
///////////////////////////////////////////////////////////
//                                                       //
//                         SAGA                          //
//                                                       //
//      System for Automated Geoscientific Analyses      //
//                                                       //
//                     Tool Library                      //
//                     ta_hydrology                      //
//                                                       //
//-------------------------------------------------------//
//                                                       //
//                   flow_by_slope.cpp                   //
//                                                       //
//                 Copyright (C) 2014 by                 //
//                      Olaf Conrad                      //
//                                                       //
//-------------------------------------------------------//
//                                                       //
// This file is part of 'SAGA - System for Automated     //
// Geoscientific Analyses'. SAGA is free software; you   //
// can redistribute it and/or modify it under the terms  //
// of the GNU General Public License as published by the //
// Free Software Foundation, either version 2 of the     //
// License, or (at your option) any later version.       //
//                                                       //
// SAGA 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 General Public        //
// License for more details.                             //
//                                                       //
// You should have received a copy of the GNU General    //
// Public License along with this program; if not, see   //
// <http://www.gnu.org/licenses/>.                       //
//                                                       //
//-------------------------------------------------------//
//                                                       //
//    e-mail:     oconrad@saga-gis.org                   //
//                                                       //
//    contact:    Olaf Conrad                            //
//                Institute of Geography                 //
//                University of Hamburg                  //
//                Germany                                //
//                                                       //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
#include "flow_by_slope.h"


///////////////////////////////////////////////////////////
//														 //
//														 //
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
CFlow_by_Slope::CFlow_by_Slope(void)
{
	Set_Name		(_TL("Slope Limited Flow Accumulation"));

	Set_Author		("O.Conrad (c) 2014");

	Set_Description	(_TW(
		"Flow accumulation is calculated as upslope contributing (catchment) area "
		"using the multiple flow direction approach of Freeman (1991). For this tool "
		"the approach has been modified to limit the flow portion routed through a cell "
		"depending on the local slope. If a cell is not inclined, no flow is routed "
		"through it at all. With increasing slopes the portion of flow routed through "
		"a cell becomes higher. Cells with slopes greater than a specified slope threshold "
		"route their entire accumulated flow downhill. "		 
	));

	Add_Reference("Freeman, G.T.", "1991",
		"Calculating catchment area with divergent flow based on a regular grid",
		"Computers and Geosciences, 17:413-22."
	);

	//-----------------------------------------------------
	Parameters.Add_Grid("", "DEM"   , _TL("Elevation"        ), _TL(""), PARAMETER_INPUT);
	Parameters.Add_Grid("", "WEIGHT", _TL("Weight"           ), _TL(""), PARAMETER_INPUT_OPTIONAL);
	Parameters.Add_Grid("", "FLOW"  , _TL("Flow Accumulation"), _TL(""), PARAMETER_OUTPUT);

	Parameters.Add_Double("", "SLOPE_MIN", _TL("Slope Minimum"),
		_TL("Assume a given minimum slope for each cell."),
		0., 0., true
	);

	Parameters.Add_Double("", "SLOPE_MAX", _TL("Slope Threshold"),
		_TL("Slope threshold, given as degree, above which flow transport is unlimited."),
		5., 0., true, 90., true
	);

	Parameters.Add_Bool("", "B_FLOW", _TL("Use Flow Threshold"),
		_TL("")
	);

	Parameters.Add_Range("B_FLOW", "T_FLOW", _TL("Flow Threshold"),
		_TL("Flow threshold, given as amount of cells, above which flow transport is unlimited. Ignored if range equals zero."),
		1., 100., 1., true
	);
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
int CFlow_by_Slope::On_Parameters_Enable(CSG_Parameters *pParameters, CSG_Parameter *pParameter)
{
	if( pParameter->Cmp_Identifier("B_FLOW") )
	{
		pParameters->Set_Enabled("T_FLOW", pParameter->asBool());
	}

