Pascal is Pain

{Project - Andrei Dodea - Modelling of systems - Zilina, Slovakia 2019-2020}
program simulation;

{ Function for generation random number }
var digits,seed:Integer;
function generateRandom():Integer;
var start,endpart:Integer;
    n:String;
    code: Integer;
begin
    code := 1;
    str((seed*seed), n);
    while length(n) < digits * 2 do
    begin
        n := '0' + n;
    end;
    start := trunc(digits/2);
    endpart := start + digits;
    code := code + 111111;
    val(copy(n,start,endpart),seed,code);
    generateRandom := seed;
end;

{ Simulation }
var
    tfinish,nrWaitingPers,service,RNGarrival,RNGservice,currentTime,indexServed,indexArrived:Integer;
    waitingTime : Array[1..2880] of Integer;
    servingTime : Array[1..2880] of Integer;
    arrivalTime : Array[1..2880] of Integer;
    i,countPersons,totalTimeWaited,totalTimeServed,totalTimeArrived:Integer;
    { statistics variables  }
    avgTimeWait,avgTimeService,avgTimeArrive:Real;

begin
  { initializating variables }
  totalTimeServed := 0;
  countPersons := 0;
  indexArrived := 1;
  digits := 2;
  seed := 1142;
  tfinish := 28800;
  nrWaitingPers := 0;
  service := 0;
  RNGarrival := generateRandom();
  RNGservice := generateRandom();
  currentTime := 0;
  indexServed := 0;
  For i := 1 to 2880 do
  Begin
    waitingTime[i] := -1;
    servingTime[i] := -1;
    arrivalTime[i] := -1;
  End;
  arrivalTime[indexArrived] := RNGarrival;
  avgTimeService := 0;
  avgTimeWait := 0;
  totalTimeWaited := 0;
  totalTimeServed := 0;
  totalTimeArrived := 0;
  { logic loop }
  write('Seed input : ');
  readln (Seed);
  While currentTime < tfinish do
  Begin
      currentTime := currentTime + 1;
      RNGarrival := RNGarrival - 1;
      if (nrWaitingPers = 0) AND (service = 0) then Begin
            if RNGarrival <= 0 then Begin
                service := 1;
                if RNGservice <= 0 then
                    RNGservice := generateRandom();
                RNGservice := RNGservice - 1;
                indexServed := indexServed + 1;
                waitingTime[indexServed] := 0;
                servingTime[indexServed] := servingTime[indexServed] + 1;
            end;
        end
      else if (nrWaitingPers = 0) AND (service = 1) then begin
            if RNGarrival <= 0 then begin
                nrWaitingPers := nrWaitingPers + 1;
            end;
            if nrWaitingPers > 0 then
                waitingTime[indexServed+nrWaitingPers] := waitingTime[indexServed+nrWaitingPers] + 1;
            servingTime[indexServed] := servingTime[indexServed] + 1;
            RNGservice := RNGservice - 1;
      end
      else if (nrWaitingPers >= 1) AND (service = 1) then begin
            if RNGarrival <= 0 then
                nrWaitingPers := nrWaitingPers + 1;
            servingTime[indexServed] := servingTime[indexServed] + 1;
            RNGservice := RNGservice - 1;
            For i := 1 to nrWaitingPers do
            Begin
                waitingTime[i] := waitingTime[i] + 1;
            End;
      end;
      if RNGarrival = 0 then begin
        RNGarrival := generateRandom();
        indexArrived := indexArrived + 1;
        arrivalTime[indexArrived] := RNGarrival;
      end;
      if RNGservice = 0 then begin
        indexServed := indexServed + 1;
        RNGservice := generateRandom();
        service := 0;
        if nrWaitingPers > 0 then
            nrWaitingPers := nrWaitingPers - 1;
      end;
  end;
  For i := 1 to 2880 do
  Begin
    if waitingTime[i] <> -1 then
        totalTimeWaited := totalTimeWaited + waitingTime[i];
    if servingTime[i] <> -1 then
        totalTimeServed := totalTimeServed + servingTime[i];
    if arrivalTime[i] <> -1 then
        totalTimeArrived := totalTimeArrived + arrivalTime[i];
  End;
  countPersons := nrWaitingPers + indexServed;
  avgTimeWait := totalTimeWaited / nrWaitingPers;
  avgTimeService := totalTimeServed / indexServed;
  avgTimeArrive := totalTimeArrived / countPersons;
  writeln('Total persons count : ',countPersons);
  writeln('Total persons served : ',indexServed);
  writeln('Total time waited : ',totalTimeWaited);
  writeln('Average time for waiting: ',avgTimeWait);
  writeln('Average time for service: ',avgTimeService);
  writeln('Average time for arrive: ',avgTimeArrive);
  writeln('Simulation time: ',tfinish);
end.