1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148

// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! The Pay trait and associated types.

use codec::{Decode, Encode, FullCodec, MaxEncodedLen};
use scale_info::TypeInfo;
use sp_core::{RuntimeDebug, TypedGet};
use sp_runtime::DispatchError;
use sp_std::fmt::Debug;

use super::{fungible, fungibles, Balance, Preservation::Expendable};

/// Can be implemented by `PayFromAccount` using a `fungible` impl, but can also be implemented with
/// XCM/Asset and made generic over assets.
pub trait Pay {
	/// The type by which we measure units of the currency in which we make payments.
	type Balance: Balance;
	/// The type by which we identify the beneficiaries to whom a payment may be made.
	type Beneficiary;
	/// The type for the kinds of asset that are going to be paid.
	///
	/// The unit type can be used here to indicate there's only one kind of asset to do payments
	/// with. When implementing, it should be clear from the context what that asset is.
	type AssetKind;
	/// An identifier given to an individual payment.
	type Id: FullCodec + MaxEncodedLen + TypeInfo + Clone + Eq + PartialEq + Debug + Copy;
	/// An error which could be returned by the Pay type
	type Error: Debug;
	/// Make a payment and return an identifier for later evaluation of success in some off-chain
	/// mechanism (likely an event, but possibly not on this chain).
	fn pay(
		who: &Self::Beneficiary,
		asset_kind: Self::AssetKind,
		amount: Self::Balance,
	) -> Result<Self::Id, Self::Error>;
	/// Check how a payment has proceeded. `id` must have been previously returned by `pay` for
	/// the result of this call to be meaningful. Once this returns anything other than
	/// `InProgress` for some `id` it must return `Unknown` rather than the actual result
	/// value.
	fn check_payment(id: Self::Id) -> PaymentStatus;
	/// Ensure that a call to pay with the given parameters will be successful if done immediately
	/// after this call. Used in benchmarking code.
	#[cfg(feature = "runtime-benchmarks")]
	fn ensure_successful(
		who: &Self::Beneficiary,
		asset_kind: Self::AssetKind,
		amount: Self::Balance,
	);
	/// Ensure that a call to `check_payment` with the given parameters will return either `Success`
	/// or `Failure`.
	#[cfg(feature = "runtime-benchmarks")]
	fn ensure_concluded(id: Self::Id);
}

/// Status for making a payment via the `Pay::pay` trait function.
#[derive(Encode, Decode, Eq, PartialEq, Clone, TypeInfo, MaxEncodedLen, RuntimeDebug)]
pub enum PaymentStatus {
	/// Payment is in progress. Nothing to report yet.
	InProgress,
	/// Payment status is unknowable. It may already have reported the result, or if not then
	/// it will never be reported successful or failed.
	Unknown,
	/// Payment happened successfully.
	Success,
	/// Payment failed. It may safely be retried.
	Failure,
}

/// Simple implementation of `Pay` which makes a payment from a "pot" - i.e. a single account.
pub struct PayFromAccount<F, A>(core::marker::PhantomData<(F, A)>);
impl<A, F> Pay for PayFromAccount<F, A>
where
	A: TypedGet,
	F: fungible::Mutate<A::Type>,
	A::Type: Eq,
{
	type Balance = F::Balance;
	type Beneficiary = A::Type;
	type AssetKind = ();
	type Id = ();
	type Error = DispatchError;
	fn pay(
		who: &Self::Beneficiary,
		_: Self::AssetKind,
		amount: Self::Balance,
	) -> Result<Self::Id, Self::Error> {
		<F as fungible::Mutate<_>>::transfer(&A::get(), who, amount, Expendable)?;
		Ok(())
	}
	fn check_payment(_: ()) -> PaymentStatus {
		PaymentStatus::Success
	}
	#[cfg(feature = "runtime-benchmarks")]
	fn ensure_successful(_: &Self::Beneficiary, _: Self::AssetKind, amount: Self::Balance) {
		<F as fungible::Mutate<_>>::mint_into(&A::get(), amount).unwrap();
	}
	#[cfg(feature = "runtime-benchmarks")]
	fn ensure_concluded(_: Self::Id) {}
}

/// Simple implementation of `Pay` for assets which makes a payment from a "pot" - i.e. a single
/// account.
pub struct PayAssetFromAccount<F, A>(core::marker::PhantomData<(F, A)>);
impl<A, F> frame_support::traits::tokens::Pay for PayAssetFromAccount<F, A>
where
	A: TypedGet,
	F: fungibles::Mutate<A::Type> + fungibles::Create<A::Type>,
	A::Type: Eq,
{
	type Balance = F::Balance;
	type Beneficiary = A::Type;
	type AssetKind = F::AssetId;
	type Id = ();
	type Error = DispatchError;
	fn pay(
		who: &Self::Beneficiary,
		asset: Self::AssetKind,
		amount: Self::Balance,
	) -> Result<Self::Id, Self::Error> {
		<F as fungibles::Mutate<_>>::transfer(asset, &A::get(), who, amount, Expendable)?;
		Ok(())
	}
	fn check_payment(_: ()) -> PaymentStatus {
		PaymentStatus::Success
	}
	#[cfg(feature = "runtime-benchmarks")]
	fn ensure_successful(_: &Self::Beneficiary, asset: Self::AssetKind, amount: Self::Balance) {
		<F as fungibles::Create<_>>::create(asset.clone(), A::get(), true, amount).unwrap();
		<F as fungibles::Mutate<_>>::mint_into(asset, &A::get(), amount).unwrap();
	}
	#[cfg(feature = "runtime-benchmarks")]
	fn ensure_concluded(_: Self::Id) {}
}