new_turtle_base

-- home is a world location
home = {x = nil, y = nil, z = nil, rotation = nil}

-- work is relative to home
work = {x = nil, y = nil, z = nil, rotation = nil}

-- location is relative to home
location = {x = nil, y = nil, z = nil, rotation = nil}

listeners = {}

validTools = {crafting = "Crafting", pickaxe = "Pickaxe", axe = "Axe", shovel = "Shovel", hoe = "Hoe", modem = "Modem", none = "None"}
tools = {left = validTools.none, right = validTools.none}

fuel = { "minecraft:coal", "minecraft:charcoal" }

-- initialises the co-ordinates system and links up rednet
function init()
  local x, y, z, rotation, startRotation = getInitialPosition()
  initHome(x, y, z).
  location.x = home.x - x
  location.y = home.y - y
  location.z = home.z - z
  location.rotation = rotation
  initWork()
  rotateTo(startRotation)
end

-- returns current x, y, z position of the turtle as well as the current rotation
function getInitialPosition()
  local x1, y1, z1 = gps.locate()
  local rotation = 0
  local worldRotation = nil
  local foundRotation = false

  -- attempt to move turtle to find the facing location of the turtle
  while not foundRotation and rotation < 4 do
    moved = turtle.forward()
    local x2, y2, z2 = gps.locate()
    if moved then
      if z2 > z1 then worldRotation = 0
      elseif x2 > x1 then worldRotation = 1
      elseif z2 < z1 then worldRotation = 2
      elseif x2 < x1 then worldRotation = 3 end
      foundRotation = true
      -- return location back to start
      turtle.turnLeft()
      turtle.turnLeft()
      turtle.forward()
    else
      -- rotate clockwise
      turtle.turnRight()
      rotation = rotation + 1
    end
  end

  -- error out if rotation could not be found
  if not foundRotation then
    sendStatus("Could not find rotation")
    error()
  end

  local startWorldRotation = (worldRotation - rotation - 2) % 4
  home.rotation = settings.get("HomeRotation", startWorldRotation)
  local startRotation = (home.rotation - startWorldRotation) % 4
  local currentRotation = (home.rotation - worldRotation) % 4
  return x1, y1, z1, currentRotation, startRotation
end

-- collects existing home location or creates home location
function initHome(x, y, z, dir)
  settings.load("settings")
  home.x = settings.get("HomeXPos", x)
  home.y = settings.get("HomeYPos", y)
  home.z = settings.get("HomeZPos", z)
  saveHome()
end

-- saves home location to settings
function saveHome()
  settings.load("settings")
  settings.set("HomeXPos", home.x)
  settings.set("HomeYPos", home.y)
  settings.set("HomeZPos", home.z)
  settings.set("HomeRotation", home.rotation)
  settings.save("settings")
end

-- sends a gps request to get current work location, uses home rotation to infer correct rotation
function initWorkLocation()
  settings.load("settings")
  work.x = settings.get("WorkXPos", location.x)
  work.y = settings.get("WorkYPos", location.y)
  work.z = settings.get("WorkZPos", location.z)
  work.rotation = settings.get("WorkRotation", location.rotation)
  saveWork()
end

-- saves work location to settings
function saveWork()
  settings.load("settings")
  settings.set("WorkXPos", work.x)
  settings.set("WorkYPos", work.y)
  settings.set("WorkZPos", work.z)
  settings.set("WorkRotation", work.rotation)
  settings.save("settings")
end

-- moves position using co-ordinates relatove to home
function moveToPosition(newX, newY, newZ, newRot, locationName)
  if not locationName then locationName = "Somewhere" end
  local newLocation = {x = newX, y = newY, z = newZ, rotation = newRot}
  local blockages = 0
  while not compareLocations(location, newLocation) and blockages < 10 do
    -- move to new y location
    while location.y ~= newLocation.y do
      if location.y > newLocation.y then
        sendStatus("Moving Down towards ".. locationName)
        moved = moveDown()
      elseif location.y < newLocation.y then
        sendStatus("Moving Up towards ".. locationName)
        moved = moveUp()
      end
      if not moved then
        blockages = blockages + 1
        break
      end
    end
    -- move to new x location
    while location.x ~= newLocation.x do
      if location.x > newLocation.x then
        sendStatus("Moving Left towards ".. locationName)
        if location.rotation ~= 3 then rotateTo(3) end
        moved = moveForward()
      elseif location.x < newLocation.x then
        sendStatus("Moving Right towards ".. locationName)
        if location.rotation ~= 1 then rotateTo(1) end
        moved = moveForward()
      end
      if not moved then
        blockages = blockages + 1
        break
      end
    end
    -- move to new z location
    while location.z ~= newLocation.z do
      if location.z > newLocation.z then
        sendStatus("Moving Backwards towards ".. locationName)
        if location.rotation ~= 2 then rotateTo(2) end
        moved = moveForward()
      elseif location.z < newLocation.z then
        sendStatus("Moving Forwards towards ".. locationName)
        if location.rotation ~= 0 then rotateTo(0) end
        moved = moveForward()
      end
      if not moved then
        blockages = blockages + 1
        break
      end
    end
  end
  rotateTo(newDir)
  return compareLocations(location, newLocation, true)
end

