🚧 check_and_calculate_fees

src/core/lockup_linear.cairo

@@ -11,6 +11,20 @@ use starknet::{ContractAddress, ClassHash};
 // Local imports.
 use za_warudo::types::lockup_linear::{Range, Broker};
 
+// ███████╗ █████╗     ██╗    ██╗ █████╗ ██████╗ ██╗   ██╗██████╗  ██████╗
+// ╚══███╔╝██╔══██╗    ██║    ██║██╔══██╗██╔══██╗██║   ██║██╔══██╗██╔═══██╗
+//   ███╔╝ ███████║    ██║ █╗ ██║███████║██████╔╝██║   ██║██║  ██║██║   ██║
+//  ███╔╝  ██╔══██║    ██║███╗██║██╔══██║██╔══██╗██║   ██║██║  ██║██║   ██║
+// ███████╗██║  ██║    ╚███╔███╔╝██║  ██║██║  ██║╚██████╔╝██████╔╝╚██████╔╝
+// ╚══════╝╚═╝  ╚═╝     ╚══╝╚══╝ ╚═╝  ╚═╝╚═╝  ╚═╝ ╚═════╝ ╚═════╝  ╚═════╝
+
+// ██╗      ██████╗  ██████╗██╗  ██╗██╗   ██╗██████╗     ██╗     ██╗███╗   ██╗███████╗ █████╗ ██████╗
+// ██║     ██╔═══██╗██╔════╝██║ ██╔╝██║   ██║██╔══██╗    ██║     ██║████╗  ██║██╔════╝██╔══██╗██╔══██╗
+// ██║     ██║   ██║██║     █████╔╝ ██║   ██║██████╔╝    ██║     ██║██╔██╗ ██║█████╗  ███████║██████╔╝
+// ██║     ██║   ██║██║     ██╔═██╗ ██║   ██║██╔═══╝     ██║     ██║██║╚██╗██║██╔══╝  ██╔══██║██╔══██╗
+// ███████╗╚██████╔╝╚██████╗██║  ██╗╚██████╔╝██║         ███████╗██║██║ ╚████║███████╗██║  ██║██║  ██║
+// ╚══════╝ ╚═════╝  ╚═════╝╚═╝  ╚═╝ ╚═════╝ ╚═╝         ╚══════╝╚═╝╚═╝  ╚═══╝╚══════╝╚═╝  ╚═╝╚═╝  ╚═╝
+
 // *************************************************************************
 //                  Interface of the `ZaWarudoLockupLinear` contract.
 // *************************************************************************
@@ -58,6 +72,7 @@ mod ZaWarudoLockupLinear {
     use za_warudo::types::lockup_linear::{Range, Broker, LockupLinearStream};
     use za_warudo::types::lockup::LockupAmounts;
     use za_warudo::tokens::erc721::{ERC721, IERC721};
+    use za_warudo::libraries::helpers;
 
     // *************************************************************************
     //                              STORAGE
@@ -143,8 +158,18 @@ mod ZaWarudoLockupLinear {
             range: Range,
             broker: Broker,
         ) -> u64 {
-            // Checks: check the fees and calculate the fee amounts.
+            // Safe Interactions: query the protocol fee. This is safe because it's a known Za Warudo contract that does
+            // not call other unknown contracts.
             // TODO: implement.
+            let protocol_fee = 0;
+
+            // TODO: Handle MAX_FEE as a constant, with handlign of fixed point numbers.
+            let MAX_FEE = 100;
+
+            // Checks: check the fees and calculate the fee amounts.
+            let create_amounts = helpers::check_and_calculate_fees(
+                total_amount, protocol_fee, broker.fee, MAX_FEE
+            );
 
             // Read the next stream id from storage.
             let stream_id = self.next_stream_id.read();

src/lib.cairo

@@ -9,6 +9,12 @@ mod types {
     mod lockup_linear;
 }
 
+/// Module containing libraries.
+mod libraries {
+    mod helpers;
+    mod errors;
+}
+
 /// Module containing tokens implementations.
 /// TODO: remove and use OpenZeppelin dependency when it's ready.
 mod tokens {

src/libraries/errors.cairo

@@ -0,0 +1,12 @@
+mod Lockup {
+    const PROTOCOL_FEE_TOO_HIGH: felt252 = 'protocol_fee_too_high';
+    const BROKER_FEE_TOO_HIGH: felt252 = 'broker_fee_too_high';
+
+    fn protocol_fee_too_high(protocol_fee: u128, max_fee: u128) {
+        panic(array![PROTOCOL_FEE_TOO_HIGH, protocol_fee.into(), max_fee.into()])
+    }
+
+    fn broker_fee_too_high(broker_fee: u128, max_fee: u128) {
+        panic(array![BROKER_FEE_TOO_HIGH, broker_fee.into(), max_fee.into()])
+    }
+}

