function [solver,problem,forced_choice] = selectsolver(options,ProblemClass,solvers,socp_are_really_qc,allsolvers);
%SELECTSOLVER Internal function to select solver based on problem category

problem = 0;

% UNDOCUMENTED
force_solver = yalmip('solver');
if length(force_solver)>0
    options.solver = force_solver;
end

% YALMIP has discovered in an previous call that the model isn't a GP, and
% now searches for a non-GP solver
if options.thisisnotagp
    ProblemClass.gppossible = 0;
end

% ***************************************************
% Maybe the user is stubborn and wants to pick solver
% ***************************************************
forced_choice = 0;
if length(options.solver)>0 & isempty(findstr(options.solver,'*'))
    
    if strfind(options.solver,'+')
        forced_choice = 1;
        options.solver = strrep(options.solver,'+','');
    end
    % Create tags with version also        
    temp = expandSolverName(solvers);  
    
    opsolver = lower(options.solver);
    splits = findstr(opsolver,',');
    if isempty(splits)
        names{1} = opsolver;
    else
        start = 1;
        for i  = 1:length(splits)
            names{i} = opsolver(start:splits(i)-1);
            start = splits(i)+1;
        end
        names{end+1} = opsolver(start:end);
    end
        
    index1 = [];
    index2 = [];
    for i = 1:length(names)
        index1 = [index1 find(strcmpi({solvers.tag},names{i}))];
        index2 = [index1 find(strcmpi({temp.tag},names{i}))];
    end
    if isempty(index1) & isempty(index2)
        % Specified solver not found among available solvers
        % Is it even a supported solver
        temp = expandSolverName(allsolvers);
        for i = 1:length(names)
            index1 = [index1 find(strcmp(lower({allsolvers.tag}),names{i}))];
            index2 = [index1 find(strcmp(lower({temp.tag}),names{i}))];
        end
        if isempty(index1) & isempty(index2)
            problem = -9;
        else
            problem = -3;
        end
        solver = [];
        return;
    else
        solvers = solvers(union(index1,index2));
    end    
end

% if forced_choice
%     solver = solvers(end);
%     problem = 0;
%     return
% end

% ************************************************
% Prune based on objective
% ************************************************
if ProblemClass.objective.sigmonial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) = solvers(i).objective.sigmonial;                         
    end
    solvers = solvers(find(keep));
end    
if ProblemClass.objective.polynomial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) =  solvers(i).constraint.equalities.quadratic | solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex | solvers(i).objective.polynomial | solvers(i).objective.sigmonial;            
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.objective.quadratic.nonconvex & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) = solvers(i).objective.polynomial | solvers(i).objective.sigmonial | solvers(i).objective.quadratic.nonconvex;        
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.objective.quadratic.convex & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        direct = solvers(i).objective.polynomial | solvers(i).objective.sigmonial | solvers(i).objective.quadratic.nonconvex | solvers(i).objective.quadratic.convex;
        indirect = solvers(i).constraint.inequalities.semidefinite.linear | solvers(i).constraint.inequalities.secondordercone.linear;
        if direct | indirect
            keep(i)=1;
        else
            keep(i)=0;
        end
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.objective.linear & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) = solvers(i).objective.polynomial | solvers(i).objective.sigmonial | solvers(i).objective.quadratic.nonconvex | solvers(i).objective.quadratic.convex | solvers(i).objective.linear;
    end
    solvers = solvers(find(keep));
end  

if ProblemClass.objective.maxdet.convex & ~ProblemClass.objective.linear & ~ProblemClass.objective.quadratic.convex & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) = solvers(i).objective.maxdet.convex | solvers(i).constraint.inequalities.semidefinite.linear;
    end
    solvers = solvers(find(keep));
end  

if ProblemClass.objective.maxdet.convex & (ProblemClass.objective.linear | ProblemClass.objective.quadratic.convex) & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) = solvers(i).objective.maxdet.convex;
    end
    solvers = solvers(find(keep));
end

if ProblemClass.objective.maxdet.nonconvex & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) = solvers(i).objective.maxdet.nonconvex;
    end
    solvers = solvers(find(keep));
end


% ******************************************************
% Prune based on rank constraints
% ******************************************************
if ProblemClass.constraint.inequalities.rank & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.rank;
    end
    solvers = solvers(find(keep));
end  

