#include "MantidAlgorithms/ConvertSpectrumAxis2.h"
#include "MantidAPI/HistogramValidator.h"
#include "MantidAPI/InstrumentValidator.h"
#include "MantidAPI/NumericAxis.h"
#include "MantidAPI/Run.h"
#include "MantidAPI/SpectraAxisValidator.h"
#include "MantidAPI/SpectrumInfo.h"
#include "MantidAPI/WorkspaceFactory.h"
#include "MantidGeometry/Instrument.h"
#include "MantidKernel/CompositeValidator.h"
#include "MantidKernel/BoundedValidator.h"
#include "MantidKernel/ListValidator.h"
#include "MantidKernel/UnitConversion.h"
#include "MantidKernel/UnitFactory.h"

#include <cfloat>

namespace Mantid {
namespace Algorithms {
// Register the algorithm into the AlgorithmFactory
DECLARE_ALGORITHM(ConvertSpectrumAxis2)
using namespace Kernel;
using namespace API;
using namespace Geometry;

void ConvertSpectrumAxis2::init() {
  // Validator for Input Workspace
  auto wsVal = boost::make_shared<CompositeValidator>();
  wsVal->add<HistogramValidator>();
  wsVal->add<SpectraAxisValidator>();
  wsVal->add<InstrumentValidator>();

  declareProperty(make_unique<WorkspaceProperty<>>("InputWorkspace", "",
                                                   Direction::Input, wsVal),
                  "The name of the input workspace.");
  declareProperty(make_unique<WorkspaceProperty<>>("OutputWorkspace", "",
                                                   Direction::Output),
                  "The name to use for the output workspace.");
  std::vector<std::string> targetOptions(6);
  targetOptions[0] = "Theta";
  targetOptions[1] = "SignedTheta";
  targetOptions[2] = "ElasticQ";
  targetOptions[3] = "ElasticQSquared";
  targetOptions[4] = "theta";
  targetOptions[5] = "signed_theta";

  declareProperty(
      "Target", "", boost::make_shared<StringListValidator>(targetOptions),
      "The unit to which spectrum axis is converted to - \"theta\" (for the "
      "angle in degrees), Q or Q^2, where elastic Q is evaluated at EFixed. "
      "Note that 'theta' and 'signed_theta' are there for compatibility "
      "purposes; they are the same as 'Theta' and 'SignedTheta' respectively");
  std::vector<std::string> eModeOptions;
  eModeOptions.emplace_back("Direct");
  eModeOptions.emplace_back("Indirect");
  declareProperty("EMode", "Direct",
                  boost::make_shared<StringListValidator>(eModeOptions),
                  "Some unit conversions require this value to be set "
                  "(\"Direct\" or \"Indirect\")");
  auto mustBePositive = boost::make_shared<BoundedValidator<double>>();
  mustBePositive->setLower(0.0);
  declareProperty("EFixed", EMPTY_DBL(), mustBePositive,
                  "Value of fixed energy in meV : EI (EMode=Direct) or EF "
                  "(EMode=Indirect))");
}

void ConvertSpectrumAxis2::exec() {
  // Get the input workspace.
  API::MatrixWorkspace_sptr inputWS = getProperty("InputWorkspace");
  // Assign value to the member variable storing the number of histograms.
  size_t nHist = inputWS->getNumberHistograms();

  // The unit to convert to.
  const std::string unitTarget = getProperty("Target");

  Progress progress(this, 0, 1, inputWS->getNumberHistograms());

  // Call the functions to convert to the different forms of theta or Q.
  if (unitTarget == "theta" || unitTarget == "Theta" ||
      unitTarget == "signed_theta" || unitTarget == "SignedTheta") {
    createThetaMap(progress, unitTarget, inputWS, nHist);
  } else if (unitTarget == "ElasticQ" || unitTarget == "ElasticQSquared") {
    createElasticQMap(progress, unitTarget, inputWS, nHist);
  }

  // Create an output workspace and set the property for it.
  MatrixWorkspace_sptr outputWS =
      createOutputWorkspace(progress, unitTarget, inputWS, nHist);
  setProperty("OutputWorkspace", outputWS);
}

/** Converts X axis to theta representation
* @param progress :: Progress indicator
* @param targetUnit :: Target conversion unit
* @param inputWS :: Input Workspace
* @param nHist :: Stores the number of histograms
*/
void ConvertSpectrumAxis2::createThetaMap(API::Progress &progress,
                                          const std::string &targetUnit,
                                          API::MatrixWorkspace_sptr &inputWS,
                                          size_t nHist) {
  // Not sure about default, previously there was a call to a null function?
  bool signedTheta = false;
  if (targetUnit.compare("signed_theta") == 0 ||
      targetUnit.compare("SignedTheta") == 0) {
    signedTheta = true;
  } else if (targetUnit == "theta" || targetUnit == "Theta") {
    signedTheta = false;
  }

  bool warningGiven = false;

  const auto &spectrumInfo = inputWS->spectrumInfo();
  for (size_t i = 0; i < nHist; ++i) {
    if (!spectrumInfo.hasDetectors(i)) {
      if (!warningGiven)
        g_log.warning("The instrument definition is incomplete - spectra "
                      "dropped from output");
      warningGiven = true;
      continue;
    }
    if (signedTheta)
      m_indexMap.emplace(spectrumInfo.signedTwoTheta(i) * rad2deg, i);
    else
      m_indexMap.emplace(spectrumInfo.twoTheta(i) * rad2deg, i);

