/*
 * @project      The CERN Tape Archive (CTA)
 * @copyright    Copyright © 2021-2022 CERN
 * @license      This program is free software, distributed under the terms of the GNU General Public
 *               Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING". You can
 *               redistribute it and/or modify it under the terms of the GPL Version 3, 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.
 *
 *               In applying this licence, CERN does not waive the privileges and immunities
 *               granted to it by virtue of its status as an Intergovernmental Organization or
 *               submit itself to any jurisdiction.
 */

#include "common/exception/Exception.hpp"
#include "common/exception/Errnum.hpp"
#include "rdbms/ConstraintError.hpp"
#include "rdbms/NullDbValue.hpp"
#include "rdbms/PrimaryKeyError.hpp"
#include "rdbms/wrapper/Sqlite.hpp"
#include "rdbms/wrapper/SqliteRset.hpp"
#include "rdbms/wrapper/SqliteStmt.hpp"

#include <cstring>
#include <sstream>
#include <stdexcept>


namespace cta::rdbms::wrapper {

/**
 * A map from column name to column index and type.
 */
class ColNameToIdxAndType {
public:

  /**
   * Structure to store a column's index and type.  With SQLite 3 the type of a
   * column needs to be stored before any type conversion has taken place.  This
   * is because the result of calling the sqlite3_column_type() function is no
   * longer meaningful after such a conversion.
   */
  struct IdxAndType {
    /**
     * The index of the column.
     */
    int colIdx;

    /**
     * The type of the column as return by the sqlite3_column_type() function
     * before any type conversion has taken place.
     */
    int colType;

    /**
     * Constructor.  Set both member-variables to 0.
     */
    IdxAndType(): colIdx(0), colType(0) {
    }
  };

  /**
   * Adds the specified mapping from column name to column index and type.
   *
   * This method throws an exception if the specified column name is a
   * duplicate, in other words has already been added to the map.
   *
   * @param name The name of the column.
   * @param idxAndType The column index and type.
   */
  void add(const std::string &name, const IdxAndType &idxAndType) {
    if(m_nameToIdxAndType.end() != m_nameToIdxAndType.find(name)) {
      throw exception::Exception(std::string(__FUNCTION__) + " failed: " + name + " is a duplicate");
    }
    m_nameToIdxAndType[name] = idxAndType;
  }

  /**
   * Returns the index and type of the column with the specified name.
   *
   * This method throws an exception if the specified column name is not in the
   * map.
   *
   * @param name The name of the column.
   * @return The index and type of the column.
   */
  IdxAndType getIdxAndType(const std::string &name) const {
    auto it = m_nameToIdxAndType.find(name);
    if(m_nameToIdxAndType.end() == it) {
      throw exception::Exception(std::string(__FUNCTION__) + " failed: Unknown column name " + name);
    }
    return it->second;
  }

  /**
   * Alias for the getIdx() method.
   *
   * @return the index of the column with the specified name.
   */
  IdxAndType operator[](const std::string &name) const {
    return getIdxAndType(name);
  }

  /**
   * Returns true if this map is empty.
   *
   * @return True if this map is empty.
   */
  bool empty() const {
    return m_nameToIdxAndType.empty();
  }

private:

  /**
   * The underlying STL map from column name to column index.
   */
  std::map<std::string, IdxAndType> m_nameToIdxAndType;

}; // class SqliteRset::ColNameToIdx

//------------------------------------------------------------------------------
// constructor
//------------------------------------------------------------------------------
SqliteRset::SqliteRset(SqliteStmt &stmt): m_stmt(stmt) {
}

//------------------------------------------------------------------------------
// getSql
//------------------------------------------------------------------------------
const std::string &SqliteRset::getSql() const {
  return m_stmt.getSql();
}

//------------------------------------------------------------------------------
// next
//------------------------------------------------------------------------------
bool SqliteRset::next() {
  const int stepRc = sqlite3_step(m_stmt.get());

  // Throw an exception if the call to sqlite3_step() failed
  if(SQLITE_DONE != stepRc && SQLITE_ROW != stepRc) {
    std::ostringstream msg;
    msg << __FUNCTION__ << " failed for SQL statement " << m_stmt.getSqlForException() + ": " <<
      Sqlite::rcToStr(stepRc);

    switch(stepRc) {
    case SQLITE_CONSTRAINT_PRIMARYKEY:
      throw PrimaryKeyError(msg.str(), "", "");
    case SQLITE_CONSTRAINT:
      throw ConstraintError(msg.str(), "", "");
    default:
      throw exception::Exception(msg.str());
    }
  }

  if(SQLITE_ROW == stepRc) {
    clearAndPopulateColNameToIdxAndTypeMap();
  }

  return SQLITE_ROW == stepRc;
}

//------------------------------------------------------------------------------
// clearAndPopulateColNameToIdxMap
//------------------------------------------------------------------------------
void SqliteRset::clearAndPopulateColNameToIdxAndTypeMap() {
  try {
    m_colNameToIdxAndType.clear();

    const int nbCols = sqlite3_column_count(m_stmt.get());
    for (int i = 0; i < nbCols; i++) {
      // Get the name of the column
      const char *const colName = sqlite3_column_name(m_stmt.get(), i);
      if (nullptr == colName) {
        std::ostringstream msg;
        msg << "Failed to get column name for column index " << i;
        throw exception::Exception(msg.str());
      }

