function [CSX,port] = AddMSLPort( CSX, prio, portnr, materialname, start, stop, dir, evec, varargin )
% [CSX,port] = AddMSLPort( CSX, prio, portnr, materialname, start, stop, dir, evec, varargin )
%
% CSX:          CSX-object created by InitCSX()
% prio:         priority for excitation and probe boxes
% portnr:       (integer) number of the port
% materialname: property for the MSL (created by AddMetal())
% start:        3D start rowvector for port definition
% stop:         3D end rowvector for port definition
% dir:          direction of wave propagation (choices: 0 1 2)
% evec:         excitation vector, which defines the direction of the e-field (must be the same as used in AddExcitation())
% 
% variable input:
% 'ExcitePort'  necessary excitation name to make the port an active feeding port
% 'FeedShift'   shift to port from start by a given distance in drawing
%               units. Default is 0. Only active if 'ExcitePort' is set!
% 'Feed_R'      Specifiy a lumped port resistance. Default is no lumped
%               port resistance --> port has to end in an ABC.
%               Only active if 'ExcitePort' is set!
% 'MeasPlaneShift'  Shift the measurement plane from start t a given distance 
%               in drawing units. Default is the middle of start/stop.
%               Only active if 'ExcitePort' is set!
% 
% the mesh must be already initialized
%
% example:
%   start = [0 0 height]; 
%   stop = [length width 0]; 
%   CSX = AddMetal( CSX, 'metal' ); %create a PEC called 'metal'
%   [CSX,port] = AddMSLPort( CSX, 0, 1, 'metal', start, stop,  ...
%                0, [0 0 -1] , 'ExcitePort', 'excite', 'Feed_R', 50 )
% 
%   this defines a MSL in x-direction (dir=0) with an e-field excitation 
%   in -z-direction (evec=[0 0 -1]) the excitation is placed at x=start(1); 
%   the wave travels towards x=stop(1) the MSL-metal is created 
%   in xy-plane at z=start(3)
%
% Sebastian Held <sebastian.held@gmx.de> May 13 2010
% Thorsten Liebig <thorsten.liebig@gmx.de> Sept 16 2011
%
% See also InitCSX AddMetal AddMaterial AddExcitation calcPort

%% validate arguments %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%check mesh
if ~isfield(CSX,'RectilinearGrid')
    error 'mesh needs to be defined! Use DefineRectGrid() first!';
    if (~isfield(CSX.RectilinearGrid,'XLines') || ~isfield(CSX.RectilinearGrid,'YLines') || ~isfield(CSX.RectilinearGrid,'ZLines'))
        error 'mesh needs to be defined! Use DefineRectGrid() first!';
    end
end

% check dir
if ~( (dir >= 0) && (dir <= 2) )
	error 'dir must have exactly one component ~= 0'
end

% check evec
if ~(evec(1) == evec(2) == 0) && ~(evec(1) == evec(3) == 0) && ~(evec(2) == evec(3) == 0) || (sum(evec) == 0)
	error 'evec must have exactly one component ~= 0'
end
evec0 = evec ./ sum(evec); % evec0 is a unit vector

%% read optional arguments %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
n_conv_arg = 8; % number of conventional arguments

%set defaults
feed_shift = 0;
feed_R = 0;
excitename = '';
measplanepos = nan;

if (nargin>n_conv_arg)
    for n=1:2:(nargin-n_conv_arg)
        if (strcmp(varargin{n},'FeedShift')==1);
            feed_shift = varargin{n+1};
            if (numel(feed_shift)>1)
                error 'FeedShift must be a scalar value'
            end
        end
        
        if (strcmp(varargin{n},'Feed_R')==1);
            feed_R = varargin{n+1};
            if (numel(feed_shift)>1)
                error 'Feed_R must be a scalar value'
            end
        end
        
        if (strcmp(varargin{n},'MeasPlaneShift')==1);
            measplanepos = varargin{n+1};
            if (numel(feed_shift)>1)
                error 'MeasPlaneShift must be a scalar value'
            end
        end
                
        if (strcmp(varargin{n},'ExcitePort')==1);
            excitename = varargin{n+1};
        end
    end
end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% normalize start and stop
nstart = min( [start;stop] );
nstop  = max( [start;stop] );

% determine index (1, 2 or 3) of propagation (length of MSL)
idx_prop = dir + 1;

% determine index (1, 2 or 3) of width of MSL
dir = [0 0 0];
dir(idx_prop) = 1;
idx_width = abs(cross(dir,evec0)) * [1;2;3];

% determine index (1, 2 or 3) of height
idx_height = abs(evec0) * [1;2;3];

% direction of propagation
if stop(idx_prop)-start(idx_prop) > 0
    direction = +1;
else
    direction = -1;
end

% direction of propagation
if stop(idx_height)-start(idx_height) > 0
    upsidedown = +1;
else
    upsidedown = -1;
end

% create the metal/material for the MSL
MSL_start = start;
MSL_stop = stop;
MSL_stop(idx_height) = MSL_start(idx_height);
CSX = AddBox( CSX, materialname, prio, MSL_start, MSL_stop );

if isnan(measplanepos)
    measplanepos = (nstart(idx_prop)+nstop(idx_prop))/2;
else
    measplanepos = start(idx_prop)+direction*measplanepos;
end

