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

local VERSION = "0.6.0"
local IDLE_TIME = 2
local WAIT_ITEM_IDLE_TIME = 5
local MIN_FUEL_NEEDED = (100 + config.firstCropZ + config.length) * 2
local MIN_FREE_SLOTS_BEFORE_COMPACT = 4
local INFERIUM_QUERY_PORT = 111
local INFERIUM_REPLY_PORT = 112

-- a table with the list of current crops
local localPlan = nil

-- UTILS

local function removeFirst(t, x)
  local res = {}
  local removed = false

  for k,v in pairs(t) do
    if not removed and x == v then
      removed = true
    else
      table.insert(res, v)
    end
  end

  return res
end

local function getIndexedCount(t)
  local res = {}

  for k,v in pairs(t) do
    local count = res[v] or 0
    res[v] = count + 1
  end

  return res
end

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)

  if not cropName then
    return cropName
  end

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

function isSeed(item)
  local tags = item and item.tags or {}
  return tags['forge:seeds'] or tags['mysticalagriculture:seeds'] or false
end

-- Inventory utils
-- the slot of the item is returned
local function waitForItem(inventory, itemName, count, sleepTime)
  sleepTime = sleepTime or 5 -- TODO: DEFAULT_IDLE_TIME

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

    os.sleep(IDLE_TIME)
  end
end

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

  turtle.turnRight()

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

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

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

  turtle.turnLeft()
  turtle.turnLeft()

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

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

  turtle.turnLeft()
end

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

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

      while not turtleUtils.dropSlot(i, turtle.dropDown) do
        os.sleep(IDLE_TIME)
      end
    end
  end
end

local function refuelProcedure()
  local refuelOk, refuelErr = turtleUtils.refuelWithBuffer('bottom', 'front', MIN_FUEL_NEEDED, IDLE_TIME)

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

local function goToHarvestPoint()
  turtle.turnLeft()

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

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

  turtle.turnLeft()
end

local function compactIfNeeded()
  if turtleUtils.countFreeSlots() < MIN_FREE_SLOTS_BEFORE_COMPACT then
    turtleUtils.compactInventory()
  end
end

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

  localPlan[index] = seedName

  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

  compactIfNeeded()
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(i)

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

  turtle.turnLeft()
  turtle.turnLeft()

  for i=1, config.length, 1 do
    if i ~= config.length then
      forward()
    end
  end
end

local function retrieveLocalPlan()
  goToHarvestPoint()

  localPlan = {}

  for i=1, config.length, 1 do
    local ok, block = turtle.inspectDown()
    local blockName = block and block.name
    localPlan[i] = getSeedNameFromCropName(blockName)

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

  turtle.turnLeft()
  turtle.turnLeft()

  for i=1, config.length, 1 do
    if i ~= config.length then
      forward()
    end
  end

  goBackToHome()
end

-- TODO: fetch timeout ?
local function fetchRemotePlan()
  local fallbackPlan = config.defaultRemotePlan or {}

  local modem = peripheral.find("modem")

  if not modem then
    return fallbackPlan
  end

  modem.open(INFERIUM_REPLY_PORT)

  local message = { type = 'getplan', payload = { computerId = os.getComputerID() } }
  modem.transmit(INFERIUM_QUERY_PORT, INFERIUM_REPLY_PORT, textutils.serialize(message))

  local channel, replyRawMessage
  repeat
    _, _, channel, _, replyRawMessage = os.pullEvent("modem_message")
  until channel == INFERIUM_REPLY_PORT

  modem.close(INFERIUM_REPLY_PORT)

  if not replyRawMessage then
    return fallbackPlan
  end

  local replyMessage = textutils.unserialize(replyRawMessage)

  if replyMessage and replyMessage.payload then
    return replyMessage.payload
  end

  return fallbackPlan
end

local function removeSeeds(seeds)
  goToHarvestPoint()

  local stateSeeds = seeds

  for i=1, config.length, 1 do
    local ok, block = turtle.inspectDown()
    local blockName = block and block.name

    local found = utils.find(stateSeeds, function(seedName) return seedName == getSeedNameFromCropName(blockName) end)

    if found then
      local digOk = turtle.digDown()
      compactIfNeeded()

      if not digOk then
        error('cannot remove seed')
      end

      stateSeeds = removeFirst(stateSeeds, found)
    end

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

  turtle.turnLeft()
  turtle.turnLeft()

  for i=1, config.length, 1 do
    if i ~= config.length then
      forward()
    end
  end

  goBackToHome()
  dropAllProcedure()
end

local function retrieveSeeds(seeds)
  local seedsCount = getIndexedCount(seeds)

  local storageInventory = turtleUtils.waitForInventory('bottom', WAIT_ITEM_IDLE_TIME)
  local bufferInventory = turtleUtils.waitForInventory('front', WAIT_ITEM_IDLE_TIME)

  for seedName, count in pairs(seedsCount) do
    local slot = waitForItem(storageInventory, seedName, count, WAIT_ITEM_IDLE_TIME)
    local pushOk = storageInventory.pushItems(peripheral.getName(bufferInventory), slot, count)

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

    local suckOk = turtle.suck()

    if not suckOk then
      error('retrieveSeeds error: cannot suck items from buffer')
    end
  end
end

local function replantSeeds()
  goToHarvestPoint()

  for i=1, config.length, 1 do
    local ok, block = turtle.inspectDown()

    if not ok then
      turtleUtils.selectItemBy(function(slot)
        local item = turtle.getItemDetail(slot, true)
        return isSeed(item)
      end)

      turtle.placeDown()
    end

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

  turtle.turnLeft()
  turtle.turnLeft()

  for i=1, config.length, 1 do
    if i ~= config.length then
      forward()
    end
  end

  goBackToHome()
end

local function replantProcedure()
  if localPlan == nil then
    retrieveLocalPlan()
  end

  if localPlan == nil then
    error('cannot retrieve the local plan')
  end

  local remotePlan = fetchRemotePlan()

  if remotePlan == nil then
    error('cannot fetch the remote plan')
  end

  local seedsToRemove = utils.shallowDiff(localPlan, remotePlan)
  local seedsToPlant = utils.shallowDiff(remotePlan, localPlan)

  if utils.sizeof(seedsToRemove) > 0 then
    removeSeeds(seedsToRemove)
  end

  if utils.sizeof(seedsToPlant) > 0 then
    retrieveSeeds(seedsToPlant)
    replantSeeds()
  end

  -- reset the local plan (it will be re-updated during the harvest procedure)
  localPlan = {}
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()

    replantProcedure()

    goToHarvestPoint()
    harvestProcedure()
    goBackToHome()
  end
end

main()