/*
 * Copyright (C) by Klaas Freitag <freitag@owncloud.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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. See the GNU General Public License
 * for more details.
 */


#include <QDateTime>
#include <QString>
#include <QDebug>
#include <QFile>
#include <QFileInfo>
#include <QDir>

#include "ownsql.h"
#include "utility.h"
#include "asserts.h"

#define SQLITE_SLEEP_TIME_USEC 100000
#define SQLITE_REPEAT_COUNT 20

#define SQLITE_DO(A) if(1) { \
    _errId = (A); if(_errId != SQLITE_OK) { _error= QString::fromUtf8(sqlite3_errmsg(_db)); \
     } }

namespace OCC {

SqlDatabase::SqlDatabase()
    :_db(0),
      _errId(0)
{

}

bool SqlDatabase::isOpen()
{
    return _db != 0;
}

bool SqlDatabase::openHelper( const QString& filename, int sqliteFlags )
{
    if( isOpen() ) {
        return true;
    }

    sqliteFlags |= SQLITE_OPEN_NOMUTEX;

    SQLITE_DO( sqlite3_open_v2(filename.toUtf8().constData(), &_db, sqliteFlags, 0) );

    if( _errId != SQLITE_OK ) {
        qDebug() << "Error:" << _error << "for" << filename;
        close();
        return false;
    }

    if( !_db ) {
        qDebug() << "Error: no database for" << filename;
        return false;
    }

    sqlite3_busy_timeout(_db, 5000);

    return true;
}

bool SqlDatabase::checkDb()
{
    // quick_check can fail with a disk IO error when diskspace is low
    SqlQuery quick_check(*this);
    quick_check.prepare("PRAGMA quick_check;", /*allow_failure=*/true);
    if( !quick_check.exec() ) {
        qDebug() << "Error running quick_check on database";
        return false;
    }

    quick_check.next();
    QString result = quick_check.stringValue(0);
    if( result != "ok" ) {
        qDebug() << "quick_check returned failure:" << result;
        return false;
    }

    return true;
}

bool SqlDatabase::openOrCreateReadWrite( const QString& filename )
{
    if( isOpen() ) {
        return true;
    }

    if( !openHelper(filename, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE) ) {
        return false;
    }

    if( !checkDb() ) {
        // When disk space is low, checking the db may fail even though it's fine.
        qint64 freeSpace = Utility::freeDiskSpace(QFileInfo(filename).dir().absolutePath());
        if (freeSpace != -1 && freeSpace < 1000000) {
            qDebug() << "Consistency check failed, disk space is low, aborting" << freeSpace;
            close();
            return false;
        }

        qDebug() << "Consistency check failed, removing broken db" << filename;
        close();
        QFile::remove(filename);

        return openHelper(filename, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE);
    }

    return true;
}

bool SqlDatabase::openReadOnly( const QString& filename )
{
    if( isOpen() ) {
        return true;
    }

    if( !openHelper(filename, SQLITE_OPEN_READONLY) ) {
        return false;
    }

    if( !checkDb() ) {
        qDebug() << "Consistency check failed in readonly mode, giving up" << filename;
        close();
        return false;
    }

    return true;
}

QString SqlDatabase::error() const
{
    const QString err(_error);
    // _error.clear();
    return err;
}

void SqlDatabase::close()
{
    if( _db ) {
        SQLITE_DO(sqlite3_close(_db) );
        // Fatal because reopening an unclosed db might be problematic.
        ENFORCE(_errId == SQLITE_OK, "Error when closing DB");
        _db = 0;
    }
}

bool SqlDatabase::transaction()
{
    if( ! _db ) {
        return false;
    }
    SQLITE_DO(sqlite3_exec(_db, "BEGIN", 0, 0, 0));
    return _errId == SQLITE_OK;
}

bool SqlDatabase::commit()
{
    if( ! _db ) {
        return false;
    }
    SQLITE_DO(sqlite3_exec(_db, "COMMIT", 0, 0, 0));
    return _errId == SQLITE_OK;
}

sqlite3* SqlDatabase::sqliteDb()
{
    return _db;
}

/* =========================================================================================== */

SqlQuery::SqlQuery( SqlDatabase& db )
    :_db(db.sqliteDb()),
      _stmt(0), _errId(0)
{

}

SqlQuery::~SqlQuery()
{
    if( _stmt ) {
        finish();
    }
}

SqlQuery::SqlQuery(const QString& sql, SqlDatabase& db)
    :_db(db.sqliteDb()),
      _stmt(0), _errId(0)
{
    prepare(sql);
}

int SqlQuery::prepare( const QString& sql, bool allow_failure )
{
    QString s(sql);
    _sql = s.trimmed();
    if(_stmt ) {
        finish();
    }
    if(!_sql.isEmpty() ) {
        int n = 0;
        int rc;
        do {
            rc = sqlite3_prepare_v2(_db, _sql.toUtf8().constData(), -1, &_stmt, 0);
            if( (rc == SQLITE_BUSY) || (rc == SQLITE_LOCKED) ) {
                n++;
                OCC::Utility::usleep(SQLITE_SLEEP_TIME_USEC);
            }
        } while( (n < SQLITE_REPEAT_COUNT) && ((rc == SQLITE_BUSY) || (rc == SQLITE_LOCKED)));
        _errId = rc;

        if( _errId != SQLITE_OK ) {
            _error = QString::fromUtf8(sqlite3_errmsg(_db));
            qWarning() << "Sqlite prepare statement error:" << _error << "in" <<_sql;
            ENFORCE(allow_failure, "SQLITE Prepare error");
        }
    }
    return _errId;
}