% ******************************************************
% Prune based on semidefinite constraints
% ******************************************************
if ProblemClass.constraint.inequalities.semidefinite.sigmonial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.semidefinite.sigmonial;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.inequalities.semidefinite.polynomial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.semidefinite.sigmonial |  solvers(i).constraint.inequalities.semidefinite.polynomial;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.inequalities.semidefinite.quadratic & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.semidefinite.sigmonial |  solvers(i).constraint.inequalities.semidefinite.polynomial | solvers(i).constraint.inequalities.semidefinite.quadratic;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.inequalities.semidefinite.linear & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.semidefinite.sigmonial |  solvers(i).constraint.inequalities.semidefinite.polynomial | solvers(i).constraint.inequalities.semidefinite.quadratic | solvers(i).constraint.inequalities.semidefinite.linear;
    end        
    solvers = solvers(find(keep));
end

% If user has specified a, e.g., LP solver for an SDP when using OPTIMIZER,
% we must bail out, as there is no chance this model instantiates as an LP.
if forced_choice &  (ProblemClass.constraint.inequalities.semidefinite.linear | ProblemClass.constraint.inequalities.semidefinite.quadratic | ProblemClass.constraint.inequalities.semidefinite.polynomial | ProblemClass.constraint.inequalities.semidefinite.sigmonial)
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.semidefinite.sigmonial |  solvers(i).constraint.inequalities.semidefinite.polynomial | solvers(i).constraint.inequalities.semidefinite.quadratic | solvers(i).constraint.inequalities.semidefinite.linear;
    end        
    solvers = solvers(find(keep));
end
% Similarily, we have a SOCP by definition. We must support that
if forced_choice & ~socp_are_really_qc & (ProblemClass.constraint.inequalities.secondordercone.linear | ProblemClass.constraint.inequalities.secondordercone.nonlinear)
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.secondordercone.linear;
    end        
    solvers = solvers(find(keep));
end

% ******************************************************
% Prune based on cone constraints
% ******************************************************
if ProblemClass.constraint.inequalities.secondordercone.linear & ~socp_are_really_qc & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         keep(i) = solvers(i).constraint.inequalities.secondordercone.linear | solvers(i).constraint.inequalities.semidefinite.linear | solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.inequalities.secondordercone.nonlinear & ~socp_are_really_qc & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         keep(i) = solvers(i).constraint.inequalities.secondordercone.nonlinear | solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.inequalities.rotatedsecondordercone.linear & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.rotatedsecondordercone.linear | solvers(i).constraint.inequalities.secondordercone.linear | solvers(i).constraint.inequalities.semidefinite.linear;
    end
    solvers = solvers(find(keep));
end
if ProblemClass.constraint.inequalities.rotatedsecondordercone.nonlinear & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.rotatedsecondordercone.nonlinear | solvers(i).constraint.inequalities.secondordercone.linear | solvers(i).constraint.inequalities.semidefinite.linear;
    end
    solvers = solvers(find(keep));
end
if ProblemClass.constraint.inequalities.powercone & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.powercone;
    end
    solvers = solvers(find(keep));
end  

% ******************************************************
% Prune based on element-wise inequality constraints
% ******************************************************
if ProblemClass.constraint.inequalities.elementwise.sigmonial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.elementwise.sigmonial;            
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.inequalities.elementwise.polynomial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex | solvers(i).constraint.inequalities.elementwise.sigmonial |  solvers(i).constraint.inequalities.elementwise.polynomial;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.inequalities.elementwise.quadratic.nonconvex & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.elementwise.sigmonial |  solvers(i).constraint.inequalities.elementwise.polynomial | solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex;
    end
    solvers = solvers(find(keep));
end 
if ProblemClass.constraint.inequalities.elementwise.quadratic.convex | (ProblemClass.constraint.inequalities.secondordercone.linear & socp_are_really_qc) & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.elementwise.sigmonial |  solvers(i).constraint.inequalities.elementwise.polynomial | solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex | solvers(i).constraint.inequalities.elementwise.quadratic.convex | solvers(i).constraint.inequalities.secondordercone.linear | solvers(i).constraint.inequalities.semidefinite.linear;
    end
    solvers = solvers(find(keep));
end 
if ProblemClass.constraint.inequalities.elementwise.linear & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.elementwise.sigmonial |  solvers(i).constraint.inequalities.elementwise.polynomial | solvers(i).constraint.inequalities.semidefinite.quadratic | solvers(i).constraint.inequalities.elementwise.linear;
    end
    solvers = solvers(find(keep));
end  

