--[[Function Module program by Al Sweigart
Provides useful utility functions.]]

-- selectItem() selects the inventory
-- slot with the named item, returns
-- true if found and false if not
function select_item(name)
-- check all inventory slots
 local item
   for slot = 1, 16 do
     item = turtle.getItemDetail(slot)
     if item ~= nil and item['name'] == name then
       turtle.select(slot)
       return true
     end
  end

  return false  -- couldn't find item
end


-- selectEmptySlot() selects inventory
-- slot that is empty, returns true if
-- found, false if no empty spaces
function select_emptySlot()

  -- loop through all slots
  for slot = 1, 16 do  
    if turtle.getItemCount(slot) == 0 then
      turtle.select(slot)
      return true
    end
  end
  return false -- couldn't find empty space
end

-- countInventory() returns the total
-- number of a given minecraft id item in the inventory
function count_inventory(minecraft_id, times)
  local total = 0

  for slot = 1, 16 do
    item = turtle.getItemDetail(slot)
    if item ~= nil and item['name'] == 'minecraft:' .. minecraft_id  then
      total = total + turtle.getItemCount(slot)
    end
  end
  return total
end

-- selectAndPlaceDown() selects a slot with given
-- minecraft id and places a block from it under the turtle
function select_and_place_down(minecraft_id)
  for slot = 1, 16 do
    item = turtle.getItemDetail(slot)
    if item ~= nil and item['name'] == 'minecraft:' .. minecraft_id  then
      turtle.select(slot)
      turtle.placeDown()
      return
    end
  end
end


-- build_wall() creates a wall stretching
-- in front of the turtle
function build_wall(length, height)
  if modules.count_inventory() > length * height then
    return false --not enough block
  end

  turtle.up()

  local movingForward = true

  for currentHeight = 1, height do
    for currentLength = 1, length do
      select_and_place_down() -- Place the block
      if movingForward and currentLength ~= length then
        turtle.forward()
      elseif not movingForward and currentLength ~= length then
        turtle.back()
      end
    end
    if currentHeight ~= height then
      turtle.up()
    end
    movingForward = not movingForward
  end

  -- done building wall; move to end position
  if movingForward then
    -- turtle is near the start position
    for currentLength = 1, length do
      turtle.forward()
    end
  else
    -- turtle is near the end position
    turtle.forward()
  end

  -- move down to the ground
  for currentHeight = 1, height do
    turtle.down()
  end

  return true
end

-- build_room() constructs four walls
-- and a ceiling
function build_room(length, width, height)
  if modules.count_inventory() < (((length -1) * height * 2) +
    ((width -1) * height * 2)) then
    return false -- not enough blocks
  end

  -- build the four walls
  build_wall(length -1, height)
  turtle.turnRight()

  build_wall(width - 1, height)
  turtle.turnRight()

  build_wall(length - 1, height)
  turtle.turnRight()

  build_wall(width - 1, height)
  turtle.turnRight()

  return true
end

-- sweepField() moves acress the rows
-- and columns of an area in front and
-- to the right of the turtle, calling
-- the provided sweepFunc at each space
function sweepField(length, width, sweepFunc)
  local turnRightNext = true

  for x = 1, width do
    for y = 1, length do
      sweepFunc()

      -- don't move forward on the last row
      if y ~= width then
        turtle.forward()
      end
    end

  
    -- don't turn on the last column
    if x ~= width then
      -- turn to the next column
      if turnRightNext then
        turtle.turnRight()
        turtle.forward()
        turtle.turnRight()
      else
        turtle.turnLeft()
        turtle.forward()
        turtle.turnLeft()
      end

      turnRightNext = not turnRightNext
    end
  end


  -- move back to the start position
  if width % 2 == 0 then
    turtle.turnRight()
  else
    for y = 1, length -1 do
      turtle.back()
    end
    turtle.turnLeft()
  end
  turtle.turnRight()

  return true
end

--findBlock() spins around searching
--for the named block next to the turtle
function findBlock(name)
  local result, block

  for i = 1, 4 do
    result, block = turtle.inspect()
    if block ~= nil and block['name'] == name then
      return true
    end
    turtle.turnRight()
  end
  return false
end

-- puke() puke everything that is in the turtles 
-- inventory out in front of it (hopefully there is
-- a chest
function puke()
  for i = 1, 16 do
    turtle.select(i)
    turtle.drop()
  end
end

-- Check Fuel checks if the turtle has enough fuel.
-- if not, it asks for fuel in slot 1 and refuels.
function check_fuel()
  local refueled = false
  while not refueled do
    if turtle.getFuelLevel() == 0 then
      print("Fuel is empty. Please put fuel in slot 1 and press a key.")
      read()
      turtle.select(1)
      turtle.refuel()
    else
      refueled = true
    end
  end
end