From c84e1d138e714f1addaefb825a11ead556ccf2a1 Mon Sep 17 00:00:00 2001
From: Foivos <foivos@umich.edu>
Date: Wed, 13 Nov 2024 17:52:22 +0200
Subject: [PATCH 1/4] move gas-service logic to versioned

---
 move/gas_service/sources/events.move          |  89 ++++++++++++
 move/gas_service/sources/gas_service.move     | 130 ++++++------------
 .../sources/versioned/gas_service_v0.move     |  91 +++++++++++-
 .../interface_gas_service_events.json         |   4 +
 4 files changed, 227 insertions(+), 87 deletions(-)
 create mode 100644 move/gas_service/sources/events.move
 create mode 100644 test/testdata/interface_gas_service_events.json

diff --git a/move/gas_service/sources/events.move b/move/gas_service/sources/events.move
new file mode 100644
index 00000000..00b196db
--- /dev/null
+++ b/move/gas_service/sources/events.move
@@ -0,0 +1,89 @@
+module gas_service::events;
+
+use std::ascii::String;
+use sui::event;
+
+// ------
+// Events
+// ------
+public struct GasPaid<phantom T> has copy, drop {
+    sender: address,
+    destination_chain: String,
+    destination_address: String,
+    payload_hash: address,
+    value: u64,
+    refund_address: address,
+    params: vector<u8>,
+}
+
+public struct GasAdded<phantom T> has copy, drop {
+    message_id: String,
+    value: u64,
+    refund_address: address,
+    params: vector<u8>,
+}
+
+public struct Refunded<phantom T> has copy, drop {
+    message_id: String,
+    value: u64,
+    refund_address: address,
+}
+
+public struct GasCollected<phantom T> has copy, drop {
+    receiver: address,
+    value: u64,
+}
+
+// Package Functions
+public(package) fun gas_paid<T>(
+    sender: address,
+    destination_chain: String,
+    destination_address: String,
+    payload_hash: address,
+    value: u64,
+    refund_address: address,
+    params: vector<u8>,
+) {
+    event::emit(GasPaid<T> {
+        sender,
+        destination_chain,
+        destination_address,
+        payload_hash,
+        value,
+        refund_address,
+        params,
+    });
+}
+
+public(package) fun gas_added<T>(
+    message_id: String,
+    value: u64,
+    refund_address: address,
+    params: vector<u8>,
+) {
+    event::emit(GasAdded<T> {
+        message_id,
+        value,
+        refund_address,
+        params,
+    });
+}
+
+public(package) fun refunded<T>(
+    message_id: String,
+    value: u64,
+    refund_address: address,
+) {
+    event::emit(Refunded<T> {
+        message_id,
+        value,
+        refund_address,
+    });
+}
+
+public(package) fun gas_collected<T>(receiver: address, value: u64) {
+    event::emit(GasCollected<T> {
+        receiver,
+        value,
+    });
+}
diff --git a/move/gas_service/sources/gas_service.move b/move/gas_service/sources/gas_service.move
index 12f9e3bb..9bee412a 100644
--- a/move/gas_service/sources/gas_service.move
+++ b/move/gas_service/sources/gas_service.move
@@ -2,9 +2,7 @@ module gas_service::gas_service;
 
 use gas_service::gas_service_v0::{Self, GasService_v0};
 use std::ascii::{Self, String};
-use sui::address;
 use sui::coin::Coin;
-use sui::event;
 use sui::hash::keccak256;
 use sui::sui::SUI;
 use sui::versioned::{Self, Versioned};
@@ -27,37 +25,6 @@ public struct GasCollectorCap has key, store {
     id: UID,
 }
 
