mod.rs

// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.

// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.

//! # Parachain `Crowdloaning` pallet
//!
//! The point of this pallet is to allow parachain projects to offer the ability to help fund a
//! deposit for the parachain. When the crowdloan has ended, the funds are returned.
//!
//! Each fund has a child-trie which stores all contributors account IDs together with the amount
//! they contributed; the root of this can then be used by the parachain to allow contributors to
//! prove that they made some particular contribution to the project (e.g. to be rewarded through
//! some token or badge). The trie is retained for later (efficient) redistribution back to the
//! contributors.
//!
//! Contributions must be of at least `MinContribution` (to account for the resources taken in
//! tracking contributions), and may never tally greater than the fund's `cap`, set and fixed at the
//! time of creation. The `create` call may be used to create a new fund. In order to do this, then
//! a deposit must be paid of the amount `SubmissionDeposit`. Substantial resources are taken on
//! the main trie in tracking a fund and this accounts for that.
//!
//! Funds may be set up during an auction period; their closing time is fixed at creation (as a
//! block number) and if the fund is not successful by the closing time, then it can be dissolved.
//! Funds may span multiple auctions, and even auctions that sell differing periods. However, for a
//! fund to be active in bidding for an auction, it *must* have had *at least one bid* since the end
//! of the last auction. Until a fund takes a further bid following the end of an auction, then it
//! will be inactive.
//!
//! Contributors will get a refund of their contributions from completed funds before the crowdloan
//! can be dissolved.
//!
//! Funds may accept contributions at any point before their success or end. When a parachain
//! slot auction enters its ending period, then parachains will each place a bid; the bid will be
//! raised once per block if the parachain had additional funds contributed since the last bid.
//!
//! Successful funds remain tracked (in the `Funds` storage item and the associated child trie) as
//! long as the parachain remains active. Users can withdraw their funds once the slot is completed
//! and funds are returned to the crowdloan account.

pub mod migration;

use crate::{
	slot_range::SlotRange,
	traits::{Auctioneer, Registrar},
};
use frame_support::{
	ensure,
	pallet_prelude::{DispatchResult, Weight},
	storage::{child, ChildTriePrefixIterator},
	traits::{
		Currency,
		ExistenceRequirement::{self, AllowDeath, KeepAlive},
		Get, ReservableCurrency,
	},
	Identity, PalletId,
};
use frame_system::pallet_prelude::BlockNumberFor;
pub use pallet::*;
use parity_scale_codec::{Decode, Encode};
use primitives::Id as ParaId;
use scale_info::TypeInfo;
use sp_runtime::{
	traits::{
		AccountIdConversion, CheckedAdd, Hash, IdentifyAccount, One, Saturating, Verify, Zero,
	},
	MultiSignature, MultiSigner, RuntimeDebug,
};
use sp_std::vec::Vec;

type CurrencyOf<T> = <<T as Config>::Auctioneer as Auctioneer<BlockNumberFor<T>>>::Currency;
type LeasePeriodOf<T> = <<T as Config>::Auctioneer as Auctioneer<BlockNumberFor<T>>>::LeasePeriod;
type BalanceOf<T> = <CurrencyOf<T> as Currency<<T as frame_system::Config>::AccountId>>::Balance;

#[allow(dead_code)]
type NegativeImbalanceOf<T> =
	<CurrencyOf<T> as Currency<<T as frame_system::Config>::AccountId>>::NegativeImbalance;

type FundIndex = u32;

pub trait WeightInfo {
	fn create() -> Weight;
	fn contribute() -> Weight;
	fn withdraw() -> Weight;
	fn refund(k: u32) -> Weight;
	fn dissolve() -> Weight;
	fn edit() -> Weight;
	fn add_memo() -> Weight;
	fn on_initialize(n: u32) -> Weight;
	fn poke() -> Weight;
}

pub struct TestWeightInfo;
impl WeightInfo for TestWeightInfo {
	fn create() -> Weight {
		Weight::zero()
	}
	fn contribute() -> Weight {
		Weight::zero()
	}
	fn withdraw() -> Weight {
		Weight::zero()
	}
	fn refund(_k: u32) -> Weight {
		Weight::zero()
	}
	fn dissolve() -> Weight {
		Weight::zero()
	}
	fn edit() -> Weight {
		Weight::zero()
	}
	fn add_memo() -> Weight {
		Weight::zero()
	}
	fn on_initialize(_n: u32) -> Weight {
		Weight::zero()
	}
	fn poke() -> Weight {
		Weight::zero()
	}
}

#[derive(Encode, Decode, Copy, Clone, PartialEq, Eq, RuntimeDebug, TypeInfo)]
pub enum LastContribution<BlockNumber> {
	Never,
	PreEnding(u32),
	Ending(BlockNumber),
}

/// Information on a funding effort for a pre-existing parachain. We assume that the parachain ID
/// is known as it's used for the key of the storage item for which this is the value (`Funds`).
#[derive(Encode, Decode, Clone, PartialEq, Eq, RuntimeDebug, TypeInfo)]
#[codec(dumb_trait_bound)]
pub struct FundInfo<AccountId, Balance, BlockNumber, LeasePeriod> {
	/// The owning account who placed the deposit.
	pub depositor: AccountId,
	/// An optional verifier. If exists, contributions must be signed by verifier.
	pub verifier: Option<MultiSigner>,
	/// The amount of deposit placed.
	pub deposit: Balance,
	/// The total amount raised.
	pub raised: Balance,
	/// Block number after which the funding must have succeeded. If not successful at this number
	/// then everyone may withdraw their funds.
	pub end: BlockNumber,
	/// A hard-cap on the amount that may be contributed.
	pub cap: Balance,
	/// The most recent block that this had a contribution. Determines if we make a bid or not.
	/// If this is `Never`, this fund has never received a contribution.
	/// If this is `PreEnding(n)`, this fund received a contribution sometime in auction
	/// number `n` before the ending period.
	/// If this is `Ending(n)`, this fund received a contribution during the current ending period,
	/// where `n` is how far into the ending period the contribution was made.
	pub last_contribution: LastContribution<BlockNumber>,
	/// First lease period in range to bid on; it's actually a `LeasePeriod`, but that's the same
	/// type as `BlockNumber`.
	pub first_period: LeasePeriod,
	/// Last lease period in range to bid on; it's actually a `LeasePeriod`, but that's the same
	/// type as `BlockNumber`.
	pub last_period: LeasePeriod,
	/// Unique index used to represent this fund.
	pub fund_index: FundIndex,
}

#[frame_support::pallet]
pub mod pallet {
	use super::*;
	use frame_support::pallet_prelude::*;
	use frame_system::{ensure_root, ensure_signed, pallet_prelude::*};

	/// The current storage version.
	const STORAGE_VERSION: StorageVersion = StorageVersion::new(2);

	#[pallet::pallet]
	#[pallet::without_storage_info]
	#[pallet::storage_version(STORAGE_VERSION)]
	pub struct Pallet<T>(_);

	#[pallet::config]
	pub trait Config: frame_system::Config {
		type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;

		/// `PalletId` for the crowdloan pallet. An appropriate value could be
		/// `PalletId(*b"py/cfund")`
		#[pallet::constant]
		type PalletId: Get<PalletId>;

		/// The amount to be held on deposit by the depositor of a crowdloan.