From eafa4cdf35a94453c81ed0f85f3fc76e21e63b1e Mon Sep 17 00:00:00 2001
From: Denis Davidyuk <denis_davidyuk@hotmail.com>
Date: Fri, 15 Nov 2024 20:22:31 +0500
Subject: [PATCH] Decode function details by contract calldata

---
 src/AciContractCallEncoder.js     | 23 +++++++++++++++++++++++
 src/AciTypeResolver.js            | 14 ++++++++++++++
 src/api/AciContractCallEncoder.js | 20 ++++++++++++++++++++
 src/main.d.ts                     |  6 ++++++
 tests/AciContractCallEncoder.js   | 16 ++++++++++++++++
 5 files changed, 79 insertions(+)

diff --git a/src/AciContractCallEncoder.js b/src/AciContractCallEncoder.js
index 1b6ecb2..c741f0d 100644
--- a/src/AciContractCallEncoder.js
+++ b/src/AciContractCallEncoder.js
@@ -86,6 +86,29 @@ class AciContractCallEncoder {
         return this._byteArrayEncoder.decodeWithType(data, calldataType)
     }
 
+    /**
+     * Decodes function details by contract calldata
+     *
+     * @example
+     * const data = encoder.decodeFunction('cb_KxHwzCuVGyl3aG9vbHltb2x5zwMSnw==')
+     * console.log(`Decoded data: ${data}`)
+     * // Outputs:
+     * // Decoded data: {
+     * //   contractName: "Test",
+     * //   functionName: "test_string",
+     * //   functionId: "f0cc2b95",
+     * // }
+     *
+     * @param {string} data - Encoded calldata in canonical format.
+     * @returns {object} Decoded function details
+    */
+    decodeFunction(data) {
+        const {functionId} = this._byteArrayEncoder.decodeWithType(data, FateTypeCalldata())
+        const {contractName, functionName} = this._typeResolver.getFunction(functionId)
+
+        return {contractName, functionName, functionId}
+    }
+
     /**
      * Decodes successful (resultType = ok) contract call return data
      *
diff --git a/src/AciTypeResolver.js b/src/AciTypeResolver.js
index bb1dbf2..6f462a2 100644
--- a/src/AciTypeResolver.js
+++ b/src/AciTypeResolver.js
@@ -1,6 +1,8 @@
 import TypeResolver from './TypeResolver.js'
 import TypeResolveError from './Errors/TypeResolveError.js'
 import {FateTypeEvent} from './FateTypes.js'
+import {symbolIdentifier} from './utils/hash.js'
+import {byteArray2Hex} from './utils/int2ByteArray.js'
 
 const isObject = (value) => {
     return value && typeof value === 'object' && value.constructor === Object
@@ -140,6 +142,18 @@ class AciTypeResolver extends TypeResolver {
 
         return [typeDef, vars]
     }
+
+    getFunction(functionId) {
+        const { contract } = this.aci.at(-1)
+        const functionName = contract.functions
+            .map(e => e.name)
+            .find((name) => byteArray2Hex(symbolIdentifier(name)) === functionId)
+        if (functionName == null) {
+            throw new TypeResolveError(`Unknown function id ${functionId}`)
+        }
+
+        return { contractName: contract.name, functionName }
+    }
 }
 
 export default AciTypeResolver
diff --git a/src/api/AciContractCallEncoder.js b/src/api/AciContractCallEncoder.js
index 76154b7..059acab 100644
--- a/src/api/AciContractCallEncoder.js
+++ b/src/api/AciContractCallEncoder.js
@@ -50,6 +50,26 @@ class AciContractCallEncoder {
         return this._internalEncoder.decodeCall(contract, funName, data)
     }
 
+    /**
+     * * Decodes function details by contract calldata
+     *
+     * @example
+     * const data = encoder.decodeFunction('cb_KxHwzCuVGyl3aG9vbHltb2x5zwMSnw==')
+     * console.log(`Decoded data: ${data}`)
+     * // Outputs:
+     * // Decoded data: {
+     * //   contractName: "Test",
+     * //   functionName: "test_string",
+     * //   functionId: "f0cc2b95",
+     * // }
+     *
+     * @param {string} data - Encoded calldata in canonical format.
+     * @returns {object} Decoded function details
+    */
+    decodeFunction(data) {
+        return this._internalEncoder.decodeFunction(data)
+    }
+
     /**
      * Decodes successful (resultType = ok) contract call return data
      *
diff --git a/src/main.d.ts b/src/main.d.ts
index e215056..3cef459 100644
--- a/src/main.d.ts
+++ b/src/main.d.ts
@@ -31,6 +31,12 @@ export class AciContractCallEncoder {
     args: any[];
   };
 
+  decodeFunction(data: `cb_${string}`): {
+    contractName: string;
+    functionName: string;
+    functionId: string;
+  };
+
   decodeResult(
     contract: string,
     funName: string,
diff --git a/tests/AciContractCallEncoder.js b/tests/AciContractCallEncoder.js
index 8719798..ed83b47 100644
--- a/tests/AciContractCallEncoder.js
+++ b/tests/AciContractCallEncoder.js
@@ -82,6 +82,22 @@ test('Decode calldata', t => {
     )
 })
 
+test('Decode calldata without function name', t => {
+    t.plan(1)
+    const decoded = encoder.decodeFunction(
+        'cb_KxGu5Sw8G6+CAAQBSzsrAgQGCK+EAAABAAIbFCg7KwIEBgj8xaf6',
+    )
+
+    t.deepEqual(
+        decoded,
+        {
+            contractName: CONTRACT,
+            functionName: 'test_template_maze',
+            functionId: 'aee52c3c',
+        }
+    )
+})
+
 test('Decode implicit init (void) result', t => {
     t.plan(1)
     t.is(