fix: prevent double minting

src/lib/nftClaimer/mint.ts

@@ -7,7 +7,8 @@ import {
   numberizeProposalId,
   validateMintInput,
   mintingAllowed,
-  hasVoted
+  hasVoted,
+  hasMinted
 } from './utils';
 import abi from './spaceCollectionImplementationAbi.json';
 import { FormatTypes, Interface } from '@ethersproject/abi';
@@ -40,10 +41,14 @@ export default async function payload(input: {
     throw new Error('Space has closed minting');
   }
 
-  if (!hasVoted(params.recipient, proposal as Proposal)) {
+  if (!(await hasVoted(params.recipient, proposal as Proposal))) {
     throw new Error('Minting is open only for voters');
   }
 
+  if (await hasMinted(params.recipient, proposal as Proposal)) {
+    throw new Error('You can only mint once per vote');
+  }
+
   const message = {
     proposer: params.proposalAuthor,
     recipient: params.recipient,

src/lib/nftClaimer/utils.ts

@@ -48,6 +48,11 @@ export async function hasVoted(address: string, proposal: Proposal) {
   return vote !== undefined;
 }
 
+export async function hasMinted(address: string, proposal: Proposal) {
+  const mint = await getMint(address, proposal.id);
+  return mint !== undefined;
+}
+
 export async function validateSpace(address: string, space: Space | null) {
   if (!space) {
     throw new Error('RECORD_NOT_FOUND');
@@ -133,6 +138,32 @@ export async function getSpaceCollection(spaceId: string) {
   return spaceCollections[0];
 }
 
+const MINT_COLLECTION_QUERY = gql`
+  query Mints($voter: String, $proposalId: String) {
+    mints(where: { minterAddress: $voter, proposal: $proposalId }, first: 1) {
+      id
+    }
+  }
+`;
+
+type Mint = {
+  id: string;
+};
+
+export async function getMint(voter: string, proposalId: string) {
+  const {
+    data: { mints }
+  }: { data: { mints: Mint[] } } = await client.query({
+    query: MINT_COLLECTION_QUERY,
+    variables: {
+      voter,
+      proposalId
+    }
+  });
+
+  return mints[0];
+}
+
 export function numberizeProposalId(id: string) {
   return BigNumber.from(id.startsWith('0x') ? id : CID.parse(id).bytes).toString();
 }

test/unit/lib/nftClaimer/mint.test.ts

@@ -36,6 +36,10 @@ const mockMintingAllowed = jest.fn((space: any): boolean => {
 const mockHasVoted = jest.fn((address: string, proposal: string): boolean => {
   return true;
 });
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+const mockHasMinted = jest.fn((address: string, proposal: string): boolean => {
+  return false;
+});
 jest.mock('../../../../src/lib/nftClaimer/utils', () => {
   // Require the original module to not be mocked...
   const originalModule = jest.requireActual('../../../../src/lib/nftClaimer/utils');
@@ -46,7 +50,8 @@ jest.mock('../../../../src/lib/nftClaimer/utils', () => {
     getProposalContract: (id: string) => mockGetProposalContract(id),
     validateProposal: (id: any) => mockValidateProposal(id),
     mintingAllowed: (space: any) => mockMintingAllowed(space),
-    hasVoted: (address: string, proposal: string) => mockHasVoted(address, proposal)
+    hasVoted: (address: string, proposal: string) => mockHasVoted(address, proposal),
+    hasMinted: (address: string, proposal: string) => mockHasMinted(address, proposal)
   };
 });
 
@@ -122,6 +127,13 @@ describe('nftClaimer', () => {
       });
     });
 
+    describe('when address has already minted', () => {
+      it('throws an error', () => {
+        mockHasMinted.mockReturnValueOnce(true);
+        return expect(async () => await payload(input)).rejects.toThrow();
+      });
+    });
+
     describe('when maxSupply has been reached', () => {
       it.todo('throws an error');
     });