feat : escrow component (#45)

* feat : escrow component

* review fix : lock_from

* review changes

---------

Co-authored-by: Chqrles <[email protected]>

contracts/src/components.cairo

@@ -1,2 +1,3 @@
+pub mod escrow;
 pub mod processors;
 pub mod registry;

contracts/src/components/escrow.cairo

@@ -0,0 +1,3 @@
+pub mod escrow;
+pub mod interface;
+

contracts/src/components/escrow/escrow.cairo

@@ -0,0 +1,76 @@
+#[starknet::component]
+pub mod EscrowComponent {
+    use openzeppelin_token::erc20::interface::{IERC20Dispatcher, IERC20DispatcherTrait};
+    use starknet::storage::Map;
+    use starknet::{ContractAddress, get_contract_address};
+    use zkramp::components::escrow::interface;
+
+    //
+    // Storage
+    //
+
+    #[storage]
+    struct Storage {
+        // (owner, token) -> amount
+        deposits: Map::<(ContractAddress, ContractAddress), u256>,
+    }
+
+    //
+    // Errors
+    //
+
+    pub mod Errors {
+        pub const PROOF_OF_DEPOSIT_FAILED: felt252 = 'Proof of deposit failed';
+        pub const INSUFFICIENT_BALANCE: felt252 = 'Insufficient deposit balance';
+    }
+
+    //
+    // Escrow impl
+    //
+
+    #[embeddable_as(RegistryImpl)]
+    impl Escrow<
+        TContractState, +HasComponent<TContractState>, +Drop<TContractState>,
+    > of interface::IEscrow<ComponentState<TContractState>> {
+        fn lock_from(
+            ref self: ComponentState<TContractState>,
+            from: ContractAddress,
+            token: ContractAddress,
+            amount: u256
+        ) {
+            let locked_amount = self.deposits.read((from, token));
+
+            // transfers funds to escrow
+            let erc20_dispatcher = IERC20Dispatcher { contract_address: token };
+
+            erc20_dispatcher.transfer_from(from, get_contract_address(), amount);
+
+            self.deposits.write((from, token), amount + locked_amount);
+        }
+
+        fn unlock_to(
+            ref self: ComponentState<TContractState>,
+            from: ContractAddress,
+            to: ContractAddress,
+            token: ContractAddress,
+            amount: u256
+        ) {
+            let locked_amount = self.deposits.read((from, token));
+
+            // TODO
+            // check for proof of deposit
+            assert(true, Errors::PROOF_OF_DEPOSIT_FAILED);
+
+            // check deposit balance
+            assert(locked_amount >= amount, Errors::INSUFFICIENT_BALANCE);
+
+            // transfert of the amount to `to`
+            let erc20_dispatcher = IERC20Dispatcher { contract_address: token };
+
+            erc20_dispatcher.transfer_from(get_contract_address(), to, amount);
+
+            // update locked amount
+            self.deposits.write((from, token), locked_amount - amount);
+        }
+    }
+}

contracts/src/components/escrow/interface.cairo

@@ -0,0 +1,15 @@
+use core::hash::HashStateExTrait;
+use starknet::ContractAddress;
+
+#[starknet::interface]
+pub trait IEscrow<TState> {
+    fn lock_from(ref self: TState, from: ContractAddress, token: ContractAddress, amount: u256);
+    fn unlock_to(
+        ref self: TState,
+        from: ContractAddress,
+        to: ContractAddress,
+        token: ContractAddress,
+        amount: u256
+    );
+}
+