--[[
  Automated Tree Farm Program for ComputerCraft Turtles

  Description:
  This program creates an automated tree farming system where the turtle follows
  a cobblestone path, harvests mature trees, plants saplings, and manages inventory
  by depositing items into a chest at the starting position.

  Setup:
  1. Place the turtle on top of a chest (starting position)
  2. Put fuel (e.g., Coal, Charcoal) in Slot 1 of the turtle's inventory
  3. Put saplings in Slot 2 (up to 32, excess will be deposited)
  4. Create a straight cobblestone path in the direction the turtle faces
  5. The turtle will follow this path, turning around when it reaches non-cobblestone

  Operation:
  - Moves forward along cobblestone path
  - Collects saplings from all 4 directions at each position
  - Checks left and right sides for trees to harvest
  - Plants saplings in empty spaces on left and right sides
  - Returns to chest when reaching end of cobblestone path
  - Deposits wood and excess saplings, then waits 5 seconds before repeating

  Usage:
  Run the program without arguments: treefarm
  The turtle will start the farming cycle automatically.
--]]

-- =============================================================================
-- Configuration
-- =============================================================================

local FUEL_SLOT = 1
local SAPLING_SLOT = 2
local FIRST_STORAGE_SLOT = 3
local LAST_STORAGE_SLOT = 16

-- Maximum saplings to keep (excess deposited in chest)
local MAX_SAPLINGS = 32

-- How long to wait on chest between farming cycles
local CHEST_WAIT_TIME = 5

-- Maximum height to climb when cutting trees (safety limit)
local MAX_TREE_HEIGHT = 20

-- Minimum fuel level before attempting to refuel
local MIN_FUEL_LEVEL = 80

-- =============================================================================
-- Helper Functions
-- =============================================================================

-- Function to check fuel and refuel if necessary
local function ensureFuel()
  local currentFuel = turtle.getFuelLevel()
  if currentFuel == "unlimited" then
    return true
  end

  if currentFuel < MIN_FUEL_LEVEL then
    print("Low on fuel (" .. currentFuel .. "). Refueling...")
    turtle.select(FUEL_SLOT)

    -- Try to refuel 2-3 items for good fuel buffer
    for i = 1, 3 do
      if turtle.refuel(1) then
        print("Refueled. Current level: " .. turtle.getFuelLevel())
      else
        if i == 1 then
          print("ERROR: No fuel items in slot " .. FUEL_SLOT .. "!")
          return false
        end
        break -- No more fuel items, but we got some
      end
    end
  end
  return true
end

-- Function to manage inventory by depositing items into chest
local function manageInventory()
  print("Managing inventory...")

  -- Count current saplings
  turtle.select(SAPLING_SLOT)
  local saplingCount = turtle.getItemCount(SAPLING_SLOT)

  -- Deposit ALL items from storage slots (slots 3-16)
  for i = FIRST_STORAGE_SLOT, LAST_STORAGE_SLOT do
    turtle.select(i)
    if turtle.getItemCount(i) > 0 then
      turtle.dropDown() -- Drop everything into chest below
    end
  end

  -- Deposit excess saplings if we have more than MAX_SAPLINGS
  if saplingCount > MAX_SAPLINGS then
    turtle.select(SAPLING_SLOT)
    local excessSaplings = saplingCount - MAX_SAPLINGS
    turtle.dropDown(excessSaplings)
    print("Deposited " .. excessSaplings .. " excess saplings.")
  end

  -- Reselect sapling slot for consistent state
  turtle.select(SAPLING_SLOT)
  print("Inventory management complete.")
end

-- Function to check if inventory is getting full
local function isInventoryFull()
  local emptySlots = 0
  for i = FIRST_STORAGE_SLOT, LAST_STORAGE_SLOT do
    if turtle.getItemCount(i) == 0 then
      emptySlots = emptySlots + 1
    end
  end
  -- Consider full if we have less than 3 empty slots (safety margin)
  return emptySlots < 3
end

-- Function to get current sapling count
local function getSaplingCount()
  turtle.select(SAPLING_SLOT)
  return turtle.getItemCount(SAPLING_SLOT)
end

-- Function to check if turtle is on cobblestone path
local function isOnCobblestone()
  local success, blockData = turtle.inspectDown()
  if success then
    return blockData.name == "minecraft:cobblestone"
  end
  return false
end

