// Copyright (c) 2020-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_INDEX_COINSTATSINDEX_H
#define BITCOIN_INDEX_COINSTATSINDEX_H

#include <arith_uint256.h>
#include <consensus/amount.h>
#include <crypto/muhash.h>
#include <index/base.h>
#include <interfaces/chain.h>
#include <uint256.h>

#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>

class CBlockIndex;
namespace kernel {
struct CCoinsStats;
}

static constexpr bool DEFAULT_COINSTATSINDEX{false};

/**
 * CoinStatsIndex maintains statistics on the UTXO set.
 */
class CoinStatsIndex final : public BaseIndex
{
private:
    std::unique_ptr<BaseIndex::DB> m_db;

    MuHash3072 m_muhash;
    uint64_t m_transaction_output_count{0};
    uint64_t m_bogo_size{0};
    CAmount m_total_amount{0};
    CAmount m_total_subsidy{0};
    arith_uint256 m_total_prevout_spent_amount{0};
    arith_uint256 m_total_new_outputs_ex_coinbase_amount{0};
    arith_uint256 m_total_coinbase_amount{0};
    CAmount m_total_unspendables_genesis_block{0};
    CAmount m_total_unspendables_bip30{0};
    CAmount m_total_unspendables_scripts{0};
    CAmount m_total_unspendables_unclaimed_rewards{0};

    uint256 m_current_block_hash{};

    [[nodiscard]] bool RevertBlock(const interfaces::BlockInfo& block);

    bool AllowPrune() const override { return true; }

protected:
    bool CustomInit(const std::optional<interfaces::BlockRef>& block) override;

    bool CustomCommit(CDBBatch& batch) override;

    bool CustomAppend(const interfaces::BlockInfo& block) override;

    bool CustomRemove(const interfaces::BlockInfo& block) override;

    BaseIndex::DB& GetDB() const override { return *m_db; }

public:
    // Constructs the index, which becomes available to be queried.
    explicit CoinStatsIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory = false, bool f_wipe = false);

    interfaces::Chain::NotifyOptions CustomOptions() override;

    // Look up stats for a specific block using CBlockIndex
    std::optional<kernel::CCoinsStats> LookUpStats(const CBlockIndex& block_index) const;
};

/// The global UTXO set hash object.
extern std::unique_ptr<CoinStatsIndex> g_coin_stats_index;

#endif // BITCOIN_INDEX_COINSTATSINDEX_H