Implement zrml-combo extrinsics (#1369)

* Extend `Config`

* wip

* Some refactors

* Implement splitting tokens

* Implement merging tokens

primitives/src/asset.rs

@@ -20,7 +20,7 @@
 use crate::traits::ZeitgeistAssetEnumerator;
 use crate::{
     traits::PoolSharesId,
-    types::{CategoryIndex, PoolId},
+    types::{CategoryIndex, PoolId, CombinatorialId},
 };
 use parity_scale_codec::{Decode, Encode, MaxEncodedLen};
 use scale_info::TypeInfo;
@@ -48,13 +48,14 @@ use serde::{Deserialize, Serialize};
 pub enum Asset<MarketId> {
     CategoricalOutcome(MarketId, CategoryIndex),
     ScalarOutcome(MarketId, ScalarPosition),
-    CombinatorialOutcome,
+    CombinatorialToken(CombinatorialId),
     PoolShare(PoolId),
     #[default]
     Ztg,
     ForeignAsset(u32),
     ParimutuelShare(MarketId, CategoryIndex),
 }
+// TODO Needs storage migration
 
 #[cfg(feature = "runtime-benchmarks")]
 impl<MarketId: MaxEncodedLen> ZeitgeistAssetEnumerator<MarketId> for Asset<MarketId> {

primitives/src/types.rs

@@ -54,6 +54,9 @@ pub type BlockNumber = u64;
 /// The index of the category for a `CategoricalOutcome` asset.
 pub type CategoryIndex = u16;
 
+/// The type used to identify combinatorial outcomes.
+pub type CombinatorialId = [u8; 32];
+
 /// Multihash for digest sizes up to 384 bit.
 /// The multicodec encoding the hash algorithm uses only 1 byte,
 /// effecitvely limiting the number of available hash types.

zrml/combo/Cargo.toml

@@ -4,6 +4,7 @@ frame-benchmarking = { workspace = true, optional = true }
 frame-support = { workspace = true }
 frame-system = { workspace = true }
 halo2curves = { workspace = true }
+orml-traits = { workspace = true }
 parity-scale-codec = { workspace = true, features = ["derive", "max-encoded-len"] }
 scale-info = { workspace = true, features = ["derive"] }
 sp-runtime = { workspace = true }

zrml/combo/src/lib.rs

@@ -29,23 +29,58 @@ pub use pallet::*;
 
 #[frame_support::pallet]
 mod pallet {
+    use crate::traits::CombinatorialIdManager;
     use core::marker::PhantomData;
     use frame_support::{
+        ensure,
         pallet_prelude::{IsType, StorageVersion},
-        require_transactional, transactional,
+        require_transactional, transactional, PalletId,
+    };
+    use frame_system::{
+        ensure_signed,
+        pallet_prelude::{BlockNumberFor, OriginFor},
+    };
+    use orml_traits::MultiCurrency;
+    use sp_runtime::{
+        traits::{AccountIdConversion, Get},
+        DispatchError, DispatchResult,
+    };
+    use zeitgeist_primitives::{
+        traits::MarketCommonsPalletApi,
+        types::{Asset, CombinatorialId},
     };
-    use frame_system::{ensure_signed, pallet_prelude::OriginFor};
-    use sp_runtime::DispatchResult;
 
     #[pallet::config]
     pub trait Config: frame_system::Config {
+        type CombinatorialIdManager: CombinatorialIdManager<
+                Asset = AssetOf<Self>,
+                MarketId = MarketIdOf<Self>,
+                CombinatorialId = CombinatorialId,
+            >;
+
+        type MarketCommons: MarketCommonsPalletApi<AccountId = Self::AccountId, BlockNumber = BlockNumberFor<Self>>;
+
+        type MultiCurrency: MultiCurrency<Self::AccountId, CurrencyId = AssetOf<Self>>;
+
+        #[pallet::constant]
+        type PalletId: Get<PalletId>;
+
         type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
     }
 
     #[pallet::pallet]
     #[pallet::storage_version(STORAGE_VERSION)]
     pub struct Pallet<T>(PhantomData<T>);
 
+    pub(crate) type AccountIdOf<T> = <T as frame_system::Config>::AccountId;
+    pub(crate) type AssetOf<T> = Asset<MarketIdOf<T>>;
+    pub(crate) type BalanceOf<T> =
+        <<T as Config>::MultiCurrency as MultiCurrency<AccountIdOf<T>>>::Balance;
+    pub(crate) type CombinatorialIdOf<T> =
+        <<T as Config>::CombinatorialIdManager as CombinatorialIdManager>::CombinatorialId;
+    pub(crate) type MarketIdOf<T> =
+        <<T as Config>::MarketCommons as MarketCommonsPalletApi>::MarketId;
+
     // TODO Types
     pub(crate) const STORAGE_VERSION: StorageVersion = StorageVersion::new(0);
 
