/*
 MDAL - Mesh Data Abstraction Library (MIT License)
 Copyright (C) 2018 Lutra Consulting Ltd.
*/

#include <stddef.h>
#include <iosfwd>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>
#include <map>
#include <cassert>
#include <memory>

#include "mdal_ascii_dat.hpp"
#include "mdal.h"
#include "mdal_utils.hpp"

#include <math.h>

#define EXIT_WITH_ERROR(error)       {  if (status) *status = (error); return; }

MDAL::LoaderAsciiDat::LoaderAsciiDat( const std::string &datFile ):
  mDatFile( datFile )
{
}

/**
 * The DAT format contains "datasets" and each dataset has N-outputs. One output
 * represents data for all vertices/faces for one timestep
 *
 * In MDAL we convert one output to one MDAL dataset;
 *
 */
void MDAL::LoaderAsciiDat::load( MDAL::Mesh *mesh, MDAL_Status *status )
{
  if ( status ) *status = MDAL_Status::None;

  if ( !MDAL::fileExists( mDatFile ) )
  {
    if ( status ) *status = MDAL_Status::Err_FileNotFound;
    return;
  }

  std::ifstream in( mDatFile, std::ifstream::in );
  std::string line;
  if ( !std::getline( in, line ) )
  {
    if ( status ) *status = MDAL_Status::Err_UnknownFormat;
    return;
  }
  line = trim( line );
  std::string basename = baseName( mDatFile );

  // http://www.xmswiki.com/xms/SMS:ASCII_Dataset_Files_*.dat
  // Apart from the format specified above, there is an older supported format used in BASEMENT (and SMS?)
  // which is simpler (has only one dataset in one file, no status flags etc)
  bool oldFormat;
  bool isVector = false;
  bool readingDataset = false; // whether we are in process of reading the dataset

  std::string baseDatasetName( basename );
  std::vector<std::shared_ptr<Dataset>> datOutputs; // DAT outputs data

  if ( line == "DATASET" )
    oldFormat = false;
  else if ( line == "SCALAR" || line == "VECTOR" )
  {
    oldFormat = true;
    isVector = ( line == "VECTOR" );
    baseDatasetName = basename;
    readingDataset = true;
  }
  else
    EXIT_WITH_ERROR( MDAL_Status::Err_UnknownFormat );

  // see if it contains element-centered results - supported by BASEMENT
  bool elementCentered = false;
  if ( !oldFormat && contains( basename, "_els_" ) )
    elementCentered = true;

  while ( std::getline( in, line ) )
  {
    std::vector<std::string> items = split( line,  " ", SplitBehaviour::SkipEmptyParts );
    if ( items.size() < 1 )
      continue; // empty line?? let's skip it

    std::string cardType = items[0];
    if ( cardType == "ND" && items.size() >= 2 )
    {
      size_t fileNodeCount = toSizeT( items[1] );
      if ( mesh->vertexIDtoIndex.size() != fileNodeCount )
        EXIT_WITH_ERROR( MDAL_Status::Err_IncompatibleMesh );
    }
    else if ( !oldFormat && cardType == "NC" && items.size() >= 2 )
    {
      size_t fileElemCount = toSizeT( items[1] );
      if ( mesh->faceIDtoIndex.size() != fileElemCount )
        EXIT_WITH_ERROR( MDAL_Status::Err_IncompatibleMesh );
    }
    else if ( !oldFormat && cardType == "OBJTYPE" )
    {
      if ( items[1] != "mesh2d" && items[1] != "\"mesh2d\"" )
        EXIT_WITH_ERROR( MDAL_Status::Err_UnknownFormat );
    }
    else if ( !oldFormat && ( cardType == "BEGSCL" || cardType == "BEGVEC" ) )
    {
      if ( readingDataset )
      {
        debug( "New dataset while previous one is still active!" );
        EXIT_WITH_ERROR( MDAL_Status::Err_UnknownFormat );
      }
      isVector = cardType == "BEGVEC";
      baseDatasetName = basename;
      readingDataset = true;
    }
    else if ( !oldFormat && cardType == "ENDDS" )
    {
      if ( !readingDataset )
      {
        debug( "ENDDS card for no active dataset!" );
        EXIT_WITH_ERROR( MDAL_Status::Err_UnknownFormat );
      }

      addDatasets( mesh, baseDatasetName, datOutputs );
    }
    else if ( !oldFormat && cardType == "NAME" && items.size() >= 2 )
    {
      if ( !readingDataset )
      {
        debug( "NAME card for no active dataset!" );
        EXIT_WITH_ERROR( MDAL_Status::Err_UnknownFormat );
      }

      size_t quoteIdx1 = line.find( '\"' );
      size_t quoteIdx2 = line.find( '\"', quoteIdx1 + 1 );
      if ( quoteIdx1 != std::string::npos && quoteIdx2 != std::string::npos )
        baseDatasetName = line.substr( quoteIdx1 + 1, quoteIdx2 - quoteIdx1 - 1 );
    }
    else if ( oldFormat && ( cardType == "SCALAR" || cardType == "VECTOR" ) )
    {
      // just ignore - we know the type from earlier...
    }
    else if ( cardType == "TS" && items.size() >= ( oldFormat ? 2 : 3 ) )
    {
      double t = toDouble( items[oldFormat ? 1 : 2] );

      if ( elementCentered )
      {
        readFaceTimestep( mesh, datOutputs, t, isVector, in );
      }
      else
      {
        bool hasStatus = ( oldFormat ? false : toBool( items[1] ) );
        readVertexTimestep( mesh, datOutputs, t, isVector, hasStatus, in );
      }

