Implement fee inclusive transactions (#657)

* Add amount_includes_fee option in TX building

* Add --amount_includes_fee CLI option

* Implement send 'max' amount

Co-authored-by: cliik <cliik@example.com>

controller/src/command.rs

@@ -322,6 +322,8 @@ where
 #[derive(Clone)]
 pub struct SendArgs {
 	pub amount: u64,
+	pub amount_includes_fee: bool,
+	pub use_max_amount: bool,
 	pub minimum_confirmations: u64,
 	pub selection_strategy: String,
 	pub estimate_selection_strategies: bool,
@@ -353,6 +355,15 @@ where
 	K: keychain::Keychain + 'static,
 {
 	let mut slate = Slate::blank(2, false);
+	let mut amount = args.amount;
+	if args.use_max_amount {
+		controller::owner_single_use(None, keychain_mask, Some(owner_api), |api, m| {
+			let (_, wallet_info) =
+				api.retrieve_summary_info(m, true, args.minimum_confirmations)?;
+			amount = wallet_info.amount_currently_spendable;
+			Ok(())
+		})?;
+	};
 	controller::owner_single_use(None, keychain_mask, Some(owner_api), |api, m| {
 		if args.estimate_selection_strategies {
 			let strategies = vec!["smallest", "all"]
@@ -360,7 +371,8 @@ where
 				.map(|strategy| {
 					let init_args = InitTxArgs {
 						src_acct_name: None,
-						amount: args.amount,
+						amount: amount,
+						amount_includes_fee: Some(args.amount_includes_fee),
 						minimum_confirmations: args.minimum_confirmations,
 						max_outputs: args.max_outputs as u32,
 						num_change_outputs: args.change_outputs as u32,
@@ -372,12 +384,13 @@ where
 					Ok((strategy, slate.amount, slate.fee_fields))
 				})
 				.collect::<Result<Vec<_>, grin_wallet_libwallet::Error>>()?;
-			display::estimate(args.amount, strategies, dark_scheme);
+			display::estimate(amount, strategies, dark_scheme);
 			return Ok(());
 		} else {
 			let init_args = InitTxArgs {
 				src_acct_name: None,
-				amount: args.amount,
+				amount: amount,
+				amount_includes_fee: Some(args.amount_includes_fee),
 				minimum_confirmations: args.minimum_confirmations,
 				max_outputs: args.max_outputs as u32,
 				num_change_outputs: args.change_outputs as u32,
@@ -394,7 +407,7 @@ where
 				Ok(s) => {
 					info!(
 						"Tx created: {} grin to {} (strategy '{}')",
-						core::amount_to_hr_string(args.amount, false),
+						core::amount_to_hr_string(amount, false),
 						args.dest,
 						args.selection_strategy,
 					);

controller/tests/transaction.rs

@@ -354,6 +354,47 @@ fn basic_transaction_api(test_dir: &'static str) -> Result<(), libwallet::Error>
 		Ok(())
 	})?;
 
+	// try to send a transaction with amount inclusive of fees, but amount too
+	// small to cover fees. Should fail.
+	wallet::controller::owner_single_use(Some(wallet1.clone()), mask1, None, |sender_api, m| {
+		// note this will increment the block count as part of the transaction "Posting"
+		let args = InitTxArgs {
+			src_acct_name: None,
+			amount: 1,
+			amount_includes_fee: Some(true),
+			minimum_confirmations: 2,
+			max_outputs: 500,
+			num_change_outputs: 1,
+			selection_strategy_is_use_all: true,
+			..Default::default()
+		};
+		let res = sender_api.init_send_tx(m, args);
+		assert!(res.is_err());
+		Ok(())
+	})?;
+
+	// try to build a transaction with amount inclusive of fees. Confirm that tx
+	// amount + fee is equal to the originally specified amount
+	let amount = 60_000_000_000;
+	wallet::controller::owner_single_use(Some(wallet1.clone()), mask1, None, |sender_api, m| {
+		// note this will increment the block count as part of the transaction "Posting"
+		let args = InitTxArgs {
+			src_acct_name: None,
+			amount: amount,
+			amount_includes_fee: Some(true),
+			minimum_confirmations: 2,
+			max_outputs: 500,
+			num_change_outputs: 1,
+			selection_strategy_is_use_all: true,
+			..Default::default()
+		};
+		let slate_i = sender_api.init_send_tx(m, args)?;
+		assert_eq!(slate_i.state, SlateState::Standard1);
+		let total_spend: u64 = slate_i.amount + slate_i.fee_fields.fee();
+		assert_eq!(amount, total_spend);
+		Ok(())
+	})?;
+
 	// let logging finish
 	stopper.store(false, Ordering::Relaxed);
 	thread::sleep(Duration::from_millis(200));