QwDatabase.h

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/*!
 * \file   QwDatabase.h
 * \brief  A class for handling connections to the Qweak database.
 *
 * \author Damon Spayde
 * \date   2010-01-07
 */
 
#pragma once
 
// System headers
#include <map>
#include <memory>
#include <vector>
#include <string>
#include <typeinfo>
#include <variant>
 
// Third Party Headers
#ifdef __USE_DATABASE__
#ifdef __USE_SQLPP11__
#include <sqlpp11/sqlpp11.h>
#ifdef __USE_DATABASE_MYSQL__
#include <sqlpp11/mysql/mysql.h>
#endif // __USE_DATABASE_MYSQL__
#ifdef __USE_DATABASE_SQLITE3__
#include <sqlpp11/sqlite3/sqlite3.h>
#endif // __USE_DATABASE_SQLITE3__
#ifdef __USE_DATABASE_POSTGRESQL__
#include <sqlpp11/postgresql/postgresql.h>
#endif // __USE_DATABASE_POSTGRESQL__
#endif // __USE_SQLPP11__
#ifdef __USE_SQLPP23__
#include <sqlpp23/sqlpp23.h>
#ifdef __USE_DATABASE_MYSQL__
#include <sqlpp23/mysql/mysql.h>
#endif // __USE_DATABASE_MYSQL__
#ifdef __USE_DATABASE_SQLITE3__
#include <sqlpp23/sqlite3/sqlite3.h>
#endif // __USE_DATABASE_SQLITE3__
#ifdef __USE_DATABASE_POSTGRESQL__
#include <sqlpp23/postgresql/postgresql.h>
#endif // __USE_DATABASE_POSTGRESQL__
 
// Compatibility shims for sqlpp23 to support sqlpp11 syntax
namespace sqlpp {
  // Make std::nullopt available as sqlpp::null for compatibility  
  static constexpr auto null = std::nullopt;
}
 
// Compatibility helper for result field null checking
// For sqlpp11: use free function is_null() to call the member function .is_null()
// For sqlpp23: result fields are std::optional<T>, provide is_null() via ADL
template<typename T>
constexpr bool is_null(const std::optional<T>& opt) {
  return !opt.has_value();
}
 
#endif // __USE_SQLPP23__
#endif // __USE_DATABASE__
 
// ROOT headers
#include "TString.h"
 
// Qweak headers
#include "QwTypes.h"
#include "QwLog.h"
#include "QwColor.h"
#include "QwOptions.h"
 
// Forward declarations
class QwDatabase;
 
/**
 *  \class QwScopedConnection
 *  \ingroup QwAnalysis
 *  \brief A RAII-style scoped database connection
 *
 * This class provides automatic connection management using RAII principles.
 * The connection is established when the object is created and automatically
 * disconnected when the object goes out of scope.
 */
class QwScopedConnection {
private:
    QwDatabase* fDatabase;
    bool fConnected;
 
public:
    explicit QwScopedConnection(QwDatabase* db);
    ~QwScopedConnection();
    
    // Delete copy constructor and assignment operator to prevent copying
    QwScopedConnection(const QwScopedConnection&) = delete;
    QwScopedConnection& operator=(const QwScopedConnection&) = delete;
    
    // Allow move constructor and assignment
    QwScopedConnection(QwScopedConnection&& other) noexcept;
    QwScopedConnection& operator=(QwScopedConnection&& other) noexcept;
    
    // Provide access to the database interface
    QwDatabase* operator->() { return fDatabase; }
    const QwDatabase* operator->() const { return fDatabase; }
    QwDatabase& operator*() { return *fDatabase; }
    const QwDatabase& operator*() const { return *fDatabase; }
    
    // Check if connection is valid
    bool IsConnected() const;
};
 
/**
 *  \class QwDatabase
 *  \ingroup QwAnalysis
 *  \brief A database interface class
 *
 * This class provides the connection to the Qweak database to other objects
 * in the Qweak analyzer.  A static global object gQwDatabase is used to
 * provide these services.
 *
 */
 
class QwDatabase {
  private:
    enum EQwDBType {kQwDatabaseNone
#ifdef __USE_DATABASE_SQLITE3__
      , kQwDatabaseSQLite3
#endif // __USE_DATABASE_SQLITE3__
#ifdef __USE_DATABASE_MYSQL__
      , kQwDatabaseMySQL
#endif // __USE_DATABASE_MYSQL__
#ifdef __USE_DATABASE_POSTGRESQL__
      , kQwDatabasePostgreSQL
#endif // __USE_DATABASE_POSTGRESQL__
    };
    EQwDBType fDBType = kQwDatabaseNone;  //!< Type of database backend to use
 