-// ------
-// Events
-// ------
-public struct GasPaid<phantom T> has copy, drop {
-    sender: address,
-    destination_chain: String,
-    destination_address: String,
-    payload_hash: address,
-    value: u64,
-    refund_address: address,
-    params: vector<u8>,
-}
-
-public struct GasAdded<phantom T> has copy, drop {
-    message_id: String,
-    value: u64,
-    refund_address: address,
-    params: vector<u8>,
-}
-
-public struct Refunded<phantom T> has copy, drop {
-    message_id: String,
-    value: u64,
-    refund_address: address,
-}
-
-public struct GasCollected<phantom T> has copy, drop {
-    receiver: address,
-    value: u64,
-}
-
 // -----
 // Setup
 // -----
@@ -98,8 +65,10 @@ macro fun value_mut(
 // Public Functions
 // ----------------
 /// Pay gas for a contract call.
-/// This function is called by the channel that wants to pay gas for a contract call.
-/// It can also be called by the user to pay gas for a contract call, while setting the sender as the channel ID.
+/// This function is called by the channel that wants to pay gas for a contract
+/// call.
+/// It can also be called by the user to pay gas for a contract call, while
+/// setting the sender as the channel ID.
 public fun pay_gas(
     self: &mut GasService,
     coin: Coin<SUI>,
@@ -110,24 +79,22 @@ public fun pay_gas(
     refund_address: address,
     params: vector<u8>,
 ) {
-    let coin_value = coin.value();
-    self.value_mut!(b"pay_gas").put(coin);
-
-    let payload_hash = address::from_bytes(keccak256(&payload));
-
-    event::emit(GasPaid<SUI> {
-        sender,
-        destination_chain,
-        destination_address,
-        payload_hash,
-        value: coin_value,
-        refund_address,
-        params,
-    })
+    self
+        .value_mut!(b"pay_gas")
+        .pay_gas(
+            coin,
+            sender,
+            destination_chain,
+            destination_address,
+            payload,
+            refund_address,
+            params,
+        );
 }
 
 /// Add gas for an existing cross-chain contract call.
-/// This function can be called by a user who wants to add gas for a contract call with insufficient gas.
+/// This function can be called by a user who wants to add gas for a contract
+/// call with insufficient gas.
 public fun add_gas(
     self: &mut GasService,
     coin: Coin<SUI>,
@@ -135,15 +102,14 @@ public fun add_gas(
     refund_address: address,
     params: vector<u8>,
 ) {
-    let coin_value = coin.value();
-    self.value_mut!(b"add_gas").put(coin);
-
-    event::emit(GasAdded<SUI> {
-        message_id,
-        value: coin_value,
-        refund_address,
-        params,
-    });
+    self
+        .value_mut!(b"add_gas")
+        .add_gas(
+            coin,
+            message_id,
+            refund_address,
+            params,
+        );
 }
 
 public fun collect_gas(
@@ -153,15 +119,13 @@ public fun collect_gas(
     amount: u64,
     ctx: &mut TxContext,
 ) {
-    transfer::public_transfer(
-        self.value_mut!(b"collect_gas").take(amount, ctx),
-        receiver,
-    );
-
-    event::emit(GasCollected<SUI> {
-        receiver,
-        value: amount,
-    });
+    self
+        .value_mut!(b"collect_gas")
+        .collect_gas(
+            receiver,
+            amount,
+            ctx,
+        )
 }
 
 public fun refund(
@@ -172,29 +136,25 @@ public fun refund(
     amount: u64,
     ctx: &mut TxContext,
 ) {
-    transfer::public_transfer(
-        self.value_mut!(b"refund").take(amount, ctx),
-        receiver,
-    );
-
-    event::emit(Refunded<SUI> {
-        message_id,
-        value: amount,
-        refund_address: receiver,
-    });
+    self
+        .value_mut!(b"refund")
+        .refund(
+            message_id,
+            receiver,
+            amount,
+            ctx,
+        );
 }
 
 // -----------------
 // Private Functions
 // -----------------
 fun version_control(): VersionControl {
-    version_control::new(
-        vector[
-            vector[b"pay_gas", b"add_gas", b"collect_gas", b"refund"].map!(
-                |function_name| function_name.to_ascii_string(),
-            ),
-        ],
-    )
+    version_control::new(vector[
+        vector[b"pay_gas", b"add_gas", b"collect_gas", b"refund"].map!(
+            |function_name| function_name.to_ascii_string(),
+        ),
+    ])
 }
 
 // -----
diff --git a/move/gas_service/sources/versioned/gas_service_v0.move b/move/gas_service/sources/versioned/gas_service_v0.move
index 400ad3d4..c1bcd83a 100644
--- a/move/gas_service/sources/versioned/gas_service_v0.move
+++ b/move/gas_service/sources/versioned/gas_service_v0.move
@@ -1,7 +1,11 @@
 module gas_service::gas_service_v0;
 
