[CC] COS-CJE navigate API

local x, y, z, f
local posFilePath = "/data/pos.txt"

function createPosFile(path)
    if not fs.exists(path) or fs.isDir(path) then
        if fs.isReadOnly(string.sub(path, string.find(path, ".*/"))) then
            return "ERR_DIR_READ_ONLY"
        end
        fs.delete(path:sub(1, path:find(".*/")))
        fs.makeDir(path:sub(1, path:find(".*/")))
    end
end

function getPosFilePath()
    return posFilePath
end

function setPosFilePath(path)
    if not path then
        return "ERR_MISSING_PATH"
    elseif fs.isReadOnly(string.sub(path, string.find(path, ".*/"))) then
        return "ERR_DIR_READ_ONLY"
    end
    if not fs.exists(path) or fs.isDir(path) then
        createPosFile(path)
    end
    posFilePath = path
end

function readFromPosFile()
    if not fs.exists(posFilePath) or fs.isDir(posFilePath) then
        return "ERR_NO_POS_FILE"
    elseif fs.isReadOnly(posFilePath) then
        return "ERR_DIR_READ_ONLY"
    end
    local posFile = fs.open(posFilePath, "r")
    x, y, z, f = unpack(textutils.unserialize(posFile.readLine()))
    posFile.close()
    return x, y, z, f
end

function writeToPosFile(xPar, yPar, zPar, fPar)
    if xPar and yPar and zPar and fPar then
        x = xPar
        y = yPar
        z = zPar
        f = fPar
    end
    local posFile = fs.open(posFilePath, "w")
    posFile.write(textutils.serialize({ x, y, z, f }))
    posFile.close()
    return true
end

function syncPos()
    if peripheral.getType("right") ~= "modem" and peripheral.getType("left") ~= "modem" then
        return false
    end
    local doClose = rednet.isOpen("right") or rednet.isOpen("left")
    if peripheral.getType("right") == "compass" then
        f = peripheral.call("right", "getFacing")
        x, y, z = gps.locate()
    elseif peripheral.getType("left") == "compass" then
        f = peripheral.call("left", "getFacing")
        x, y, z = gps.locate()
    else
        forward(1, 1)
        xTemp, yTemp, zTemp = gps.locate()
        back()
        x, y, z = gps.locate()
        if zTemp > z then
            f = 0
        elseif xTemp < x then
            f = 1
        elseif zTemp < z then
            f = 2
        elseif xTemp > x then
            f = 3
        end
    end
    return writeToPosFile(x, y, z, f)
end

local function updatePos(fPar)
    if fPar < 0 then
        return false
    end
    fPar = fPar % 4
    if fPar == 0 then
        z = z + 1
    elseif fPar == 1 then
        x = x - 1
    elseif fPar == 2 then
        z = z - 1
    elseif fPar == 3 then
        x = x + 1
    end
    return true
end

local function init()
    readFromPosFile()
end

function up(n, doBreak)
    init()
    if not n then
        n = 1
    end
    if turtle.getFuelLevel() < n or y + n > 255 then
        return false
    end
    for i = 1, n do
        y = y + 1
        if not turtle.up() then
            if doBreak then
                while not turtle.up() do
                    if not turtle.digUp() then
                        y = y - 1
                        return false
                    end
                end
            else
                y = y - 1
                return false
            end
        else
            writeToPosFile(x, y, z, f)
        end
    end
    return true
end

function down(n, doBreak)
    init()
    if not n then
        n = 1
    end
    if turtle.getFuelLevel() < n or y - n < 0 then
        return false
    end
    for i = 1, n do
        y = y - 1
        if not turtle.down() then
            if doBreak then
                while not turtle.down() do
                    if not turtle.digDown() then
                        y = y + 1
                        return false
                    end
                end
            else
                y = y + 1
                return false
            end
        else
            writeToPosFile(x, y, z, f)
        end
    end
    return true
end

function forward(n, blockedBehaviour)
    init()
    if not n then
        n = 1
    end
    if not blockedBehaviour then
        blockedBehaviour = 0
    end
    if turtle.getFuelLevel() < n then
        return false
    end
    for i = 1, n do
        if not updatePos(f) then
            return false
        end
        if not turtle.forward() then
            if blockedBehaviour == 1 then
                while not turtle.forward() do
                    if not turtle.dig() then
                        updatePos(f + 2)
                        return false
                    end
                end
            elseif blockedBehaviour == 2 then
                while not turtle.forward() do
                    if not up(1, true) then
                        updatePos(f + 2)
                        return false
                    end
                end
            else
                updatePos(f + 2)
                return false
            end
        else
            writeToPosFile(x, y, z, f)
        end
    end
    return true
end

function back(n)
    init()
    if not n then
        n = 1
    end
    if turtle.getFuelLevel() < n then
        return false
    end
    for i = 1, n do
        if not updatePos(f + 2) then
            break
        end
        if not turtle.back() then
            updatePos(f)
            return false
        else
            writeToPosFile(x, y, z, f)
        end
    end
    return true
end

function turnLeft(n)
    init()
    if not n then
        n = 1
    end
    for i = 1, n do
        f = f == 0 and 3 or f - 1
        writeToPosFile(x, y, z, f)
        turtle.turnLeft()
    end
end

function turnRight(n)
    init()
    if not n then
        n = 1
    end
    for i = 1, n do
        f = f == 3 and 0 or f + 1
        writeToPosFile(x, y, z, f)
        turtle.turnRight()
    end
end

function turnLeftTo(fPar)
    while f ~= fPar do
        turnLeft()
    end
end

function turnRightTo(fPar)
    while f ~= fPar do
        turnRight()
    end
end