unit moversProc;

interface

uses dataUnit;

procedure moveMovers(var g: GameState);

implementation

function turnMover(c: char; d: integer): char;
const
  period = ord(high(TMoverDir))+1;
var
  j, x: integer;
  i :TMoverType;
begin
  for i := low(TMoverType) to high(TMoverType) do
    for j := ord(low(TMoverDir)) to ord(high(TMoverDir)) do
      if c = movers[i, TMoverDir(j)] then
       begin
        x := (j+d) mod period;
        Exit(movers[i, TMoverDir(x)]);
       end;
  Exit(c);
end;

procedure rotateStep(var rstep, cstep: integer; clockWise: boolean);
begin
  cstep := cstep + rstep;
  rstep := cstep - rstep;
  cstep := cstep - rstep;
  if clockWise then
    cstep := -cstep
  else
    rstep := -rstep;
end;

procedure moveMover(var g: GameState; row, col, rstep, cstep: integer);
var
  rns	: integer = 0;
  cns	: integer = 0;
begin

  (* I don't move if I'm cought by a magnet *)
  If (rstep <> 0) and (g.map[row - rstep, col] = 'Z') then Exit;
  If (cstep <> 0) and (g.map[row, col - cstep] = 'N') then Exit;

  (* I don't move beyond the map *)
  if (col + cstep > g.mapWidth) or (col + cstep < 1) or
    (row + rstep > g.mapHeight) or (row + rstep < 1) then
  begin
    if g.map[row,col] in pushers then
      g.map[row, col] := turnMover(g.map[row,col], 2);
    Exit;
  end;

  (* Turners turn me *)
  case g.map[row + rstep, col + cstep] of
    'a':
    begin
      g.map[row, col] := turnMover(g.map[row,col], 1);
      rotateStep(rstep, cstep, True);
    end;
    'c':
    begin
      g.map[row, col] := turnMover(g.map[row,col], -1);
      rotateStep(rstep, cstep, False);
    end;
  end;

  (* Simple movement *)
  if g.map[row + rstep, col + cstep] = empty then
   begin
      g.map[row + rstep, col + cstep] := g.map[row,col];
      g.map[row, col] := empty;
      Exit;
    end;


  (* Pushers turn around and push pushables *)
  if (g.map[row,col] in pushers) then
  begin
    if (g.map[row + rstep, col + cstep] in pushable) and
      (g.map[row + 2 * rstep, col + 2 * cstep] = empty) then
    begin
      g.map[row + 2 * rstep, col + 2 * cstep] := g.map[row + rstep, col + cstep];
      g.map[row + rstep, col + cstep] := empty;
    end;
    g.map[row, col] := turnMover(g.map[row,col], 2);
    Exit;
  end;

  (* Gliders slip on slipery things*)
  if (g.map[row,col] in gliders) and
     (g.map[row + rstep, col + cstep] in slipery) then
  begin
    if cstep <> 0 then
      rns := 2 * random(1) - 1
    else
      cns := 2 * random(1) - 1;

    if (g.map[row + rns, col + cns] = empty) and
      (g.map[row + rstep + rns, col + cstep + cns] = empty) then
    begin
      g.map[row + rstep + rns, col + cstep + cns] := g.map[row,col];
      g.map[row, col] := empty;
    end
    else if (g.map[row - rns, col - cns] = empty) and
      (g.map[row + rstep - rns, col + cstep - cns] = empty) then
    begin
      g.map[row + rstep - rns, col + cstep - cns] := g.map[row,col];
      g.map[row, col] := empty;
    end;
  end;
end;

procedure moveMovers(var g: GameState);

var
  idx, row, col, Width, Height: integer;
begin
  Width := g.mapWidth;
  Height := g.mapHeight;
  for idx := 0 to Height * Width - 1 do
  begin
    (* for up movers *)
    row := idx div Width + 1;
    col := idx mod Width + 1;
    if (g.map[row, col] in UpMovers) then
      moveMover(g, row, col, -1, 0);
    (* for left movers *)
    col := idx div Height + 1;
    row := idx mod Height + 1;
    if (g.map[row, col] in LeftMovers) then
      moveMover(g, row, col, 0, -1);
    (* for down movers *)
    row := Height - idx div Width + 1;
    col := Width - idx mod Width + 1;
    if (g.map[row, col] in DownMovers) then
      moveMover(g, row, col, 1, 0);
    (* for Right movers *)
    col := Width - idx div Height + 1;
    row := Height - idx mod Height + 1;
    if (g.map[row, col] in RightMovers) then
      moveMover(g, row, col, 0, 1);
  end;
end;

end.