-- DIRECTIONS
north = "n"
south = "s"
east = "e"
west = "w"
up = "u"
down = "d"

-- TURTLE POSITION
absPos = {} --{x=0,y=0,z=0,dir=north}
homePos = {}

-- gets all global variables
function init( global )
	setfenv(1,global)
	-- gps functions included in CC
	gpsModule = _G["gps".._G.oldAPISyntax]
end

function isDir( dir )
	if dir == north
	or dir == south
	or dir == east
	or dir == west
	or dir == up
	or dir == down
	then
		return true
	else
		return false
	end
end

function getDirectionOffset( dir )
	local x,y,z = 0,0,0

	if dir == up then y = y + 1 end
	if dir == down then y = y - 1 end

	if dir == south then z = z + 1 end
	if dir == north then z = z - 1 end

	if dir == east then x = x + 1 end
	if dir == west then x = x - 1 end

	return x,y,z
end

function getPosition( offset,dir )
	local ox,oy,oz = 0,0,0
	local x,y,z = absPos.x,absPos.y,absPos.z

	if type(offset) ~= "number" then
		offset = 0
	end

	if type(dir) == "string" then
		ox,oy,oz = getDirectionOffset(dir)
	end

	x = x + ox*offset
	y = y + oy*offset
	z = z + oz*offset

	return x,y,z,absPos.dir
end

function setPosition( x,y,z,dir )
	absPos.x = x or absPos.x
	absPos.y = y or absPos.y
	absPos.z = z or absPos.z
	absPos.dir = dir or absPos.dir
end

function addPosition( x,y,z )
	absPos.x = absPos.x + (x or 0)
	absPos.y = absPos.y + (y or 0)
	absPos.z = absPos.z + (z or 0)
end

function getHome( offset,dir )
	local ox,oy,oz = 0,0,0
	local x,y,z = homePos.x,homePos.y,homePos.z

	if type(offset) ~= "number" then
		offset = 0
	end

	if type(dir) == "string" then
		ox,oy,oz = getDirectionOffset(dir)
	end

	x = x + ox*offset
	y = y + oy*offset
	z = z + oz*offset

	return x,y,z,homePos.dir
end

function setHome( x,y,z,dir )
	homePos.x = x or homePos.x
	homePos.y = y or homePos.y
	homePos.z = z or homePos.z
	homePos.dir = dir or homePos.dir
end

function dirToValue( dir )
	if dir == south then return 0 end
	if dir == west then return 1 end
	if dir == north then return 2 end
	if dir == east then return 3 end
	if dir == up then return math.huge end
	if dir == down then return -math.huge end
end

function valueToDir( value )
	if value == 0 then return south end
	if value == 1 then return west end
	if value == 2 then return north end
	if value == 3 then return east end
	if value == math.huge then return up end
	if value == -math.huge then return down end
end

function turnRight( times )
	if type(times)~="number" then times = 1 end
	if times<1 then times = 1 end
	if times%1~=0 then times = math.floor(times) end

	for count = 1,times do
		-- turn the dir var
		absPos.dir = valueToDir(((dirToValue(absPos.dir) or 0)+1)%4)

		turtle.turnRight()
	end
end

function turnLeft( times )
	if type(times)~="number" then times = 1 end
	if times<1 then times = 1 end
	if times%1~=0 then times = math.floor(times) end

	for count = 1,times do
		-- turn the dir var
		absPos.dir = valueToDir(((dirToValue(absPos.dir) or 0)+3)%4)

		turtle.turnLeft()
	end
end

-- locate where the turtle is in the real world by using the built in gps system
-- requires the turtle to have a wireless modem on the right side
function autoSetPosition()
	print("gps start")
	if peripheral.getType("right")~="modem" then return false end
	rednet.open("right")

	print("gps step 1")

	local x1,y1,z1 = gpsModule.locate()print("gps step 2")
	if type(x1)~="number" or type(y1)~="number" or type(z1)~="number" then return false end

	local dir = "unknown"

	local try = 0
	while not turtle.forward() do
		try = try + 1
		turtle.turnRight()
		if try == 4 then return false end
	end
	print("gps step 3")

	local x2,y2,z2 = gpsModule.locate()print("gps step 4")
	if type(x2)~="number" or type(y2)~="number" or type(z2)~="number" then return false end

	if x2 == x1 + 1 then dir = east end
	if x2 == x1 - 1 then dir = west end
	if z2 == z1 + 1 then dir = south end
	if z2 == z1 - 1 then dir = north end

	if dir == "unknown" then
		return false
	end
	print("gps step 5")
	setPosition(x2,y2,z2,dir)
	print("gps step final")
	return true
end

function getFacing()
	return absPos.dir
end

function face( dir )
	-- stop if dir is not a valid direction
	if not isDir(dir) then return end
	if dir == up then return end
	if dir == down then return end