    // Define connection types conditionally
#ifdef __USE_DATABASE_SQLITE3__
    using SQLiteConnection = std::shared_ptr<sqlpp::sqlite3::connection>;
#endif
#ifdef __USE_DATABASE_MYSQL__
    using MySQLConnection = std::shared_ptr<sqlpp::mysql::connection>;
#endif
#ifdef __USE_DATABASE_POSTGRESQL__
    using PostgreSQLConnection = std::shared_ptr<sqlpp::postgresql::connection>;
#endif
 
    // Build the variant type conditionally
    using DatabaseConnection = std::variant<
      std::monostate  // Always include monostate as fallback
#ifdef __USE_DATABASE_SQLITE3__
      , SQLiteConnection
#endif
#ifdef __USE_DATABASE_MYSQL__
      , MySQLConnection
#endif
#ifdef __USE_DATABASE_POSTGRESQL__
      , PostgreSQLConnection
#endif
    >;
 
    // Return type for QuerySelect that supports all possible result types
    template<typename Statement>
    using QuerySelectReturnType = std::variant<
      std::monostate  // Always include monostate as fallback
#ifdef __USE_DATABASE_SQLITE3__
      , decltype((*std::declval<SQLiteConnection>())(std::declval<Statement>()))
#endif
#ifdef __USE_DATABASE_MYSQL__
      , decltype((*std::declval<MySQLConnection>())(std::declval<Statement>()))
#endif
#ifdef __USE_DATABASE_POSTGRESQL__
      , decltype((*std::declval<PostgreSQLConnection>())(std::declval<Statement>()))
#endif
    >;
 
    DatabaseConnection fDBConnection;
 
  private:
    // Enum to control connection checking behavior
    enum class EConnectionCheck : bool {
      kUnchecked = false,
      kChecked = true
    };
 
    // Unified helper function to abstract the visitor pattern for database operations
    template<EConnectionCheck CheckConnection = EConnectionCheck::kChecked, typename Lambda>
    auto VisitConnection(Lambda&& lambda) {
      return std::visit([&lambda](auto& connection) -> decltype(lambda(connection)) {
        using T = std::decay_t<decltype(connection)>;
        if constexpr (std::is_same_v<T, std::monostate>) {
          if constexpr (CheckConnection == EConnectionCheck::kChecked) {
            throw std::runtime_error("Database not connected (no backend available)");
          } else {
            // For unchecked mode with monostate, return appropriate default
            if constexpr (std::is_void_v<decltype(lambda(connection))>) {
              return; // Return void for void lambdas
            } else {
              return decltype(lambda(connection)){}; // Return default-constructed value
            }
          }
        } else {
          if constexpr (CheckConnection == EConnectionCheck::kChecked) {
            if (!connection) {
              throw std::runtime_error("Database not connected");
            }
          }
          return lambda(connection);
        }
      }, fDBConnection);
    }
 
  public:
 
    // Helper function to iterate over QuerySelect results safely
    template<typename Statement, typename Lambda>
    void QuerySelectForEachResult(const Statement& statement, Lambda&& lambda) {
      auto results = QuerySelect(statement);
      ForEachResult(results, std::forward<Lambda>(lambda));
    }
 
    // Overload to work with already-executed query results
    template<typename QueryResult, typename Lambda>
    void ForEachResult(QueryResult& result, Lambda&& lambda) const {
      std::visit([&lambda](auto& res) {
        using T = std::decay_t<decltype(res)>;
        if constexpr (!std::is_same_v<T, std::monostate>) {
          for (const auto& row : res) {
            lambda(row);
          }
        }
        // If T is std::monostate, do nothing (no results to iterate over)
      }, result);
    }
 
    // Helper function to count QuerySelect results safely
    template<typename Statement>
    size_t QuerySelectCountResults(const Statement& statement) {
      size_t count = 0;
      QuerySelectForEachResult(statement, [&count](const auto& row) {
        (void)row; // Suppress unused variable warning
        count++;
      });
      return count;
    }
 
