turtle_gps

--once program is added refer to the gps.functions only by there name, you don't have to add gps.
--to use in your program add(make sure program is called turtle_gps)
--[[
if(not shell.run("turtle_gps"))then
  term.clear(); term.setCursorPos(1,1);
  print("ERROR: You need turtle_gps to run this program!");
  return false;
end
]]

local gps = {};
local position = {0,0,0};
local orientation = 0;
  --0 = x+
  --1 = z+
  --2 = x-
  --3 = z-
local dir_moves = {
  {1,0},
  {0,1},
  {-1,0},
  {0,-1},
  {1,0}
};

gps.setCoordinate = function(x,y,z)
  position[1] = x;
  position[2] = y;
  position[3] = z;
end

gps.requestCoordinate = function()
  term.clear(); term.setCursorPos(1,1);
  local x,y,z;
  print("Enter turtle coordinates!");
  term.write("X: "); x=tonumber(read());

  term.setCursorPos(1,3);
  term.write("Y: "); y=tonumber(read());
  term.setCursorPos(1,4);
  term.write("Z: "); z=tonumber(read());
  position[1] = x;
  position[2] = y;
  position[3] = z;
  print("If turtle is not facing x+ then it will have inaccurate gps readings!");
end

gps.getPosition = function()
  return unpack(position);
end

gps.getDirection = function()
  return orientation;
end

gps.getOrientation = gps.getDirection;

gps.moveVertical = function(id)
  id = id or 1;
  local moved;
  if(id == 1)then
    moved = turtle.up();
    if(not moved)then return false; end
    position[2] = position[2] + 1;
  else
    moved = turtle.down();
    if(not moved)then return false; end
    position[2] = position[2] - 1;
  end
  return true;
end

gps.forward = function(text)
  local moved = turtle.forward();
  if(not moved)then return false; end
  local dir = dir_moves[orientation%4+1];
  position[1] = position[1] + dir[1];
  position[3] = position[3] + dir[2];
  return true;
end

gps.turnLeft = function()
  turtle.turnLeft();
  orientation = (orientation - 1) % 4;
end

gps.turnRight = function()
  turtle.turnRight();
  orientation = (orientation + 1) % 4;
end

gps.setOrientation = function(o)
  o = o % 4;
  if(orientation==o)then return; end
  local x;
  if( (orientation-1) % 4 == o)then
    x = gps.turnLeft;
  else
    x = gps.turnRight;
  end
  while(orientation~=o)do
    x();
  end
  if(orientation~=o)then print("[GPS] ERROR! Orientation mismatch!"); return false; end
  return true;
end

gps.loadAPI = function()
  local env = getfenv();
  for i,v in pairs(gps)do
    env[i] = v;
  end
end
gps.setCoordinate = gps.requestCoordinate;

gps.loadAPI();