/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2023 Osimis S.A., Belgium
 * Copyright (C) 2021-2023 Sebastien Jodogne, ICTEAM UCLouvain, 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 "PostgreSQLIncludes.h"  // Must be the first
#include "PostgreSQLResult.h"

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

#include <Compatibility.h>  // For std::unique_ptr<>
#include <OrthancException.h>
#include <Logging.h>
#include <Endianness.h>

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


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())
  {
    if (database_.IsVerboseEnabled())
    {
      LOG(INFO) << "PostgreSQL: " << statement.sql_;
    }
    
    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));
  }


  std::string PostgreSQLResult::GetLargeObjectOid(unsigned int column) const
  {
    CheckColumn(column, OIDOID);

    /**
     * In PostgreSQL, the type "Oid" corresponds to "unsigned int", cf.
     * /usr/include/postgresql/10/server/postgres_ext.h
     **/
    Oid oid;
    assert(PQfsize(reinterpret_cast<PGresult*>(result_), column) == sizeof(oid));

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

    return boost::lexical_cast<std::string>(oid);
  }


  void PostgreSQLResult::GetLargeObjectContent(std::string& content,
                                               unsigned int column) const
  {
    PostgreSQLLargeObject::ReadWhole(content, database_, GetLargeObjectOid(column));
  }


  class PostgreSQLResult::LargeObjectResult : public ResultFileValue
  {
  private:
    PostgreSQLDatabase&  database_;
    std::string          oid_;

  public:
    LargeObjectResult(PostgreSQLDatabase& database,
                      const std::string& oid) :
      database_(database),
      oid_(oid)
    {
    }

    virtual void ReadWhole(std::string& target) const ORTHANC_OVERRIDE
    {
      PostgreSQLLargeObject::ReadWhole(target, database_, oid_);
    }
    
    virtual void ReadRange(std::string& target,
                           uint64_t start,
                           size_t length) const ORTHANC_OVERRIDE
    {
      PostgreSQLLargeObject::ReadRange(target, database_, oid_, start, length);
    }
  };


  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:
        return new LargeObjectResult(database_, GetLargeObjectOid(column));

      case VOIDOID:
        return NULL;

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