    // Overload to work with already-executed query results
    template<typename QueryResult>
    size_t CountResults(QueryResult& result) const {
      size_t count = 0;
      ForEachResult(result, [&count](const auto& row) {
        (void)row; // Suppress unused variable warning
        count++;
      });
      return count;
    }
 
    // Helper function to get first result safely (returns optional-like behavior)
    template<typename Statement, typename Lambda>
    bool QuerySelectForFirstResult(const Statement& statement, Lambda&& lambda) {
      bool found = false;
      QuerySelectForEachResult(statement, [&lambda, &found](const auto& row) {
        if (!found) {  // Only process first result
          lambda(row);
          found = true;
        }
      });
      return found;
    }
 
    // Overload to work with already-executed query results
    template<typename QueryResult, typename Lambda>
    bool ForFirstResult(QueryResult& result, Lambda&& lambda) const {
      bool found = false;
      ForEachResult(result, [&lambda, &found](const auto& row) {
        if (!found) {  // Only process first result
          lambda(row);
          found = true;
        }
      });
      return found;
    }
 
    // Specialized helper for QuerySelect that returns a variant of all possible result types
    template<typename Statement, typename Lambda>
    auto VisitConnectionForSelect(Lambda&& lambda) -> QuerySelectReturnType<Statement> {
      using ReturnVariant = QuerySelectReturnType<Statement>;
      return std::visit([&lambda](auto& connection) -> ReturnVariant {
        using T = std::decay_t<decltype(connection)>;
        if constexpr (std::is_same_v<T, std::monostate>) {
          throw std::runtime_error("Database not connected (no backend available)");
        } else {
          if (!connection) {
            throw std::runtime_error("Database not connected");
          }
          return ReturnVariant{lambda(connection)};
        }
      }, fDBConnection);
    }
 
  public:
 
    QwDatabase(const string &major = "00", const string &minor = "00", const string &point = "0000"); //!< Simple constructor
    QwDatabase(QwOptions &options, const string &major = "00", const string &minor = "00", const string &point = "0000"); //!< Constructor with QwOptions object
 
    virtual ~QwDatabase(); //!< Destructor
 
    void         SetAccessLevel(string accesslevel);  //!< Sets the access level flag based on string labels:  "off", "ro", "rw".
 
    Bool_t       AllowsReadAccess(){return (fAccessLevel==kQwDatabaseReadOnly || fAccessLevel==kQwDatabaseReadWrite);};
    Bool_t       AllowsWriteAccess(){return (fAccessLevel==kQwDatabaseReadWrite);};
 
    Bool_t       Connect();                    //!< Open a connection to the database using the predefined parameters.
    void         Disconnect() {
      VisitConnection<EConnectionCheck::kUnchecked>([](auto& conn) {
        using T = std::decay_t<decltype(conn)>;
        if constexpr (!std::is_same_v<T, std::monostate>) {
          if (conn) {
            conn.reset();
          }
        }
      });
    }; //<! Close an open database connection
    Bool_t       Connected() {
      return VisitConnection<EConnectionCheck::kUnchecked>([](const auto& conn) -> bool {
        using T = std::decay_t<decltype(conn)>;
        if constexpr (std::is_same_v<T, std::monostate>) {
          return false;
        } else {
          return conn != nullptr;
        }
      });
    }
    
    //!< Get a scoped connection that automatically disconnects when destroyed
    QwScopedConnection GetScopedConnection() {
      return QwScopedConnection(this);
    }
    const string GetServerVersion() {
      // FIXME (wdconinc) implement server_version();
      return "";
    }; //<! Get database server version
    static void  DefineOptions(QwOptions& options); //!< Defines available class options for QwOptions
    void ProcessOptions(QwOptions &options); //!< Processes the options contained in the QwOptions object.
    void ProcessOptions(const EQwDBType& dbtype, const TString& dbname, const TString& username, const TString& passwd, const TString& dbhost="localhost", const Int_t dbport = 0, const TString& accesslevel = "ro"); //!< Processes database options
 
    // Separate methods for different query types to avoid std::visit return type issues
    template<typename Statement>
    size_t QueryCount(const Statement& statement) {
      return VisitConnection<EConnectionCheck::kChecked>([&statement](auto& connection) -> size_t {
        using T = std::decay_t<decltype(connection)>;
        if constexpr (!std::is_same_v<T, std::monostate>) {
          auto result = (*connection)(statement);
          size_t count = 0;
          for (const auto& row : result) {
            (void)row; // Suppress unused variable warning
            count++;
          }
          return count;
        }
        // This should never be reached due to VisitConnection logic
        throw std::runtime_error("Unreachable: monostate in QueryCount lambda");
      });
    }
    
    template<typename Statement>
    bool QueryExists(const Statement& statement) {
      return QueryCount(statement) > 0;
    } //<! Generate a query to check existence in the database.
    
