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

local VERSION = "0.3.0"
local IDLE_TIME = 2
local MIN_FUEL_NEEDED = (10 + config.firstCropZ + config.length) * 2

-- UTILS

local function assertEnoughFuel()
  if turtle.getFuelLevel() < MIN_FUEL_NEEDED then
    error('Not enough fuel')
  end
end

local function retrieveChestFuelOrientation()
  local inventoryFound = false

  for i=1, 4, 1 do
    if turtleUtils.getInventory('front') then
      inventoryFound = true
      break
    end

    turtle.turnRight()
  end

  if not inventoryFound then
    error('chest fuel not found')
  end
end

local function getSeedNameFromCropName(cropName)
  return string.gsub(cropName, 'crop', 'seeds')
end

-- Implementations
local function retrieveHomePositionProcedure()
  if turtleUtils.getInventory('bottom') then
    retrieveChestFuelOrientation()
    turtle.turnLeft()
  end

  turtle.turnRight()

  if turtle.inspect() then
    turtle.turnRight()
  end

  while true do
    if turtleUtils.getInventory('bottom') then
      return
    end

    if turtle.inspect() then
      break
    else
      turtle.forward()
    end
  end

  turtle.turnLeft()
  turtle.turnLeft()

  while true do
    if turtleUtils.getInventory('bottom') then
      return
    end

    if turtle.inspect() then
      error('Cannot retrieve home position')
    else
      turtle.forward()
    end
  end
end

local function dropAllProcedure()
  for i=1, 16, 1 do
    local count = turtle.getItemCount(i)

    if count > 0 then
      while not turtleUtils.dropSlot(i, turtle.dropDown) do
        os.sleep(IDLE_TIME)
      end
    end
  end
end

local function refuelProcedure()
  turtle.turnLeft()
  turtleUtils.waitForInventory('front', IDLE_TIME)

  local refuelOk, refuelErr = turtleUtils.refuel(MIN_FUEL_NEEDED, turtle.suck, IDLE_TIME)

  if not refuelOk then
    error('Cannot refuel the turtle: "' .. refuelErr .. '"')
  end

  turtle.turnLeft()
end

local function goToHarvestPoint()
  for i=1, config.firstCropZ, 1 do
    turtle.forward()
  end
end

local function goBackToHome()
  for i=1, config.firstCropZ, 1 do
    turtle.forward()
  end
end

local function harvestDown()
  local cropName = turtleUtils.waitForMatureCrop(turtle.inspectDown, IDLE_TIME)
  local seedName = getSeedNameFromCropName(cropName)

  if not turtle.digDown() then
    error('turtle cannot harvest crop')
  end

  if not turtleUtils.selectItemByName(seedName) then
    error('turtle cannot find any crop to place')
  end

  if not turtle.placeDown() then
    error('turtle cannot place crop')
  end

  turtleUtils.compactInventory()
end

local function forward()
  if not turtle.forward() then
    error('turtle is blocked')
  end
end

local function harvestProcedure()
  for i=1, config.length, 1 do
    harvestDown()

    if i ~= config.length then
      forward()
    end
  end

  turtle.turnLeft()
  turtle.turnLeft()

  for i=1, config.length, 1 do
    if config.energySaving then
      harvestDown()
    end

    if i ~= config.length then
      forward()
    end
  end
end

-- Main procedure
local function main()
  print("Starting Trap's inferium harvester v" .. VERSION)

  turtleUtils.refuelAllFromInventory()
  assertEnoughFuel()

  print("> retrieving home position")
  retrieveHomePositionProcedure()

  print("> start the harvesting process")

  while true do
    dropAllProcedure()
    refuelProcedure()

    goToHarvestPoint()
    harvestProcedure()
    goBackToHome()
  end
end

main()