/**
 * @file mega/db.h
 * @brief Database access interface
 *
 * (c) 2013-2014 by Mega Limited, Auckland, New Zealand
 *
 * This file is part of the MEGA SDK - Client Access Engine.
 *
 * Applications using the MEGA API must present a valid application key
 * and comply with the the rules set forth in the Terms of Service.
 *
 * The MEGA SDK 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.
 *
 * @copyright Simplified (2-clause) BSD License.
 *
 * You should have received a copy of the license along with this
 * program.
 */

#ifndef MEGA_DB_H
#define MEGA_DB_H 1

#include "filesystem.h"
#include "logging.h"
#include "node.h"

#include <filesystem>
#include <optional>

namespace mega {
// generic host transactional database access interface
class DBTableTransactionCommitter;

// Class to load serialized node from data base
class NodeSerialized
{
public:
    std::string mNode;
    std::string mNodeCounter;
};

enum class DBError
{
    DB_ERROR_UNKNOWN = 0,
    DB_ERROR = 1,
    DB_ERROR_INTERNAL = 2,
    DB_ERROR_PERM = 3,
    DB_ERROR_ABORT = 4,
    DB_ERROR_BUSY = 5,
    DB_ERROR_LOCKED = 6,
    DB_ERROR_NOMEM = 7,
    DB_ERROR_READONLY = 8,
    DB_ERROR_INTERRUPT = 9,
    DB_ERROR_IO = 10,
    DB_ERROR_CORRUPT = 11,
    DB_ERROR_NOTFOUND = 12,
    DB_ERROR_FULL = 13,
    DB_ERROR_CANTOPEN = 14,
    DB_ERROR_PROTOCOL = 15,
    DB_ERROR_EMPTY = 16,
    DB_ERROR_SCHEMA = 17,
    DB_ERROR_TOOBIG = 18,
    DB_ERROR_CONSTRAINT = 19,
    DB_ERROR_MISMATCH = 20,
    DB_ERROR_MISUSE = 21,
    DB_ERROR_NOLFS = 22,
    DB_ERROR_AUTH = 23,
    DB_ERROR_FORMAT = 24,
    DB_ERROR_RANGE = 25,
    DB_ERROR_NOTADB = 26,
    DB_ERROR_INDEX_OVERFLOW = 100, // SDK internal error
};

using DBErrorCallback = std::function<void(DBError)>;


class MEGA_API DbTable
{
    PrnGen &rng;

protected:
    bool mCheckAlwaysTransacted = false;
    DBTableTransactionCommitter* mTransactionCommitter = nullptr;
    DBErrorCallback mDBErrorCallBack;
    friend class DBTableTransactionCommitter;
    void checkTransaction();
    // should be called by the subclass' destructor
    void resetCommitter();

public:
    static const int IDSPACING = 16;
    // for a full sequential get: rewind to first record
    virtual void rewind() = 0;

    // get next record in sequence
    virtual bool next(uint32_t*, string*) = 0;
    bool next(uint32_t*, string*, SymmCipher*);

    // get specific record by key
    virtual bool get(uint32_t, string*) = 0;

    // update or add specific record
    virtual bool put(uint32_t, char*, unsigned) = 0;
    bool put(uint32_t, string*);
    bool put(uint32_t, Cacheable *, SymmCipher*);

    // delete specific record
    virtual bool del(uint32_t) = 0;

    // delete all records
    virtual void truncate() = 0;

    // begin transaction
    virtual void begin() = 0;

    // commit transaction
    virtual void commit() = 0;

    // abort transaction
    virtual void abort() = 0;

    // permanantly remove all database info
    virtual void remove() = 0;

    void checkCommitter(DBTableTransactionCommitter*);

    // autoincrement
    uint32_t nextid;

    DbTable(PrnGen &rng, bool alwaysTransacted, DBErrorCallback dBErrorCallBack);
    virtual ~DbTable() = default;
    DBTableTransactionCommitter *getTransactionCommitter() const;
};

class NodeSearchFilter;
class NodeSearchPage;
struct NodeSearchLexicographicalOffset;

class MEGA_API DBTableNodes
{
public:

    // add or update a node
    virtual bool put(Node* node) = 0;

    // remove one node from 'nodes' table
    virtual bool remove(NodeHandle nodehandle) = 0;

