Program Game_Snake;
 Uses crt;
 const
      Max_X = 60;
      Max_Y = 25;
      Min_X = 1;
      Min_Y = 1;
      Than =#219;
      Dau = #219;
 Var
    dai,foodx,foody,foodcl,rancl,speed, score, MaxScore: integer;
    ranx,rany: array[1..100] of integer;
    dir_food,time,t: integer;
    f: text;
    ReGame: char;

 Procedure Draw_Range;
 var i: integer;
 Begin
      TextColor(Green);
      for i:= Min_X to Max_X do
      begin
           Gotoxy(i,Min_Y);
           Write(#178);
           Gotoxy(i,Max_Y);
           Write(#178);
      end;

      for i:= Min_Y to Max_Y do
      begin
           Gotoxy(Min_X,i);
           Write(#178);
           Gotoxy(Max_X,i);
           Write(#178);
      end;
 End;

 Procedure Write_Snake;
 var i: integer;
 Begin
       Gotoxy(ranx[dai],rany[dai]);Write(#32);
       for i := dai downto 2 do
       begin
            ranx[i] := ranx[i-1];
            rany[i] := rany[i-1];
            TextColor(rancl);
            gotoxy(ranx[i],rany[i]);
            write(than);
       end;
       TextColor(White);
       gotoxy(ranx[1],rany[1]);
       write(dau);

      {Draw Food}
      Textcolor(foodcl);
      Gotoxy(foodx,foody);Write(#220);
 End;

 Procedure Create_Food;
 Begin
      Randomize;
      repeat
      foodx := Random(Max_X - 1);
      foody := Random(Max_Y - 1);
      foodcl := random(10);
      Until (foodx > 1) and (foody > 1) and (foodcl > 1);
      Textcolor(foodcl);
      Gotoxy(foodx,foody);Write(#220);
 End;

 Function Die: Boolean;
 var x,y,i: integer;
 Begin
      Die := False;
      x := ranx[1];
      y := rany[1];
      if (x > Min_X) and (x < Max_X) and (y > Min_Y) and (y < Max_Y) then
      begin
      for i := dai downto 4 do
      if (x = ranx[i]) and (y = rany[i]) then
      begin
           Die := True;
           break;
      end;
      end
      else Die := True;
 End;

 Procedure Set_Dir_Food;
 Begin
      repeat
      time := 5 + random(5);
      dir_food := random(5);
      until (time > 0) and (dir_food > 0);
      t:= 0;
 End;

 Procedure Move_Food;
 Begin
      t := t+1;
      if t mod 3 = 0 then
      case dir_food of
      1: if foody > Min_Y + 1 then begin
                                        gotoxy(foodx,foody);Write(#32);
                                        foody := foody - 1;
                                   end;
      2: if foodx > Min_X + 1 then begin
                                        gotoxy(foodx,foody);Write(#32);
                                        foodx := foodx - 1;
                                   end;
      3: if foody < Max_Y - 1 then begin
                                        gotoxy(foodx,foody);Write(#32);
                                        foody := foody + 1;
                                   end;
      4: if foodx < Max_X - 1 then begin
                                        gotoxy(foodx,foody);Write(#32);
                                        foodx := foodx + 1;
                                   end;
      end;
      if t = time then Set_Dir_Food;
 End;

 Procedure Move;
 var k,lk: char;
 Begin
      Set_Dir_Food;
      k := lk;
      repeat until Keypressed;
      repeat
      Move_Food;
      if Keypressed then begin lk:= k;k := ReadKey;end;
      case k of
      #72: rany[1] := rany[1] - 1;
      #75: ranx[1] := ranx[1] - 1;
      #77: ranx[1] := ranx[1] + 1;
      #80: rany[1] := rany[1] + 1;
      'p':
      begin
           TextColor(Red);
           repeat
                 gotoxy(63,10);
                 Write('Bam p de tiep tuc!');
           until readkey = 'p';
                 Gotoxy(63,10);
                 Write('                  ');
      end;
      end;
      if k = 'p' then k := lk;
      if (ranx[1] = foodx) and (rany[1] = foody) then
      Begin
           dai := dai + 1;
           score := score + 1;
           rancl := Foodcl;
           Create_Food;
           TextColor(Cyan);
           Gotoxy(63,3);
           Write('Diem: ',score);
      End;
      Write_Snake;
      Delay(Speed);
      Until (k = #27) or Die;
      if k = #27 then ReGame := #27;
 End;

 Procedure Choose_Level;
 var level: integer;
 Begin
      TextColor(White);
      Writeln('Chon che do: ');
      Writeln('1. Kho');
      Writeln('2. Vua');
      Writeln('3. De');
      repeat readln(level); until (level >=1) and (level <= 3);
      speed := level*50;
      clrscr;
      TextColor(Cyan);
      Gotoxy(63,7);
      Write('Muc do: ');
      case level of
      1: Write('Kho');
      2: Write('Vua');
      3: Write('De');
      end;
 End;

 Procedure OpenFile;
 Begin
      reset(f);
      read(f,MaxScore);
      close(f);
 End;
 Procedure ReWriteFile;
 Begin
      if Score > MaxScore then
      begin
           ReWrite(f);
           Write(f,Score);
           Close(f);
      end;
 End;

 Procedure Main;
 var i: integer;
 Begin
       Repeat
       clrscr;
       Assign(f,'MaxScore.txt');
       OpenFile;
       Choose_Level;
       dai := 5;
       rancl := Blue;
       score := 0;
       TextColor(Cyan);
       Gotoxy(63,3);
       Write('Diem: ',score);
       Gotoxy(63,5);
       Write('Diem cao nhat:',MaxScore);
       for i := 1 to dai do
       begin
            ranx[i] := i+3;
            rany[i] := 5;
            TextColor(rancl);
            gotoxy(ranx[i],rany[i]);
            write(than);
       end;
       TextColor(White);
       gotoXy(ranx[1],rany[1]);Write(dau);
       rancl := Blue;
       Draw_Range;
       Create_Food;
       Move;
       ReWriteFile;
       if ReGame <> #27 then
       begin
            readln;
            clrscr;
            TextColor(White);
            Write('Ban co muon choi lai khong. Bam "y" neu co.');
            repeat until keypressed;
            ReGame := readkey;
       end;
       Until ReGame <> 'y';
 End;

 BEGIN
      clrscr;
      Main;
      Gotoxy(20,12);
      Write('Bam Enter de thoat...');
      readln;
 END.