-- Function to safely move forward with path verification
local function moveForwardSafely()
  if not ensureFuel() then
    return false
  end

  -- Clear any obstacles in front
  while turtle.detect() do
    if not turtle.dig() then
      print("Cannot clear obstacle ahead!")
      return false
    end
  end

  -- Move forward
  if not turtle.forward() then
    print("Cannot move forward!")
    return false
  end

  return true
end

-- Function to return to chest (turn around and go back)
local function returnToChest(stepsFromChest)
  print("Returning to chest (" .. stepsFromChest .. " steps)...")

  -- Make sure we have fuel for the return trip
  if not ensureFuel() then
    print("ERROR: Cannot refuel for return trip!")
    return false
  end

  -- Turn around 180 degrees to face back toward chest
  turtle.turnLeft()
  turtle.turnLeft()

  -- Walk back to chest with progress tracking
  for i = 1, stepsFromChest do
    print("Returning... step " .. i .. "/" .. stepsFromChest)

    if not moveForwardSafely() then
      print("ERROR: Cannot return to chest! Stopped at step " .. i)
      print("Turtle position: " .. (stepsFromChest - i + 1) .. " steps from chest")
      return false
    end
  end

  -- Turn around 180 degrees again to face original direction
  print("Turning to face original direction...")
  turtle.turnLeft()
  turtle.turnLeft()

  print("Successfully returned to chest and oriented correctly.")
  return true
end

-- Function to move off chest to first cobblestone block
local function moveToPath()
  if not ensureFuel() then
    return false
  end

  print("Moving from chest to cobblestone path...")
  if not moveForwardSafely() then
    return false
  end

  if not isOnCobblestone() then
    print("WARNING: Not on cobblestone path! Check your setup.")
    return false
  end

  print("On cobblestone path.")
  return true
end

-- Function to collect saplings from all 6 directions (including up and down)
local function collectSaplings()
  local initialSaplings = getSaplingCount()
  local collected = 0

  turtle.select(SAPLING_SLOT)

  -- Try to suck from current position (items on ground at same level)
  if turtle.suck() then
    collected = collected + 1
  end

  -- Check above (saplings on leaf blocks or dropped from height)
  if turtle.suckUp() then
    collected = collected + 1
  end

  -- Check below (saplings that fell directly underneath)
  if turtle.suckDown() then
    collected = collected + 1
  end

  -- Check front
  if turtle.suck() then
    collected = collected + 1
  end

  -- Check left
  turtle.turnLeft()
  if turtle.suck() then
    collected = collected + 1
  end

  -- Check back
  turtle.turnLeft()
  if turtle.suck() then
    collected = collected + 1
  end

  -- Check right
  turtle.turnLeft()
  if turtle.suck() then
    collected = collected + 1
  end

  -- Return to original orientation
  turtle.turnLeft()

  if collected > 0 then
    local finalSaplings = getSaplingCount()
    local actuallyCollected = finalSaplings - initialSaplings
    if actuallyCollected > 0 then
      print("Collected " .. actuallyCollected .. " saplings.")
    end
  end
end

-- Function to check if a block is a log (tree block)
local function isLog(blockData)
  if not blockData then
    return false
  end
  return string.find(blockData.name, "log") ~= nil
end

-- Function to detect tree in a given direction (left or right)
local function detectTree(direction)
  if direction == "left" then
    turtle.turnLeft()
  elseif direction == "right" then
    turtle.turnRight()
  end

  local success, blockData = turtle.inspect()
  local hasTree = success and isLog(blockData)

  -- Return to original orientation
  if direction == "left" then
    turtle.turnRight()
  elseif direction == "right" then
    turtle.turnLeft()
  end

  return hasTree
end

-- Function to cut down a tree (turtle must be facing the tree base)
local function cutTreeInDirection()
  if not ensureFuel() then
    return false
  end

  print("Cutting tree...")