% ******************************************************
% Prune based on element-wise constraints
% ******************************************************
if ProblemClass.constraint.equalities.sigmonial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.inequalities.elementwise.sigmonial | solvers(i).constraint.equalities.sigmonial;            
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.equalities.polynomial & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)    
        indirect = solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex | solvers(i).constraint.inequalities.elementwise.sigmonial |  solvers(i).constraint.inequalities.elementwise.polynomial;
        indirect = indirect | solvers(i).constraint.inequalities.elementwise.sigmonial | solvers(i).constraint.inequalities.elementwise.polynomial;
        direct = solvers(i).constraint.equalities.sigmonial |  solvers(i).constraint.equalities.polynomial;
        keep(i) = direct | indirect;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.equalities.quadratic & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        indirect = solvers(i).constraint.inequalities.elementwise.sigmonial | solvers(i).constraint.inequalities.elementwise.polynomial | solvers(i).constraint.inequalities.elementwise.quadratic.nonconvex;
        direct = solvers(i).constraint.equalities.sigmonial |  solvers(i).constraint.equalities.polynomial |  solvers(i).constraint.equalities.quadratic;
        keep(i) = direct | indirect;
    end
    solvers = solvers(find(keep));
end 
if ProblemClass.constraint.equalities.linear & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers) 
        indirect = solvers(i).constraint.inequalities.elementwise.linear | solvers(i).constraint.inequalities.elementwise.sigmonial |  solvers(i).constraint.inequalities.elementwise.polynomial;
        direct = solvers(i).constraint.equalities.linear | solvers(i).constraint.equalities.sigmonial |  solvers(i).constraint.equalities.polynomial;
        keep(i) = direct | indirect;
    end
    solvers = solvers(find(keep));
end  

% ******************************************************
% Discrete data
% ******************************************************
if ProblemClass.constraint.integer & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).constraint.integer;
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.binary & ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         keep(i) = solvers(i).constraint.integer | solvers(i).constraint.binary;            
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.sos1 
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         %keep(i) = solvers(i).constraint.integer | solvers(i).constraint.binary | solvers(i).constraint.sos2;            
         keep(i) = solvers(i).constraint.sos2;            
    end
    solvers = solvers(find(keep));
end 
if ProblemClass.constraint.sos2
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         keep(i) = solvers(i).constraint.integer | solvers(i).constraint.binary | solvers(i).constraint.sos2;                       
    end
    solvers = solvers(find(keep));
end  
if ProblemClass.constraint.semicont
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         %keep(i) = solvers(i).constraint.integer | solvers(i).constraint.binary | solvers(i).constraint.sos2;            
         keep(i) = solvers(i).constraint.semivar;            
    end
    solvers = solvers(find(keep));
end  

% ******************************************************
% Equalities with multiple monomoials (rule out GP)
% ******************************************************
if ProblemClass.constraint.equalities.multiterm
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         keep(i) = solvers(i).constraint.equalities.multiterm;
    end
    solvers = solvers(find(keep));
end  
% FIXME
% No support for multiterm is YALMIPs current way of saying "GP solver". We
% use this flag to prune GPs based on objective too
if ~ProblemClass.gppossible
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         keep(i) = solvers(i).constraint.equalities.multiterm;
    end
    solvers = solvers(find(keep));
end  

% ******************************************************
% Complementarity constraints
% ******************************************************
if ProblemClass.constraint.complementarity.linear
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
         keep(i) = solvers(i).constraint.complementarity.linear | solvers(i).constraint.integer | solvers(i).constraint.binary | solvers(i).constraint.equalities.polynomial | solvers(i).constraint.equalities.quadratic;            
    end
    solvers = solvers(find(keep));
end  

% ******************************************************
% Interval data
% ******************************************************
if ProblemClass.interval
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)                      
        keep(i) = solvers(i).interval;
    end
    solvers = solvers(find(keep));
end  


% ******************************************************
% Parametric problem
% ******************************************************
if ~forced_choice
    keep = ones(length(solvers),1);
    for i = 1:length(solvers)
        keep(i) = (ProblemClass.parametric == solvers(i).parametric);
    end
    solvers = solvers(find(keep));
end