-- moves position using gps and world co-ordinates
function moveToWorldPosition()

end

-- rotates the turtle once to the left and updates it's rotation
function rotateLeft()
  location.rotation = location.rotation-1
  if (location.rotation == -1) then
    location.rotation = 3
  end
  turtle.turnLeft()
end

-- rotates the turtle once to the right and updates it's rotation
function rotateRight()
  location.rotation = location.rotation+1
  if (location.rotation == 4) then
    location.rotation = 0
  end
  turtle.turnRight()
end

-- rotates the turtle to a new rotation based on home relative rotation
function rotateTo(newDir)
  if location.rotation == newDir then
    return
  elseif (location.rotation + 1) % 4 == newDir then
    rotateRight()
  elseif (location.rotation - 1) % 4 == newDir then
    rotateLeft()
  else
    while location.rotation ~= newDir do
      rotateLeft()
    end
  end
end

-- rotates the turtle to face a world rotation
function rotateToGlobal(newDir)

end

-- moves the turtle forward and updates the location based on relative rotation
-- returns true on successful movement
function moveForward()

end

-- moves the turtle up one block and updates the location
-- returns true on successful movement
function moveUp()
  if canDig() then
    while turtle.detectUp() do
      turtle.digUp()
    end
  end
  local moved = turtle.up()
  if not moved then return false end
  location.y = location.y + 1
  return true
end

-- moves the turtle down one block and updates the location
-- returns true on successful movement
function moveDown()
  if canDig() then
    while turtle.detectDown() do
      turtle.digDown()
    end
  end
  local moved = turtle.down()
  if not moved then return false end
  location.y = location.y - 1
  return true
end

-- returns the turtle's current world position
function currentWorldPosition()
  local x, y, z = gps.locate()
  local rotation = getWorldRotation()
  return "[".. x..", ".. y..", ".. z..", ".. rotation .."]"
end

-- returns the turtle's current relative position
function currentPosition()
  local x = location.x
  local x = location.y
  local x = location.z
  local x = location.rotation
  return "[".. x..", ".. y..", ".. z..", ".. rotation .."]"
end

function compareLocations(tab1, tab2, includeRotation)
  if includeRotation then
    return tab1.x == tab2.x and tab1.y == tab2.y and tab1.z == tab2.z and tab1.rotation == tab2.rotation
  else
    return tab1.x == tab2.x and tab1.y == tab2.y and tab1.z == tab2.z
  end
end

-- returns list of valid tools
function getValidToolText()
  local text = ""
  for k, v in pairs(validTools) do
    if text ~= "" then text = text.. ", " end
    text = text .. v
  end
  return text
end

-- asks the player to input in the currently equipped tools on the turtle
function getTools()
  local complete = false
  local toolText = "Valid Tools: ".. getValidToolText()
  local sides = peripheral.getNames()
  if tableContains("left", sides) then
    complete = true
    tools.left = validTools.modem
  end
  while not complete do
    term.clear()
    term.setCursorPos(1,1)
    print(toolText)
    io.write("Enter Left Tool: ")
    local leftTool = io.read()
    local valid, leftTool = validTool(leftTool)
    if valid then
      complete = true
      tools.left = leftTool
    end
  end
  complete = false
  if tableContains("right", sides) then
    complete = true
    tools.right = validTools.modem
  end
  while not complete do
    term.clear()
    term.setCursorPos(1,1)
    print(toolText)
    io.write("Enter Right Tool: ")
    local rightTool = io.read()
    local valid, rightTool = validTool(rightTool)
    if valid then
      complete = true
      tools.right = rightTool
    end
  end
end

-- returns true if tool is a tool found in the valid tools list
function validTool(tool)
  for k,v in pairs(validTools) do
    if string.lower(v) == string.lower(tool) then
      return true, v
    end
  end
  return false, validTools.none
end

-- returns true if table contains str
function tableContains(str, table)
  for k, v in pairs(table) do
    if v == str then return true end
  end
  return false
end

-- resets the turtles working settings
function resetSettings()
  settings.load("settings")
  settings.clear()
  settings.save("settings")
end

