From a054e7e54e926da52aed7dfcb8d73183c9bea675 Mon Sep 17 00:00:00 2001
From: Nenad <xinef.it@gmail.com>
Date: Thu, 19 Sep 2024 11:31:21 +0200
Subject: [PATCH] Add safe_transfer_from

---
 contracts/src/token/erc20/utils/safe_erc20.rs | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/contracts/src/token/erc20/utils/safe_erc20.rs b/contracts/src/token/erc20/utils/safe_erc20.rs
index dc22b1c5..c21860ab 100644
--- a/contracts/src/token/erc20/utils/safe_erc20.rs
+++ b/contracts/src/token/erc20/utils/safe_erc20.rs
@@ -58,6 +58,15 @@ pub trait SafeErc20 {
         to: Address,
         value: U256,
     ) -> Result<(), Self::Error>;
+
+    /// Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
+    /// calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
+    fn safe_transfer_from(
+        &self,
+        from: Address,
+        to: Address,
+        value: U256,
+    ) -> Result<(), Self::Error>;
 }
 
 impl SafeErc20 for Erc20 {
@@ -74,6 +83,23 @@ impl SafeErc20 for Erc20 {
 
         self.call_optional_return(calldata)
     }
+
+    fn safe_transfer_from(
+        &self,
+        from: Address,
+        to: Address,
+        value: U256,
+    ) -> Result<(), Self::Error> {
+        type TransferType = (SOLAddress, SOLAddress, Uint<256>);
+        let tx_data = (from, to, value);
+        let data = TransferType::abi_encode_params(&tx_data);
+        let hashed_function_selector =
+            function_selector!("transferFrom", Address, Address, U256);
+        // Combine function selector and input data (use abi_packed way)
+        let calldata = [&hashed_function_selector[..4], &data].concat();
+
+        self.call_optional_return(calldata)
+    }
 }
 
 /// NOTE: Implementation of [`TopLevelStorage`] to be able use `&mut self` when
@@ -150,4 +176,27 @@ mod tests {
         assert_eq!(initial_alice_balance + one, contract.balance_of(alice));
         assert_eq!(initial_supply, contract.total_supply());
     }
+
+    #[motsu::test]
+    fn transfers_from(contract: Erc20) {
+        let alice = address!("A11CEacF9aa32246d767FCCD72e02d6bCbcC375d");
+        let bob = address!("B0B0cB49ec2e96DF5F5fFB081acaE66A2cBBc2e2");
+        let sender = msg::sender();
+
+        // Alice approves `msg::sender`.
+        let one = uint!(1_U256);
+        contract._allowances.setter(alice).setter(sender).set(one);
+
+        // Mint some tokens for Alice.
+        let two = uint!(2_U256);
+        contract._update(Address::ZERO, alice, two).unwrap();
+        assert_eq!(two, contract.balance_of(alice));
+
+        let result = contract.safe_transfer_from(alice, bob, one);
+        assert!(result.is_ok());
+
+        assert_eq!(one, contract.balance_of(alice));
+        assert_eq!(one, contract.balance_of(bob));
+        assert_eq!(U256::ZERO, contract.allowance(alice, sender));
+    }
 }