#include "MantidAlgorithms/CalculateResolution.h"
#include "MantidAPI/MatrixWorkspace.h"
#include "MantidAPI/WorkspaceValidators.h"
#include "MantidGeometry/IComponent.h"
#include "MantidGeometry/Instrument.h"

#include <cmath>

#include <boost/shared_ptr.hpp>

namespace Mantid
{
  namespace Algorithms
  {

    using namespace Mantid::API;
    using namespace Mantid::Geometry;
    using namespace Mantid::Kernel;

    // Register the algorithm into the AlgorithmFactory
    DECLARE_ALGORITHM(CalculateResolution)


    //----------------------------------------------------------------------------------------------
    /** Constructor
    */
    CalculateResolution::CalculateResolution()
    {
    }

    //----------------------------------------------------------------------------------------------
    /** Destructor
    */
    CalculateResolution::~CalculateResolution()
    {
    }

    //----------------------------------------------------------------------------------------------

    /// Algorithm's name for identification. @see Algorithm::name
    const std::string CalculateResolution::name() const { return "CalculateResolution";};

    /// Algorithm's version for identification. @see Algorithm::version
    int CalculateResolution::version() const { return 1;};

    /// Algorithm's category for identification. @see Algorithm::category
    const std::string CalculateResolution::category() const { return "Reflectometry\\ISIS";}

    /// Algorithm's summary for use in the GUI and help. @see Algorithm::summary
    const std::string CalculateResolution::summary() const { return "Calculates the reflectometry resolution (dq/q) for a given workspace.";};

    //----------------------------------------------------------------------------------------------
    /** Initialize the algorithm's properties.
    */
    void CalculateResolution::init()
    {
      declareProperty(new WorkspaceProperty<>("Workspace","",Direction::Input,boost::make_shared<InstrumentValidator>()),
      "Workspace to calculate the instrument resolution of.");

      declareProperty("TwoTheta", Mantid::EMPTY_DBL(), "Two theta scattering angle in degrees.");
      declareProperty("FirstSlitName", "slit1", "Component name of the first slit.");
      declareProperty("SecondSlitName", "slit2", "Component name of the second slit.");
      declareProperty("VerticalGapParameter", "vertical gap", "Parameter the vertical gap of each slit can be found in.");
      declareProperty("TwoThetaLogName", "THETA", "Name two theta can be found in the run log as.");

      declareProperty("Resolution", Mantid::EMPTY_DBL(), "Calculated resolution (dq/q).", Direction::Output);
    }

    //----------------------------------------------------------------------------------------------
    /** Execute the algorithm.
    */
    void CalculateResolution::exec()
    {
      const MatrixWorkspace_sptr ws = getProperty("Workspace");
      double twoTheta = getProperty("TwoTheta");
      const std::string slit1Name = getProperty("FirstSlitName");
      const std::string slit2Name = getProperty("SecondSlitName");
      const std::string vGapParam = getProperty("VerticalGapParameter");
      const std::string twoThetaLogName = getProperty("TwoThetaLogName");

      if(isEmpty(twoTheta))
      {
        const Kernel::Property* logData = ws->mutableRun().getLogData(twoThetaLogName);

        if(!logData)
          throw std::runtime_error("Value for two theta could not be found in log. You must provide it.");

        const std::string twoThetaStr = logData->value();
        Mantid::Kernel::Strings::convert<double>(twoThetaStr, twoTheta);

        g_log.notice() << "Found '" << twoTheta << "' as value for two theta in log." << std::endl;
      }

      Instrument_const_sptr instrument = ws->getInstrument();
      IComponent_const_sptr slit1 = instrument->getComponentByName(slit1Name);
      IComponent_const_sptr slit2 = instrument->getComponentByName(slit2Name);

      if(!slit1)
        throw std::runtime_error("Could not find component in instrument with name: '" + slit1Name + "'");

      if(!slit2)
        throw std::runtime_error("Could not find component in instrument with name: '" + slit2Name + "'");

      const V3D slitDiff = (slit2->getPos() - slit1->getPos()) * 1000; //Convert from mm to m.

      std::vector<double> slit1VGParam = slit1->getNumberParameter(vGapParam);
      std::vector<double> slit2VGParam = slit2->getNumberParameter(vGapParam);

      if(slit1VGParam.size() < 1)
        throw std::runtime_error("Could not find a value for the first slit's vertical gap with given parameter name: '" + vGapParam + "'.");

      if(slit2VGParam.size() < 1)
        throw std::runtime_error("Could not find a value for the second slit's vertical gap with given parameter name: '" + vGapParam + "'.");

      const double slit1VG = slit1VGParam[0];
      const double slit2VG = slit2VGParam[0];

      const double totalVertGap = slit1VG + slit2VG;
      const double slitDist = sqrt(slitDiff.X() * slitDiff.X() + slitDiff.Y() * slitDiff.Y() + slitDiff.Z() * slitDiff.Z());

      const double resolution = atan(totalVertGap / (2 * slitDist)) * 180.0 / M_PI / twoTheta;

      setProperty("Resolution", resolution);
    }

  } // namespace Algorithms
} // namespace Mantid