Add rules and unfounding to society. (#4671)

* Add rules and unfounding to society.

* Docs and event

* Extra bit of docs.

* Cunningly reduce complexity

* Remove candidates when unfounding.

* Remove suspended candidates when unfounding, too.

substrate/frame/democracy/src/lib.rs

@@ -497,7 +497,7 @@ decl_module! {
 		}
 
 		/// Vote in a referendum on behalf of a stash. If `vote.is_aye()`, the vote is to enact
-		/// the proposal;  otherwise it is a vote to keep the status quo.
+		/// the proposal; otherwise it is a vote to keep the status quo.
 		///
 		/// # <weight>
 		/// - O(1).

substrate/frame/society/src/lib.rs

@@ -228,6 +228,7 @@
 //! * `defender_vote` - A member can vote to approve or reject a defender's continued membership
 //! to the society.
 //! * `payout` - A member can claim their first matured payment.
+//! * `unfound` - Allow the founder to unfound the society when they are the only member.
 //!
 //! #### For Super Users
 //!
@@ -254,7 +255,7 @@ use sp_std::prelude::*;
 use codec::{Encode, Decode};
 use sp_runtime::{Percent, ModuleId, RuntimeDebug,
 	traits::{
-		StaticLookup, AccountIdConversion, Saturating, Zero, IntegerSquareRoot,
+		StaticLookup, AccountIdConversion, Saturating, Zero, IntegerSquareRoot, Hash,
 		TrailingZeroInput, CheckedSub, EnsureOrigin
 	}
 };
@@ -404,6 +405,10 @@ decl_storage! {
 		pub Founder get(founder) build(|config: &GenesisConfig<T, I>| config.members.first().cloned()):
 			Option<T::AccountId>;
 
+		/// A hash of the rules of this society concerning membership. Can only be set once and
+		/// only by the founder.
+		pub Rules get(rules): Option<T::Hash>;
+
 		/// The current set of candidates; bidders that are attempting to become members.
 		pub Candidates get(candidates): Vec<Bid<T::AccountId, BalanceOf<T, I>>>;
 
@@ -805,6 +810,7 @@ decl_module! {
 		/// Parameters:
 		/// - `founder` - The first member and head of the newly founded society.
 		/// - `max_members` - The initial max number of members for the society.
+		/// - `rules` - The rules of this society concerning membership.
 		///
 		/// # <weight>
 		/// - Two storage mutates to set `Head` and `Founder`. O(1)
@@ -814,7 +820,7 @@ decl_module! {
 		/// Total Complexity: O(1)
 		/// # </weight>
 		#[weight = SimpleDispatchInfo::FixedNormal(10_000)]
-		fn found(origin, founder: T::AccountId, max_members: u32) {
+		fn found(origin, founder: T::AccountId, max_members: u32, rules: Vec<u8>) {
 			T::FounderSetOrigin::ensure_origin(origin)?;
 			ensure!(!<Head<T, I>>::exists(), Error::<T, I>::AlreadyFounded);
 			ensure!(max_members > 1, Error::<T, I>::MaxMembers);
@@ -823,8 +829,38 @@ decl_module! {
 			Self::add_member(&founder)?;
 			<Head<T, I>>::put(&founder);
 			<Founder<T, I>>::put(&founder);
+			Rules::<T, I>::put(T::Hashing::hash(&rules));
 			Self::deposit_event(RawEvent::Founded(founder));
 		}
+
+		/// Anull the founding of the society.
+		///
+		/// The dispatch origin for this call must be Signed, and the signing account must be both
+		/// the `Founder` and the `Head`. This implies that it may only be done when there is one
+		/// member.
+		///
+		/// # <weight>
+		/// - Two storage reads O(1).
+		/// - Four storage removals O(1).
+		/// - One event.
+		///
+		/// Total Complexity: O(1)
+		/// # </weight>
+		#[weight = SimpleDispatchInfo::FixedNormal(20_000)]
+		fn unfound(origin) {
+			let founder = ensure_signed(origin)?;
+			ensure!(Founder::<T, I>::get() == Some(founder.clone()), Error::<T, I>::NotFounder);
+			ensure!(Head::<T, I>::get() == Some(founder.clone()), Error::<T, I>::NotHead);
+
+			Members::<T, I>::kill();
+			Head::<T, I>::kill();
+			Founder::<T, I>::kill();
+			Rules::<T, I>::kill();
+			Candidates::<T, I>::kill();
+			SuspendedCandidates::<T, I>::remove_all();
+			Self::deposit_event(RawEvent::Unfounded(founder));
+		}
+
 		/// Allow suspension judgement origin to make judgement on a suspended member.
 		///
 		/// If a suspended member is forgiven, we simply add them back as a member, not affecting
@@ -1047,6 +1083,10 @@ decl_error! {
 		NotCandidate,
 		/// Too many members in the society.
 		MaxMembers,
+		/// The caller is not the founder.
+		NotFounder,
+		/// The caller is not the head.
+		NotHead,
 	}
 }
 