  -- Select a storage slot for tree cutting (not fuel or saplings)
  turtle.select(FIRST_STORAGE_SLOT)

  -- Mine the base log
  if not turtle.dig() then
    print("Cannot mine tree base!")
    return false
  end

  -- Move to tree base position
  if not turtle.forward() then
    print("Cannot move to tree base!")
    return false
  end

  local height = 0
  local maxRetries = 3

  -- Go up while there are logs above, mining as we go
  while height < MAX_TREE_HEIGHT do
    -- Check fuel before each major operation
    if not ensureFuel() then
      print("Low fuel during tree cutting! Descending...")
      break
    end

    -- Check if there's a log above us
    local success, blockData = turtle.inspectUp()
    if not (success and isLog(blockData)) then
      break -- No more logs above
    end

    -- Mine the log above with retries
    local digRetries = 0
    while not turtle.digUp() and digRetries < maxRetries do
      digRetries = digRetries + 1
      os.sleep(0.5) -- Wait for falling blocks
    end

    if digRetries >= maxRetries then
      print("Cannot mine log above after " .. maxRetries .. " attempts!")
      break
    end

    -- Try to move up with retries
    local moveRetries = 0
    while not turtle.up() and moveRetries < maxRetries do
      moveRetries = moveRetries + 1
      turtle.digUp() -- Clear any obstruction
      os.sleep(0.5)
    end

    if moveRetries >= maxRetries then
      print("Cannot move up after " .. maxRetries .. " attempts!")
      break
    end

    height = height + 1

    -- Also mine any logs in front while we're going up
    local frontDigAttempts = 0
    while turtle.detect() and frontDigAttempts < 5 do
      local frontSuccess, frontData = turtle.inspect()
      if frontSuccess and isLog(frontData) then
        turtle.dig()
      else
        break
      end
      frontDigAttempts = frontDigAttempts + 1
    end
  end

  -- Emergency failsafe: if we went too high, record it
  if height >= MAX_TREE_HEIGHT then
    print("WARNING: Reached maximum tree height limit!")
  end

  -- Go all the way back down to ground level
  print("Descending from height " .. height .. "...")
  for i = 1, height do
    local downRetries = 0
    while not turtle.down() and downRetries < maxRetries do
      downRetries = downRetries + 1
      turtle.digDown() -- Clear any obstruction below
      os.sleep(0.5)
    end

    if downRetries >= maxRetries then
      print("CRITICAL ERROR: Cannot descend! Stuck at height " .. (height - i + 1))
      print("Manual intervention required!")
      return false
    end
  end

  -- Move back to the path with retries
  local backRetries = 0
  while not turtle.back() and backRetries < maxRetries do
    backRetries = backRetries + 1
    turtle.dig() -- Clear any obstruction in the way
    os.sleep(0.5)
  end

  if backRetries >= maxRetries then
    print("ERROR: Cannot return to path after " .. maxRetries .. " attempts!")
    return false
  end

  print("Tree cut successfully.")
  return true
end

-- Function to check and cut tree on left or right side
local function checkAndCutTree(direction)
  if not detectTree(direction) then
    return true -- No tree, nothing to do
  end

  -- Turn to face the tree
  if direction == "left" then
    turtle.turnLeft()
  elseif direction == "right" then
    turtle.turnRight()
  end

  -- Cut the tree
  local success = cutTreeInDirection()

  -- Return to original orientation
  if direction == "left" then
    turtle.turnRight()
  elseif direction == "right" then
    turtle.turnLeft()
  end

  return success
end

-- Function to check if there's air (empty space) in a given direction
local function detectAir(direction)
  if direction == "left" then
    turtle.turnLeft()
  elseif direction == "right" then
    turtle.turnRight()
  end

  local hasAir = not turtle.detect()

  -- Return to original orientation
  if direction == "left" then
    turtle.turnRight()
  elseif direction == "right" then
    turtle.turnLeft()
  end

  return hasAir
end

-- Function to plant sapling in a given direction (if there's air and we have saplings)
local function plantSapling(direction)
  -- Check if we have saplings to plant
  local saplingCount = getSaplingCount()
  if saplingCount == 0 then
    return true -- No saplings to plant, but that's okay
  end

  -- Check if there's air where we want to plant
  if not detectAir(direction) then
    return true -- No air space, nothing to do
  end

  -- Turn to face the planting direction
  if direction == "left" then
    turtle.turnLeft()
  elseif direction == "right" then
    turtle.turnRight()
  end

  -- Select saplings and plant
  turtle.select(SAPLING_SLOT)
  local success = turtle.place()

  -- Return to original orientation
  if direction == "left" then
    turtle.turnRight()
  elseif direction == "right" then
    turtle.turnLeft()
  end

  if success then
    print("Planted sapling on " .. direction .. " side.")
  end

  return true
end

-- =============================================================================
-- Main Program Logic
-- =============================================================================

-- Function to perform one complete farming cycle
local function farmingCycle()
  local stepsFromChest = 0

  print("Starting farming cycle...")

