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// Copyright (C) 2019-2021 Aleo Systems Inc.
// This file is part of the snarkVM library.

// The snarkVM library 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.

// The snarkVM library 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 the snarkVM library. If not, see <https://www.gnu.org/licenses/>.

use crate::traits::{BlockScheme, Transaction};

use std::{path::Path, sync::Arc};

#[allow(clippy::len_without_is_empty)]
pub trait LedgerScheme: Sized {
    type Block: BlockScheme;
    type Commitment;
    type MerkleParameters;
    type MerklePath;
    type MerkleTreeDigest;
    type SerialNumber;
    type Transaction: Transaction;

    /// Instantiates a new ledger with a genesis block.
    fn new(
        path: Option<&Path>,
        parameters: Arc<Self::MerkleParameters>,
        genesis_block: Self::Block,
    ) -> anyhow::Result<Self>;

    /// Returns the number of blocks including the genesis block
    fn len(&self) -> usize;

    /// Return the parameters used to construct the ledger Merkle tree.
    fn parameters(&self) -> &Arc<Self::MerkleParameters>;

    /// Return a digest of the latest ledger Merkle tree.
    fn digest(&self) -> Option<Self::MerkleTreeDigest>;

    /// Check that st_{ts} is a valid digest for some (past) ledger state.
    fn validate_digest(&self, digest: &Self::MerkleTreeDigest) -> bool;

    /// Returns true if the given commitment exists in the ledger.
    fn contains_cm(&self, cm: &Self::Commitment) -> bool;

    /// Returns true if the given serial number exists in the ledger.
    fn contains_sn(&self, sn: &Self::SerialNumber) -> bool;

    /// Returns true if the given memorandum exists in the ledger.
    fn contains_memo(&self, memo: &<Self::Transaction as Transaction>::Memorandum) -> bool;

    /// Returns the Merkle path to the latest ledger digest
    /// for a given commitment, if it exists in the ledger.
    fn prove_cm(&self, cm: &Self::Commitment) -> anyhow::Result<Self::MerklePath>;

    /// Returns true if the given Merkle path is a valid witness for
    /// the given ledger digest and commitment.
    fn verify_cm(
        parameters: &Arc<Self::MerkleParameters>,
        digest: &Self::MerkleTreeDigest,
        cm: &Self::Commitment,
        witness: &Self::MerklePath,
    ) -> bool;
}