// 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.

//! Substrate core types around sessions.

#![cfg_attr(not(feature = "std"), no_std)]

extern crate alloc;

use codec::{Decode, Encode};

#[cfg(feature = "std")]

use sp_api::ProvideRuntimeApi;

#[cfg(feature = "std")]

use sp_runtime::traits::Block as BlockT;

use alloc::vec::Vec;

use sp_core::RuntimeDebug;

use sp_staking::SessionIndex;

pub mod runtime_api;

pub use runtime_api::*;

/// Number of validators in a given session.

pub type ValidatorCount = u32;

/// Proof of membership of a specific key in a given session.

pub struct MembershipProof {

	/// The session index on which the specific key is a member.

	pub session: SessionIndex,

	/// Trie nodes of a merkle proof of session membership.

	pub trie_nodes: Vec<Vec<u8>>,

	/// The validator count of the session on which the specific key is a member.

	pub validator_count: ValidatorCount,

}

/// A utility trait to get a session number. This is implemented for

/// `MembershipProof` below to fetch the session number the given session

/// membership proof is for. It is useful when we need to deal with key owner

/// proofs generically (i.e. just typing against the `KeyOwnerProofSystem`

/// trait) but still restrict their capabilities.

pub trait GetSessionNumber {

	fn session(&self) -> SessionIndex;

}

/// A utility trait to get the validator count of a given session. This is

/// implemented for `MembershipProof` below and fetches the number of validators

/// in the session the membership proof is for. It is useful when we need to

/// deal with key owner proofs generically (i.e. just typing against the

/// `KeyOwnerProofSystem` trait) but still restrict their capabilities.

pub trait GetValidatorCount {

	fn validator_count(&self) -> ValidatorCount;

}

impl GetSessionNumber for sp_core::Void {

}

impl GetValidatorCount for sp_core::Void {

}

impl GetSessionNumber for MembershipProof {

}

impl GetValidatorCount for MembershipProof {

}

/// Generate the initial session keys with the given seeds, at the given block and store them in

/// the client's keystore.

#[cfg(feature = "std")]

	use sp_api::ApiExt;

	}