/* -*- mode: c++; indent-tabs-mode: nil -*- */
/*
    DatasourcePool.h

    Qore Programming Language

    Copyright (C) 2003 - 2023 Qore Technologies, s.r.o.

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.

    Note that the Qore library is released under a choice of three open-source
    licenses: MIT (as above), LGPL 2+, or GPL 2+; see README-LICENSE for more
    information.
*/

#ifndef _QORUS_DATASOURCE_POOL_H

#define _QORUS_DATASOURCE_POOL_H

#include <qore/Datasource.h>
#include <qore/QoreThreadLock.h>
#include <qore/QoreCondition.h>
#include <qore/QoreString.h>
#include <qore/AbstractThreadResource.h>

#include "qore/intern/DatasourceStatementHelper.h"
#include "qore/intern/QoreSQLStatement.h"

#include <map>
#include <deque>
#include <string>

typedef std::map<int, int> thread_use_t;   // for marking a datasource in use
typedef std::deque<int> free_list_t;       // for the free list

// class holding datasource configuration params
class DatasourceConfig {
protected:
    DBIDriver* driver;

    std::string user,
        pass,
        db,
        encoding,
        host;

    int port;

    // options
    QoreHashNode* opts;
    // event queue
    Queue* q;
    // Queue argument
    QoreValue arg;

public:
    DLLLOCAL DatasourceConfig(DBIDriver* n_driver, const char* n_user, const char* n_pass, const char* n_db,
                                const char* n_encoding, const char* n_host, int n_port,
                                const QoreHashNode* n_opts, Queue* n_q, QoreValue n_arg) :
        driver(n_driver), user(n_user ? n_user : ""), pass(n_pass ? n_pass : ""), db(n_db ? n_db : ""),
        encoding(n_encoding ? n_encoding : ""), host(n_host ? n_host : ""), port(n_port),
        opts(n_opts ? n_opts->hashRefSelf() : 0), q(n_q), arg(n_arg) {
    }

    DLLLOCAL DatasourceConfig(const DatasourceConfig& old) :
        driver(old.driver), user(old.user), pass(old.pass), db(old.db), encoding(old.encoding), host(old.host),
        port(old.port), opts(old.opts ? old.opts->hashRefSelf() : nullptr),
        q(old.q ? old.q->queueRefSelf() : nullptr), arg(old.arg.refSelf()) {
    }

    DLLLOCAL ~DatasourceConfig() {
        assert(!q);
        assert(!arg);
        assert(!opts);
    }

    DLLLOCAL void del(ExceptionSink* xsink) {
        if (q) {
            q->deref(xsink);
#ifdef DEBUG
            q = nullptr;
#endif
        }
        arg.discard(xsink);
#ifdef DEBUG
        arg = QoreValue();
#endif
        if (opts) {
            opts->deref(xsink);
#ifdef DEBUG
            opts = nullptr;
#endif
        }
    }

    // the first connection (opened in the DatasourcePool constructor) is passed with an xsink obj
    // because invalid options can cause an exception to be thrown
    DLLLOCAL Datasource* get(DatasourceStatementHelper* dsh, ExceptionSink* xsink) const;

    DLLLOCAL void setQueue(Queue* n_q, QoreValue n_arg, ExceptionSink* xsink) {
        if (q)
            q->deref(xsink);
        q = n_q;
        arg.discard(xsink);
        arg = n_arg;
    }
};

class DatasourcePool : public AbstractThreadResource, public QoreCondition, public QoreThreadLock, public DatasourceStatementHelper {
    friend class DatasourcePoolActionHelper;
protected:
    Datasource** pool;
    int* tid_list;            // list of thread IDs per pool index
    thread_use_t tmap;        // map from tids to pool index
    free_list_t free_list;

    unsigned min,
        max,
        cmax,                      // current max
        wait_count,
        wait_max,
        tl_warning_ms;

    int64 tl_timeout_ms,
        stats_reqs,
        stats_hits
        ;

    ResolvedCallReferenceNode* warning_callback;
    QoreValue callback_arg;

    DatasourceConfig config;

    bool valid;