-- finds an item in the turtle's inventory based off supplied id and returns as a list of inventory slots
function findItem(id)
  local itemTable = {}
  for i = 1, 16, 1 do
    local slotData = turtle.getItemDetail(i)
    if (slotData and slotData.name == id) then
      table.insert(itemTable, i)
    end
  end
  if table.getn(itemTable) > 0 then
    return itemTable
  end
  return nil
end

-- returns true if empty slot was found and item was moved
function moveItemToEmpty(slot)
  turtle.select(slot)
  for i = 1, 16, 1 do
    if i ~= slot then
      if turtle.transferTo(i) then
        return true
      end
    end
  end
  return false
end

-- returns true if space remains
function checkSpace()
  for i = 1, 16, 1 do
    if not turtle.getItemDetail(i) then
      return true
    end
  end
  return false
end

-- attempts to merge stacks of all items starting from the bottom moving to the top most slot
function minifyStacks()
  for i = 16, 1, -1 do
    local slotData = turtle.getItemDetail(i)
    if slotData then
      slotsTable = findItem(slotData.name)
      if slotsTable and table.getn(slotsTable) > 1 then
        for k,v in pairs(slotsTable or {}) do
          turtle.select(v)
          turtle.transferTo(i, turtle.getItemSpace(i))
        end
      end
    end
  end
end

-- returns home and requests more fuel
function giveMeFuel()
  while not hasFuel() do
    sleep(2)
  end
  returnToWork()
end

-- attempts to fill fuel slot, returns true if enough fuel is located in the fuel slot.
function hasFuel()
  local fuelSlots = {}

  local slotData = turtle.getItemDetail(1)
  -- search the first slot for a valid fuel item
  for k,v in pairs(fuel or {}) do
    -- find if any other slots contain any fuel
    local slotTable = findItem(v)
    table.insert(fuelSlots, slotTable)

    -- look in slot one, if contains fuel return
    if (slotData and slotData.name == v) then
      return turtle.getItemCount(1) > 1, slotTable
    end
  end

  -- move item out of fuel slot
  if slotData then
    moveItemToEmpty(1)
  end

  -- move valid fuel into slot
  for k,v in pairs(fuelSlots or {}) do
    if v then
      if table.getn(v) > 0 then
        turtle.select(v[1])
        turtle.transferTo(1)
      end
      return turtle.getItemCount(1) > 1, v
    end
  end
  return false, nil
end

-- returns true if item is a valid source of fuel
function isFuel(slotData)
  for k,v in pairs(fuel or {}) do
    if slotData.name == v then return true end
  end
  return false
end

-- attempts to find the minimum fuel level required to return home safely
function getMinFuelLevel()
  if locationNil(work) or locationNil(home) then return 800 end
  return math.abs(work.x) + math.abs(work.z) + math.abs(home.y - work.y) + 50
end

-- checks fuel levels and attempts to refuel the turtle
function refuel()
  local hasFuelLeft, fuelSlots = hasFuel()
  if turtle.getFuelLevel() < getMinFuelLevel() then
    if not hasFuelLeft then
      giveMeFuel()
    end
  end

  if turtle.getFuelLevel() < 5120 then
    turtle.select(1)
    coalCount = turtle.getItemCount(1)
    if coalCount > 0 then turtle.refuel(coalCount-1) end
  end
end

-- drops any extra stacks of items found in the turtle's inventory, maintaining only one stack of the given item
function dumpExtraStacks(itemId)
  items = findItem(itemId)
  if items and #items > 1 then
    for i = 2, #items, 1 do
      turtle.select(items[i])
      turtle.drop()
    end
  end
end

-- sends a rednet message to find listening computers to send further status updates to
function getListeners()
  listeners = {rednet.lookup("turtle_status")}
  if listeners then
    for k, v in pairs(listeners) do
      rednet.send(v, "request_connect")
    end
  end
end

-- opens up the turtle's rednet system
function openRednet()
  side = getModemSide()
  if not side then error("could not find modem") end
  rednet.open(side, 255)
end

-- returns the side of the turtle the modem is on else it returns nil if no modem is found
function getModemSide()
  sides = peripheral.getNames()
  for k, v in pairs(sides) do
    if peripheral.getType(v) == "modem" then return v end
  end
  return nil
end

-- initialises the turtle's rednet system
function initRednet()
  term.clear()
  term.setCursorPos(1,1)
  print("Initialising Rednet System")
  openRednet()
  getListeners()
end

-- sends a status update to all connected computers registered to listen for status updates
function sendStatus(status)
  for k, v in pairs(listeners) do
    rednet.send(v, status.. "\n" .. currentWorldPosition())
  end
end