nav.lua

--navigation api to keep track of location
dirTable = {}
dirTable[0], dirTable[1], dirTable[2], dirTable[3] = 'front', 'right', 'back', 'left'
pos = {x = 0, y = 0, z = 0, dir = 0}

if not fs.exists('position.txt') then
    local position = fs.open('position.txt', 'w')
    pos.dir = pos.dir % 4
    position.write(textutils.serialise(pos))
    position.close()
else
    local position = fs.open('position.txt', 'r')
    pos = textutils.unserialise(position.readAll())
    position.close()
end

function updatePos()
    pos.dir = pos.dir % 4
    local position = fs.open('position.txt', 'w')
    position.write(textutils.serialise(pos))
    position.close()
end

function returnPos()
    return pos.x, pos.y, pos.z, pos.dir
end

function calibrate()
    pos.x, pos.y, pos.z, pos.dir = 0, 0, 0, 0
    updatePos()
end

function direction(isForward)
    local xDir = 0
    local yDir = 0
    pos.dir = pos.dir % 4
    if pos.dir == 0 then
        xDir = 1
        yDir = 0
    elseif pos.dir == 1 then
        xDir = 0
        yDir = 1
    elseif pos.dir == 2 then
        xDir = -1
        yDir = 0
    elseif pos.dir == 3 then
        xDir = 0
        yDir = -1
    end
    if isForward == true then
        pos.x = pos.x + xDir
        pos.y = pos.y + yDir
    else
        pos.x = pos.x - xDir
        pos.y = pos.y - yDir
    end
    updatePos()
end

function forward(x)
    for i = 1, x do
        while not turtle.forward() do
            turtle.dig()
        end
        direction(true)
    end
    updatePos()
end

function back(x)
    for i = 1, x do
        repeat until turtle.back()
        direction(false)
    end
    updatePos()
end


function up(x)
    for i = 1, x do
        while not turtle.up() do
            turtle.digUp()
        end
        pos.z = pos.z + 1
    end
    updatePos()
end

function down(x)
    for i = 1, x do
        while not turtle.down() do
            turtle.digDown()
        end
        pos.z = pos.z - 1
    end
    updatePos()
end

function turnRight(x)
    for i = 1, x do
        turtle.turnRight()
        pos.dir = pos.dir + 1
    end
    updatePos()
end

function turnLeft(x)
    for i = 1, x do
        turtle.turnLeft()
        pos.dir = pos.dir + 3
    end
    updatePos()
end

function turnAround()
    turnLeft(2)
end

function goDir(dir)
    while pos.dir % 4 ~= dir do
        turnLeft()
    end
    updatePos()
end