// Copyright (c) 2018-2022 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_INTERFACES_CHAIN_H

#define BITCOIN_INTERFACES_CHAIN_H

#include <blockfilter.h>

#include <common/settings.h>

#include <primitives/transaction.h> // For CTransactionRef

#include <util/result.h>

#include <functional>

#include <memory>

#include <optional>

#include <stddef.h>

#include <stdint.h>

#include <string>

#include <vector>

class ArgsManager;

class CBlock;

class CBlockUndo;

class CFeeRate;

class CRPCCommand;

class CScheduler;

class Coin;

class uint256;

enum class MemPoolRemovalReason;

enum class RBFTransactionState;

enum class ChainstateRole;

struct bilingual_str;

struct CBlockLocator;

struct FeeCalculation;

namespace node {

struct NodeContext;

} // namespace node

namespace interfaces {

class Handler;

class Wallet;

//! Helper for findBlock to selectively return pieces of block data. If block is

//! found, data will be returned by setting specified output variables. If block

//! is not found, output variables will keep their previous values.

class FoundBlock

{

public:

    FoundBlock& hash(uint256& hash) { m_hash = &hash; return *this; }

    FoundBlock& height(int& height) { m_height = &height; return *this; }

    FoundBlock& time(int64_t& time) { m_time = &time; return *this; }

    FoundBlock& maxTime(int64_t& max_time) { m_max_time = &max_time; return *this; }

    FoundBlock& mtpTime(int64_t& mtp_time) { m_mtp_time = &mtp_time; return *this; }

    //! Return whether block is in the active (most-work) chain.

    FoundBlock& inActiveChain(bool& in_active_chain) { m_in_active_chain = &in_active_chain; return *this; }

    //! Return locator if block is in the active chain.

    FoundBlock& locator(CBlockLocator& locator) { m_locator = &locator; return *this; }

    //! Return next block in the active chain if current block is in the active chain.

    FoundBlock& nextBlock(const FoundBlock& next_block) { m_next_block = &next_block; return *this; }

    //! Read block data from disk. If the block exists but doesn't have data

    //! (for example due to pruning), the CBlock variable will be set to null.

    FoundBlock& data(CBlock& data) { m_data = &data; return *this; }

    uint256* m_hash = nullptr;

    int* m_height = nullptr;

    int64_t* m_time = nullptr;

    int64_t* m_max_time = nullptr;

    int64_t* m_mtp_time = nullptr;

    bool* m_in_active_chain = nullptr;

    CBlockLocator* m_locator = nullptr;

    const FoundBlock* m_next_block = nullptr;

    CBlock* m_data = nullptr;

    mutable bool found = false;

};

//! Block data sent with blockConnected, blockDisconnected notifications.

struct BlockInfo {

    const uint256& hash;

    const uint256* prev_hash = nullptr;

    int height = -1;

    int file_number = -1;

    unsigned data_pos = 0;

    const CBlock* data = nullptr;

    const CBlockUndo* undo_data = nullptr;

    // The maximum time in the chain up to and including this block.

    // A timestamp that can only move forward.

    unsigned int chain_time_max{0};

    BlockInfo(const uint256& hash LIFETIMEBOUND) : hash(hash) {}

};

//! The action to be taken after updating a settings value.

//! WRITE indicates that the updated value must be written to disk,

//! while SKIP_WRITE indicates that the change will be kept in memory-only

//! without persisting it.

enum class SettingsAction {

    WRITE,

    SKIP_WRITE

};

using SettingsUpdate = std::function<std::optional<interfaces::SettingsAction>(common::SettingsValue&)>;

//! Interface giving clients (wallet processes, maybe other analysis tools in

//! the future) ability to access to the chain state, receive notifications,

//! estimate fees, and submit transactions.

//!

//! TODO: Current chain methods are too low level, exposing too much of the

//! internal workings of the bitcoin node, and not being very convenient to use.

//! Chain methods should be cleaned up and simplified over time. Examples:

//!

//! * The initMessages() and showProgress() methods which the wallet uses to send

//!   notifications to the GUI should go away when GUI and wallet can directly

//!   communicate with each other without going through the node

//!   (https://github.com/bitcoin/bitcoin/pull/15288#discussion_r253321096).

//!

//! * The handleRpc, registerRpcs, rpcEnableDeprecated methods and other RPC

//!   methods can go away if wallets listen for HTTP requests on their own

//!   ports instead of registering to handle requests on the node HTTP port.

//!

//! * Move fee estimation queries to an asynchronous interface and let the

//!   wallet cache it, fee estimation being driven by node mempool, wallet

//!   should be the consumer.

//!