@@ -1087,6 +1127,8 @@ decl_event! {
 		DefenderVote(AccountId, bool),
 		/// A new max member count has been set
 		NewMaxMembers(u32),
+		/// Society is unfounded.
+		Unfounded(AccountId),
 	}
 }
 
@@ -1224,16 +1266,16 @@ impl<T: Trait<I>, I: Instance> Module<T, I> {
 		ensure!(Self::head() != Some(m.clone()), Error::<T, I>::Head);
 		ensure!(Self::founder() != Some(m.clone()), Error::<T, I>::Founder);
 
-		<Members<T, I>>::mutate(|members|
-			match members.binary_search(&m) {
-				Err(_) => Err(Error::<T, I>::NotMember)?,
-				Ok(i) => {
-					members.remove(i);
-					T::MembershipChanged::change_members_sorted(&[], &[m.clone()], members);
-					Ok(())
-				}
+		let mut members = <Members<T, I>>::get();
+		match members.binary_search(&m) {
+			Err(_) => Err(Error::<T, I>::NotMember)?,
+			Ok(i) => {
+				members.remove(i);
+				T::MembershipChanged::change_members_sorted(&[], &[m.clone()], &members[..]);
+				<Members<T, I>>::put(members);
+				Ok(())
 			}
-		)
+		}
 	}
 
 	/// End the current period and begin a new one.

substrate/frame/society/src/tests.rs

@@ -21,6 +21,7 @@ use mock::*;
 
 use frame_support::{assert_ok, assert_noop};
 use sp_runtime::traits::BadOrigin;
+use sp_core::blake2_256;
 
 #[test]
 fn founding_works() {
@@ -31,9 +32,9 @@ fn founding_works() {
 		assert_eq!(Society::pot(), 0);
 		// Account 1 is set as the founder origin
 		// Account 5 cannot start a society
-		assert_noop!(Society::found(Origin::signed(5), 20, 100), BadOrigin);
+		assert_noop!(Society::found(Origin::signed(5), 20, 100, vec![]), BadOrigin);
 		// Account 1 can start a society, where 10 is the founding member
-		assert_ok!(Society::found(Origin::signed(1), 10, 100));
+		assert_ok!(Society::found(Origin::signed(1), 10, 100, b"be cool".to_vec()));
 		// Society members only include 10
 		assert_eq!(Society::members(), vec![10]);
 		// 10 is the head of the society
@@ -42,11 +43,39 @@ fn founding_works() {
 		assert_eq!(Society::founder(), Some(10));
 		// 100 members max
 		assert_eq!(Society::max_members(), 100);
+		// rules are correct
+		assert_eq!(Society::rules(), Some(blake2_256(b"be cool").into()));
 		// Pot grows after first rotation period
 		run_to_block(4);
 		assert_eq!(Society::pot(), 1000);
 		// Cannot start another society
-		assert_noop!(Society::found(Origin::signed(1), 20, 100), Error::<Test, _>::AlreadyFounded);
+		assert_noop!(
+			Society::found(Origin::signed(1), 20, 100, vec![]),
+			Error::<Test, _>::AlreadyFounded
+		);
+	});
+}
+
+#[test]
+fn unfounding_works() {
+	EnvBuilder::new().with_max_members(0).with_members(vec![]).execute(|| {
+		// Account 1 sets the founder...
+		assert_ok!(Society::found(Origin::signed(1), 10, 100, vec![]));
+		// Account 2 cannot unfound it as it's not the founder.
+		assert_noop!(Society::unfound(Origin::signed(2)), Error::<Test, _>::NotFounder);
+		// Account 10 can, though.
+		assert_ok!(Society::unfound(Origin::signed(10)));
+
+		// 1 sets the founder to 20 this time
+		assert_ok!(Society::found(Origin::signed(1), 20, 100, vec![]));
+		// Bring in a new member...
+		assert_ok!(Society::bid(Origin::signed(10), 0));
+		run_to_block(4);
+		assert_ok!(Society::vote(Origin::signed(20), 10, true));
+		run_to_block(8);
+
+		// Unfounding won't work now, even though it's from 20.
+		assert_noop!(Society::unfound(Origin::signed(20)), Error::<Test, _>::NotHead);
 	});
 }