+use gas_service::events;
+use std::ascii::String;
+use sui::address;
 use sui::balance::{Self, Balance};
 use sui::coin::{Self, Coin};
+use sui::hash::keccak256;
 use sui::sui::SUI;
 use version_control::version_control::VersionControl;
 
@@ -27,11 +31,94 @@ public(package) fun version_control(self: &GasService_v0): &VersionControl {
     &self.version_control
 }
 
-public(package) fun put(self: &mut GasService_v0, coin: Coin<SUI>) {
+public(package) fun pay_gas(
+    self: &mut GasService_v0,
+    coin: Coin<SUI>,
+    sender: address,
+    destination_chain: String,
+    destination_address: String,
+    payload: vector<u8>,
+    refund_address: address,
+    params: vector<u8>,
+) {
+    let coin_value = coin.value();
+    self.put(coin);
+
+    let payload_hash = address::from_bytes(keccak256(&payload));
+
+    events::gas_paid<SUI>(
+        sender,
+        destination_chain,
+        destination_address,
+        payload_hash,
+        coin_value,
+        refund_address,
+        params,
+    );
+}
+
+public(package) fun add_gas(
+    self: &mut GasService_v0,
+    coin: Coin<SUI>,
+    message_id: String,
+    refund_address: address,
+    params: vector<u8>,
+) {
+    let coin_value = coin.value();
+    self.put(coin);
+
+    events::gas_added<SUI>(
+        message_id,
+        coin_value,
+        refund_address,
+        params,
+    );
+}
+
+public(package) fun collect_gas(
+    self: &mut GasService_v0,
+    receiver: address,
+    amount: u64,
+    ctx: &mut TxContext,
+) {
+    transfer::public_transfer(
+        self.take(amount, ctx),
+        receiver,
+    );
+
+    events::gas_collected<SUI>(
+        receiver,
+        amount,
+    );
+}
+
+public(package) fun refund(
+    self: &mut GasService_v0,
+    message_id: String,
+    receiver: address,
+    amount: u64,
+    ctx: &mut TxContext,
+) {
+    transfer::public_transfer(
+        self.take(amount, ctx),
+        receiver,
+    );
+
+    events::refunded<SUI>(
+        message_id,
+        amount,
+        receiver,
+    );
+}
+
+// -----------------
+// Private Functions
+// -----------------
+fun put(self: &mut GasService_v0, coin: Coin<SUI>) {
     coin::put(&mut self.balance, coin);
 }
 
-public(package) fun take(
+fun take(
     self: &mut GasService_v0,
     amount: u64,
     ctx: &mut TxContext,
diff --git a/test/testdata/interface_gas_service_events.json b/test/testdata/interface_gas_service_events.json
new file mode 100644
index 00000000..0b162a70
--- /dev/null
+++ b/test/testdata/interface_gas_service_events.json
@@ -0,0 +1,4 @@
+{
+  "structs": {},
+  "publicFunctions": {}
+}

From e832a63996744b9255d84d81ea1036e57af6bead Mon Sep 17 00:00:00 2001
From: Foivos <foivos@umich.edu>
Date: Tue, 19 Nov 2024 16:11:19 +0200
Subject: [PATCH 2/4] added a method to pay gas using a message ticket

---
 move/example/Move.toml                        |  2 +-
 move/gas_service/Move.lock                    | 24 +++++++++++++++--
 move/gas_service/Move.toml                    |  1 +
 move/gas_service/sources/gas_service.move     | 18 +++++++++++++
 .../sources/versioned/gas_service_v0.move     | 26 +++++++++++++++++++
 5 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/move/example/Move.toml b/move/example/Move.toml
index e988646d..71a64333 100644
--- a/move/example/Move.toml
+++ b/move/example/Move.toml
@@ -5,8 +5,8 @@ edition = "2024.beta"
 
 [dependencies]
 Sui = { git = "https://github.com/MystenLabs/sui.git", subdir = "crates/sui-framework/packages/sui-framework", rev = "mainnet-v1.35.2" }
-AxelarGateway = { local = "../axelar_gateway" }
 GasService = { local = "../gas_service" }
+AxelarGateway = { local = "../axelar_gateway" }
 Utils = { local = "../utils" }
 VersionControl = { local = "../version_control" }
 ITS = { local = "../its" }
diff --git a/move/gas_service/Move.lock b/move/gas_service/Move.lock
index f9b3f51b..16161b14 100644
--- a/move/gas_service/Move.lock
+++ b/move/gas_service/Move.lock
@@ -2,13 +2,25 @@
 