//! * `guessVerificationProgress` and similar methods can go away if rescan

//!   logic moves out of the wallet, and the wallet just requests scans from the

//!   node (https://github.com/bitcoin/bitcoin/issues/11756)

class Chain

{

public:

    virtual ~Chain() = default;

    //! Get current chain height, not including genesis block (returns 0 if

    //! chain only contains genesis block, nullopt if chain does not contain

    //! any blocks)

    virtual std::optional<int> getHeight() = 0;

    //! Get block hash. Height must be valid or this function will abort.

    virtual uint256 getBlockHash(int height) = 0;

    //! Check that the block is available on disk (i.e. has not been

    //! pruned), and contains transactions.

    virtual bool haveBlockOnDisk(int height) = 0;

    //! Get locator for the current chain tip.

    virtual CBlockLocator getTipLocator() = 0;

    //! Return a locator that refers to a block in the active chain.

    //! If specified block is not in the active chain, return locator for the latest ancestor that is in the chain.

    virtual CBlockLocator getActiveChainLocator(const uint256& block_hash) = 0;

    //! Return height of the highest block on chain in common with the locator,

    //! which will either be the original block used to create the locator,

    //! or one of its ancestors.

    virtual std::optional<int> findLocatorFork(const CBlockLocator& locator) = 0;

    //! Returns whether a block filter index is available.

    virtual bool hasBlockFilterIndex(BlockFilterType filter_type) = 0;

    //! Returns whether any of the elements match the block via a BIP 157 block filter

    //! or std::nullopt if the block filter for this block couldn't be found.

    virtual std::optional<bool> blockFilterMatchesAny(BlockFilterType filter_type, const uint256& block_hash, const GCSFilter::ElementSet& filter_set) = 0;

    //! Return whether node has the block and optionally return block metadata

    //! or contents.

    virtual bool findBlock(const uint256& hash, const FoundBlock& block={}) = 0;

    //! Find first block in the chain with timestamp >= the given time

    //! and height >= than the given height, return false if there is no block

    //! with a high enough timestamp and height. Optionally return block

    //! information.

    virtual bool findFirstBlockWithTimeAndHeight(int64_t min_time, int min_height, const FoundBlock& block={}) = 0;

    //! Find ancestor of block at specified height and optionally return

    //! ancestor information.

    virtual bool findAncestorByHeight(const uint256& block_hash, int ancestor_height, const FoundBlock& ancestor_out={}) = 0;

    //! Return whether block descends from a specified ancestor, and

    //! optionally return ancestor information.

    virtual bool findAncestorByHash(const uint256& block_hash,

        const uint256& ancestor_hash,

        const FoundBlock& ancestor_out={}) = 0;

    //! Find most recent common ancestor between two blocks and optionally

    //! return block information.

    virtual bool findCommonAncestor(const uint256& block_hash1,

        const uint256& block_hash2,

        const FoundBlock& ancestor_out={},

        const FoundBlock& block1_out={},

        const FoundBlock& block2_out={}) = 0;

    //! Look up unspent output information. Returns coins in the mempool and in

    //! the current chain UTXO set. Iterates through all the keys in the map and

    //! populates the values.

    virtual void findCoins(std::map<COutPoint, Coin>& coins) = 0;

    //! Estimate fraction of total transactions verified if blocks up to

    //! the specified block hash are verified.

    virtual double guessVerificationProgress(const uint256& block_hash) = 0;

    //! Return true if data is available for all blocks in the specified range

    //! of blocks. This checks all blocks that are ancestors of block_hash in

    //! the height range from min_height to max_height, inclusive.

    virtual bool hasBlocks(const uint256& block_hash, int min_height = 0, std::optional<int> max_height = {}) = 0;

    //! Check if transaction is RBF opt in.

    virtual RBFTransactionState isRBFOptIn(const CTransaction& tx) = 0;

    //! Check if transaction is in mempool.

    virtual bool isInMempool(const uint256& txid) = 0;

    //! Check if transaction has descendants in mempool.

    virtual bool hasDescendantsInMempool(const uint256& txid) = 0;

    //! Transaction is added to memory pool, if the transaction fee is below the

    //! amount specified by max_tx_fee, and broadcast to all peers if relay is set to true.