  -- Step 1: Start on chest, manage inventory, check fuel
  print("Managing inventory and checking fuel...")
  manageInventory()
  if not ensureFuel() then
    print("ERROR: Not enough fuel to start farming cycle!")
    return false
  end

  -- Step 2: Move to cobblestone path
  if not moveToPath() then
    print("ERROR: Cannot reach cobblestone path!")
    return false
  end
  stepsFromChest = 1

  -- Step 3: Main farming loop
  while true do
    -- Check fuel before operations
    if not ensureFuel() then
      print("Low fuel detected. Returning to chest early.")
      break
    end

    -- Check if inventory is getting full
    if isInventoryFull() then
      print("Inventory full. Returning to chest.")
      break
    end

    print("Farming at position " .. stepsFromChest .. " steps from chest.")

    -- Collect saplings from all directions
    collectSaplings()

    -- Ensure fuel before tree operations
    ensureFuel()

    -- Check and cut left tree, then plant sapling if needed
    if not checkAndCutTree("left") then
      print("Error cutting left tree. Continuing...")
    end
    plantSapling("left")

    -- Check and cut right tree, then plant sapling if needed
    if not checkAndCutTree("right") then
      print("Error cutting right tree. Continuing...")
    end
    plantSapling("right")

    -- Try to move forward
    if not moveForwardSafely() then
      print("Cannot move forward. Returning to chest.")
      break
    end
    stepsFromChest = stepsFromChest + 1

    -- Check if we're still on cobblestone path
    if not isOnCobblestone() then
      print("Reached end of cobblestone path. Returning to chest.")
      -- Step back onto the cobblestone
      if turtle.back() then
        stepsFromChest = stepsFromChest - 1
      end
      break
    end
  end

  -- Step 4: Return to chest
  if not returnToChest(stepsFromChest) then
    print("ERROR: Failed to return to chest!")
    return false
  end

  print("Farming cycle completed successfully.")
  return true
end

-- Main program function
local function main()
  print("=== Tree Farm v1.0 ===")
  print("Automated tree farming system starting...")
  print("")
  print("Setup verification:")
  print("- Turtle should be on top of a chest")
  print("- Current fuel level: " .. turtle.getFuelLevel())
  print("- Fuel in slot 1: " .. turtle.getItemCount(FUEL_SLOT) .. " items")
  print("- Saplings in slot 2: " .. turtle.getItemCount(SAPLING_SLOT) .. " items")
  print("- Cobblestone path should extend forward")
  print("")

  -- Initial sapling check
  if getSaplingCount() == 0 then
    print("WARNING: No saplings found in slot 2!")
    print("The turtle will still collect saplings but cannot plant any initially.")
  end

  -- Proactive refueling at startup
  print("Ensuring fuel at startup...")
  if not ensureFuel() then
    print("ERROR: Cannot refuel at startup! Please add fuel to slot 1.")
    return
  end

  print("Starting continuous farming operation...")
  print("Press Ctrl+T to stop the program.")
  print("")

  local cycleCount = 0

  -- Main farming loop
  while true do
    cycleCount = cycleCount + 1
    print("=== Cycle " .. cycleCount .. " ===")

    -- Ensure fuel at start of each cycle
    if not ensureFuel() then
      print("ERROR: Cannot refuel for cycle " .. cycleCount .. "! Stopping program.")
      break
    end

    -- Perform farming cycle
    if not farmingCycle() then
      print("ERROR: Farming cycle failed! Stopping program.")
      break
    end

    -- Wait on chest between cycles
    print("Waiting " .. CHEST_WAIT_TIME .. " seconds before next cycle...")
    os.sleep(CHEST_WAIT_TIME)
  end

  print("Tree farming program ended.")
end

-- Run the main program
main()