% calculate position of the voltage probes
mesh{1} = sort(CSX.RectilinearGrid.XLines);
mesh{2} = sort(CSX.RectilinearGrid.YLines);
mesh{3} = sort(CSX.RectilinearGrid.ZLines);
meshlines = interp1( mesh{idx_prop}, 1:numel(mesh{idx_prop}), measplanepos, 'nearest' );
meshlines = mesh{idx_prop}(meshlines-1:meshlines+1); % get three lines (approx. at center)
if direction == -1
    meshlines = fliplr(meshlines);
end
MSL_w2 = interp1( mesh{idx_width}, 1:numel(mesh{idx_width}), (nstart(idx_width)+nstop(idx_width))/2, 'nearest' );
MSL_w2 = mesh{idx_width}(MSL_w2); % get e-line at center of MSL (MSL_width/2)
v1_start(idx_prop)   = meshlines(1);
v1_start(idx_width)  = MSL_w2;
v1_start(idx_height) = start(idx_height);
v1_stop  = v1_start;
v1_stop(idx_height)  = stop(idx_height);
v2_start = v1_start;
v2_stop  = v1_stop;
v2_start(idx_prop)   = meshlines(2);
v2_stop(idx_prop)    = meshlines(2);
v3_start = v2_start;
v3_stop  = v2_stop;
v3_start(idx_prop)   = meshlines(3);
v3_stop(idx_prop)    = meshlines(3);

% calculate position of the current probes
idx = interp1( mesh{idx_width}, 1:numel(mesh{idx_width}), nstart(idx_width), 'nearest' );
i1_start(idx_width)  = mesh{idx_width}(idx) - diff(mesh{idx_width}(idx-1:idx))/2;
idx = interp1( mesh{idx_height}, 1:numel(mesh{idx_height}), start(idx_height), 'nearest' );
i1_start(idx_height) = mesh{idx_height}(idx-1) - diff(mesh{idx_height}(idx-2:idx-1))/2;
i1_stop(idx_height)  = mesh{idx_height}(idx+1) + diff(mesh{idx_height}(idx+1:idx+2))/2;
i1_start(idx_prop)   = sum(meshlines(1:2))/2;
i1_stop(idx_prop)    = i1_start(idx_prop);
idx = interp1( mesh{idx_width}, 1:numel(mesh{idx_width}), nstop(idx_width), 'nearest' );
i1_stop(idx_width)   = mesh{idx_width}(idx) + diff(mesh{idx_width}(idx:idx+1))/2;
i2_start = i1_start;
i2_stop  = i1_stop;
i2_start(idx_prop)   = sum(meshlines(2:3))/2;
i2_stop(idx_prop)    = i2_start(idx_prop);

% create the probes
name = ['port_ut' num2str(portnr) 'A'];
% weight = sign(stop(idx_height)-start(idx_height))
weight = upsidedown;
CSX = AddProbe( CSX, name, 0, weight );
CSX = AddBox( CSX, name, prio, v1_start, v1_stop );
name = ['port_ut' num2str(portnr) 'B'];
CSX = AddProbe( CSX, name, 0, weight );
CSX = AddBox( CSX, name, prio, v2_start, v2_stop );
name = ['port_ut' num2str(portnr) 'C'];
CSX = AddProbe( CSX, name, 0, weight );
CSX = AddBox( CSX, name, prio, v3_start, v3_stop );
name = ['port_it' num2str(portnr) 'A'];

weight = direction;
CSX = AddProbe( CSX, name, 1, weight );
CSX = AddBox( CSX, name, prio, i1_start, i1_stop );
name = ['port_it' num2str(portnr) 'B'];
CSX = AddProbe( CSX, name, 1, weight );
CSX = AddBox( CSX, name, prio, i2_start, i2_stop );

% create port structure
port.LengthScale = 1;
if ((CSX.ATTRIBUTE.CoordSystem==1) && (idx_prop==2))
    port.LengthScale = MSL_stop(idx_height);
end
port.nr = portnr;
port.drawingunit = CSX.RectilinearGrid.ATTRIBUTE.DeltaUnit;
port.v_delta = diff(meshlines)*port.LengthScale;
port.i_delta = diff( meshlines(1:end-1) + diff(meshlines)/2 )*port.LengthScale;
port.direction = direction;
port.excite = 0;
port.measplanepos = abs(v2_start(idx_prop) - start(idx_prop))*port.LengthScale;
% port

% create excitation
% excitation of this port is enabled
port.excite = 1;
meshline = interp1( mesh{idx_prop}, 1:numel(mesh{idx_prop}), start(idx_prop) + feed_shift*direction, 'nearest' );
ex_start(idx_prop)   = mesh{idx_prop}(meshline) ;
ex_start(idx_width)  = nstart(idx_width);
ex_start(idx_height) = nstart(idx_height);
ex_stop(idx_prop)    = ex_start(idx_prop);
ex_stop(idx_width)   = nstop(idx_width);
ex_stop(idx_height)  = nstop(idx_height);

if ~isempty(excitename)
    CSX = AddExcitation( CSX, excitename, 0, evec );
    CSX = AddBox( CSX, excitename, prio, ex_start, ex_stop );
end
if feed_R > 0
    CSX = AddLumpedElement( CSX, [excitename '_R'], idx_height-1, 'R', feed_R );
    CSX = AddBox( CSX, [excitename '_R'], prio, ex_start, ex_stop );
    port.Feed_R = feed_R;
end
end