    // remove all nodes from 'nodes' table (truncate)
    virtual bool removeNodes() = 0;

    // get nodes and queries about nodes
    virtual bool getNode(NodeHandle nodehandle, NodeSerialized& nodeSerialized) = 0;
    virtual bool getNodesByOrigFingerprint(const std::string& fingerprint, std::vector<std::pair<NodeHandle, NodeSerialized>>& nodes) = 0;

    virtual uint64_t getNumberOfChildren(NodeHandle parentHandle) = 0;
    virtual bool getChildren(const NodeSearchFilter& filter, int order, std::vector<std::pair<NodeHandle, NodeSerialized>>& nodes, CancelToken cancelFlag, const NodeSearchPage& page) = 0;
    virtual bool listChildNodesLexicographically(
        const handle parenthandle,
        std::vector<std::pair<NodeHandle, NodeSerialized>>& children,
        CancelToken cancelFlag,
        const size_t maxElements,
        const std::optional<NodeSearchLexicographicalOffset>& offset) = 0;
    virtual bool searchNodes(const NodeSearchFilter& filter, int order, std::vector<std::pair<NodeHandle, NodeSerialized>>& nodes, CancelToken cancelFlag, const NodeSearchPage& page) = 0;

    /**
     * @brief
     * Returns a set of all distinct tags below a set of specified parents.
     *
     * @param cancelToken
     * A cancel token that can be used to abort the query.
     *
     * @param handle
     * Handle specifing the node we should search for tags below.
     *
     * @param pattern
     * A search pattern that can used to filter which tags are returned.
     *
     * An empty pattern specifies that there are no constraints as to what
     * tags should be returned.
     *
     * A non-empty pattern specifies that only the tags matching that
     * pattern should be returned. Wildcards are accepted.
     *
     * @return
     * A set of tags if successful.
     * nullopt if unsuccessful.
     */
    virtual auto getNodeTagsBelow(CancelToken cancelToken,
                                  NodeHandle handle,
                                  const std::string& pattern)
        -> std::optional<std::set<std::string>> = 0;

    virtual bool getRecentNodes(const NodeSearchPage& page,
                                m_time_t since,
                                std::vector<std::pair<NodeHandle, NodeSerialized>>& nodes) = 0;
    virtual bool getNodeByFingerprint(const std::string& fingerprint, mega::NodeSerialized& node, NodeHandle& handle) = 0;
    virtual bool
        getNodesByFingerprintNoMtime(const std::string& fingerprint,
                                     std::vector<std::pair<NodeHandle, NodeSerialized>>& nodes) = 0;
    virtual bool getRootNodes(std::vector<std::pair<NodeHandle, NodeSerialized>>& nodes) = 0;

    virtual bool getNodesWithSharesOrLink(std::vector<std::pair<NodeHandle, NodeSerialized>>&, ShareType_t shareType) = 0;

    virtual bool getFavouritesHandles(NodeHandle node, uint32_t count, std::vector<mega::NodeHandle>& nodes) = 0;
    virtual bool childNodeByNameType(NodeHandle parentHandle, const std::string& name, nodetype_t nodeType, std::pair<NodeHandle, NodeSerialized>& node) = 0;

    virtual bool isAncestor(NodeHandle node, NodeHandle ancestror, CancelToken cancelFlag) = 0;

    // count of items in 'nodes' table. Returns 0 if error
    virtual uint64_t getNumberOfNodes() = 0;

    // count of children nodes of by type
    virtual uint64_t getNumberOfChildrenByType(NodeHandle parentHandle, nodetype_t nodeType) = 0;


    // -- get node properties --

    virtual bool getNodeSizeTypeAndFlags(NodeHandle node, m_off_t& size, nodetype_t& nodeType, uint64_t& oldFlags) = 0;

    virtual void updateCounter(NodeHandle nodeHandle, const std::string& nodeCounterBlob) = 0;

    virtual void updateCounterAndFlags(NodeHandle nodeHandle, uint64_t flags, const std::string& nodeCounterBlob) = 0;

    virtual void createIndexes(bool enableIndexesForSearching,
                               bool enableIndexesForLexicographicalList) = 0;

    virtual void dropSearchDBIndexes() = 0;
    virtual void dropLexicographicDBIndexes() = 0;
};