	--
	if type(absPos.dir) ~= "string" then
		locate()
	end

	local wantedValue = dirToValue(dir)
	local currentValue = dirToValue(absPos.dir)

	-- continue looping until you face the desired direction
	while currentValue ~= wantedValue do
		if (currentValue+1)%4 == wantedValue then
			-- disered direction is to the right
			turnRight()
		elseif (currentValue+3)%4 == wantedValue then
			-- disered direction is to the left
			turnLeft()
		else
			-- desired direction is behind us, so turn either right or left
			if math.random(0,1) == 1 then
				turnRight()
			else
				turnLeft()
			end
		end

		-- update currentValue variable
		currentValue = dirToValue(absPos.dir)
	end
end

function moveUp( times,killMobs,destroyBlocks )
	if type(times)~="number" then times = 1 end
	--if times<1 then times = 1 end
	if times%1~=0 then times = math.floor(times) end

	if type(absPos.dir) ~= "string" then
		autoSetPosition()
	end

	for count = 1,times do
		while not turtle.up() do
			if not destroyBlocks then return false end
			dig.up(killMobs,destroyBlocks)
		end
		addPosition(_,1)
	end
	return true
end

function moveDown( times,killMobs,destroyBlocks )
	if type(times)~="number" then times = 1 end
	--if times<1 then times = 1 end
	if times%1~=0 then times = math.floor(times) end

	if type(absPos.dir) ~= "string" then
		autoSetPosition()
	end

	for count = 1,times do
		while not turtle.down() do
			if not destroyBlocks then return false end
			dig.down(killMobs,destroyBlocks)
		end
		addPosition(_,-1)
	end
	return true
end

function moveForward( times,killMobs,destroyBlocks )
	if type(times)~="number" then times = 1 end
	--if times<1 then times = 1 end
	if times%1~=0 then times = math.floor(times) end

	if type(absPos.dir) ~= "string" then
		autoSetPosition()
	end

	for count = 1,times do
		while not turtle.forward() do
			if destroyBlocks then
				dig.forward(killMobs,destroyBlocks)
			else
				return false
			end
		end
		addPosition(getDirectionOffset(absPos.dir))
	end
	return true
end

function goto( x,y,z,dir,killMobs,destroyBlocks )
	--print("goto function: x="..tostring(x).." y="..tostring(y).." z="..tostring(z).." killMobs="..tostring(killMobs).." destroyBlocks="..tostring(destroyBlocks))
	if type(x)~="number" then x=absPos.x end
	if type(y)~="number" then y=absPos.y end
	if type(z)~="number" then z=absPos.z end
	x=math.floor(x)	y=math.floor(y)	z=math.floor(z)
	if type(killMobs)~="boolean" then killMobs=false end
	if type(destroyBlocks)~="boolean" then destroyBlocks=false end

	if type(absPos.dir) ~= "string" then
		autoSetPosition()
	end

	while absPos.x~=x or absPos.y~=y or absPos.z~=z do
		-- current location
		local cx,cy,cz = getPosition()

		-- y
		if y~=cy then
			for count = math.min(cy,y),math.max(cy,y)-1 do
				if y>cy then
					if not moveUp(_,killMobs,destroyBlocks) then break end
				elseif y<cy then
					if not moveDown(_,killMobs,destroyBlocks) then break end
				end
			end
		end

		-- x
		if x~=cx then
			for count = math.min(cx,x),math.max(cx,x)-1 do
				if x>cx then -- x increasing
					face(east)
				elseif x<cx then -- x decreasing
					face(west)
				end
				if not moveForward(_,killMobs,destroyBlocks) then break end
			end
		end

		-- z
		if z~=cz then
			for count = math.min(cz,z),math.max(cz,z)-1 do
				if z>cz then -- z increasing
					face(south)
				elseif z<cz then -- z decreasing
					face(north)
				end
				if not moveForward(_,killMobs,destroyBlocks) then break end
			end
		end
	end

	if isDir(dir) then
		face(dir)
	end
end