    template<typename Statement>
    auto QuerySelect(const Statement& statement) {
      return VisitConnectionForSelect<Statement>([&statement](auto& connection) {
        using T = std::decay_t<decltype(connection)>;
        if constexpr (!std::is_same_v<T, std::monostate>) {
          return (*connection)(statement);
        }
        // This should never be reached due to VisitConnectionForSelect logic
        throw std::runtime_error("Unreachable: monostate in QuerySelect lambda");
      });
    } //<! Execute a SELECT statement and return the result.
    
    template<typename Statement>
    void QueryExecute(const Statement& statement) {
      VisitConnection<EConnectionCheck::kChecked>([&statement](auto& connection) {
        using T = std::decay_t<decltype(connection)>;
        if constexpr (!std::is_same_v<T, std::monostate>) {
          (*connection)(statement);
        }
      });
    } //<! Execute a statement without returning a result.
    
    template<typename InsertStatement>
    uint64_t QueryInsertAndGetId(const InsertStatement& statement) {
      return VisitConnection<EConnectionCheck::kChecked>([&statement](auto& connection) -> uint64_t {
        using T = std::decay_t<decltype(connection)>;
        if constexpr (!std::is_same_v<T, std::monostate>) {
          auto result = (*connection)(statement);
          // For INSERT operations, most databases return the ID directly as uint64_t
          if constexpr (std::is_integral_v<decltype(result)>) {
            return static_cast<uint64_t>(result);
          } else {
            throw std::runtime_error("Unexpected result type from INSERT operation - expected integral type");
          }
        }
        // This should never be reached due to VisitConnection logic
        throw std::runtime_error("Unreachable: monostate in QueryInsertAndGetId lambda");
      });
    } //<! Execute an INSERT statement and return the auto-increment ID.
    
    const string GetVersion();                             //! Return a full version string for the DB schema
    const string GetVersionMajor() {return fVersionMajor;} //<! fVersionMajor getter
    const string GetVersionMinor() {return fVersionMinor;} //<! fVersionMinor getter
    const string GetVersionPoint() {return fVersionPoint;} //<! fVersionPoint getter
    const string GetValidVersion();                        //<! Return a full required version string.
 
    void         PrintServerInfo();                        //<! Print Server Information
 
 private:
    enum EQwDBAccessLevel{kQwDatabaseOff, kQwDatabaseReadOnly, kQwDatabaseReadWrite};
 private:
 
    Bool_t       ValidateConnection();                  //!< Checks that given connection parameters result in a valid connection
    bool StoreDBVersion();  //!< Retrieve database schema version information from database
 
    // Do not allow compiler to automatically generated these functions
    QwDatabase(const QwDatabase& rhs);  //!< Copy Constructor (not implemented)
    QwDatabase& operator= (const QwDatabase& rhs); //!< Assignment operator (not implemented)
//    QwDatabase* operator& (); //!< Address-of operator (not implemented)
//    const QwDatabase* operator& () const; //!< Address-of operator (not implemented)
 
    EQwDBAccessLevel fAccessLevel;  //!< Access level of the database instance
 
    string fDatabase;        //!< Name of database to connect to
    string fDBServer;        //!< Name of server carrying DB to connect to
    string fDBUsername;      //!< Name of account to connect to DB server with
    string fDBPassword;      //!< DB account password
    UInt_t fDBPortNumber;    //!< Port number to connect to on server (mysql default port is 3306)
    Bool_t fValidConnection; //!< True if a valid connection was established using defined connection information
    Bool_t fDBDebug;         //!< True if database debug information should be printed to stdout
 
    string fVersionMajor;    //!< Major version number of current DB schema
    string fVersionMinor;    //!< Minor version number of current DB schema
    string fVersionPoint;    //!< Point version number of current DB schema
    const string kValidVersionMajor;
    const string kValidVersionMinor;
    const string kValidVersionPoint;
 
  protected:
    Bool_t fDBInsertMissingKeys; //!< True if missing keys should be inserted into the database automatically
 
};