      // Get the type of the column
      ColumnNameToIdxAndType::IdxAndType idxAndType;
      idxAndType.colIdx = i;
      idxAndType.colType = sqlite3_column_type(m_stmt.get(), i);

      // Add the mapping from column name to index and type
      m_colNameToIdxAndType.add(colName, idxAndType);
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

//------------------------------------------------------------------------------
// columnIsNull
//------------------------------------------------------------------------------
bool SqliteRset::columnIsNull(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    return SQLITE_NULL == idxAndType.colType;
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

std::string SqliteRset::columnBlob(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    if(SQLITE_NULL == idxAndType.colType) {
      return std::string();
    } else {
      const char *const colValue = reinterpret_cast<const char*>(sqlite3_column_blob(m_stmt.get(), idxAndType.colIdx));
      if(nullptr == colValue) {
        return std::string();
      }
      int blobsize = sqlite3_column_bytes(m_stmt.get(), idxAndType.colIdx);
      return std::string(colValue,blobsize);
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

//------------------------------------------------------------------------------
// columnOptionalString
//------------------------------------------------------------------------------
std::optional<std::string> SqliteRset::columnOptionalString(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    if(SQLITE_NULL == idxAndType.colType) {
      return std::nullopt;
    } else {
      const char *const colValue = (const char *)sqlite3_column_text(m_stmt.get(), idxAndType.colIdx);
      if(nullptr == colValue) {
        exception::Exception ex;
        ex.getMessage() << __FUNCTION__ << " failed: sqlite3_column_text() returned NULL when"
          " m_colNameToIdxAndType map states otherwise: colName=" << colName << ",colIdx=" << idxAndType.colIdx;
        throw ex;
      }
      return std::optional<std::string>(colValue);
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

//------------------------------------------------------------------------------
// columnOptionalUint8
//------------------------------------------------------------------------------
std::optional<uint8_t> SqliteRset::columnOptionalUint8(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    if(SQLITE_NULL == idxAndType.colType) {
      return std::nullopt;
    } else {
      return std::optional<uint8_t>(sqlite3_column_int(m_stmt.get(), idxAndType.colIdx));
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

//------------------------------------------------------------------------------
// columnOptionalUint16
//------------------------------------------------------------------------------
std::optional<uint16_t> SqliteRset::columnOptionalUint16(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    if(SQLITE_NULL == idxAndType.colType) {
      return std::nullopt;
    } else {
      return std::optional<uint16_t>(sqlite3_column_int(m_stmt.get(), idxAndType.colIdx));
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

//------------------------------------------------------------------------------
// columnOptionalUint32
//------------------------------------------------------------------------------
std::optional<uint32_t> SqliteRset::columnOptionalUint32(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    if(SQLITE_NULL == idxAndType.colType) {
      return std::nullopt;
    } else {
      return std::optional<uint32_t>(sqlite3_column_int(m_stmt.get(), idxAndType.colIdx));
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

//------------------------------------------------------------------------------
// columnOptionalUint64
//------------------------------------------------------------------------------
std::optional<uint64_t> SqliteRset::columnOptionalUint64(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    if(SQLITE_NULL == idxAndType.colType) {
      return std::nullopt;
    } else {
      return std::optional<uint64_t>(sqlite3_column_int64(m_stmt.get(), idxAndType.colIdx));
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

//------------------------------------------------------------------------------
// columnOptionalDouble
//------------------------------------------------------------------------------
std::optional<double> SqliteRset::columnOptionalDouble(const std::string &colName) const {
  try {
    const ColumnNameToIdxAndType::IdxAndType idxAndType = m_colNameToIdxAndType.getIdxAndType(colName);
    if(SQLITE_NULL == idxAndType.colType) {
      return std::nullopt;
    } else {
      return std::optional<double>(sqlite3_column_double(m_stmt.get(), idxAndType.colIdx));
    }
  } catch(exception::Exception &ex) {
    throw exception::Exception(std::string(__FUNCTION__) + " failed: " + ex.getMessage().str());
  }
}

} // namespace cta::rdbms::wrapper