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

local IDLE_TIME = 3
local TIME_TO_START = 3
local IDLE_TIME_BETWEEN_TUNNELS = 1
local SPACE_BETWEEN_TUNNELS = 3

local VERSION = "1.0.1"

local MOVES_BY_DIRECTION = {
  right = {
    turnLeft = turtle.turnLeft,
    turnRight = turtle.turnRight
  },
  left = { -- this is inversed
    turnLeft = turtle.turnRight,
    turnRight = turtle.turnLeft
  }
}

local function getMoves(config)
  return MOVES_BY_DIRECTION[config.DIRECTION]
end

local function getMinFuelNeeded(config)
  return (config.DISTANCE_Z * 2) + SPACE_BETWEEN_TUNNELS + config.FUEL_MARGIN
end

local function checkEnoughFuelForTunnel(config)
  local minFuelNeeded = getMinFuelNeeded(config)

  if turtle.getFuelLevel() < minFuelNeeded then
    turtleUtils.refuelAllFromInventory()
    return turtle.getFuelLevel() < minFuelNeeded
  end

  return true
end

local function assertEnoughFuelForTunnel(config)
  if not checkEnoughFuelForTunnel(config) then
    error('not enough fuel', 0)
  end
end

local function assertValidConfig(config)
  if config.DIRECTION ~= 'left' and config.DIRECTION ~= 'right' then
    error('config.DIRECTION should be "left" or "right"', 0)
  end

  if config.DISTANCE_Z <= 0 then
    error('config.DISTANCE_Z should be a positive number', 0)
  end

  local minFuelMargin = 6
  if config.FUEL_MARGIN < minFuelMargin then
    error('config.FUEL_MARGIN cannot be lower than ' .. minFuelMargin)
  end
end

local function printFuelReport(config)
  print('> current fuel: ' .. turtleUtils.getFuelPercentage() .. '%')
  print('> fuel needed: ' .. turtleUtils.getFuelPercentage(getMinFuelNeeded(config)) .. '%')
end

local function assertInventoryIsEmpty()
  if not turtleUtils.isInventoryEmpty() then
    error('turtle inventory should be empty', 0)
  end
end

local function findGroundProcedure()
  local foundGround, errMessage = turtleUtils.goGround()
  if not foundGround then
    error('cannot find the ground because ' .. tostring(errMessage), 0)
  end
end

local function digForward(n)
  n = n or 1
  for _=1, n, 1 do
    turtleUtils.forceForward()
    turtle.digDown()
  end
end

local function mineTunnelProcedure(config)
  local distance = config.DISTANCE_Z

  digForward(distance)
  getMoves(config).turnRight()
  digForward(SPACE_BETWEEN_TUNNELS)
  getMoves(config).turnRight()
  digForward(distance)
end

local function dropAllProcedure(config)
  turtleUtils.forceDown()
  getMoves(config).turnLeft()

  -- try to refuel before dropping items
  turtleUtils.refuel(getMinFuelNeeded(config), turtle.suck, IDLE_TIME)
  turtleUtils.refuelAllFromInventory()

  -- drop all items
  for i=1, 16, 1 do
    local count = turtle.getItemCount(i)

    if count > 0 then
      turtleUtils.waitForInventory('front', IDLE_TIME)

      while turtle.getItemCount(i) and not turtleUtils.dropSlot(i, turtle.drop) do
        os.sleep(IDLE_TIME)
      end
    end
  end

  getMoves(config).turnRight()
  turtleUtils.forceUp()
end

local function goToNextMineProcedure(config)
  getMoves(config).turnRight()
  digForward(SPACE_BETWEEN_TUNNELS)
  getMoves(config).turnLeft()
end

local function main(config)
  assertValidConfig(config)
  printFuelReport(config)
  assertEnoughFuelForTunnel(config)

  findGroundProcedure()
  turtleUtils.forceUp()
  assertEnoughFuelForTunnel(config)

  print('> Starting tunnels-miner v' .. VERSION ..  ' in ' .. TIME_TO_START .. ' seconds...')
  os.sleep(TIME_TO_START)

  local tunnelNumber = 1
  while true do
    if tunnelNumber > 1 then
      printFuelReport()
      assertEnoughFuelForTunnel(config)
    end
    assertInventoryIsEmpty() -- Warning here when implementing persistance

    print('> Start mining tunnel number ' .. tostring(tunnelNumber))

    mineTunnelProcedure(config)
    dropAllProcedure(config)
    goToNextMineProcedure(config)

    os.sleep(IDLE_TIME_BETWEEN_TUNNELS)
    tunnelNumber = tunnelNumber + 1
  end
end

main(STATIC_CONFIG)