feat: Update selector computation

yarn-project/foundation/src/abi/decoder.ts

@@ -1,4 +1,4 @@
-import { ABIType, FunctionAbi } from '@aztec/foundation/abi';
+import { ABIParameter, ABIType, FunctionAbi } from '@aztec/foundation/abi';
 import { Fr } from '@aztec/foundation/fields';
 
 /**
@@ -86,3 +86,44 @@ class ReturnValuesDecoder {
 export function decodeReturnValues(abi: FunctionAbi, returnValues: Fr[]) {
   return new ReturnValuesDecoder(abi, returnValues.slice()).decode();
 }
+
+/**
+ * Decodes the signature of a function from the name and parameters.
+ */
+export class FunctionSignatureDecoder {
+  constructor(private name: string, private parameters: ABIParameter[]) {}
+
+  /**
+   * Decodes a single function parameter for the function signature.
+   * @param param - The parameter to decode.
+   * @returns A string representing the parameter type.
+   */
+  private decodeParameter(param: ABIType): string {
+    switch (param.kind) {
+      case 'field':
+        return 'Field';
+      case 'integer':
+        if (param.sign === 'signed') {
+          throw new Error('Unsupported type: signed integer');
+        }
+        return `u${param.width}`;
+      case 'boolean':
+        return 'bool';
+      case 'array':
+        return `[${this.decodeParameter(param.type)};${param.length}]`;
+      case 'struct':
+        return `(${param.fields.map(field => `${this.decodeParameter(field.type)}`).join(',')})`;
+      default:
+        throw new Error(`Unsupported type: ${param.kind}`);
+    }
+  }
+
+  /**
+   * Decodes all the parameters and build the function signature
+   * @returns The function signature.
+   */
+  public decode(): string {
+    const hmm = this.parameters.map(param => this.decodeParameter(param.type));
+    return `${this.name}(${hmm.join(',')})`;
+  }
+}

yarn-project/foundation/src/abi/function_selector.ts

@@ -1,4 +1,4 @@
-import { ABIParameter } from '@aztec/foundation/abi';
+import { ABIParameter, FunctionSignatureDecoder } from '@aztec/foundation/abi';
 import { toBigIntBE, toBufferBE } from '@aztec/foundation/bigint-buffer';
 import { keccak } from '@aztec/foundation/crypto';
 import { Fr } from '@aztec/foundation/fields';
@@ -97,7 +97,7 @@ export class FunctionSelector {
    * @returns A Buffer containing the 4-byte function selector.
    */
   static fromNameAndParameters(name: string, parameters: ABIParameter[]) {
-    const signature = name === 'constructor' ? name : `${name}(${parameters.map(p => p.type.kind).join(',')})`;
+    const signature = new FunctionSignatureDecoder(name, parameters).decode();
     return FunctionSelector.fromSignature(signature);
   }