--[[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 selectItem(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 selectEmptySlot()

  -- 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
-- numer of items in the inventory
function countInventory()
    local total = 0

    for slot = 1, 16 do
        total = total + turtle.getItem(slot)
    end
    return total
end

-- selectAndPlaceDown() selects a nonempty slot
-- and places a block from it under the turtle
function selectAndPlaceDown()
    for slot = 1, 16 do
        if turtle.getItemCount(slot) > 0 then
            turtle.select(slot)
            turtle.placeDown()
            return
        end
    end
end


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

    turtle.up()

    local movingForward = true

    for currentHeight = 1, height do
        for currentLength = 1, length do
            selectAndPlaceDown() -- 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

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

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

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

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

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

    return true
end