 [move]
 version = 3
-manifest_digest = "C29AEC3A18805EA1C5A2FCA5811D6AAD6BE44E394A8FDF0B02FB34D3409F4D3E"
-deps_digest = "3C4103934B1E040BB6B23F1D610B4EF9F2F1166A50A104EADCF77467C004C600"
+manifest_digest = "C04CC08DC1212FBCB4F5A869F32A9607A3C3E3586BC3BEFC0C0F1DBD3CE563CE"
+deps_digest = "060AD7E57DFB13104F21BE5F5C3759D03F0553FC3229247D9A7A6B45F50D03A3"
 dependencies = [
+  { id = "AxelarGateway", name = "AxelarGateway" },
   { id = "Sui", name = "Sui" },
   { id = "VersionControl", name = "VersionControl" },
 ]
 
+[[move.package]]
+id = "AxelarGateway"
+source = { local = "../axelar_gateway" }
+
+dependencies = [
+  { id = "MoveStdlib", name = "MoveStdlib" },
+  { id = "Sui", name = "Sui" },
+  { id = "Utils", name = "Utils" },
+  { id = "VersionControl", name = "VersionControl" },
+]
+
 [[move.package]]
 id = "MoveStdlib"
 source = { git = "https://github.com/MystenLabs/sui.git", rev = "mainnet-v1.35.2", subdir = "crates/sui-framework/packages/move-stdlib" }
@@ -21,6 +33,14 @@ dependencies = [
   { id = "MoveStdlib", name = "MoveStdlib" },
 ]
 
+[[move.package]]
+id = "Utils"
+source = { local = "../utils" }
+
+dependencies = [
+  { id = "Sui", name = "Sui" },
+]
+
 [[move.package]]
 id = "VersionControl"
 source = { local = "../version_control" }
diff --git a/move/gas_service/Move.toml b/move/gas_service/Move.toml
index 1e804f9b..c83e94eb 100644
--- a/move/gas_service/Move.toml
+++ b/move/gas_service/Move.toml
@@ -6,6 +6,7 @@ edition = "2024.beta"
 [dependencies]
 Sui = { git = "https://github.com/MystenLabs/sui.git", subdir = "crates/sui-framework/packages/sui-framework", rev = "mainnet-v1.35.2" }
 VersionControl = { local = "../version_control" }
+AxelarGateway = { local = "../axelar_gateway" }
 
 [addresses]
 gas_service = "0xa2"
diff --git a/move/gas_service/sources/gas_service.move b/move/gas_service/sources/gas_service.move
index 9bee412a..8d5b443b 100644
--- a/move/gas_service/sources/gas_service.move
+++ b/move/gas_service/sources/gas_service.move
@@ -1,5 +1,6 @@
 module gas_service::gas_service;
 
+use axelar_gateway::message_ticket::MessageTicket;
 use gas_service::gas_service_v0::{Self, GasService_v0};
 use std::ascii::{Self, String};
 use sui::coin::Coin;
@@ -112,6 +113,23 @@ public fun add_gas(
         );
 }
 
+public fun pay_gas_for_message_ticket(
+    self: &mut GasService,
+    message_ticket: &MessageTicket,
+    coin: Coin<SUI>,
+    refund_address: address,
+    params: vector<u8>,
+) {
+    self
+        .value_mut!(b"pay_gas_for_message_ticket")
+        .pay_gas_for_message_ticket(
+            message_ticket,
+            coin,
+            refund_address,
+            params,
+        );
+}
+
 public fun collect_gas(
     self: &mut GasService,
     _: &GasCollectorCap,
diff --git a/move/gas_service/sources/versioned/gas_service_v0.move b/move/gas_service/sources/versioned/gas_service_v0.move
index c1bcd83a..727fe00a 100644
--- a/move/gas_service/sources/versioned/gas_service_v0.move
+++ b/move/gas_service/sources/versioned/gas_service_v0.move
@@ -1,5 +1,6 @@
 module gas_service::gas_service_v0;
 
