local turtleUtils = require('libs/turtle-utils')

local NB_NEEDED_COAL = 64 * 2
local WAIT_INVENTORY_TIME = 3
local IDLE_TIME = 30
local IDLE_TIME_ENOUGH_COAL = 120
local MIN_ESSENCE_NEEDED = 8
local COAL_ESSENCE_NAME = 'mysticalagriculture:coal_essence'
local COAL_NAME = 'minecraft:coal'

local function countCoalItems(inventory)
  local total = 0

  for slot, item in pairs(inventory.list()) do
    if item.name == COAL_NAME then
      total = total + item.count
    end
  end

  return total
end

local function waitForNotEnoughCoal(inventory)
  while true do
    local nbCoals = countCoalItems(inventory)

    if nbCoals < NB_NEEDED_COAL then
      return
    end

    os.sleep(IDLE_TIME_ENOUGH_COAL)
  end
end

-- the slot of the coal essence is returned
local function waitForCoalEssence(inventory)

  while true do
    for slot, item in pairs(inventory.list()) do
      if item.name == COAL_ESSENCE_NAME and item.count >= MIN_ESSENCE_NEEDED then
        return slot
      end
    end

    os.sleep(IDLE_TIME)
  end
end

local function strictTransferOne(slot)
  local ok = turtle.transferTo(slot, 1)

  if not ok then
    error('cannot transfer item')
  end

  return ok
end

local function prepareCraftShape()
  strictTransferOne(2)
  strictTransferOne(3)

  strictTransferOne(5)
  strictTransferOne(7)

  strictTransferOne(9)
  strictTransferOne(10)
  strictTransferOne(11)
end

local function craft()
  local craftOk = turtle.craft()

  if not craftOk then
    error('cannot craft')
  end

  return craftOk
end

local function dropSelected()
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.drop()
  turtle.turnRight()
  turtle.turnRight()
end

local function findBufferChestOrientation()
  for i=1, 3, 1 do
    local inv = turtleUtils.getInventory('front')
    if inv and #inv.list() == 0 then
      return
    end

    turtle.turnRight()
  end

  error('buffer inventory not found (empty chest expected)')
end

local function main()
  turtle.select(1)

  findBufferChestOrientation()

  print('> Waiting for the back inventory (storage)')
  local storageInventory = turtleUtils.waitForInventory('back', WAIT_INVENTORY_TIME)

  print('> Waiting for the front inventory (buffer chest)')
  local bufferInventory = turtleUtils.waitForInventory('front', WAIT_INVENTORY_TIME)

  print('> coal-crafter process started')

  while true do
    storageInventory = turtleUtils.waitForInventory('back', WAIT_INVENTORY_TIME)
    bufferInventory = turtleUtils.waitForInventory('front', WAIT_INVENTORY_TIME)

    waitForNotEnoughCoal(storageInventory)
    local coalEssenceSlot = waitForCoalEssence(storageInventory)
    local pushOk = storageInventory.pushItems(peripheral.getName(bufferInventory), coalEssenceSlot, MIN_ESSENCE_NEEDED)

    if not pushOk then
      error('cannot pushItems from storage to buffer')
    end

    local suckOk, suckErr = turtle.suck()

    if not suckOk then
      error('cannot suck into front buffer chest: ' .. tostring(suckErr))
    end

    prepareCraftShape()
    craft()
    dropSelected()
  end
end

main()