// Copyright (c) 2009-2010 Satoshi Nakamoto

// Copyright (c) 2009-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_KERNEL_CHAINPARAMS_H

#define BITCOIN_KERNEL_CHAINPARAMS_H

#include <consensus/params.h>

#include <kernel/messagestartchars.h>

#include <primitives/block.h>

#include <uint256.h>

#include <util/chaintype.h>

#include <util/hash_type.h>

#include <util/vector.h>

#include <cstddef>

#include <cstdint>

#include <memory>

#include <optional>

#include <string>

#include <unordered_map>

#include <vector>

struct AssumeutxoHash : public BaseHash<uint256> {

    explicit AssumeutxoHash(const uint256& hash) : BaseHash(hash) {}

};

/**

 * Holds configuration for use during UTXO snapshot load and validation. The contents

 * here are security critical, since they dictate which UTXO snapshots are recognized

 * as valid.

 */

struct AssumeutxoData {

    int height;

    //! The expected hash of the deserialized UTXO set.

    AssumeutxoHash hash_serialized;

    //! Used to populate the m_chain_tx_count value, which is used during BlockManager::LoadBlockIndex().

    //!

    //! We need to hardcode the value here because this is computed cumulatively using block data,

    //! which we do not necessarily have at the time of snapshot load.

    uint64_t m_chain_tx_count;

    //! The hash of the base block for this snapshot. Used to refer to assumeutxo data

    //! prior to having a loaded blockindex.

    uint256 blockhash;

};

/**

 * Holds various statistics on transactions within a chain. Used to estimate

 * verification progress during chain sync.

 *

 * See also: CChainParams::TxData, GuessVerificationProgress.

 */

struct ChainTxData {

    int64_t nTime;    //!< UNIX timestamp of last known number of transactions

    uint64_t tx_count; //!< total number of transactions between genesis and that timestamp

    double dTxRate;   //!< estimated number of transactions per second after that timestamp

};

//! Configuration for headers sync memory usage.

struct HeadersSyncParams {

    //! Distance in blocks between header commitments.

    size_t commitment_period{0};

    //! Minimum number of validated headers to accumulate in the redownload

    //! buffer before feeding them into the permanent block index.

    size_t redownload_buffer_size{0};

};

/**

 * CChainParams defines various tweakable parameters of a given instance of the

 * Bitcoin system.

 */

class CChainParams

{

public:

    enum Base58Type {

        PUBKEY_ADDRESS,

        SCRIPT_ADDRESS,

        SECRET_KEY,

        EXT_PUBLIC_KEY,

        EXT_SECRET_KEY,

        MAX_BASE58_TYPES

    };

    const Consensus::Params& GetConsensus() const { return consensus; }

    const MessageStartChars& MessageStart() const { return pchMessageStart; }

    uint16_t GetDefaultPort() const { return nDefaultPort; }

    std::vector<int> GetAvailableSnapshotHeights() const;

    const CBlock& GenesisBlock() const { return genesis; }

    /** Default value for -checkmempool and -checkblockindex argument */

    bool DefaultConsistencyChecks() const { return fDefaultConsistencyChecks; }

    /** If this chain is exclusively used for testing */

    bool IsTestChain() const { return m_chain_type != ChainType::MAIN; }

    /** If this chain allows time to be mocked */

    bool IsMockableChain() const { return m_is_mockable_chain; }

    uint64_t PruneAfterHeight() const { return nPruneAfterHeight; }

    /** Minimum free space (in GB) needed for data directory */

    uint64_t AssumedBlockchainSize() const { return m_assumed_blockchain_size; }

    /** Minimum free space (in GB) needed for data directory when pruned; Does not include prune target*/

    uint64_t AssumedChainStateSize() const { return m_assumed_chain_state_size; }

    /** Whether it is possible to mine blocks on demand (no retargeting) */

    bool MineBlocksOnDemand() const { return consensus.fPowNoRetargeting; }

    /** Return the chain type string */

    std::string GetChainTypeString() const { return ChainTypeToString(m_chain_type); }

