feat: As a user i want to get decoded attestation data via the subgraph

subgraph/schema.graphql

@@ -11,6 +11,8 @@ type Attestation @entity {
     revoked: Boolean!
     subject: Bytes!
     attestationData: Bytes!
+    schemaString: String
+    decodedData:[String!]
 }
 
 type Module @entity {

subgraph/src/attestation-registry.ts

@@ -2,12 +2,12 @@ import {
   AttestationRegistered as AttestationRegisteredEvent,
   AttestationRegistry,
 } from "../generated/AttestationRegistry/AttestationRegistry";
-import { Attestation } from "../generated/schema";
-import { BigInt } from "@graphprotocol/graph-ts";
+import { Attestation, Schema } from "../generated/schema";
+import { BigInt, ByteArray, Bytes, ethereum } from "@graphprotocol/graph-ts";
 
 export function handleAttestationRegistered(event: AttestationRegisteredEvent): void {
-  const contract = AttestationRegistry.bind(event.address);
-  const attestationData = contract.getAttestation(event.params.attestationId);
+  const attestationRegistryContract = AttestationRegistry.bind(event.address);
+  const attestationData = attestationRegistryContract.getAttestation(event.params.attestationId);
   const attestation = new Attestation(event.params.attestationId.toHex());
 
   attestation.schemaId = attestationData.schemaId;
@@ -22,5 +22,91 @@ export function handleAttestationRegistered(event: AttestationRegisteredEvent):
   attestation.subject = attestationData.subject;
   attestation.attestationData = attestationData.attestationData;
 
+  // Get matching Schema
+  const schema = Schema.load(attestationData.schemaId.toHex());
+
+  if (schema) {
+    // Split Schema into a "type fieldName" array
+    const splitSchema = schema.schema.split(",");
+
+    // Keep only the Schema's types
+    const schemaTypes = splitSchema.map<string>((item) => item.trim().split(" ")[0]);
+
+    // Join the types in a single coma-separated string
+    const schemaString = schemaTypes.toString();
+
+    // Add this Schema string to the Attestation Entity
+    attestation.schemaString = schemaString;
+
+    const encodedData = attestationData.attestationData;
+
+    // Initiate the decoded data in case it's not decoded at all
+    attestation.decodedData = ["NOT DECODED"];
+
+    // Decode the encoded attestation data
+    let decoded = ethereum.decode("(" + schemaString + ")", Bytes.fromUint8Array(encodedData));
+
+    // If the decoding function didn't give anything, re-try with the encoded data as a tuple
+    if (!decoded) {
+      // Change attestation encoded data into an encoded Tuple
+      const tuplePrefix = ByteArray.fromHexString("0x0000000000000000000000000000000000000000000000000000000000000020");
+      const encodedDataAsTuple = new Uint8Array(tuplePrefix.length + encodedData.length);
+      encodedDataAsTuple.set(tuplePrefix, 0);
+      encodedDataAsTuple.set(encodedData, tuplePrefix.length);
+
+      // Decode the tuple
+      decoded = ethereum.decode("(" + schemaString + ")", Bytes.fromUint8Array(encodedDataAsTuple));
+    }
+
+    // If the decode function went through, save it as an Array of Strings
+    if (decoded) {
+      const tempStringArray: string[] = [];
+
+      // Make the decoded data into a Tuple
+      const tupleValue = decoded.toTuple();
+
+      // Convert every field of the Tuple into a String
+      for (let i = 0; i < tupleValue.length; i++) {
+        tempStringArray.push(valueToString(tupleValue[i]));
+      }
+
+      // Add this decoded Array to the Attestation Entity
+      attestation.decodedData = tempStringArray;
+    }
+  }
+
   attestation.save();
 }
+
+function valueToString(value: ethereum.Value): string {
+  switch (value.kind) {
+    case ethereum.ValueKind.ADDRESS:
+      return value.toAddress().toHexString();
+    case ethereum.ValueKind.FIXED_BYTES:
+      return value.toBytes().toHex();
+    case ethereum.ValueKind.BYTES:
+      return value.toString();
+    case ethereum.ValueKind.INT:
+      return value.toBigInt().toHexString();
+    case ethereum.ValueKind.UINT:
+      return value.toBigInt().toHexString();
+    case ethereum.ValueKind.BOOL:
+      return value.toBoolean().toString();
+    case ethereum.ValueKind.STRING:
+      return value.toString();
+    case ethereum.ValueKind.FIXED_ARRAY:
+      return value
+        .toArray()
+        .map<string>((item) => valueToString(item))
+        .toString();
+    case ethereum.ValueKind.ARRAY:
+      return value
+        .toArray()
+        .map<string>((item) => valueToString(item))
+        .toString();
+    case ethereum.ValueKind.TUPLE:
+      return "TUPLE NOT SUPPORTED";
+    default:
+      return "UNKNOWN TYPE";
+  }
+}