// SqlTable.h

#ifndef dset__SqlTable_H
#define dset__SqlTable_H

// Chitra Kannan
// April 2004
//
// Abstract class for running SQL queries.

#include <vector>

#include "dataset_sql/SqlQuery.h"
#include "dataset_sql/SelectQuery.h"
#include "dataset_sql/SqlResult.h"

namespace dset {

class SqlTable {

public: // typedef

  // Creator.
  // Arguments are extracted from connection string name:params
  typedef SqlTable* (*Creator) (std::string name, std::string params);

  // Creator name.
  typedef std::string CreatorName;

  // List of class names.
  typedef std::vector<CreatorName> CreatorList;

  // Callback function to receive notification when a creator is
  // registered.
  typedef void (*Callback) (std::string name);

public: // static functions

  // Register a table.
  // The function pointed to by pfun will called when the an element
  // with name name is encountered.
  // Returns nonzero for error (e.g. same name already used for a
  // differenct function).
  static int register_creator(std::string name, Creator pfun);

  // Create a table using the appropriate function.
  // Caller is responsible for managing (deleting) the table.
  // Returns 0 if the element has an unknown name.
  static SqlTable* create(std::string name, std::string params);

  // Return the list of names for which functions have been registered.
  static const CreatorList& creators();

  // Return if a specified name is registered.
  static bool has_creator(std::string name);

  // Register a function to be called whenever a creator is
  // registered. This makes if possible for SqlTable names to also be
  // used as catalog (repository, selection and replica) names.
  static int register_creator_callback(Callback pfun);

public:  // methods

  // Default constructor.
  SqlTable();
  
  // Destructor.
  virtual ~SqlTable();

  // Error.
  virtual int error() const =0;
 
  // Error message.
  virtual std::string error_string(int ecode) const =0;

  // Is this a valid table?
  virtual bool is_valid() const =0;

  // Fetch the table schema.
  virtual SqlResult get_schema() const =0;
  
  // Fetch the description of the column holding the modification time.
  // The returned time must be in unix format (seconds since 1970).
  // E.g. "modtime" or "unix_timestamp(modtime)".
  // Blank if there is no such column.
  virtual std::string modify_time_column() const =0;
  
  // Fetch the description of the column holding the creation time.
  // The returned time must be in unix format (seconds since 1970).
  // E.g. "createtime" or "unix_timestamp(createtime)".
  // Blank if there is no such column.
  virtual std::string create_time_column() const =0;
  
  // Fetch the total number of rows.
  virtual int get_row_count(SelectQuery query =SelectQuery()) const =0;

  // Fetch the total number of columns/fields.
  virtual int get_col_count(SelectQuery query =SelectQuery()) const =0;

  // Get result of executing Select sql query.
  // Argument carries the select clause (column names ) as well 
  // as the constraint; not from clause.
  virtual SqlResult execute_select_query(SelectQuery query =SelectQuery()) const =0;

  // Get result of executing Insert sql query.
  // Argument carries the select clause (column names ) as well 
  // as the constraint; not from clause.
  virtual int execute_insert_query(InsertQuery query) =0;

  // Get result of executing Update sql query.
  // Argument carries the select clause (column names ) as well 
  // as the constraint; not from clause.
  virtual int execute_update_query(InsertQuery insquery, SelectQuery selquery) =0;

  // Get result of executing Delete sql query.
  // Argument carries the select clause (column names ) as well 
  // as the constraint; not from clause.
  virtual int execute_delete_query(DeleteQuery query =DeleteQuery()) =0;

};

}  // end dset namespace

#endif