    /** Return the chain type */

    ChainType GetChainType() const { return m_chain_type; }

    /** Return the list of hostnames to look up for DNS seeds */

    const std::vector<std::string>& DNSSeeds() const { return vSeeds; }

    const std::vector<unsigned char>& Base58Prefix(Base58Type type) const { return base58Prefixes[type]; }

    const std::string& Bech32HRP() const { return bech32_hrp; }

    const std::vector<uint8_t>& FixedSeeds() const { return vFixedSeeds; }

    const HeadersSyncParams& HeadersSync() const { return m_headers_sync_params; }

    std::optional<AssumeutxoData> AssumeutxoForHeight(int height) const

    {

        return FindFirst(m_assumeutxo_data, [&](const auto& d) { return d.height == height; });

    }

    std::optional<AssumeutxoData> AssumeutxoForBlockhash(const uint256& blockhash) const

    {

        return FindFirst(m_assumeutxo_data, [&](const auto& d) { return d.blockhash == blockhash; });

    }

    const ChainTxData& TxData() const { return chainTxData; }

    /**

     * VersionBitsParameters holds activation parameters

     */

    struct VersionBitsParameters {

        int64_t start_time;

        int64_t timeout;

        int min_activation_height;

    };

    struct DeploymentOptions {

        std::unordered_map<Consensus::DeploymentPos, VersionBitsParameters> version_bits_parameters{};

        std::unordered_map<Consensus::BuriedDeployment, int> activation_heights{};

    };

    /**

     * SigNetOptions holds configurations for creating a signet CChainParams.

     */

    struct SigNetOptions {

        DeploymentOptions dep_opts{};

        std::optional<std::vector<uint8_t>> challenge{};

        std::optional<std::vector<std::string>> seeds{};

    };

    /**

     * RegTestOptions holds configurations for creating a regtest CChainParams.

     */

    struct RegTestOptions {

        DeploymentOptions dep_opts{};

        bool fastprune{false};

        bool enforce_bip94{false};

    };

    struct MainNetOptions {

        DeploymentOptions dep_opts{};

    };

    struct TestNetOptions {

        DeploymentOptions dep_opts{};

    };

    static std::unique_ptr<const CChainParams> RegTest(const RegTestOptions& options);

    static std::unique_ptr<const CChainParams> RegTest() { const RegTestOptions opts{}; return RegTest(opts); }

    static std::unique_ptr<const CChainParams> SigNet(const SigNetOptions& options);

    static std::unique_ptr<const CChainParams> SigNet() { const SigNetOptions opts{}; return SigNet(opts); }

    static std::unique_ptr<const CChainParams> Main(const MainNetOptions& options);

    static std::unique_ptr<const CChainParams> Main() { const MainNetOptions opts{}; return Main(opts); }

    static std::unique_ptr<const CChainParams> TestNet(const TestNetOptions& options);

    static std::unique_ptr<const CChainParams> TestNet() { const TestNetOptions opts{}; return TestNet(opts); }

    static std::unique_ptr<const CChainParams> TestNet4(const TestNetOptions& options);

    static std::unique_ptr<const CChainParams> TestNet4() { const TestNetOptions opts{}; return TestNet4(opts); }

protected:

    CChainParams() = default;

    Consensus::Params consensus;

    MessageStartChars pchMessageStart;

    uint16_t nDefaultPort;

    uint64_t nPruneAfterHeight;

    uint64_t m_assumed_blockchain_size;

    uint64_t m_assumed_chain_state_size;

    std::vector<std::string> vSeeds;

    std::vector<unsigned char> base58Prefixes[MAX_BASE58_TYPES];

    std::string bech32_hrp;

    ChainType m_chain_type;

    CBlock genesis;

    std::vector<uint8_t> vFixedSeeds;

    bool fDefaultConsistencyChecks;

    bool m_is_mockable_chain;

    std::vector<AssumeutxoData> m_assumeutxo_data;

    ChainTxData chainTxData;

    HeadersSyncParams m_headers_sync_params;

    void ApplyDeploymentOptions(const DeploymentOptions& opts);

};

std::optional<ChainType> GetNetworkForMagic(const MessageStartChars& pchMessageStart);

#endif // BITCOIN_KERNEL_CHAINPARAMS_H