS {
     // -- Pool --
 
-    struct NameCurationPool {
-        uint256 vSignal; // The token of the subgraph deployment bonding curve
-        uint256 nSignal; // The token of the name curation bonding curve
+    struct SubgraphData {
+        uint256 vSignal; // The token of the subgraph-deployment bonding curve
+        uint256 nSignal; // The token of the subgraph bonding curve
         mapping(address => uint256) curatorNSignal;
         bytes32 subgraphDeploymentID;
         uint32 reserveRatio;
         bool disabled;
         uint256 withdrawableGRT;
     }
 
+    struct LegacySubgraphKey {
+        address account;
+        uint256 accountSeqID;
+    }
+
     // -- Configuration --
 
     function approveAll() external;
@@ -30,53 +35,41 @@ interface IGNS {
         string calldata _name
     ) external;
 
-    function updateSubgraphMetadata(
-        address _graphAccount,
-        uint256 _subgraphNumber,
-        bytes32 _subgraphMetadata
-    ) external;
+    function updateSubgraphMetadata(uint256 _subgraphID, bytes32 _subgraphMetadata) external;
 
     function publishNewSubgraph(
-        address _graphAccount,
         bytes32 _subgraphDeploymentID,
         bytes32 _versionMetadata,
         bytes32 _subgraphMetadata
     ) external;
 
     function publishNewVersion(
-        address _graphAccount,
-        uint256 _subgraphNumber,
+        uint256 _subgraphID,
         bytes32 _subgraphDeploymentID,
         bytes32 _versionMetadata
     ) external;
 
-    function deprecateSubgraph(address _graphAccount, uint256 _subgraphNumber) external;
+    function deprecateSubgraph(uint256 _subgraphID) external;
 
     // -- Curation --
 
-    function mintNSignal(
-        address _graphAccount,
-        uint256 _subgraphNumber,
+    function mintSignal(
+        uint256 _subgraphID,
         uint256 _tokensIn,
         uint256 _nSignalOutMin
     ) external;
 
-    function burnNSignal(
-        address _graphAccount,
-        uint256 _subgraphNumber,
+    function burnSignal(
+        uint256 _subgraphID,
         uint256 _nSignal,
         uint256 _tokensOutMin
     ) external;
 
-    function withdraw(address _graphAccount, uint256 _subgraphNumber) external;
+    function withdraw(uint256 _subgraphID) external;
 
     // -- Getters --
 
-    function tokensToNSignal(
-        address _graphAccount,
-        uint256 _subgraphNumber,
-        uint256 _tokensIn
-    )
+    function tokensToNSignal(uint256 _subgraphID, uint256 _tokensIn)
         external
         view
         returns (
@@ -85,32 +78,25 @@ interface IGNS {
             uint256
         );
 
-    function nSignalToTokens(
-        address _graphAccount,
-        uint256 _subgraphNumber,
-        uint256 _nSignalIn
-    ) external view returns (uint256, uint256);
-
-    function vSignalToNSignal(
-        address _graphAccount,
-        uint256 _subgraphNumber,
-        uint256 _vSignalIn
-    ) external view returns (uint256);
+    function nSignalToTokens(uint256 _subgraphID, uint256 _nSignalIn)
+        external
+        view
+        returns (uint256, uint256);
 
-    function nSignalToVSignal(
-        address _graphAccount,
-        uint256 _subgraphNumber,
-        uint256 _nSignalIn
-    ) external view returns (uint256);
+    function vSignalToNSignal(uint256 _subgraphID, uint256 _vSignalIn)
+        external
+        view
+        returns (uint256);
 
-    function getCuratorNSignal(
-        address _graphAccount,
-        uint256 _subgraphNumber,
-        address _curator
-    ) external view returns (uint256);
+    function nSignalToVSignal(uint256 _subgraphID, uint256 _nSignalIn)
+        external
+        view
+        returns (uint256);
 
-    function isPublished(address _graphAccount, uint256 _subgraphNumber)
+    function getCuratorSignal(uint256 _subgraphID, address _curator)
         external
         view
-        returns (bool);
+        returns (uint256);
+
+    function isPublished(uint256 _subgraphID) external view returns (bool);
 }

contracts/discovery/IGNS.sol

@@ -25,6 +25,7 @@
     "@nomiclabs/hardhat-etherscan": "^2.1.1",
     "@nomiclabs/hardhat-waffle": "^2.0.1",
     "@openzeppelin/contracts": "^3.4.1",
+    "@openzeppelin/contracts-upgradeable": "3.4.2",
     "@openzeppelin/hardhat-upgrades": "^1.6.0",
     "@tenderly/hardhat-tenderly": "^1.0.11",
     "@typechain/ethers-v5": "^7.0.0",