// CnnectionResolver.h

#ifndef ConnectionResolver_H
#define ConnectionResolver_H

// Vinay Sambamurthy
// August 2004
// Modified by D. Adams
// November 2004
// 
// Class to resolve and provide other manipulations for the connection
// string used to specify catalogs.
//
// A connection string is of the form
//   LOCATION or LOCATION@ACCESSOR 
// where LOCATION and ACCESSOR is of the form
//   NAME:PARAMS
// where PARAMS is a colon delimited list of parameters.
//
// LOCATION specifies the location of the catalog and ACCESSOR is an
// optional means to access that service. Commonly the location is
// a database table and the accessor is a web service providing access
// to that table.
//
// The name in each case is a string that specifies the technology,
// e.g. FILE, MYSQL or AMI for locations and WS for the accessor.
//
// A configuration file, be default located at $DIAL_CATALOG_CONF
// lists all the allowed connection strings in order of preference for
// each type of catalog (DatasetRepository, DatasetSelectionCatalog,
// TaskRepository, ...). This class provides means to resolve a
// user request for a connection string, i.e to find the first
// connection matching the request. All the fields in the user request
// must match the first fields in the connection.
//
// The number and meaning of the parameters in the location or accessor
// depend on the respective type.
//
// If requested, the password is resolved before returning the
// connection string using the following algorithm:
// If the connection ends with the string "<pwlocal>", then that field
// is replaced with the contents of the file at $HOME/.dial/pw<PREFIX>
// where PREFIX is the part of the connection string preceding that field.
// E.g. MYTECH:MyDb:Server:my_table:myname:<pwlocal> becomes
// MYTECH:MyDb:Server:my_table:myname:1234 if 1234 is the content of
// $HOME/.dial/pwMYTECH:MyDb:Server:my_table:myname .
// WARNING: the connection string most likely cannot be resolved again
// once the password is resolved.

#include <string>
#include "dataset_util/Text.h"

namespace dset {

class ConnectionResolver {

private: // data

  Text m_txt;
  
public: // static member functions
  
  // Set the name for the configuration file.
  // Default is $DIAL_CATALOG_CONF.
  static void set_configuration_file(std::string cfile);
  
  // Get the name for the configuration file.
  static std::string get_configuration_file();
  
  // Return the name from a location in a connection string.
  // If blank, the connection is not valid.
  static std::string location_name(std::string conn);

  // Return the name from the last accssor in a connection string.
  // IF blank, the connection does not have an accessor.
  static std::string accessor_name(std::string conn);

public: // member functions
  
  // Constructor from the file at DIAL_CATALOG_CONF.
  ConnectionResolver();

  // Destructor.
  ~ConnectionResolver();   

  // Validity.
  // True if the file is not empty.
  bool is_valid() const;

  // Return the connection string with the longest match in the
  // specified catalog. 
  // Returns blank if no match is found.
  //   type = catalog type (e.g. DatasetRepository)
  //   conn = connection string
  //   findpass = flag indicating that password should be resolved
  std::string resolve(std::string type, std::string conn,
                      bool findpass =false) const;

};

} // end namespace dset

#endif