@@ -58,36 +93,218 @@ mod pallet {
         T: Config, {}
 
     #[pallet::error]
-    pub enum Error<T> {}
+    pub enum Error<T> {
+        /// The specified partition is empty, contains overlaps or is too long.
+        InvalidPartition,
+
+        /// The specified collection ID is invalid.
+        InvalidCollectionId,
+    }
 
     #[pallet::call]
     impl<T: Config> Pallet<T> {
         #[pallet::call_index(0)]
         #[pallet::weight(0)] // TODO
         #[transactional]
-        pub fn split_position(origin: OriginFor<T>) -> DispatchResult {
-            let _ = ensure_signed(origin)?;
-            Self::do_split_position()
+        pub fn split_position(
+            origin: OriginFor<T>,
+            // TODO Abstract this into a separate type.
+            parent_collection_id: Option<CombinatorialIdOf<T>>,
+            market_id: MarketIdOf<T>,
+            partition: Vec<Vec<bool>>,
+            amount: BalanceOf<T>,
+        ) -> DispatchResult {
+            let who = ensure_signed(origin)?;
+            Self::do_split_position(who, parent_collection_id, market_id, partition, amount)
         }
 
         #[pallet::call_index(1)]
         #[pallet::weight(0)] // TODO
         #[transactional]
-        pub fn merge_position(origin: OriginFor<T>) -> DispatchResult {
-            let _ = ensure_signed(origin)?;
-            Self::do_merge_position()
+        pub fn merge_position(
+            origin: OriginFor<T>,
+            parent_collection_id: Option<CombinatorialIdOf<T>>,
+            market_id: MarketIdOf<T>,
+            partition: Vec<Vec<bool>>,
+            amount: BalanceOf<T>,
+        ) -> DispatchResult {
+            let who = ensure_signed(origin)?;
+            Self::do_merge_position(who, parent_collection_id, market_id, partition, amount)
         }
     }
 
     impl<T: Config> Pallet<T> {
         #[require_transactional]
-        fn do_split_position() -> DispatchResult {
+        fn do_split_position(
+            who: AccountIdOf<T>,
+            parent_collection_id: Option<CombinatorialIdOf<T>>,
+            market_id: MarketIdOf<T>,
+            partition: Vec<Vec<bool>>,
+            amount: BalanceOf<T>,
+        ) -> DispatchResult {
+            let market = T::MarketCommons::market(&market_id)?;
+            let collateral_token = market.base_asset;
+
+            let free_index_set = Self::free_index_set(parent_collection_id, market_id, &partition)?;
+
+            // Destroy/store the tokens to be split.
+            if free_index_set.iter().any(|&i| i) {
+                // Vertical split.
+                if let Some(pci) = parent_collection_id {
+                    // Split combinatorial token into higher level position. Destroy the tokens.
+                    let position_id =
+                        T::CombinatorialIdManager::get_position_id(collateral_token, pci);
+                    let position = Asset::CombinatorialToken(position_id);
+                    T::MultiCurrency::withdraw(position, &who, amount)?;
+                } else {
+                    // Split collateral into first level position. Store the collateral in the
+                    // pallet account. This is the legacy `buy_complete_set`.
+                    T::MultiCurrency::transfer(
+                        collateral_token,
+                        &who,
+                        &Self::account_id(),
+                        amount,
+                    )?;
+                }
+            } else {
+                // Horizontal split.
+                let remaining_index_set = free_index_set.into_iter().map(|i| !i).collect();
+                let position = Self::position_from_collection(
+                    parent_collection_id,
+                    market_id,
+                    remaining_index_set,
+                )?;
+                T::MultiCurrency::withdraw(position, &who, amount)?;
+            }
+
+            // Deposit the new tokens.
+            let position_ids = partition
+                .iter()
+                .cloned()
+                .map(|index_set| {
+                    Self::position_from_collection(parent_collection_id, market_id, index_set)
+                })
+                .collect::<Result<Vec<_>, _>>()?;
+            for &position in position_ids.iter() {
+                T::MultiCurrency::deposit(position, &who, amount)?;
+            }
+
             Ok(())
         }
 