+use axelar_gateway::message_ticket::MessageTicket;
 use gas_service::events;
 use std::ascii::String;
 use sui::address;
@@ -75,6 +76,31 @@ public(package) fun add_gas(
     );
 }
 
+public(package) fun pay_gas_for_message_ticket(
+    self: &mut GasService_v0,
+    message_ticket: &MessageTicket,
+    coin: Coin<SUI>,
+    refund_address: address,
+    params: vector<u8>,
+) {
+    let coin_value = coin.value();
+    self.put(coin);
+
+    let payload_hash = address::from_bytes(
+        keccak256(&message_ticket.payload()),
+    );
+
+    events::gas_paid<SUI>(
+        message_ticket.source_id(),
+        message_ticket.destination_chain(),
+        message_ticket.destination_address(),
+        payload_hash,
+        coin_value,
+        refund_address,
+        params,
+    );
+}
+
 public(package) fun collect_gas(
     self: &mut GasService_v0,
     receiver: address,

From 273013c7b8c67434e25e1ccdfeca4e3d52a368d2 Mon Sep 17 00:00:00 2001
From: Foivos <foivos@umich.edu>
Date: Tue, 19 Nov 2024 19:21:56 +0200
Subject: [PATCH 3/4] remode pay_gas entirely

---
 .changeset/fair-dots-explode.md               |  5 ++
 move/example/sources/gmp/gmp.move             | 17 +++---
 move/example/sources/its/its.move             |  5 +-
 move/gas_service/sources/gas_service.move     | 57 +++++++------------
 .../sources/versioned/gas_service_v0.move     | 28 +--------
 5 files changed, 37 insertions(+), 75 deletions(-)
 create mode 100644 .changeset/fair-dots-explode.md

diff --git a/.changeset/fair-dots-explode.md b/.changeset/fair-dots-explode.md
new file mode 100644
index 00000000..1a624436
--- /dev/null
+++ b/.changeset/fair-dots-explode.md
@@ -0,0 +1,5 @@
+---
+'@axelar-network/axelar-cgp-sui': minor
+---
+
+Paying for gas now requires the message ticket instead of the call information.
diff --git a/move/example/sources/gmp/gmp.move b/move/example/sources/gmp/gmp.move
index 06408989..c95cce56 100644
--- a/move/example/sources/gmp/gmp.move
+++ b/move/example/sources/gmp/gmp.move
@@ -77,20 +77,19 @@ public fun send_call(
     coin: Coin<SUI>,
     params: vector<u8>,
 ) {
-    gas_service.pay_gas(
-        coin,
-        sui::object::id_address(&singleton.channel),
-        destination_chain,
-        destination_address,
-        payload,
-        refund_address,
-        params,
-    );
+
     let message_ticket = gateway::prepare_message(
         &singleton.channel,
         destination_chain,
         destination_address,
         payload,
+    );    
+    
+    gas_service.pay_gas(
+        &message_ticket,
+        coin,
+        refund_address,
+        params,
     );
 
     gateway.send_message(message_ticket);
diff --git a/move/example/sources/its/its.move b/move/example/sources/its/its.move
index 48f0b94a..ca1b2806 100644
--- a/move/example/sources/its/its.move
+++ b/move/example/sources/its/its.move
@@ -267,11 +267,8 @@ fun pay_gas_and_send_message(
     gas_params: vector<u8>,
 ) {
     gas_service.pay_gas(
+        &message_ticket,
         gas,
-        message_ticket.source_id(),
-        message_ticket.destination_chain(),
-        message_ticket.destination_address(),
-        message_ticket.payload(),
         refund_address,
         gas_params,
     );
diff --git a/move/gas_service/sources/gas_service.move b/move/gas_service/sources/gas_service.move
index 8d5b443b..3eb8338f 100644
--- a/move/gas_service/sources/gas_service.move
+++ b/move/gas_service/sources/gas_service.move
@@ -65,34 +65,6 @@ macro fun value_mut(
 // ----------------
 // Public Functions
 // ----------------
-/// Pay gas for a contract call.
-/// This function is called by the channel that wants to pay gas for a contract
-/// call.
-/// It can also be called by the user to pay gas for a contract call, while
-/// setting the sender as the channel ID.
-public fun pay_gas(
-    self: &mut GasService,
-    coin: Coin<SUI>,
-    sender: address,
-    destination_chain: String,
-    destination_address: String,
-    payload: vector<u8>,
-    refund_address: address,
-    params: vector<u8>,
-) {
-    self
-        .value_mut!(b"pay_gas")
-        .pay_gas(
-            coin,
-            sender,
-            destination_chain,
-            destination_address,
-            payload,
-            refund_address,
-            params,
-        );
-}
-
 /// Add gas for an existing cross-chain contract call.
 /// This function can be called by a user who wants to add gas for a contract
 /// call with insufficient gas.
@@ -113,7 +85,12 @@ public fun add_gas(
         );
 }
 
