feat: add solution to ex01

Author: tdelabro

exercises/ex01-fungible-token/assets/src/lib.rs

@@ -145,8 +145,15 @@ pub mod pallet {
 
 			// TODO:
 			// - Create a new AssetMetadata instance based on the call arguments.
+			let metadata = AssetMetadata::new(name.clone(), symbol.clone());
 			// - Insert this metadata in the Metadata storage, under the asset_id key.
+			Metadata::<T>::insert(asset_id, metadata);
 			// - Deposit a `MetadataSet` event.
+			Self::deposit_event(Event::<T>::MetadataSet {
+				asset_id,
+				name,
+				symbol,
+			});
 
 			Ok(())
 		}
@@ -160,15 +167,19 @@ pub mod pallet {
 		) -> DispatchResult {
 			// TODO:
 			// - Ensure the extrinsic origin is a signed transaction.
+			let origin = ensure_signed(origin)?;
 			// - Ensure the caller is the asset owner.
+			Self::ensure_is_owner(asset_id, origin)?;
 
 			let mut minted_amount = 0;
+			let mut total_supply = 0;
 
 			Asset::<T>::try_mutate(asset_id, |maybe_details| -> DispatchResult {
 				let details = maybe_details.as_mut().ok_or(Error::<T>::UnknownAssetId)?;
 
 				let old_supply = details.supply;
 				details.supply = details.supply.saturating_add(amount);
+				total_supply = details.supply;
 				minted_amount = details.supply - old_supply;
 
 				Ok(())
@@ -179,6 +190,11 @@ pub mod pallet {
 			});
 
 			// TODO: Deposit a `Minted` event.
+			Self::deposit_event(Event::<T>::Minted {
+				asset_id,
+				owner: to,
+				total_supply,
+			});
 
 			Ok(())
 		}
@@ -187,9 +203,34 @@ pub mod pallet {
 		pub fn burn(origin: OriginFor<T>, asset_id: AssetId, amount: u128) -> DispatchResult {
 			// TODO:
 			// - Ensure the extrinsic origin is a signed transaction.
+			let origin = ensure_signed(origin)?;
 			// - Mutate the total supply.
-			// - Mutate the account balance.
+			let mut total_supply = 0;
+
+			Asset::<T>::try_mutate(asset_id, |maybe_details| -> DispatchResult {
+				let details = maybe_details.as_mut().ok_or(Error::<T>::UnknownAssetId)?;
+
+				let mut burned_amount = 0;
+
+				// - Mutate the account balance.
+				Account::<T>::mutate(asset_id, origin.clone(), |balance| {
+					let old_balance = *balance;
+					*balance = balance.saturating_sub(amount);
+					burned_amount = old_balance - *balance;
+				});
+
+				details.supply -= burned_amount;
+				total_supply = details.supply;
+
+				Ok(())
+			})?;
+
 			// - Emit a `Burned` event.
+			Self::deposit_event(Event::<T>::Burned {
+				asset_id,
+				owner: origin,
+				total_supply,
+			});
 
 			Ok(())
 		}
@@ -203,8 +244,27 @@ pub mod pallet {
 		) -> DispatchResult {
 			// TODO:
 			// - Ensure the extrinsic origin is a signed transaction.
+			let origin = ensure_signed(origin)?;
+			ensure!(Self::asset(asset_id).is_some(), Error::<T>::UnknownAssetId);
 			// - Mutate both account balances.
+			let mut transfered_amount = 0;
+
+			Account::<T>::mutate(asset_id, origin.clone(), |balance| {
+				let old_balance = *balance;
+				*balance = balance.saturating_sub(amount);
+				transfered_amount = old_balance - *balance;
+			});
+
+			Account::<T>::mutate(asset_id, to.clone(), |balance| {
+				*balance = balance.saturating_add(transfered_amount);
+			});
 			// - Emit a `Transferred` event.
+			Self::deposit_event(Event::<T>::Transferred {
+				asset_id,
+				from: origin,
+				to,
+				amount,
+			});
 
 			Ok(())
 		}