/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2019 Osimis S.A., Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, 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
 * Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/


#include "PostgreSQLResult.h"

#include "../Common/BinaryStringValue.h"
#include "../Common/FileValue.h"
#include "../Common/Integer64Value.h"
#include "../Common/NullValue.h"
#include "../Common/Utf8StringValue.h"

#include <pg_config.h>

#if PG_VERSION_NUM >= 110000
#  include <postgres.h>
#  undef LOG  // This one comes from <postgres.h>, and conflicts with <Core/Logging.h>
#endif

#include <Core/OrthancException.h>
#include <Core/Logging.h>

#include <cassert>
#include <boost/lexical_cast.hpp>

// PostgreSQL includes
#include <libpq-fe.h>
#include <c.h>
#include <catalog/pg_type.h>

#include <Core/Endianness.h>


namespace OrthancDatabases
{
  void PostgreSQLResult::Clear()
  {
    if (result_ != NULL)
    {
      PQclear(reinterpret_cast<PGresult*>(result_));
      result_ = NULL;
    }
  }


  void PostgreSQLResult::CheckDone()
  {
    if (position_ >= PQntuples(reinterpret_cast<PGresult*>(result_)))
    {
      // We are at the end of the result set
      Clear();
    }
  }


  void PostgreSQLResult::CheckColumn(unsigned int column, unsigned int /*Oid*/ expectedType) const
  {
    if (IsDone())
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
    }

    if (column >= static_cast<unsigned int>(PQnfields(reinterpret_cast<PGresult*>(result_))))
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
    }

    if (expectedType != 0 &&
        expectedType != PQftype(reinterpret_cast<PGresult*>(result_), column))
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadParameterType);
    }
  }


  PostgreSQLResult::PostgreSQLResult(PostgreSQLStatement& statement) : 
    position_(0), 
    database_(statement.GetDatabase())
  {
    result_ = statement.Execute();
    assert(result_ != NULL);   // An exception would have been thrown otherwise

    // This is the first call to "Next()"
    if (PQresultStatus(reinterpret_cast<PGresult*>(result_)) == PGRES_TUPLES_OK)
    {
      CheckDone();
      columnsCount_ = static_cast<unsigned int>(PQnfields(reinterpret_cast<PGresult*>(result_)));
    }
    else
    {
      // This is not a SELECT request, we're done
      Clear();
      columnsCount_ = 0;
    }
  }


  PostgreSQLResult::~PostgreSQLResult()
  {
    try
    {
      Clear();
    }
    catch (Orthanc::OrthancException&)
    {
      // Ignore possible exceptions due to connection loss
    }
  }


  void PostgreSQLResult::Next()
  {
    position_++;
    CheckDone();
  }


  bool PostgreSQLResult::IsNull(unsigned int column) const
  {
    CheckColumn(column, 0);
    return PQgetisnull(reinterpret_cast<PGresult*>(result_), position_, column) != 0;
  }


  bool PostgreSQLResult::GetBoolean(unsigned int column) const
  {
    CheckColumn(column, BOOLOID);
    assert(PQfsize(reinterpret_cast<PGresult*>(result_), column) == 1);
    const uint8_t *v = reinterpret_cast<const uint8_t*>
      (PQgetvalue(reinterpret_cast<PGresult*>(result_), position_, column));
    return (v[0] != 0);
  }


  int PostgreSQLResult::GetInteger(unsigned int column) const
  {
    CheckColumn(column, INT4OID);
    assert(PQfsize(reinterpret_cast<PGresult*>(result_), column) == 4);
    char *v = PQgetvalue(reinterpret_cast<PGresult*>(result_), position_, column);
    return htobe32(*reinterpret_cast<int32_t*>(v));
  }


  int64_t PostgreSQLResult::GetInteger64(unsigned int column) const
  {
    CheckColumn(column, INT8OID);
    assert(PQfsize(reinterpret_cast<PGresult*>(result_), column) == 8);
    char *v = PQgetvalue(reinterpret_cast<PGresult*>(result_), position_, column);
    return htobe64(*reinterpret_cast<int64_t*>(v));
  }


  std::string PostgreSQLResult::GetString(unsigned int column) const
  {
    CheckColumn(column, 0);

    Oid oid = PQftype(reinterpret_cast<PGresult*>(result_), column);
    if (oid != TEXTOID && oid != VARCHAROID && oid != BYTEAOID)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadParameterType);
    }

    return std::string(PQgetvalue(reinterpret_cast<PGresult*>(result_), position_, column));
  }


  void PostgreSQLResult::GetLargeObject(std::string& result,
                                        unsigned int column) const
  {
    CheckColumn(column, OIDOID);

    Oid oid;
    assert(PQfsize(reinterpret_cast<PGresult*>(result_), column) == sizeof(oid));

    oid = *(const Oid*) PQgetvalue(reinterpret_cast<PGresult*>(result_), position_, column);
    oid = ntohl(oid);

    PostgreSQLLargeObject::Read(result, database_, boost::lexical_cast<std::string>(oid));
  }


  void PostgreSQLResult::GetLargeObject(void*& result,
                                           size_t& size,
                                           unsigned int column) const
  {
    CheckColumn(column, OIDOID);

    Oid oid;
    assert(PQfsize(reinterpret_cast<PGresult*>(result_), column) == sizeof(oid));

    oid = *(const Oid*) PQgetvalue(reinterpret_cast<PGresult*>(result_), position_, column);
    oid = ntohl(oid);

    PostgreSQLLargeObject::Read(result, size, database_, boost::lexical_cast<std::string>(oid));
  }


  IValue* PostgreSQLResult::GetValue(unsigned int column) const
  {
    if (IsNull(column))
    {
      return new NullValue;
    }

    Oid type = PQftype(reinterpret_cast<PGresult*>(result_), column);

    switch (type)
    {
      case BOOLOID:
        // Convert Boolean values as integers
        return new Integer64Value(GetBoolean(column) ? 1 : 0);

      case INT4OID:
        return new Integer64Value(GetInteger(column));

      case INT8OID:
        return new Integer64Value(GetInteger64(column));

      case TEXTOID:
      case VARCHAROID:
        return new Utf8StringValue(GetString(column));

      case BYTEAOID:
        return new BinaryStringValue(GetString(column));

      case OIDOID:
      {
        std::auto_ptr<FileValue> value(new FileValue);
        GetLargeObject(value->GetContent(), column);
        return value.release();
      }

      default:
        throw Orthanc::OrthancException(Orthanc::ErrorCode_NotImplemented);
    }
  }
}