/* Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.

 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; version 2 of the License.

 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.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */

#ifndef SQL_GET_DIAGNOSTICS_H
#define SQL_GET_DIAGNOSTICS_H

/** Diagnostics information forward reference. */
class Diagnostics_information;


/**
 Sql_cmd_get_diagnostics represents a GET DIAGNOSTICS statement.

 The GET DIAGNOSTICS statement retrieves exception or completion
 condition information from a diagnostics area, usually pertaining
 to the last non-diagnostic SQL statement that was executed.
*/
class Sql_cmd_get_diagnostics : public Sql_cmd
{
public:
 /**
 Constructor, used to represent a GET DIAGNOSTICS statement.

 @param info Diagnostics information to be obtained.
 */
 Sql_cmd_get_diagnostics(Diagnostics_information *info)
 : m_info(info)
 {}

 virtual enum_sql_command sql_command_code() const
 {
 return SQLCOM_GET_DIAGNOSTICS;
 }

 virtual bool execute(THD *thd);

private:
 /** The information to be obtained. */
 Diagnostics_information *m_info;
};


/**
 Represents the diagnostics information to be obtained.

 Diagnostic information is made available through statement
 information and condition information items.
*/
class Diagnostics_information : public Sql_alloc
{
public:
 /**
 Which diagnostics area to access.
 Only CURRENT is supported for now.
 */
 enum Which_area
 {
 /** Access the first diagnostics area. */
 CURRENT_AREA
 };

 /** Set which diagnostics area to access. */
 void set_which_da(Which_area area)
 { m_area= area; }

 /** Get which diagnostics area to access. */
 Which_area get_which_da(void) const
 { return m_area; }

 /**
 Aggregate diagnostics information.

 @param thd The current thread.
 @param da The diagnostics area.

 @retval false on success.
 @retval true on error
 */
 virtual bool aggregate(THD *thd, const Diagnostics_area *da) = 0;

protected:
 /**
 Diagnostics_information objects are allocated in thd->mem_root.
 Do not rely on the destructor for any cleanup.
 */
 virtual ~Diagnostics_information()
 {
 DBUG_ASSERT(false);
 }

 /**
 Evaluate a diagnostics information item in a specific context.

 @param thd The current thread.
 @param diag_item The diagnostics information item.
 @param ctx The context to evaluate the item.

 @retval false on success.
 @retval true on error.
 */
 template <typename Diag_item, typename Context>
 bool evaluate(THD *thd, Diag_item *diag_item, Context ctx)
 {
 Item *value;

 /* Get this item's value. */
 if (! (value= diag_item->get_value(thd, ctx)))
 return true;

 /* Set variable/parameter value. */
 return diag_item->set_value(thd, &value);
 }

private:
 /** Which diagnostics area to access. */
 Which_area m_area;
};


/**
 A diagnostics information item. Used to associate a specific
 diagnostics information item to a target variable.
*/
class Diagnostics_information_item : public Sql_alloc
{
public:
 /**
 Set a value for this item.

 @param thd The current thread.
 @param value The obtained value.

 @retval false on success.
 @retval true on error.
 */
 bool set_value(THD *thd, Item **value);

protected:
 /**
 Constructor, used to represent a diagnostics information item.

 @param target A target that gets the value of this item.
 */
 Diagnostics_information_item(Item *target)
 : m_target(target)
 {}

 /**
 Diagnostics_information_item objects are allocated in thd->mem_root.
 Do not rely on the destructor for any cleanup.
 */
 virtual ~Diagnostics_information_item()
 {
 DBUG_ASSERT(false);
 }

private:
 /** The target variable that will receive the value of this item. */
 Item *m_target;
};


/**
 A statement information item.
*/
class Statement_information_item : public Diagnostics_information_item
{
public:
 /** The name of a statement information item. */
 enum Name
 {
 NUMBER,
 ROW_COUNT
 };

 /**
 Constructor, used to represent a statement information item.

 @param name The name of this item.
 @param target A target that gets the value of this item.
 */
 Statement_information_item(Name name, Item *target)
 : Diagnostics_information_item(target), m_name(name)
 {}

 /** Obtain value of this statement information item. */
 Item *get_value(THD *thd, const Diagnostics_area *da);

private:
 /** The name of this statement information item. */
 Name m_name;
};


/**
 Statement information.

 @remark Provides information about the execution of a statement.
*/
class Statement_information : public Diagnostics_information
{
public:
 /**
 Constructor, used to represent the statement information of a
 GET DIAGNOSTICS statement.

 @param items List of requested statement information items.
 */
 Statement_information(List<Statement_information_item> *items)
 : m_items(items)
 {}

 /** Obtain statement information in the context of a diagnostics area. */
 bool aggregate(THD *thd, const Diagnostics_area *da);

private:
 /* List of statement information items. */
 List<Statement_information_item> *m_items;
};


/**
 A condition information item.
*/
class Condition_information_item : public Diagnostics_information_item
{
public:
 /**
 The name of a condition information item.
 */
 enum Name
 {
 CLASS_ORIGIN,
 SUBCLASS_ORIGIN,
 CONSTRAINT_CATALOG,
 CONSTRAINT_SCHEMA,
 CONSTRAINT_NAME,
 CATALOG_NAME,
 SCHEMA_NAME,
 TABLE_NAME,
 COLUMN_NAME,
 CURSOR_NAME,
 MESSAGE_TEXT,
 MYSQL_ERRNO,
 RETURNED_SQLSTATE
 };

 /**
 Constructor, used to represent a condition information item.

 @param name The name of this item.
 @param target A target that gets the value of this item.
 */
 Condition_information_item(Name name, Item *target)
 : Diagnostics_information_item(target), m_name(name)
 {}

 /** Obtain value of this condition information item. */
 Item *get_value(THD *thd, const Sql_condition *cond);

private:
 /** The name of this condition information item. */
 Name m_name;

 /** Create an string item to represent a condition item string. */
 Item *make_utf8_string_item(THD *thd, const String *str);
};


/**
 Condition information.

 @remark Provides information about conditions raised during the
 execution of a statement.
*/
class Condition_information : public Diagnostics_information
{
public:
 /**
 Constructor, used to represent the condition information of a
 GET DIAGNOSTICS statement.

 @param cond_number_expr Number that identifies the diagnostic condition.
 @param items List of requested condition information items.
 */
 Condition_information(Item *cond_number_expr,
 List<Condition_information_item> *items)
 : m_cond_number_expr(cond_number_expr), m_items(items)
 {}

 /** Obtain condition information in the context of a diagnostics area. */
 bool aggregate(THD *thd, const Diagnostics_area *da);

private:
 /**
 Number that identifies the diagnostic condition for which
 information is to be obtained.
 */
 Item *m_cond_number_expr;

 /** List of condition information items. */
 List<Condition_information_item> *m_items;
};

#endif