% ******************************************************
% Exponential cone representable (exp, log,...)
% ******************************************************
keep = ones(length(solvers),1);
if ~forced_choice
    for i = 1:length(solvers)
        keep(i) = (ProblemClass.exponentialcone <= solvers(i).exponentialcone) || (ProblemClass.exponentialcone <= solvers(i).evaluation);
    end
    solvers = solvers(find(keep));
end

% ******************************************************
% General functions (sin, cos,...)
% ******************************************************
keep = ones(length(solvers),1);
if ~forced_choice
    for i = 1:length(solvers)
        keep(i) = (ProblemClass.evaluation <= solvers(i).evaluation) || (ProblemClass.exponentialcone && solvers(i).exponentialcone);
    end
    solvers = solvers(find(keep));
end

% FIX : UUUUUUGLY
if isempty(solvers)
    solver = [];
else
    if length(options.solver)>0
        solver = [];

        % FIX : Re-use from above
        opsolver = lower(options.solver);
        splits = findstr(opsolver,',');
        if isempty(splits)
            names{1} = opsolver;
        else
            names = {};
            start = 1;
            for i  = 1:length(splits)
                names{i} = opsolver(start:splits(i)-1);
                start = splits(i)+1;
            end
            names{end+1} = opsolver(start:end);
        end

        temp = solvers;
        for i = 1:length(temp)
        if length(temp(i).version)>0
            temp(i).tag = lower([temp(i).tag '-' temp(i).version]);
        end
        end
    
        for i = 1:length(names)
            if isequal(names{i},'*')
                solver = solvers(1);
                break
            else
                j = find(strcmpi(lower({solvers.tag}),names{i}));
                if ~isempty(j)
                    solver = solvers(j(1));
                    break
                end
                j = find(strcmpi(lower({temp.tag}),names{i}));
                if ~isempty(j)
                    solver = solvers(j(1));
                    break
                end                
            end
        end
    else
        solver = solvers(1);
    end
end

if isempty(solver)
    if length(options.solver)>0 % User selected available solver, but it is not applicable
        problem = -4;
    else
        problem = -2;
    end
end

% FIX : Hack when chosing the wrong fmincon thingy
if ~isempty(solver)
    c1 = (length(options.solver)==0 | isequal(lower(options.solver),'fmincon')) & isequal(lower(solver.tag),'fmincon') & isequal(solver.version,'geometric');
    c2 = (length(options.solver)==0 | isequal(lower(options.solver),'snopt')) & isequal(lower(solver.tag),'snopt') & isequal(solver.version,'geometric');
    if c1 | c2
        if ~(ProblemClass.objective.sigmonial | ProblemClass.constraint.inequalities.elementwise.sigmonial)
            solver.version = 'standard';
            solver.call    = strrep(solver.call,'gp','');
            solver.objective.linear = 1;
            solver.objective.quadratic.convex = 1;
            solver.objective.quadratic.nonconvex = 1;
            solver.objective.polynomial = 1;
            solver.objective.sigmonial = 1;
            solver.constraint.equalities.elementwise.linear = 1;
            solver.constraint.equalities.elementwise.quadratic.convex = 1;
            solver.constraint.equalities.elementwise.quadratic.nonconvex = 1;
            solver.constraint.equalities.elementwise.polynomial = 1;
            solver.constraint.equalities.elementwise.sigmonial = 1;
            solver.constraint.inequalities.elementwise.linear = 1;
            solver.constraint.inequalities.elementwise.quadratic.convex = 1;
            solver.constraint.inequalities.elementwise.quadratic.nonconvex = 1;
            solver.constraint.inequalities.elementwise.polynomial = 1;
            solver.constraint.inequalities.elementwise.sigmonial = 1;
            solver.constraint.inequalities.semidefinite.linear = 1;
            solver.constraint.inequalities.semidefinite.quadratic = 1;
            solver.constraint.inequalities.semidefinite.polynomial = 1;
            solver.dual = 1;
            solver.evaluation = 1;
        end
    end
end

function temp = expandSolverName(temp)
for i = 1:length(temp)
    if length(temp(i).version)>0
        temp(i).tag = lower([temp(i).tag '-' temp(i).version]);
    end
end