From 8538d307d5d227e2b8a3439fb3461b5de087f250 Mon Sep 17 00:00:00 2001
From: Warm Beer <mickvd99@gmail.com>
Date: Mon, 21 Oct 2024 11:06:47 +0200
Subject: [PATCH] feat(evmlib): add token allowance and approval functions &
 set contract approval to infinite

---
 evmlib/src/contract/network_token.rs | 14 ++++++++
 evmlib/src/wallet.rs                 | 52 ++++++++++++++++++++++++----
 2 files changed, 59 insertions(+), 7 deletions(-)

diff --git a/evmlib/src/contract/network_token.rs b/evmlib/src/contract/network_token.rs
index a6fad9243d..013d572037 100644
--- a/evmlib/src/contract/network_token.rs
+++ b/evmlib/src/contract/network_token.rs
@@ -75,6 +75,20 @@ where
         Ok(balance)
     }
 
+    /// See how many tokens are approved to be spent.
+    pub async fn allowance(&self, owner: Address, spender: Address) -> Result<U256, Error> {
+        debug!("Getting allowance of owner: {owner} for spender: {spender}",);
+        let balance = self
+            .contract
+            .allowance(owner, spender)
+            .call()
+            .await
+            .inspect_err(|err| error!("Error getting allowance: {err:?}"))?
+            ._0;
+        debug!("Allowance of owner: {owner} for spender: {spender} is: {balance}");
+        Ok(balance)
+    }
+
     /// Approve spender to spend a raw amount of tokens.
     pub async fn approve(&self, spender: Address, value: U256) -> Result<TxHash, Error> {
         debug!("Approving spender to spend raw amt of tokens: {value}");
diff --git a/evmlib/src/wallet.rs b/evmlib/src/wallet.rs
index 8c4ec78298..b9504f69a1 100644
--- a/evmlib/src/wallet.rs
+++ b/evmlib/src/wallet.rs
@@ -70,12 +70,12 @@ impl Wallet {
 
     /// Returns the raw balance of payment tokens for this wallet.
     pub async fn balance_of_tokens(&self) -> Result<U256, network_token::Error> {
-        balance_of_tokens(wallet_address(&self.wallet), &self.network).await
+        balance_of_tokens(self.address(), &self.network).await
     }
 
     /// Returns the raw balance of gas tokens for this wallet.
     pub async fn balance_of_gas_tokens(&self) -> Result<U256, network_token::Error> {
-        balance_of_gas_tokens(wallet_address(&self.wallet), &self.network).await
+        balance_of_gas_tokens(self.address(), &self.network).await
     }
 
     /// Transfer a raw amount of payment tokens to another address.
@@ -96,6 +96,20 @@ impl Wallet {
         transfer_gas_tokens(self.wallet.clone(), &self.network, to, amount).await
     }
 
+    /// See how many tokens of the owner may be spent by the spender.
+    pub async fn token_allowance(&self, spender: Address) -> Result<U256, network_token::Error> {
+        token_allowance(&self.network, self.address(), spender).await
+    }
+
+    /// Approve an address / smart contract to spend this wallet's payment tokens.
+    pub async fn approve_to_spend_tokens(
+        &self,
+        spender: Address,
+        amount: U256,
+    ) -> Result<TxHash, network_token::Error> {
+        approve_to_spend_tokens(self.wallet.clone(), &self.network, spender, amount).await
+    }
+
     /// Pays for a single quote. Returns transaction hash of the payment.
     pub async fn pay_for_quote(
         &self,
@@ -188,8 +202,20 @@ pub async fn balance_of_gas_tokens(
     Ok(balance)
 }
 
+/// See how many tokens of the owner may be spent by the spender.
+pub async fn token_allowance(
+    network: &Network,
+    owner: Address,
+    spender: Address,
+) -> Result<U256, network_token::Error> {
+    debug!("Getting allowance for owner: {owner} and spender: {spender}",);
+    let provider = http_provider(network.rpc_url().clone());
+    let network_token = NetworkToken::new(*network.payment_token_address(), provider);
+    network_token.allowance(owner, spender).await
+}
+
 /// Approve an address / smart contract to spend this wallet's payment tokens.
-async fn approve_to_spend_tokens(
+pub async fn approve_to_spend_tokens(
     wallet: EthereumWallet,
     network: &Network,
     spender: Address,
@@ -250,16 +276,28 @@ pub async fn pay_for_quotes<T: IntoIterator<Item = QuotePayment>>(
 
     let mut tx_hashes_by_quote = BTreeMap::new();
 
-    // Approve the contract to spend enough of the client's tokens.
-    approve_to_spend_tokens(
-        wallet.clone(),
+    // Check allowance
+    let allowance = token_allowance(
         network,
+        wallet_address(&wallet),
         *network.data_payments_address(),
-        total_amount,
     )
     .await
     .map_err(|err| PayForQuotesError(Error::from(err), tx_hashes_by_quote.clone()))?;
 
+    // TODO: Get rid of approvals altogether, by using permits or whatever..
+    if allowance < total_amount {
+        // Approve the contract to spend all the client's tokens.
+        approve_to_spend_tokens(
+            wallet.clone(),
+            network,
+            *network.data_payments_address(),
+            U256::MAX,
+        )
+        .await
+        .map_err(|err| PayForQuotesError(Error::from(err), tx_hashes_by_quote.clone()))?;
+    }
+
     let provider = http_provider_with_wallet(network.rpc_url().clone(), wallet);
     let data_payments = DataPaymentsHandler::new(*network.data_payments_address(), provider);