         #[require_transactional]
-        fn do_merge_position() -> DispatchResult {
+        fn do_merge_position(
+            who: AccountIdOf<T>,
+            parent_collection_id: Option<CombinatorialIdOf<T>>,
+            market_id: MarketIdOf<T>,
+            partition: Vec<Vec<bool>>,
+            amount: BalanceOf<T>,
+        ) -> DispatchResult {
+            let market = T::MarketCommons::market(&market_id)?;
+            let collateral_token = market.base_asset;
+
+            let free_index_set = Self::free_index_set(parent_collection_id, market_id, &partition)?;
+
+            // Destory the old tokens.
+            let position_ids = partition
+                .iter()
+                .cloned()
+                .map(|index_set| {
+                    Self::position_from_collection(parent_collection_id, market_id, index_set)
+                })
+                .collect::<Result<Vec<_>, _>>()?;
+            for &position in position_ids.iter() {
+                T::MultiCurrency::withdraw(position, &who, amount)?;
+            }
+
+            // Destroy/store the tokens to be split.
+            if free_index_set.iter().any(|&i| i) {
+                // Vertical merge.
+                if let Some(pci) = parent_collection_id {
+                    // Merge combinatorial token into higher level position. Destroy the tokens.
+                    let position_id =
+                        T::CombinatorialIdManager::get_position_id(collateral_token, pci);
+                    let position = Asset::CombinatorialToken(position_id);
+                    T::MultiCurrency::deposit(position, &who, amount)?;
+                } else {
+                    // Merge first-level tokens into collateral. Move collateral from the pallet
+                    // account to the user's wallet. This is the legacy `sell_complete_set`.
+                    T::MultiCurrency::transfer(
+                        collateral_token,
+                        &Self::account_id(),
+                        &who,
+                        amount,
+                    )?;
+                }
+            } else {
+                // Horizontal merge.
+                let remaining_index_set = free_index_set.into_iter().map(|i| !i).collect();
+                let position = Self::position_from_collection(
+                    parent_collection_id,
+                    market_id,
+                    remaining_index_set,
+                )?;
+                T::MultiCurrency::deposit(position, &who, amount)?;
+            }
+
             Ok(())
         }
+
+        fn free_index_set(
+            parent_collection_id: Option<CombinatorialIdOf<T>>,
+            market_id: MarketIdOf<T>,
+            partition: &Vec<Vec<bool>>,
+        ) -> Result<Vec<bool>, DispatchError> {
+            let market = T::MarketCommons::market(&market_id)?;
+            let asset_count = market.outcomes() as usize;
+            let mut free_index_set = vec![true; asset_count];
+
+            for index_set in partition.iter() {
+                // Ensure that the partition is not trivial.
+                let ones = index_set.iter().fold(0usize, |acc, &val| acc + (val as usize));
+                ensure!(ones > 0, Error::<T>::InvalidPartition);
+                ensure!(ones < asset_count, Error::<T>::InvalidPartition);
+
+                // Ensure that `index_set` is disjoint from the previously iterated elements of the
+                // partition.
+                ensure!(
+                    free_index_set.iter().zip(index_set.iter()).all(|(i, j)| *i || !*j),
+                    Error::<T>::InvalidPartition
+                );
+
+                // Remove indices of `index_set` from `free_index_set`.
+                free_index_set =
+                    free_index_set.iter().zip(index_set.iter()).map(|(i, j)| *i && !*j).collect();
+            }
+
+            Ok(free_index_set)
+        }
+
+        fn position_from_collection(
+            parent_collection_id: Option<CombinatorialIdOf<T>>,
+            market_id: MarketIdOf<T>,
+            index_set: Vec<bool>,
+        ) -> Result<AssetOf<T>, DispatchError> {
+            let market = T::MarketCommons::market(&market_id)?;
+            let collateral_token = market.base_asset;
+
+            let collection_id = T::CombinatorialIdManager::get_collection_id(
+                parent_collection_id,
+                market_id,
+                index_set,
+                false, // TODO Expose this parameter!
+            )
+            .ok_or(Error::<T>::InvalidCollectionId)?;
+
+            let position_id =
+                T::CombinatorialIdManager::get_position_id(collateral_token, collection_id);
+            let asset = Asset::CombinatorialToken(position_id);
+
+            Ok(asset)
+        }
+
+        fn account_id() -> T::AccountId {
+            T::PalletId::get().into_account_truncating()
+        }
     }
 }

zrml/combo/src/traits/id_manager.rs → zrml/combo/src/traits/combinatorial_id_manager.rs

@@ -1,20 +1,20 @@
 use sp_runtime::DispatchError;
 
-pub(crate) trait IdManager {
+pub(crate) trait CombinatorialIdManager {
     type Asset;
     type MarketId;
-    type Id;
+    type CombinatorialId;
 
     // TODO Replace `Vec<bool>` with a more effective bit mask type.
     fn get_collection_id(
-        parent_collection_id: Option<Self::Id>,
+        parent_collection_id: Option<Self::CombinatorialId>,
         market_id: Self::MarketId,
         index_set: Vec<bool>,
         force_max_work: bool,
-    ) -> Option<Self::Id>;
+    ) -> Option<Self::CombinatorialId>;
 
     fn get_position_id(
         collateral: Self::Asset,
-        collection_id: Self::Id,
-    ) -> Option<Self::Id>;
+        collection_id: Self::CombinatorialId,
+    ) -> Self::CombinatorialId;
 }

zrml/combo/src/traits/mod.rs

@@ -1,3 +1,3 @@
-mod id_manager;
+mod combinatorial_id_manager;
 
-pub(crate) use id_manager::IdManager;
+pub(crate) use combinatorial_id_manager::CombinatorialIdManager;