    progress.report("Converting to theta...");
  }
}

/** Convert X axis to Elastic Q representation
* @param progress :: Progress indicator
* @param targetUnit :: Target conversion unit
* @param inputWS :: Input workspace
* @param nHist :: Stores the number of histograms
*/
void ConvertSpectrumAxis2::createElasticQMap(API::Progress &progress,
                                             const std::string &targetUnit,
                                             API::MatrixWorkspace_sptr &inputWS,
                                             size_t nHist) {
  IComponent_const_sptr source = inputWS->getInstrument()->getSource();
  IComponent_const_sptr sample = inputWS->getInstrument()->getSample();

  const std::string emodeStr = getProperty("EMode");
  int emode = 0;
  if (emodeStr == "Direct")
    emode = 1;
  else if (emodeStr == "Indirect")
    emode = 2;

  for (size_t i = 0; i < nHist; i++) {
    IDetector_const_sptr detector = inputWS->getDetector(i);
    double twoTheta(0.0), efixed(0.0);
    if (!detector->isMonitor()) {
      twoTheta = 0.5 * inputWS->detectorTwoTheta(*detector);
      efixed = getEfixed(detector, inputWS, emode); // get efixed
    } else {
      twoTheta = 0.0;
      efixed = DBL_MIN;
    }

    // Convert to MomentumTransfer
    double elasticQInAngstroms = Kernel::UnitConversion::run(twoTheta, efixed);

    if (targetUnit == "ElasticQ") {
      m_indexMap.emplace(elasticQInAngstroms, i);
    } else if (targetUnit == "ElasticQSquared") {
      // The QSquared value.
      double elasticQSquaredInAngstroms =
          elasticQInAngstroms * elasticQInAngstroms;

      m_indexMap.emplace(elasticQSquaredInAngstroms, i);
    }

    progress.report("Converting to Elastic Q...");
  }
}

/** Create the final output workspace after converting the X axis
* @returns the final output workspace
*
* @param progress :: Progress indicator
* @param targetUnit :: Target conversion unit
* @param inputWS :: Input workspace
* @param nHist :: Stores the number of histograms
*/
MatrixWorkspace_sptr ConvertSpectrumAxis2::createOutputWorkspace(
    API::Progress &progress, const std::string &targetUnit,
    API::MatrixWorkspace_sptr &inputWS, size_t nHist) {
  // Create the output workspace. Can not re-use the input one because the
  // spectra are re-ordered.
  MatrixWorkspace_sptr outputWorkspace = WorkspaceFactory::Instance().create(
      inputWS, m_indexMap.size(), inputWS->x(0).size(), inputWS->y(0).size());

  // Now set up a new numeric axis holding the theta values corresponding to
  // each spectrum.
  auto const newAxis = new NumericAxis(m_indexMap.size());
  outputWorkspace->replaceAxis(1, newAxis);

  progress.setNumSteps(nHist + m_indexMap.size());

  // Set the units of the axis.
  if (targetUnit == "theta" || targetUnit == "Theta" ||
      targetUnit == "signed_theta" || targetUnit == "SignedTheta") {
    newAxis->unit() = boost::make_shared<Units::Degrees>();
  } else if (targetUnit == "ElasticQ") {
    newAxis->unit() = UnitFactory::Instance().create("MomentumTransfer");
  } else if (targetUnit == "ElasticQSquared") {
    newAxis->unit() = UnitFactory::Instance().create("QSquared");
  }

  std::multimap<double, size_t>::const_iterator it;
  size_t currentIndex = 0;
  for (it = m_indexMap.begin(); it != m_indexMap.end(); ++it) {
    // Set the axis value.
    newAxis->setValue(currentIndex, it->first);
    // Copy over the data.
    outputWorkspace->setHistogram(currentIndex, inputWS->histogram(it->second));
    // We can keep the spectrum numbers etc.
    outputWorkspace->getSpectrum(currentIndex)
        .copyInfoFrom(inputWS->getSpectrum(it->second));
    ++currentIndex;

    progress.report("Creating output workspace...");
  }
  return outputWorkspace;
}

double ConvertSpectrumAxis2::getEfixed(IDetector_const_sptr detector,
                                       MatrixWorkspace_const_sptr inputWS,
                                       int emode) const {
  double efixed(0);
  double efixedProp = getProperty("Efixed");
  if (efixedProp != EMPTY_DBL()) {
    efixed = efixedProp;
    g_log.debug() << "Detector: " << detector->getID() << " Efixed: " << efixed
                  << "\n";
  } else {
    if (emode == 1) {
      if (inputWS->run().hasProperty("Ei")) {
        efixed = inputWS->run().getLogAsSingleValue("Ei");
      } else {
        throw std::invalid_argument("Could not retrieve Efixed from the "
                                    "workspace. Please provide a value.");
      }
    } else if (emode == 2) {
      std::vector<double> efixedVec = detector->getNumberParameter("Efixed");
      if (efixedVec.empty()) {
        int detid = detector->getID();
        IDetector_const_sptr detectorSingle =
            inputWS->getInstrument()->getDetector(detid);
        efixedVec = detectorSingle->getNumberParameter("Efixed");
      }
      if (!efixedVec.empty()) {
        efixed = efixedVec.at(0);
        g_log.debug() << "Detector: " << detector->getID()
                      << " EFixed: " << efixed << "\n";
      } else {
        g_log.warning() << "Efixed could not be found for detector "
                        << detector->getID() << ", please provide a value\n";
        throw std::invalid_argument("Could not retrieve Efixed from the "
                                    "detector. Please provide a value.");
      }
    }
  }
  return efixed;
}

} // namespace Algorithms
} // namespace Mantid