% get connected eles for every ele
% check down, right, up, left connected eles
function connectEle = checkConnectEle(eles,nodes,eleNum,optNeighbor)
    if optNeighbor==4
        % down, right, up, left
        connectEle = zeros(eleNum,4); % max connect ele = 4
        for i = 1:eleNum
            node = eles(i,:);
            tempEles = eles;
            tempEles(i,:) = 0;    
            
            connectEle(i,1) = connectThisEle(node(1),node(2),tempEles);
            connectEle(i,2) = connectThisEle(node(3),node(2),tempEles);
            connectEle(i,3) = connectThisEle(node(3),node(4),tempEles);
            connectEle(i,4) = connectThisEle(node(1),node(4),tempEles);
        end
    else
        % 8 dir:
        % down, right, up, left, down-left, down-right, up-right, up-left 
        connectEle = mooreNeighbor(eles,nodes,eleNum);
    end
end

% get connected eles for edge(node1,node2)
function ce = connectThisEle(node1,node2,eles)

    ce = 0; % no connected ele
    
    compn(:,:,1) = repmat(node1,size(eles));
    compn(:,:,2) = repmat(node2,size(eles));    
    compe = repmat(eles,[1,1,2]);
    
    ifcom = compn==compe;
    com = sum(sum(ifcom,3),2); % sum by 3rd dim, by 2nd dim(cols)
    
    if find(com>1)
        [ce,~] = find(com>1);
    end
end

function ce = connectThisNode(node,eles)
    ce = 0;
    
    compn = repmat(node,size(eles));
    ifcom = compn==eles;
    com = sum(ifcom,2);
    
    if find(com>0)
        [ce,~] = find(com>0);
    end
end

% get surronding 8 neighbor eles
% down, right, up, left, down-left, down-right, up-right, up-left 
function [connectEle] = mooreNeighbor(eles,nodes,eleNum)
    connectEle = zeros(eleNum,8); % max connect ele = 8
    for i = 1:eleNum
        node = eles(i,:);
        tempEles = eles;
        tempEles(i,:) = 0;
        
        conn = zeros(3*4, 1);
        for j = 1:4
            ce = connectThisNode(node(j),tempEles);
            conn((j-1)*3+1:(j-1)*3+size(ce),1) = ce;
        end              
        conn = setdiff(unique(conn),0);
        
        % the center coordinate of this ele 
        nodesIdx = eles(i,:);
        nodesCoor = nodes(nodesIdx,1:2);
        coori = mean(nodesCoor);
        
        % decide the dir by the center coordinate of connected ele                   
        connNum = size(conn);
        for j = 1:connNum
            nodesIdx = eles(conn(j),:);
            nodesCoor = nodes(nodesIdx,1:2);
            coorj = mean(nodesCoor); % the center coordinate
            
            if abs(coorj(1)-coori(1))<1e-5
                if coorj(2)-coori(2)>1e-5
                    connectEle(i, 3) = conn(j); % up
                else
                    connectEle(i, 1) = conn(j); % down
                end
                
            elseif abs(coorj(2)-coori(2))<1e-5
                if coorj(1)-coori(1)>1e-5
                    connectEle(i, 2) = conn(j); % right
                else
                    connectEle(i, 4) = conn(j); % left
                end
                
            elseif coorj(1)-coori(1)>1e-5 && coorj(2)-coori(2)>1e-5
                connectEle(i, 7) = conn(j); % up-right
                
            elseif coori(1)-coorj(1)>1e-5 && coorj(2)-coori(2)>1e-5
                connectEle(i, 8) = conn(j); % up-left
                
            elseif coori(1)-coorj(1)>1e-5 && coori(2)-coorj(2)>1e-5
                connectEle(i, 5) = conn(j); % down-left
                
            elseif coorj(1)-coori(1)>1e-5 && coori(2)-coorj(2)>1e-5
                connectEle(i, 6) = conn(j); % down-right
            end
        end
    end
end