#ifdef DEBUG
    QoreThreadLocalStorage<QoreString> thread_local_storage;
    void addSQL(const char* cmd, const QoreString* sql);
    void resetSQL();
#endif

    DLLLOCAL Datasource* getAllocatedDS();
    DLLLOCAL Datasource* getDSIntern(bool& new_ds, int64& wait_total, ExceptionSink* xsink);
    DLLLOCAL Datasource* getDS(bool& new_ds, ExceptionSink* xsink);
    DLLLOCAL void freeDS(ExceptionSink* xsink);
    // share the code for exec() and execRaw()
    DLLLOCAL QoreValue exec_internal(bool doBind, const QoreString* sql, const QoreListNode* args, ExceptionSink* xsink);
    DLLLOCAL int checkWait(int64 warn_total, ExceptionSink* xsink);
    DLLLOCAL void init(ExceptionSink* xsink);

public:
#ifdef DEBUG
    QoreString* getAndResetSQL();
#endif

    // min must be 1 or more, max must be greater than min
    DLLLOCAL DatasourcePool(ExceptionSink* xsink, DBIDriver* ndsl, const char* user, const char* pass, const char* db, const char* charset, const char* hostname, unsigned mn, unsigned mx, int port = 0, const QoreHashNode* opts = 0, Queue* q = nullptr, QoreValue a = QoreValue());
    DLLLOCAL DatasourcePool(const DatasourcePool& old, ExceptionSink* xsink);

    DLLLOCAL virtual ~DatasourcePool();

    using AbstractPrivateData::deref;
    DLLLOCAL virtual void deref(ExceptionSink* xsink) {
        // if the object is obliterated (due to a constructor error in a child class or a serialization error), make sure
        // it's destroyed properly
        if (ROdereference()) {
            config.del(xsink);
            delete this;
        }
    }

    DLLLOCAL void destructor(ExceptionSink* xsink);
    DLLLOCAL virtual void cleanup(ExceptionSink* xsink);
    DLLLOCAL QoreValue select(const QoreString* sql, const QoreListNode* args, ExceptionSink* xsink);
    DLLLOCAL QoreHashNode* selectRow(const QoreString* sql, const QoreListNode* args, ExceptionSink* xsink);
    DLLLOCAL QoreValue selectRows(const QoreString* sql, const QoreListNode* args, ExceptionSink* xsink);
    DLLLOCAL int beginTransaction(ExceptionSink* xsink);
    DLLLOCAL QoreValue exec(const QoreString* sql, const QoreListNode* args, ExceptionSink* xsink);
    DLLLOCAL QoreValue execRaw(const QoreString* sql, ExceptionSink* xsink);
    DLLLOCAL QoreHashNode* describe(const QoreString* query_str, const QoreListNode* args, ExceptionSink* xsink);
    DLLLOCAL int commit(ExceptionSink* xsink);
    DLLLOCAL int rollback(ExceptionSink* xsink);
    DLLLOCAL QoreStringNode* toString();
    DLLLOCAL unsigned getMin() const;
    DLLLOCAL unsigned getMax() const;
    DLLLOCAL QoreStringNode* getPendingUsername() const;
    DLLLOCAL QoreStringNode* getPendingPassword() const;
    DLLLOCAL QoreStringNode* getPendingDBName() const;
    DLLLOCAL QoreStringNode* getPendingDBEncoding() const;
    DLLLOCAL QoreStringNode* getPendingHostName() const;
    DLLLOCAL int getPendingPort() const;
    DLLLOCAL const QoreEncoding* getQoreEncoding() const;
    DLLLOCAL const DBIDriver* getDriver() const {
        return pool[0]->getDriver();
    }
    DLLLOCAL const char* getDriverName() const {
        return pool[0]->getDriverName();
    }

    DLLLOCAL QoreListNode* getCapabilityList() const;
    DLLLOCAL int getCapabilities() const;

    DLLLOCAL QoreValue getServerVersion(ExceptionSink* xsink);
    DLLLOCAL QoreValue getClientVersion(ExceptionSink* xsink) {
        return pool[0]->getClientVersion(xsink);
    }