    }
    else
    {
      std::stringstream str;
      str << " Unknown card:" << line;
      debug( str.str() );
    }
  }

  if ( oldFormat )
  {
    if ( datOutputs.size() == 0 )
      EXIT_WITH_ERROR( MDAL_Status::Err_UnknownFormat );

    addDatasets( mesh, baseDatasetName, datOutputs );
  }
}

void MDAL::LoaderAsciiDat::addDatasets( MDAL::Mesh *mesh,
                                        const std::string &name,
                                        const std::vector<std::shared_ptr<Dataset>> &datOutputs ) const
{
  for ( const std::shared_ptr<Dataset> &ds : datOutputs )
  {
    ds->uri = mDatFile;
    ds->setName( name );
    ds->isValid = true;
  }

  //https://stackoverflow.com/a/2551785/2838364
  mesh->datasets.insert(
    mesh->datasets.end(),
    datOutputs.begin(),
    datOutputs.end()
  );
}

void MDAL::LoaderAsciiDat::readVertexTimestep( const MDAL::Mesh *mesh, std::vector<std::shared_ptr<MDAL::Dataset> > &datOutputs, double t, bool isVector, bool hasStatus, std::ifstream &stream )
{
  size_t vertexCount = mesh->vertices.size();
  size_t faceCount = mesh->faces.size();

  std::shared_ptr<MDAL::Dataset> dataset( new MDAL::Dataset );
  dataset->isScalar = !isVector; //everything else to be set in addDatasets
  dataset->setMetadata( "time", std::to_string( t / 3600. ) );
  dataset->values.resize( vertexCount );
  dataset->active.resize( faceCount );
  dataset->isOnVertices = true;

  // only for new format
  for ( size_t i = 0; i < faceCount; ++i )
  {
    if ( hasStatus )
    {
      std::string line;
      std::getline( stream, line );
      dataset->active[i] = toBool( line );
    }
    else
      dataset->active[i] = true;
  }

  for ( size_t i = 0; i < mesh->vertexIDtoIndex.size(); ++i )
  {
    std::string line;
    std::getline( stream, line );
    std::vector<std::string> tsItems = split( line,  " ", SplitBehaviour::SkipEmptyParts );

    auto idx = mesh->vertexIDtoIndex.find( i + 1 ); // ID in 2dm are numbered from 1
    if ( idx == mesh->vertexIDtoIndex.end() )
      continue; // node ID that does not exist in the mesh

    size_t index = idx->second;

    if ( isVector )
    {
      if ( tsItems.size() >= 2 ) // BASEMENT files with vectors have 3 columns
      {
        dataset->values[index].x = toDouble( tsItems[0] );
        dataset->values[index].y = toDouble( tsItems[1] );
      }
      else
      {
        debug( "invalid timestep line" );
        dataset->values[index].noData = true;
      }
    }
    else
    {
      if ( tsItems.size() >= 1 )
        dataset->values[index].x = toDouble( tsItems[0] );
      else
      {
        debug( "invalid timestep line" );
        dataset->values[index].noData = true;
      }
    }
  }

  datOutputs.push_back( std::move( dataset ) );
}

void MDAL::LoaderAsciiDat::readFaceTimestep( const MDAL::Mesh *mesh, std::vector<std::shared_ptr<MDAL::Dataset> > &datOutputs, double t, bool isVector, std::ifstream &stream )
{
  size_t faceCount = mesh->faces.size();

  std::shared_ptr<MDAL::Dataset> dataset( new MDAL::Dataset );
  dataset->isScalar = !isVector; //everything else to be set in addDatasets
  dataset->setMetadata( "time", std::to_string( t / 3600. ) );
  dataset->values.resize( faceCount );
  dataset->isOnVertices = false;

  // TODO: hasStatus
  for ( size_t index = 0; index < faceCount; ++index )
  {
    std::string line;
    std::getline( stream, line );
    std::vector<std::string> tsItems = split( line,  " ", SplitBehaviour::SkipEmptyParts );

    if ( isVector )
    {
      if ( tsItems.size() >= 2 ) // BASEMENT files with vectors have 3 columns
      {
        dataset->values[index].x = toDouble( tsItems[0] );
        dataset->values[index].y = toDouble( tsItems[1] );
      }
      else
      {
        debug( "invalid timestep line" );
        dataset->values[index].noData = true;
      }
    }
    else
    {
      if ( tsItems.size() >= 1 )
        dataset->values[index].x = toDouble( tsItems[0] );
      else
      {
        debug( "invalid timestep line" );
        dataset->values[index].noData = true;
      }
    }
  }

  datOutputs.push_back( std::move( dataset ) );
}