src/libraries/helpers.cairo

@@ -0,0 +1,49 @@
+// *************************************************************************
+//                                  IMPORTS
+// *************************************************************************
+
+// Core lib imports.
+use zeroable::Zeroable;
+
+// Local imports.
+use za_warudo::types::lockup::CreateAmounts;
+use za_warudo::libraries::errors;
+
+//Checks that neither fee is greater than `max_fee`, and then calculates the protocol fee amount, the
+/// broker fee amount, and the deposit amount from the total amount.
+fn check_and_calculate_fees(
+    total_amount: u128, protocol_fee: u128, broker_fee: u128, max_fee: u128
+) -> CreateAmounts {
+    // TODO: Handle fixed point arithmetic everywhere.
+
+    // When the total amount is zero, the fees are also zero.
+    if (total_amount.is_zero()) {
+        return Zeroable::zero();
+    }
+
+    // Checks: the protocol fee is not greater than `max_fee`.
+    if (protocol_fee > max_fee) {
+        errors::Lockup::protocol_fee_too_high(protocol_fee, max_fee);
+    }
+
+    // Checks: the broker fee is not greater than `max_fee`.
+    if (broker_fee > max_fee) {
+        errors::Lockup::broker_fee_too_high(broker_fee, max_fee);
+    }
+
+    // Calculate the protocol fee amount.
+    let protocol_fee = total_amount * protocol_fee;
+
+    // Calculate the broker fee amount.
+    let broker_fee = total_amount * broker_fee;
+
+    // Assert that the total amount is strictly greater than the sum of the protocol fee amount and the
+    // broker fee amount.
+    assert(total_amount > protocol_fee + broker_fee, 'total_amount_too_low');
+
+    // Calculate the deposit amount (the amount to stream, net of fees).
+    let deposit = total_amount - protocol_fee - broker_fee;
+
+    // Return the amounts.
+    CreateAmounts { protocol_fee, broker_fee, deposit }
+}

src/types/lockup.cairo

@@ -7,6 +7,8 @@ use array::ArrayTrait;
 use result::ResultTrait;
 use option::OptionTrait;
 use traits::{TryInto, Into};
+use zeroable::Zeroable;
+use debug::PrintTrait;
 
 /// Represent Lockup amounts.
 // Struct encapsulating the deposit, withdrawn, and refunded amounts, all denoted in units
@@ -20,3 +22,41 @@ struct LockupAmounts {
     /// The amount refunded to the sender. Unless the stream was canceled, this is always zero.
     refunded: u128,
 }
+
+/// Represent Create amounts.
+/// Struct encapsulating the deposit amount, the protocol fee amount, and the broker fee amount,
+/// all denoted in units of the asset's decimals.
+#[derive(Drop, Copy, starknet::Store, Serde)]
+struct CreateAmounts {
+    /// The amount to deposit in the stream.
+    deposit: u128,
+    /// The protocol fee amount.
+    protocol_fee: u128,
+    /// The broker fee amount.
+    broker_fee: u128,
+}
+
+/// Implementation of `Zeroable` trait for `CreateAmounts`.
+impl CreateAmountsZeroable of Zeroable<CreateAmounts> {
+    fn zero() -> CreateAmounts {
+        CreateAmounts { deposit: 0, protocol_fee: 0, broker_fee: 0, }
+    }
+    #[inline(always)]
+    fn is_zero(self: CreateAmounts) -> bool {
+        self.deposit.is_zero() && self.protocol_fee.is_zero() && self.broker_fee.is_zero()
+    }
+    #[inline(always)]
+    fn is_non_zero(self: CreateAmounts) -> bool {
+        !self.is_zero()
+    }
+}
+
+/// Implementation of `PrintTrait` trait for `CreateAmounts`.
+impl CreateAmountsPrintTrait of PrintTrait<CreateAmounts> {
+    fn print(self: CreateAmounts) {
+        let message = array![
+            'CreateAmounts: ', self.deposit.into(), self.protocol_fee.into(), self.broker_fee.into()
+        ];
+        message.print();
+    }
+}

tests/test_lockup_linear.cairo

@@ -1,4 +1,4 @@
-//! Test file for `src/deposit/deposit_vault.cairo`.
+//! Test file for `src/core/lockup_linear.cairo`.
 
 // *************************************************************************
 //                                  IMPORTS