bool SqlQuery::isSelect()
{
    return (!_sql.isEmpty() && _sql.startsWith("SELECT", Qt::CaseInsensitive));
}

bool SqlQuery::isPragma()
{
    return (!_sql.isEmpty() && _sql.startsWith("PRAGMA", Qt::CaseInsensitive));
}

bool SqlQuery::exec()
{
    if (!_stmt) {
        return false;
    }

    // Don't do anything for selects, that is how we use the lib :-|
    if( !isSelect() && !isPragma() ) {
        int rc, n = 0;
        do {
            rc = sqlite3_step(_stmt);
            if( rc == SQLITE_LOCKED ) {
                rc = sqlite3_reset(_stmt); /* This will also return SQLITE_LOCKED */
                n++;
                OCC::Utility::usleep(SQLITE_SLEEP_TIME_USEC);
            } else if( rc == SQLITE_BUSY ) {
                OCC::Utility::usleep(SQLITE_SLEEP_TIME_USEC);
                n++;
            }
        } while( (n < SQLITE_REPEAT_COUNT) && ((rc == SQLITE_BUSY) || (rc == SQLITE_LOCKED)));
        _errId = rc;

        if (_errId != SQLITE_DONE && _errId != SQLITE_ROW) {
            _error = QString::fromUtf8(sqlite3_errmsg(_db));
            qDebug() << "Sqlite exec statement error:" << _errId << _error << "in" <<_sql;
        }
        return (_errId == SQLITE_DONE); // either SQLITE_ROW or SQLITE_DONE
    }

    return true;
}

bool SqlQuery::next()
{
    SQLITE_DO(sqlite3_step(_stmt));
    return _errId == SQLITE_ROW;
}

void SqlQuery::bindValue(int pos, const QVariant& value)
{
    int res = -1;
    if (!_stmt) {
        ASSERT(false);
        return;
    }

    switch (value.type()) {
    case QVariant::Int:
    case QVariant::Bool:
        res = sqlite3_bind_int(_stmt, pos, value.toInt());
        break;
    case QVariant::Double:
        res = sqlite3_bind_double(_stmt, pos, value.toDouble());
        break;
    case QVariant::UInt:
    case QVariant::LongLong:
        res = sqlite3_bind_int64(_stmt, pos, value.toLongLong());
        break;
    case QVariant::DateTime: {
        const QDateTime dateTime = value.toDateTime();
        const QString str = dateTime.toString(QLatin1String("yyyy-MM-ddThh:mm:ss.zzz"));
        res = sqlite3_bind_text16(_stmt, pos, str.utf16(),
                                  str.size() * sizeof(ushort), SQLITE_TRANSIENT);
        break;
    }
    case QVariant::Time: {
        const QTime time = value.toTime();
        const QString str = time.toString(QLatin1String("hh:mm:ss.zzz"));
        res = sqlite3_bind_text16(_stmt, pos, str.utf16(),
                                  str.size() * sizeof(ushort), SQLITE_TRANSIENT);
        break;
    }
    case QVariant::String: {
        if( !value.toString().isNull() ) {
            // lifetime of string == lifetime of its qvariant
            const QString *str = static_cast<const QString*>(value.constData());
            res = sqlite3_bind_text16(_stmt, pos, str->utf16(),
                                      (str->size()) * sizeof(QChar), SQLITE_TRANSIENT);
        } else {
            res = sqlite3_bind_null(_stmt, pos);
        }
        break; }
    case QVariant::ByteArray: {
        auto ba = value.toByteArray();
        res = sqlite3_bind_text(_stmt, pos, ba.constData(), ba.size(), SQLITE_TRANSIENT);
        break;
    }
    default: {
        QString str = value.toString();
        // SQLITE_TRANSIENT makes sure that sqlite buffers the data
        res = sqlite3_bind_text16(_stmt, pos, str.utf16(),
                                  (str.size()) * sizeof(QChar), SQLITE_TRANSIENT);
        break; }
    }
    if (res != SQLITE_OK) {
        qDebug() << Q_FUNC_INFO << "ERROR" << value << res;
    }
    ASSERT( res == SQLITE_OK );
}

bool SqlQuery::nullValue(int index)
{
    return sqlite3_column_type(_stmt, index) == SQLITE_NULL;
}

QString SqlQuery::stringValue(int index)
{
    return QString::fromUtf16(static_cast<const ushort*>(sqlite3_column_text16(_stmt, index)));
}

int SqlQuery::intValue(int index)
{
    return sqlite3_column_int(_stmt, index);
}

quint64 SqlQuery::int64Value(int index)
{
    return sqlite3_column_int64(_stmt, index);
}

QByteArray SqlQuery::baValue(int index)
{
    return QByteArray( static_cast<const char*>(sqlite3_column_blob(_stmt, index)),
                       sqlite3_column_bytes(_stmt, index));
}

QString SqlQuery::error() const
{
    return _error;
}

int SqlQuery::errorId() const
{
    return _errId;
}

QString SqlQuery::lastQuery() const
{
    return _sql;
}

int SqlQuery::numRowsAffected()
{
    return sqlite3_changes(_db);
}

void SqlQuery::finish()
{
    SQLITE_DO(sqlite3_finalize(_stmt));
    _stmt = 0;
}

void SqlQuery::reset_and_clear_bindings()
{
    if (_stmt) {
        SQLITE_DO(sqlite3_reset(_stmt));
        SQLITE_DO(sqlite3_clear_bindings(_stmt));
    }
}

} // namespace OCC