    //! Return false if the transaction could not be added due to the fee or for another reason.

    virtual bool broadcastTransaction(const CTransactionRef& tx,

        const CAmount& max_tx_fee,

        bool relay,

        std::string& err_string) = 0;

    //! Calculate mempool ancestor and descendant counts for the given transaction.

    virtual void getTransactionAncestry(const uint256& txid, size_t& ancestors, size_t& descendants, size_t* ancestorsize = nullptr, CAmount* ancestorfees = nullptr) = 0;

    //! For each outpoint, calculate the fee-bumping cost to spend this outpoint at the specified

    //  feerate, including bumping its ancestors. For example, if the target feerate is 10sat/vbyte

    //  and this outpoint refers to a mempool transaction at 3sat/vbyte, the bump fee includes the

    //  cost to bump the mempool transaction to 10sat/vbyte (i.e. 7 * mempooltx.vsize). If that

    //  transaction also has, say, an unconfirmed parent with a feerate of 1sat/vbyte, the bump fee

    //  includes the cost to bump the parent (i.e. 9 * parentmempooltx.vsize).

    //

    //  If the outpoint comes from an unconfirmed transaction that is already above the target

    //  feerate or bumped by its descendant(s) already, it does not need to be bumped. Its bump fee

    //  is 0. Likewise, if any of the transaction's ancestors are already bumped by a transaction

    //  in our mempool, they are not included in the transaction's bump fee.

    //

    //  Also supported is bump-fee calculation in the case of replacements. If an outpoint

    //  conflicts with another transaction in the mempool, it is assumed that the goal is to replace

    //  that transaction. As such, the calculation will exclude the to-be-replaced transaction, but

    //  will include the fee-bumping cost. If bump fees of descendants of the to-be-replaced

    //  transaction are requested, the value will be 0. Fee-related RBF rules are not included as

    //  they are logically distinct.

    //

    //  Any outpoints that are otherwise unavailable from the mempool (e.g. UTXOs from confirmed

    //  transactions or transactions not yet broadcast by the wallet) are given a bump fee of 0.

    //

    //  If multiple outpoints come from the same transaction (which would be very rare because

    //  it means that one transaction has multiple change outputs or paid the same wallet using multiple

    //  outputs in the same transaction) or have shared ancestry, the bump fees are calculated

    //  independently, i.e. as if only one of them is spent. This may result in double-fee-bumping. This

    //  caveat can be rectified per use of the sister-function CalculateCombinedBumpFee(…).

    virtual std::map<COutPoint, CAmount> calculateIndividualBumpFees(const std::vector<COutPoint>& outpoints, const CFeeRate& target_feerate) = 0;

    //! Calculate the combined bump fee for an input set per the same strategy

    //  as in CalculateIndividualBumpFees(…).

    //  Unlike CalculateIndividualBumpFees(…), this does not return individual

    //  bump fees per outpoint, but a single bump fee for the shared ancestry.

    //  The combined bump fee may be used to correct overestimation due to

    //  shared ancestry by multiple UTXOs after coin selection.

    virtual std::optional<CAmount> calculateCombinedBumpFee(const std::vector<COutPoint>& outpoints, const CFeeRate& target_feerate) = 0;

    //! Get the node's package limits.

    //! Currently only returns the ancestor and descendant count limits, but could be enhanced to

    //! return more policy settings.

    virtual void getPackageLimits(unsigned int& limit_ancestor_count, unsigned int& limit_descendant_count) = 0;

    //! Check if transaction will pass the mempool's chain limits.

    virtual util::Result<void> checkChainLimits(const CTransactionRef& tx) = 0;

    //! Estimate smart fee.

    virtual CFeeRate estimateSmartFee(int num_blocks, bool conservative, FeeCalculation* calc = nullptr) = 0;

    //! Fee estimator max target.

    virtual unsigned int estimateMaxBlocks() = 0;

    //! Mempool minimum fee.

    virtual CFeeRate mempoolMinFee() = 0;

    //! Relay current minimum fee (from -minrelaytxfee and -incrementalrelayfee settings).

    virtual CFeeRate relayMinFee() = 0;

    //! Relay incremental fee setting (-incrementalrelayfee), reflecting cost of relay.

    virtual CFeeRate relayIncrementalFee() = 0;

    //! Relay dust fee setting (-dustrelayfee), reflecting lowest rate it's economical to spend.

    virtual CFeeRate relayDustFee() = 0;

    //! Check if any block has been pruned.

    virtual bool havePruned() = 0;

    //! Get the current prune height.

    virtual std::optional<int> getPruneHeight() = 0;

    //! Check if the node is ready to broadcast transactions.

    virtual bool isReadyToBroadcast() = 0;

    //! Check if in IBD.

    virtual bool isInitialBlockDownload() = 0;

    //! Check if shutdown requested.

    virtual bool shutdownRequested() = 0;

    //! Send init message.

    virtual void initMessage(const std::string& message) = 0;

    //! Send init warning.

    virtual void initWarning(const bilingual_str& message) = 0;

    //! Send init error.

    virtual void initError(const bilingual_str& message) = 0;