	return( CSG_Tool_Grid::On_Parameters_Enable(pParameters, pParameter) );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
bool CFlow_by_Slope::On_Execute(void)
{
	m_Slope_Min = Parameters("SLOPE_MIN")->asDouble() * M_DEG_TO_RAD;
	m_Slope_Max = Parameters("SLOPE_MAX")->asDouble() * M_DEG_TO_RAD;

	if( m_Slope_Max <= 0. )
	{
		Error_Set(_TL("slope threshold must not be zero!"));

		return( false );
	}

	if( Parameters("B_FLOW")->asBool() )
	{
		m_Flow_Min = Parameters("T_FLOW")->asRange()->Get_Min() * Get_Cellarea();
		m_Flow_Max = Parameters("T_FLOW")->asRange()->Get_Max() * Get_Cellarea();
	}
	else
	{
		m_Flow_Min = m_Flow_Max = 0.;
	}

	//-----------------------------------------------------
	m_pDEM  = Parameters("DEM" )->asGrid();
	m_pFlow = Parameters("FLOW")->asGrid();

	m_pFlow->Assign(Get_Cellarea());

	if( Parameters("WEIGHT")->asGrid() )
	{
		m_pFlow->Multiply(*Parameters("WEIGHT")->asGrid());
	}

	DataObject_Set_Colors(m_pFlow, 0, SG_COLORS_WHITE_BLUE, false);

	if( !m_pDEM->Set_Index() )
	{
		Error_Set(_TL("index creation failed"));

		return( false );
	}

	//-----------------------------------------------------
	for(sLong i=0; i<Get_NCells() && Set_Progress_Cells(i); i++)
	{
		int	x, y;

		if( m_pDEM->Get_Sorted(i, x, y, true) )
		{
			if( m_pDEM->is_NoData(x, y) )
			{
				m_pFlow->Set_NoData(x, y);
			}
			else
			{
				Set_Area(x, y);
			}
		}
	}

	//-----------------------------------------------------
	return( true );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
inline double CFlow_by_Slope::Get_Fuzzy(double Value, double Minimum, double Maximum)
{
	return( Value <= Minimum ? 0. : Value >= Maximum ? 1. :
		0.5 * (1. - cos(M_PI * ((Value - Minimum) / (Maximum - Minimum))))
	);
}

//---------------------------------------------------------
inline bool CFlow_by_Slope::Get_Decay(int x, int y, double &Decay)
{
	double d;

	if( !m_pDEM->Get_Gradient(x, y, d, Decay) )
	{
		return( false );
	}

	if( d < m_Slope_Min )
	{
		d = m_Slope_Min;
	}

	Decay = Get_Fuzzy(d, 0., m_Slope_Max);

	if( m_Flow_Min > 0. )
	{
		d = Get_Fuzzy(m_pFlow->asDouble(x, y), m_Flow_Min, m_Flow_Max);

		switch( 1 )
		{
		default: Decay = M_GET_MAX(Decay, d)  ; break;
		case  1: Decay = Decay + d - Decay * d; break;
		}
	}

	return( Decay > 0. );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
void CFlow_by_Slope::Set_Area(int x, int y)
{
	double Decay;

	if( Get_Decay(x, y, Decay) )
	{
		double z = m_pDEM->asDouble(x, y), dzSum = 0., dz[8];

		for(int i=0; i<8; i++)
		{
			int ix = Get_xTo(i, x), iy = Get_yTo(i, y);

			if( m_pDEM->is_InGrid(ix, iy) && (dz[i] = z - m_pDEM->asDouble(ix, iy)) > 0. )
			{
				dzSum += (dz[i] = pow(dz[i] / Get_Length(i), 1.1));
			}
			else
			{
				dz[i] = 0.;
			}
		}

		if( dzSum > 0. )
		{
			Decay *= m_pFlow->asDouble(x, y) / dzSum;

			for(int i=0; i<8; i++)
			{
				if( dz[i] > 0. )
				{
					m_pFlow->Add_Value(Get_xTo(i, x), Get_yTo(i, y), Decay * dz[i]);
				}
			}
		}
	}
}


///////////////////////////////////////////////////////////
//														 //
//														 //
//														 //
///////////////////////////////////////////////////////////

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