From e59b4b6aba8746bd41e399a2b49762262f906d7a Mon Sep 17 00:00:00 2001
From: Alain Nicolas <alain.nicolas@consensys.net>
Date: Tue, 26 Sep 2023 15:23:42 +0200
Subject: [PATCH] feat: As a user, I want to get decoded Attestation data via
 the subgraph

---
 subgraph/schema.graphql              |  2 +
 subgraph/src/attestation-registry.ts | 81 ++++++++++++++++++++++++++--
 2 files changed, 79 insertions(+), 4 deletions(-)

diff --git a/subgraph/schema.graphql b/subgraph/schema.graphql
index ba4e6e18..9ceb0218 100644
--- a/subgraph/schema.graphql
+++ b/subgraph/schema.graphql
@@ -11,6 +11,8 @@ type Attestation @entity {
     revoked: Boolean!
     subject: Bytes!
     attestationData: Bytes!
+    schemaString: String
+    decodedData:[String!]
 }
 
 type Module @entity {
diff --git a/subgraph/src/attestation-registry.ts b/subgraph/src/attestation-registry.ts
index 028ba275..3d2c1b4c 100644
--- a/subgraph/src/attestation-registry.ts
+++ b/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 +22,78 @@ 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 field name" 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;
+
+    // Change attestation encoded data into an encoded Tuple
+    const encodedData = attestationData.attestationData;
+    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
+    const decoded = ethereum.decode("(" + schemaString + ")", Bytes.fromUint8Array(encodedDataAsTuple));
+
+    // Initiate the decoded data in case it's not decoded at all
+    attestation.decodedData = ["NOT DECODED"];
+
+    // 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 "ADDRESS";
+    case ethereum.ValueKind.FIXED_BYTES:
+      return "FIXED_BYTES";
+    case ethereum.ValueKind.BYTES:
+      return "BYTES";
+    case ethereum.ValueKind.INT:
+      return "INT";
+    case ethereum.ValueKind.UINT:
+      return "UINT";
+    case ethereum.ValueKind.BOOL:
+      return "BOOL";
+    case ethereum.ValueKind.STRING:
+      return "STRING";
+    case ethereum.ValueKind.FIXED_ARRAY:
+      return "FIXED_ARRAY";
+    case ethereum.ValueKind.ARRAY:
+      return "ARRAY";
+    case ethereum.ValueKind.TUPLE:
+      return "TUPLE";
+    default:
+      return "UNKNOWN";
+  }
+}