    //! Send progress indicator.

    virtual void showProgress(const std::string& title, int progress, bool resume_possible) = 0;

    //! Chain notifications.

    class Notifications

    {

    public:

        virtual ~Notifications() = default;

        virtual void transactionAddedToMempool(const CTransactionRef& tx) {}

        virtual void transactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRemovalReason reason) {}

        virtual void blockConnected(ChainstateRole role, const BlockInfo& block) {}

        virtual void blockDisconnected(const BlockInfo& block) {}

        virtual void updatedBlockTip() {}

        virtual void chainStateFlushed(ChainstateRole role, const CBlockLocator& locator) {}

    };

    //! Register handler for notifications.

    virtual std::unique_ptr<Handler> handleNotifications(std::shared_ptr<Notifications> notifications) = 0;

    //! Wait for pending notifications to be processed unless block hash points to the current

    //! chain tip.

    virtual void waitForNotificationsIfTipChanged(const uint256& old_tip) = 0;

    //! Register handler for RPC. Command is not copied, so reference

    //! needs to remain valid until Handler is disconnected.

    virtual std::unique_ptr<Handler> handleRpc(const CRPCCommand& command) = 0;

    //! Check if deprecated RPC is enabled.

    virtual bool rpcEnableDeprecated(const std::string& method) = 0;

    //! Run function after given number of seconds. Cancel any previous calls with same name.

    virtual void rpcRunLater(const std::string& name, std::function<void()> fn, int64_t seconds) = 0;

    //! Get settings value.

    virtual common::SettingsValue getSetting(const std::string& arg) = 0;

    //! Get list of settings values.

    virtual std::vector<common::SettingsValue> getSettingsList(const std::string& arg) = 0;

    //! Return <datadir>/settings.json setting value.

    virtual common::SettingsValue getRwSetting(const std::string& name) = 0;

    //! Updates a setting in <datadir>/settings.json.

    //! Null can be passed to erase the setting. There is intentionally no

    //! support for writing null values to settings.json.

    //! Depending on the action returned by the update function, this will either

    //! update the setting in memory or write the updated settings to disk.

    virtual bool updateRwSetting(const std::string& name, const SettingsUpdate& update_function) = 0;

    //! Replace a setting in <datadir>/settings.json with a new value.

    //! Null can be passed to erase the setting.

    //! This method provides a simpler alternative to updateRwSetting when

    //! atomically reading and updating the setting is not required.

    virtual bool overwriteRwSetting(const std::string& name, common::SettingsValue value, SettingsAction action = SettingsAction::WRITE) = 0;

    //! Delete a given setting in <datadir>/settings.json.

    //! This method provides a simpler alternative to overwriteRwSetting when

    //! erasing a setting, for ease of use and readability.

    virtual bool deleteRwSettings(const std::string& name, SettingsAction action = SettingsAction::WRITE) = 0;

    //! Synchronously send transactionAddedToMempool notifications about all

    //! current mempool transactions to the specified handler and return after

    //! the last one is sent. These notifications aren't coordinated with async

    //! notifications sent by handleNotifications, so out of date async

    //! notifications from handleNotifications can arrive during and after

    //! synchronous notifications from requestMempoolTransactions. Clients need

    //! to be prepared to handle this by ignoring notifications about unknown

    //! removed transactions and already added new transactions.

    virtual void requestMempoolTransactions(Notifications& notifications) = 0;

    //! Return true if an assumed-valid chain is in use.

    virtual bool hasAssumedValidChain() = 0;

    //! Get internal node context. Useful for testing, but not

    //! accessible across processes.

    virtual node::NodeContext* context() { return nullptr; }

};

//! Interface to let node manage chain clients (wallets, or maybe tools for

//! monitoring and analysis in the future).

class ChainClient

{

public:

    virtual ~ChainClient() = default;

    //! Register rpcs.

    virtual void registerRpcs() = 0;

    //! Check for errors before loading.

    virtual bool verify() = 0;

    //! Load saved state.

    virtual bool load() = 0;

    //! Start client execution and provide a scheduler.

    virtual void start(CScheduler& scheduler) = 0;

    //! Save state to disk.

    virtual void flush() = 0;

    //! Shut down client.

    virtual void stop() = 0;

    //! Set mock time.

    virtual void setMockTime(int64_t time) = 0;

    //! Mock the scheduler to fast forward in time.

    virtual void schedulerMockForward(std::chrono::seconds delta_seconds) = 0;

};

//! Return implementation of Chain interface.

std::unique_ptr<Chain> MakeChain(node::NodeContext& node);

} // namespace interfaces

#endif // BITCOIN_INTERFACES_CHAIN_H