-public fun pay_gas_for_message_ticket(
+/// Pay gas for a contract call.
+/// This function is called by the channel that wants to pay gas for a contract
+/// call.
+/// It can also be called by the user to pay gas for a contract call, while
+/// setting the sender as the channel ID.
+public fun pay_gas(
     self: &mut GasService,
     message_ticket: &MessageTicket,
     coin: Coin<SUI>,
@@ -121,8 +98,8 @@ public fun pay_gas_for_message_ticket(
     params: vector<u8>,
 ) {
     self
-        .value_mut!(b"pay_gas_for_message_ticket")
-        .pay_gas_for_message_ticket(
+        .value_mut!(b"pay_gas")
+        .pay_gas(
             message_ticket,
             coin,
             refund_address,
@@ -238,14 +215,22 @@ fun test_pay_gas() {
     let digest = ctx.digest();
     let value = (((digest[0] as u16) << 8) | (digest[1] as u16) as u64) + 1;
     let c: Coin<SUI> = coin::mint_for_testing(value, ctx);
+    let channel = axelar_gateway::channel::new(ctx);
+    let destination_chain = b"destination chain".to_ascii_string();
+    let destination_address = b"destination address".to_ascii_string();
+    let payload = b"payload";
+
+    let ticket = axelar_gateway::gateway::prepare_message(
+        &channel,
+        destination_chain,
+        destination_address,
+        payload,
+    );
 
     service.pay_gas(
+        &ticket,
         c,
         ctx.sender(),
-        std::ascii::string(b"destination chain"),
-        std::ascii::string(b"destination address"),
-        vector[],
-        ctx.sender(),
         vector[],
     );
 
@@ -253,6 +238,8 @@ fun test_pay_gas() {
 
     cap.destroy_cap();
     service.destroy();
+    channel.destroy();
+    sui::test_utils::destroy(ticket);
 }
 
 #[test]
diff --git a/move/gas_service/sources/versioned/gas_service_v0.move b/move/gas_service/sources/versioned/gas_service_v0.move
index 727fe00a..e3bea124 100644
--- a/move/gas_service/sources/versioned/gas_service_v0.move
+++ b/move/gas_service/sources/versioned/gas_service_v0.move
@@ -32,32 +32,6 @@ public(package) fun version_control(self: &GasService_v0): &VersionControl {
     &self.version_control
 }
 
-public(package) fun pay_gas(
-    self: &mut GasService_v0,
-    coin: Coin<SUI>,
-    sender: address,
-    destination_chain: String,
-    destination_address: String,
-    payload: vector<u8>,
-    refund_address: address,
-    params: vector<u8>,
-) {
-    let coin_value = coin.value();
-    self.put(coin);
-
-    let payload_hash = address::from_bytes(keccak256(&payload));
-
-    events::gas_paid<SUI>(
-        sender,
-        destination_chain,
-        destination_address,
-        payload_hash,
-        coin_value,
-        refund_address,
-        params,
-    );
-}
-
 public(package) fun add_gas(
     self: &mut GasService_v0,
     coin: Coin<SUI>,
@@ -76,7 +50,7 @@ public(package) fun add_gas(
     );
 }
 
-public(package) fun pay_gas_for_message_ticket(
+public(package) fun pay_gas(
     self: &mut GasService_v0,
     message_ticket: &MessageTicket,
     coin: Coin<SUI>,

From 690834b4c662b437ce96034193022c898f471d12 Mon Sep 17 00:00:00 2001
From: Foivos <foivos@umich.edu>
Date: Wed, 20 Nov 2024 15:11:11 +0200
Subject: [PATCH 4/4] move pay_gas above add_gas

