function res=calTSA(SysData,options,caseName,varargin)

%
% FUNCTION calTSA
%
% Function for transient stability assessment
% Author: Rui Yao <ruiyao@ieee.org>
%
% Copyright (C) 2021, UChicago Argonne, LLC. All rights reserved.
%
% OPEN SOURCE LICENSE
% 
% Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
% 
% 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
% 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
% 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
% 
% 
% ******************************************************************************************************
% DISCLAIMER
% 
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
% WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
% PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY 
% DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
% PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
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% ***************************************************************************************************
%

res=[];

simSettings=getDefaultSimSettings();

if nargin<2
    options=regulateOptions();
else
    options=regulateOptions(options);
end

if nargin<3||isempty(caseName)
    caseName=['d_~',num2str(size(SysData.bus,1))];
end

nVarargs=length(varargin);
if nVarargs<1
    ME=MException('PowerSAS:invalidArgument','TSA should have arguments specifying faults.');
    throw(ME);
else
    faultSpec=[];
    
    if nVarargs>=1
        faultSpec=varargin{1};
    end
    if nVarargs>=2
        snapshot=varargin{2};
        hotStart=1;
    else
        snapshot=[];
        hotStart=0;
    end
    options.hotStart=hotStart;
    
    faultSpec=faultSpec((faultSpec(:,end)-faultSpec(:,end-1)>0),:);
    faultAdd=[faultSpec(:,1:end-2),zeros(size(faultSpec,1),1),faultSpec(:,end-1)];
    faultClear=[faultSpec(:,1:end-2),ones(size(faultSpec,1),1),faultSpec(:,end)];
    faultEvents=[faultAdd;faultClear];
    faultEvents=faultEvents(faultEvents(:,end)>=0&faultEvents(:,end)<=options.simLen,:);
    [~,isort]=sort(faultEvents(:,end),'ascend');
    faultEventsSort=faultEvents(isort,:);
    
    faultEvtTime=[0;faultEventsSort(:,end)];
    dFaultEvtTime=faultEvtTime(2:end)-faultEvtTime(1:end-1);
    aggFaultIdxAux=[find(dFaultEvtTime~=0);size(faultEvtTime,1)];
    
    nAggFault=size(aggFaultIdxAux,1)-1;
    simSettings.evtFault=[(1:nAggFault)',aggFaultIdxAux(1:nAggFault),aggFaultIdxAux(2:nAggFault+1)-1];
    simSettings.evtFaultSpec=faultEventsSort(:,1:end-1);
    simSettings.eventList=[simSettings.eventList;[(2:nAggFault+1)',faultEventsSort(aggFaultIdxAux(1:nAggFault),end),...
        zeros(nAggFault,1),6*ones(nAggFault,1),(1:nAggFault)',repmat(simSettings.eventList(1,[6,7]),nAggFault,1)]];
    simSettings.eventList=[simSettings.eventList;[nAggFault+2,options.simLen,0,99,0,simSettings.eventList(1,[6,7])]];
    
    res=runDynamicSimulationExec(caseName,SysData,simSettings,options,snapshot);
end

end

function options=regulateOptions(options)
if nargin<1
    options=[];
end

if ~isfield(options,'nlvl');options.nlvl=15;end
if ~isfield(options,'taylorN');options.taylorN=4;end
if ~isfield(options,'segAlpha');options.segAlpha=0.15;end
if ~isfield(options,'dAlpha');options.dAlpha=1;end
if ~isfield(options,'alphaTol');options.alphaTol=0.001;end
if ~isfield(options,'diffTol');options.diffTol=1e-6;end
if ~isfield(options,'diffTolMax');options.diffTolMax=1e-2;end
if ~isfield(options,'method');options.method=0;end
if ~isfield(options,'simLen');options.simLen=10;end
if ~isfield(options,'diffTolCtrl');options.diffTolCtrl=1e-5;end
if ~isfield(options,'Efstd');options.Efstd=1.2;end
end