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// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program 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.

// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.

//! Proof utilities
use crate::{CompactProof, StorageProof};
use sp_runtime::traits::Block as BlockT;
use sp_state_machine::{KeyValueStates, KeyValueStorageLevel};
use sp_storage::ChildInfo;

/// Interface for providing block proving utilities.
pub trait ProofProvider<Block: BlockT> {
	/// Reads storage value at a given block + key, returning read proof.
	fn read_proof(
		&self,
		hash: Block::Hash,
		keys: &mut dyn Iterator<Item = &[u8]>,
	) -> sp_blockchain::Result<StorageProof>;

	/// Reads child storage value at a given block + storage_key + key, returning
	/// read proof.
	fn read_child_proof(
		&self,
		hash: Block::Hash,
		child_info: &ChildInfo,
		keys: &mut dyn Iterator<Item = &[u8]>,
	) -> sp_blockchain::Result<StorageProof>;

	/// Execute a call to a contract on top of state in a block of given hash
	/// AND returning execution proof.
	///
	/// No changes are made.
	fn execution_proof(
		&self,
		hash: Block::Hash,
		method: &str,
		call_data: &[u8],
	) -> sp_blockchain::Result<(Vec<u8>, StorageProof)>;

	/// Given a `Hash` iterate over all storage values starting at `start_keys`.
	/// Last `start_keys` element contains last accessed key value.
	/// With multiple `start_keys`, first `start_keys` element is
	/// the current storage key of of the last accessed child trie.
	/// at last level the value to start at exclusively.
	/// Proofs is build until size limit is reached and always include at
	/// least one key following `start_keys`.
	/// Returns combined proof and the numbers of collected keys.
	fn read_proof_collection(
		&self,
		hash: Block::Hash,
		start_keys: &[Vec<u8>],
		size_limit: usize,
	) -> sp_blockchain::Result<(CompactProof, u32)>;

	/// Given a `Hash` iterate over all storage values starting at `start_key`.
	/// Returns collected keys and values.
	/// Returns the collected keys values content of the top trie followed by the
	/// collected keys values of child tries.
	/// Only child tries with their root part of the collected content or
	/// related to `start_key` are attached.
	/// For each collected state a boolean indicates if state reach
	/// end.
	fn storage_collection(
		&self,
		hash: Block::Hash,
		start_key: &[Vec<u8>],
		size_limit: usize,
	) -> sp_blockchain::Result<Vec<(KeyValueStorageLevel, bool)>>;

	/// Verify read storage proof for a set of keys.
	/// Returns collected key-value pairs and a the nested state
	/// depth of current iteration or 0 if completed.
	fn verify_range_proof(
		&self,
		root: Block::Hash,
		proof: CompactProof,
		start_keys: &[Vec<u8>],
	) -> sp_blockchain::Result<(KeyValueStates, usize)>;
}