canopy

-- Set constants

MAX_RADIUS = 20
EMPTY_HARVEST = 10
EMPTY_LEVELS = 3

-- Get the first parameter value that is passed to the program.  This will be
-- the radius of the expanding square search.  If no paramter is passed, default
-- to a radius of 10.

args = {...}

if #args == 0 then
   args[1] = 10
end

if args[1] > MAX_RADIUS then
   args[1] = MAX_RADIUS
end

harvestLeg = {}

for i = 1, 5, 1 do
   harvestLeg[i] = args[1] * 4
end

-- Initialize the variables needed to run the loop and keep track of the
-- harvesting progress.

levelTotal = 0
legTotal = 0
harvestTotal = 0

heading = 0
xPos = 0
yPos = 0
emptyLevels = 0

moveDown = 1

-- Refuel the turtle as needed.

if turtle.getFuelLevel() == 0 then
   turtle.select(1)
   turtle.refuel()
end

-- Loop for each level that is harvested.

while moveDown == 1 do

   legCount = 0
   legTarget = 0
   legLength = 1
   harvestCount = 0

   -- Examine the last five levels that have been processed, and find the
   -- maximum leg on which something was harvested.

   for i = 1, 5, 1 do
      if harvestLeg[i] > legTarget then
         legTarget = harvestLeg[i]
      end
   end

   legTarget = legTarget + 12

   -- Move the turtle down to the next level and begin recording whether
   -- anything is harvested.

   lastHarvestLeg = -1

   if turtle.detectDown() then
      turtle.digDown()
      harvestCount = harvestCount + 1
      lastHarvestLeg = 0
   end

   turtle.down()
   levelTotal = levelTotal + 1

   -- Begin looping through the different legs of the search. Note that the
   -- target leg value will be revaluated after each leg, and can expand as
   -- more harvesting takes place.

   while legCount < legTarget do

      legCount = legCount + 1

      -- On every second leg, the length of the leg increases by 1.  Ensure
      -- that there is enough fuel to accomplish the leg.

      if legCount % 2 == 0 then
         legLength = legLength + 1
      end

      if legCount < 5 then

      print("On leg " .. legCount .. ", length " .. legLength)

      end

      while turtle.getFuelLevel() < legLength + 1 and turtle.getItemCount(1) > 0 do
         turtle.select(1)
         turtle.refuel()
      end

      -- Run through the length of the leg, harvesting as needed and keeping
      -- track of the progress.

      for blockIndex = 1, legLength, 1 do

         if turtle.detect() then
            turtle.dig()
            harvestCount = harvestCount + 1
            lastHarvestLeg = legCount
         end

         turtle.forward()

         if heading == 0 then
            yPos = yPos + 1
         elseif heading == 90 then
            xPos = xPos + 1
         elseif heading == 180 then
            yPos = yPos - 1
         elseif heading == 270 then
            xPos = xPos - 1
         end

      end

      -- As new items are harvested within the canopy, reset the target value.

      if legTarget < lastHarvestLeg + 12 then
         legTarget = lastHarvestLeg + 12
      end

      if legTarget > MAX_RADIUS * 4 then
         legTarget = MAX_RADIUS * 4
      end

      -- Turn the turtle 90 degrees to the right and adjust its heading value.

      turtle.turnRight()

      heading = heading + 90

      if heading == 360 then
         heading = 0
      end

   end

   -- The turtle has now completed all of the legs needed for this level.
   -- Update all of the tracking variables and print progress messages.

   legTotal = legTotal + legCount
   harvestTotal = harvestTotal + harvestCount

   print("Level " .. levelTotal .. ": " .. legCount .. " legs, " .. harvestCount .. " harvested")

   -- Ensure that the turtle has enough fuel to return to the starting position.

   while turtle.getFuelLevel() < legLength + 10 and turtle.getItemCount(1) > 0 do
      turtle.select(1)
      turtle.refuel()
   end

   -- Return the turtle to its starting position. Turn it 90 degrees to the
   -- right to backtrack along the last leg.

   turtle.turnRight()
   heading = heading + 90

   if heading == 360 then
      heading = 0
   end

   -- Move the turtle foward until it is even with its starting position.

   if heading == 0 then
      while yPos ~= 0 do
         turtle.forward()
         yPos = yPos + 1
      end
   elseif heading == 90 then
      while xPos ~= 0 do
         turtle.forward()
         xPos = xPos + 1
      end
   elseif heading == 180 then
      while yPos ~= 0 do
         turtle.forward()
         yPos = yPos - 1
      end
   elseif heading == 270 then
      while xPos ~= 0 do
         turtle.forward()
         xPos = xPos - 1
      end
   end

   -- Turn the turtle 90 degrees to the left, and move it to the starting
   -- position.

   turtle.turnLeft()
   heading = heading - 90

   if heading == 360 then
      heading = 0
   end

   if heading == 0 then
      while yPos ~= 0 do
         turtle.forward()
         yPos = yPos + 1
      end
   elseif heading == 90 then
      while xPos ~= 0 do
         turtle.forward()
         xPos = xPos + 1
      end
   elseif heading == 180 then
      while yPos ~= 0 do
         turtle.forward()
         yPos = yPos - 1
      end
   elseif heading == 270 then
      while xPos ~= 0 do
         turtle.forward()
         xPos = xPos - 1
      end
   end

   moveDown = 0

end