%MA40128 Game Theory Project- G.Taylor
%reads in player's own moves, opponents moves and a strategy. 
%Returns 1 to cooperate or 0 to defect.
%Strategies implemented-
% 1= always defect
% 2= always cooperate
% 3= Tit-for-tat
% 4= GRIM (defect forever if opponent ever defects)
% 5= Soton Master
% 6= Soton Slave
% Any other input implements RANDOM- 50% chance of either.
function x=play(player,opp,strategy) 
SotonM=[1,0,1,1,0,1,1,1];
SotonS=[0,1,0,0,1,0,0,0];
if(strategy==1) %always defect
    x=0;
elseif(strategy==2) %always cooperate
    x=1;
elseif(strategy==3) %titfortat
    if(length(opp)==0)
        x=1;
    else
        x=opp(length(opp));
    end
elseif(strategy==4) %GRIM
    if(length(opp)==0)
        x=1;
    else
        if(sum(opp)<length(opp))
            x=0;
        else
            x=1;
        end
    end
elseif(strategy==5) %Soton Master
    if(length(opp)==0)
        x=SotonM(1);
    elseif(length(opp)<8&&length(opp)>0)
        if(opp(1:length(opp))==SotonS(1:length(opp))) %Opponent has so far signalled correctly as a slave
            x=SotonM(length(player)+1); %Give the next signal
        elseif(opp(1:length(opp))==SotonM(1:length(opp))) %Opponent has so far signalled as a master
            x=SotonM(length(player)+1); %Give the next signal
        else
            x=0; %Otherwise, cease signalling and sabotage opponent
        end
    else
        if(opp(1:8)==SotonS) %found a slave
            x=0; %exploit
        elseif(opp(1:8)==SotonM) %found another master
            x=1; %cooperate
        else 
            x=0; %Not a Soton program; sabotage
        end
    end
elseif(strategy==6) %Soton slave
    if(length(opp)==0)
        x=SotonS(1);
    elseif(length(opp)<8&&length(opp)>0)
        if(opp(1:length(opp))==SotonS(1:length(opp))) %Opponent has so far signalled correctly as a slave
            x=SotonS(length(player)+1); %Give the next signal
        elseif(opp(1:length(opp))==SotonM(1:length(opp))) %Opponent has so far signalled as a master
            x=SotonS(length(player)+1); %Give the next signal
        else
            x=0; %Otherwise, cease signalling and sabotage opponent
        end
    else
        if(opp(1:8)==SotonS) %found a slave
            x=1; %cooperate
        elseif(opp(1:8)==SotonM) %found a master
            x=1; %self-sacrifice
        else 
            x=0; %Not a Soton program; sabotage
        end
    end

else %50/50 
    s=randn;
    if(s<0)
        x=0;
    else
        x=1;
    end
end