---
 move/gas_service/sources/gas_service.move     | 36 +++++++++----------
 .../sources/versioned/gas_service_v0.move     | 30 ++++++++--------
 2 files changed, 33 insertions(+), 33 deletions(-)

diff --git a/move/gas_service/sources/gas_service.move b/move/gas_service/sources/gas_service.move
index 3eb8338f..c27a5659 100644
--- a/move/gas_service/sources/gas_service.move
+++ b/move/gas_service/sources/gas_service.move
@@ -65,43 +65,43 @@ macro fun value_mut(
 // ----------------
 // Public Functions
 // ----------------
-/// Add gas for an existing cross-chain contract call.
-/// This function can be called by a user who wants to add gas for a contract
-/// call with insufficient gas.
-public fun add_gas(
+/// Pay gas for a contract call.
+/// This function is called by the channel that wants to pay gas for a contract
+/// call.
+/// It can also be called by the user to pay gas for a contract call, while
+/// setting the sender as the channel ID.
+public fun pay_gas(
     self: &mut GasService,
+    message_ticket: &MessageTicket,
     coin: Coin<SUI>,
-    message_id: String,
     refund_address: address,
     params: vector<u8>,
 ) {
     self
-        .value_mut!(b"add_gas")
-        .add_gas(
+        .value_mut!(b"pay_gas")
+        .pay_gas(
+            message_ticket,
             coin,
-            message_id,
             refund_address,
             params,
         );
 }
 
-/// Pay gas for a contract call.
-/// This function is called by the channel that wants to pay gas for a contract
-/// call.
-/// It can also be called by the user to pay gas for a contract call, while
-/// setting the sender as the channel ID.
-public fun pay_gas(
+/// Add gas for an existing cross-chain contract call.
+/// This function can be called by a user who wants to add gas for a contract
+/// call with insufficient gas.
+public fun add_gas(
     self: &mut GasService,
-    message_ticket: &MessageTicket,
     coin: Coin<SUI>,
+    message_id: String,
     refund_address: address,
     params: vector<u8>,
 ) {
     self
-        .value_mut!(b"pay_gas")
-        .pay_gas(
-            message_ticket,
+        .value_mut!(b"add_gas")
+        .add_gas(
             coin,
+            message_id,
             refund_address,
             params,
         );
diff --git a/move/gas_service/sources/versioned/gas_service_v0.move b/move/gas_service/sources/versioned/gas_service_v0.move
index e3bea124..84a676d5 100644
--- a/move/gas_service/sources/versioned/gas_service_v0.move
+++ b/move/gas_service/sources/versioned/gas_service_v0.move
@@ -32,43 +32,43 @@ public(package) fun version_control(self: &GasService_v0): &VersionControl {
     &self.version_control
 }
 
-public(package) fun add_gas(
+public(package) fun pay_gas(
     self: &mut GasService_v0,
+    message_ticket: &MessageTicket,
     coin: Coin<SUI>,
-    message_id: String,
     refund_address: address,
     params: vector<u8>,
 ) {
     let coin_value = coin.value();
     self.put(coin);
 
-    events::gas_added<SUI>(
-        message_id,
+    let payload_hash = address::from_bytes(
+        keccak256(&message_ticket.payload()),
+    );
+
+    events::gas_paid<SUI>(
+        message_ticket.source_id(),
+        message_ticket.destination_chain(),
+        message_ticket.destination_address(),
+        payload_hash,
         coin_value,
         refund_address,
         params,
     );
 }
 
-public(package) fun pay_gas(
+public(package) fun add_gas(
     self: &mut GasService_v0,
-    message_ticket: &MessageTicket,
     coin: Coin<SUI>,
+    message_id: String,
     refund_address: address,
     params: vector<u8>,
 ) {
     let coin_value = coin.value();
     self.put(coin);
 
-    let payload_hash = address::from_bytes(
-        keccak256(&message_ticket.payload()),
-    );
-
-    events::gas_paid<SUI>(
-        message_ticket.source_id(),
-        message_ticket.destination_chain(),
-        message_ticket.destination_address(),
-        payload_hash,
+    events::gas_added<SUI>(
+        message_id,
         coin_value,
         refund_address,
         params,