From 2c709b9e0d9e4d4f39c447bb6d6c33663fe60349 Mon Sep 17 00:00:00 2001
From: Luke Van Seters <lukevanseters@gmail.com>
Date: Wed, 21 Jul 2021 00:54:27 -0400
Subject: [PATCH] Add support for decoding ABIs

---
 mev_inspect/decode.py            | 36 ++++++++++++++++++++++++++++++++
 mev_inspect/schemas/abi.py       |  1 +
 mev_inspect/schemas/call_data.py |  9 ++++++++
 3 files changed, 46 insertions(+)
 create mode 100644 mev_inspect/decode.py
 create mode 100644 mev_inspect/schemas/call_data.py

diff --git a/mev_inspect/decode.py b/mev_inspect/decode.py
new file mode 100644
index 0000000..fc0a1ec
--- /dev/null
+++ b/mev_inspect/decode.py
@@ -0,0 +1,36 @@
+from typing import Dict, Optional
+
+from hexbytes import HexBytes
+from eth_abi import decode_abi
+
+from mev_inspect.schemas.abi import ABI, ABIFunctionDescription
+from mev_inspect.schemas.call_data import CallData
+
+
+class ABIDecoder:
+    def __init__(self, abi: ABI):
+        self._functions_by_selector: Dict[str, ABIFunctionDescription] = {
+            description.get_selector(): description
+            for description in abi
+            if isinstance(description, ABIFunctionDescription)
+        }
+
+    def decode(self, data: str) -> Optional[CallData]:
+        hex_data = HexBytes(data)
+        selector, params = hex_data[:4], hex_data[4:]
+
+        func = self._functions_by_selector.get(selector)
+
+        if func is None:
+            return None
+
+        names = [input.name for input in func.inputs]
+        types = [input.type for input in func.inputs]
+
+        decoded = decode_abi(types, params)
+
+        return CallData(
+            function_name=func.name,
+            function_signature=func.get_signature(),
+            inputs={name: value for name, value in zip(names, decoded)},
+        )
diff --git a/mev_inspect/schemas/abi.py b/mev_inspect/schemas/abi.py
index 3c54837..7d91130 100644
--- a/mev_inspect/schemas/abi.py
+++ b/mev_inspect/schemas/abi.py
@@ -24,6 +24,7 @@ NON_FUNCTION_DESCRIPTION_TYPES = Union[
 
 
 class ABIDescriptionInput(BaseModel):
+    name: str
     type: str
 
 
diff --git a/mev_inspect/schemas/call_data.py b/mev_inspect/schemas/call_data.py
new file mode 100644
index 0000000..0ddd9e3
--- /dev/null
+++ b/mev_inspect/schemas/call_data.py
@@ -0,0 +1,9 @@
+from typing import Any, Dict
+
+from pydantic import BaseModel
+
+
+class CallData(BaseModel):
+    function_name: str
+    function_signature: str
+    inputs: Dict[str, Any]