class MEGA_API DBTableTransactionCommitter
{
    DbTable* mTable;
    bool mStarted = false;
    std::thread::id threadId;

public:
    void beginOnce()
    {
        if (mTable && !mStarted)
        {
            mTable->begin();
            mStarted = true;
        }
    }

    void commitNow()
    {
        if (mTable)
        {
            if (mStarted)
            {
                mTable->commit();
                mStarted = false;
            }
        }
    }

    void reset()
    {
        mTable = nullptr;
    }

    virtual ~DBTableTransactionCommitter()
    {
        if (mTable)
        {
            commitNow();
            mTable->mTransactionCommitter = nullptr;
        }
    }

    explicit DBTableTransactionCommitter(unique_ptr<DbTable>& t)
        : mTable(t.get()), threadId(std::this_thread::get_id())
    {
        if (mTable)
        {
            if (mTable->mTransactionCommitter)
            {
                assert(mTable->mTransactionCommitter->threadId == threadId);
                mTable = nullptr;  // we are nested; this one does nothing.  This can occur during eg. putnodes response when the core sdk and the intermediate layer both do db work.
            }
            else
            {
                mTable->mTransactionCommitter = this;
            }
        }
    }


    MEGA_DISABLE_COPY_MOVE(DBTableTransactionCommitter)
};


class MEGA_API TransferDbCommitter : public DBTableTransactionCommitter
{
public:

    uint32_t addFileCount = 0;
    uint32_t addTransferCount = 0;
    uint32_t removeFileCount = 0;
    uint32_t removeTransferCount = 0;

    explicit TransferDbCommitter(unique_ptr<DbTable>& t) : DBTableTransactionCommitter(t) {}

    ~TransferDbCommitter()
    {
        if (addFileCount || addTransferCount || removeFileCount || removeTransferCount)
        {
            LOG_debug << "Committed transfer db with new transfers : " << addTransferCount <<
                            " and new transfer files: " << addFileCount <<
                            " removed transfers: " << removeTransferCount <<
                            " and removed transfer files: " << removeFileCount;
        }
    }
};

enum DbOpenFlag
{
    // Recycle legacy database, if present.
    DB_OPEN_FLAG_RECYCLE = 0x1,
    // Operations should always be transacted.
    DB_OPEN_FLAG_TRANSACTED = 0x2
}; // DbOpenFlag

struct MEGA_API DbAccess
{
    static const int LEGACY_DB_VERSION;
    static const int DB_VERSION;
    static const int LAST_DB_VERSION_WITHOUT_NOD;
    static const int LAST_DB_VERSION_WITHOUT_SRW;
    static const int LAST_DB_VERSION_WITHOUT_VFINGERPRINT;

    DbAccess();

    virtual ~DbAccess() { }

    virtual bool checkDbFileAndAdjustLegacy(FileSystemAccess& fsAccess, const string& name, const int flags, LocalPath& dbPath) = 0;

    // Compute the path of a database with this name.
    virtual LocalPath databasePath(const FileSystemAccess& fsAccess,
                                   const string& name,
                                   const int version) const = 0;

    virtual DbTable* open(PrnGen &rng, FileSystemAccess& fsAccess, const string& name, const int flags, DBErrorCallback dBErrorCallBack) = 0;

    // use this method to get a `DbTable` that also implements `DbTableNodes` interface
    virtual DbTable* openTableWithNodes(PrnGen &rng, FileSystemAccess& fsAccess, const string& name, const int flags, DBErrorCallback dBErrorCallBack) = 0;

    // Check if the specified database exists on disk.
    virtual bool probe(FileSystemAccess& fsAccess, const string& name) const = 0;

    virtual std::optional<std::filesystem::path>
        getExistingDbPath(const FileSystemAccess& fsAccess, const std::string& fname) const = 0;

    // Where are we storing our databases?
    virtual const LocalPath& rootPath() const = 0;

    virtual bool renameDBFiles(FileSystemAccess& fsAccess,
                               const LocalPath& legacyPath,
                               const LocalPath& dbPath) = 0;

    int currentDbVersion;
};

// Convenience.
using DbAccessPtr = unique_ptr<DbAccess>;
using DbTablePtr = unique_ptr<DbTable>;

} // namespace

#endif