    DLLLOCAL QoreStringNode* getDriverRealName(ExceptionSink* xsink);

    DLLLOCAL bool inTransaction();

    DLLLOCAL QoreHashNode* getOptionHash() const {
        return pool[0]->getOptionHash();
    }

    DLLLOCAL QoreValue getOption(const char* opt, ExceptionSink* xsink) {
        return pool[0]->getOption(opt, xsink);
    }

    // functions supporting DatasourceStatementHelper
    DLLLOCAL DatasourceStatementHelper* helperRefSelfImpl() {
        ref();
        return this;
    }

    // implementing DatasourceStatementHelper virtual functions
    DLLLOCAL virtual void helperDestructorImpl(QoreSQLStatement* s, ExceptionSink* xsink) {
        deref(xsink);
    }

    DLLLOCAL virtual Datasource* helperStartActionImpl(ExceptionSink* xsink, bool& new_transaction) {
        return getDS(new_transaction, xsink);
    }

    DLLLOCAL virtual Datasource* helperEndActionImpl(char cmd, bool new_transaction, ExceptionSink* xsink) {
        //printd(5, "DatasourcePool::helperEndAction() cmd: %d '%s', nt: %d\n", cmd, DAH_TEXT(cmd), new_transaction);
        if (cmd == DAH_RELEASE) {
            freeDS(xsink);
            return 0;
        }

        return getAllocatedDS();
    }

    DLLLOCAL bool currentThreadInTransaction() const {
        SafeLocker sl((QoreThreadLock*)this);
        return tmap.find(q_gettid()) != tmap.end();
    }

    DLLLOCAL QoreHashNode* getConfigHash(ExceptionSink* xsink);
    DLLLOCAL QoreStringNode* getConfigString(ExceptionSink* xsink);

    DLLLOCAL void clearWarningCallback(ExceptionSink* xsink);
    DLLLOCAL void setWarningCallback(int64 warning_ms, ResolvedCallReferenceNode* cb, QoreValue arg, ExceptionSink* xsink);
    DLLLOCAL QoreHashNode* getUsageInfo() const;

    DLLLOCAL void setErrorTimeout(unsigned t_ms) {
        tl_timeout_ms = t_ms;
    }

    DLLLOCAL unsigned getErrorTimeout() const {
        return tl_timeout_ms;
    }

    DLLLOCAL void setEventQueue(Queue* q, QoreValue arg, ExceptionSink* xsink);
};

class DatasourcePoolActionHelper {
protected:
    DatasourcePool& dsp;
    ExceptionSink* xsink;
    Datasource* ds;
    bool new_ds;
    char cmd;

public:
    DLLLOCAL DatasourcePoolActionHelper(DatasourcePool& n_dsp, ExceptionSink* n_xsink, char n_cmd = DAH_NOCHANGE) : dsp(n_dsp), xsink(n_xsink), new_ds(false), cmd(n_cmd) {
        ds = dsp.getDS(new_ds, xsink);
    }

    /* release the connection if:
            1) the connection was aborted (exception already raised)
            2) the connection was acquired for this call, and
                the command was NOCHANGE, meaning, leave the connection in the same state it was before the call
    */
    DLLLOCAL ~DatasourcePoolActionHelper();

    // issue #3509: allow connections to be released if a beginTransaction() cmd fails on a new datasource
    DLLLOCAL void releaseNew() {
        assert(cmd == DAH_ACQUIRE);
        if (new_ds) {
            cmd = DAH_RELEASE;
        }
    }

#if 0
    DLLLOCAL void addSQL(const QoreString* sql) {
        if (ds && !((cmd == DAH_RELEASE) || (new_ds && (cmd == DAH_NOCHANGE)) || ds->wasConnectionAborted()))
            dsp.addSQL(cmd == DAH_NOCHANGE ? "select" : "exec", sql);
    }
#endif

    DLLLOCAL operator bool() const { return ds; }

    DLLLOCAL Datasource* operator*() const { return ds; }
    DLLLOCAL Datasource* operator->() const { return ds; }
};

#endif
