exf

local size = 16

local depth = 0
local unloaded = 0
local collected = 0

local xPos,zPos = 0,0
local xDir,zDir = 0,1

local Dir = {
  Front = 0,
  Back = 1,
  Left = 2,
  Right = 3,
  Up = 4,
  Down = 5
}

local goTo
local refuel

local function printr( message )
    print(message)
    rednet.broadcast(message)
end

local function myVec(depth, dir)
  return {depth=depth, dir=dir}
end

local function alignDir(dir, depth, track)
  if (dir == Dir.Left) then
    turtle.turnLeft()
    table.insert(track, myVec(depth, Dir.Left))
  elseif (dir == Dir.Right) then
    turtle.turnRight()
    table.insert(track, myVec(depth, Dir.Right))
  elseif (dir == Dir.Back) then
    turtle.turnRight()
    turtle.turnRight()
    table.insert(track, myVec(depth, Dir.Right))
    table.insert(track, myVec(depth, Dir.Right))
  end
end

local function undoAlignDir(depth, track)
  while (#track > 0 and track[#track].depth == depth) do
    local vec = table.remove(track)
    if (vec.dir == Dir.Left) then
      turtle.turnRight()
    elseif (vec.dir == Dir.Right) then
      turtle.turnLeft()
    end
  end
end

local function isMine(hasBlock, blockInfo)
    local mine = hasBlock and string.find(blockInfo.name, "ore")
    if mine then
        printr("Found "..blockInfo.name)
    end
    return mine
end

local function inspectDirIsMine(dir)
  local hasBlock, blockInfo
  if (dir == Dir.Up) then
    hasBlock, blockInfo = turtle.inspectUp()
  elseif (dir == Dir.Down) then
    hasBlock, blockInfo = turtle.inspectDown()
  else
    hasBlock, blockInfo = turtle.inspect()
  end

  return isMine(hasBlock, blockInfo)
end

local function excavateDir(dir, depth, track)
  if (dir == Dir.Up) then
    turtle.digUp()
    turtle.up()
    table.insert(track, myVec(depth, Dir.Up))
  elseif (dir == Dir.Down) then
    turtle.digDown()
    turtle.down()
    table.insert(track, myVec(depth, Dir.Down))
  else
    local counter = 0
    repeat
      turtle.dig()
      counter = counter + 1
    until turtle.forward()
    table.insert(track, myVec(depth, Dir.Front))
    -- if counter > 1 then
    --   printr("WARNING: encountered gravity block during DFS")
    -- end
  end
end

local function selectFillBlock()
  for i = 1, 16 do
    local info = turtle.getItemDetail(i)
    if info and info.name == FILL_BLOCK then
      turtle.select(i)
      return
    end
  end
  -- printr("[W] no fill blocks")
end

local function backtrack(currentDepth, targetDepth, moveTrack, turnTrack)
  while (currentDepth ~= targetDepth) do
    while (#moveTrack > 0 and moveTrack[#moveTrack].depth == currentDepth - 1) do
      local vec = table.remove(moveTrack)
      if (vec.dir == Dir.Front) then
        turtle.back()
        selectFillBlock()
        turtle.place()
      elseif (vec.dir == Dir.Up) then
        turtle.down()
        selectFillBlock()
        turtle.placeUp()
      elseif (vec.dir == Dir.Down) then
        turtle.up()
        selectFillBlock()
        turtle.placeDown()
      end
    end
    undoAlignDir(currentDepth - 1, turnTrack)
    currentDepth = currentDepth - 1
  end
end

local function dfs(initDir)
  local stack = {}
  local turnTrack = {}
  local moveTrack = {}
  local depth = 0
  table.insert(stack, myVec(depth, initDir))

  while (#stack > 0) do
    local vec = table.remove(stack)
    backtrack(depth, vec.depth, moveTrack, turnTrack)
    depth = vec.depth

    alignDir(vec.dir, depth, turnTrack)

    if (inspectDirIsMine(vec.dir)) then
      excavateDir(vec.dir, depth, moveTrack)
      depth = depth + 1

      if isMine(turtle.inspect()) then
        table.insert(stack, myVec(depth, Dir.Front))
      end

      if isMine(turtle.inspectUp()) then
        table.insert(stack, myVec(depth, Dir.Up))
      end
      if isMine(turtle.inspectDown()) then
        table.insert(stack, myVec(depth, Dir.Down))
      end
      turtle.turnRight()
      if isMine(turtle.inspect()) then
        table.insert(stack, myVec(depth, Dir.Right))
      end
      turtle.turnRight()
      if isMine(turtle.inspect()) then
        table.insert(stack, myVec(depth, Dir.Back))
      end
      turtle.turnRight()
      if isMine(turtle.inspect()) then
        table.insert(stack, myVec(depth, Dir.Left))
      end
      turtle.turnRight()
    else
      undoAlignDir(depth, turnTrack)
    end
  end

  backtrack(depth, 0, moveTrack, turnTrack)
end

local function triggerDfs(dir)
    local x,y,z,xd,zd = xPos,depth,zPos,xDir,zDir
    if inspectDirIsMine(dir) then
        dfs(dir)
    end
    goTo( x,y,z,xd,zd )
end

local function organize()
    for i = 1,16 do
      if turtle.getItemCount(i) > 0 and turtle.getItemCount(i) < 64 then
        turtle.select(i)
        for j = i+1,16 do
          if turtle.compareTo(j) then
            turtle.select(j)
            turtle.transferTo(i)
            turtle.select(i)
          end
        end
      end
    end

    for i = 1,16 do
      if turtle.getItemCount(i) > 0 then
        for j = 1,i do
          if turtle.getItemCount(j) == 0 then
            turtle.select(i)
            turtle.transferTo(j)
            break
          end
        end
      end
    end
end

local function unload( _bKeepOneFuelStack )
    for n=1,16 do
        local nCount = turtle.getItemCount(n)
        if nCount > 0 then
            turtle.select(n)
            local bDrop = true
            if _bKeepOneFuelStack and turtle.refuel(0) then
                bDrop = false
                _bKeepOneFuelStack = false
            end
            if bDrop then
                turtle.drop()
                unloaded = unloaded + nCount
            end
        end
    end
    collected = 0
    turtle.select(1)
end

local function returnSupplies()
    local x,y,z,xd,zd = xPos,depth,zPos,xDir,zDir
    goTo( 0,0,0,0,-1 )

    local fuelNeeded = 2*(x+y+z) + 1
    if not refuel( fuelNeeded ) then
        unload( false )
        printr( "Waiting for fuel" )
        while not refuel( fuelNeeded ) do
            os.pullEvent( "turtle_inventory" )
        end
    else
        unload( false )
    end

    goTo( x,y,z,xd,zd )
end

local function collect()
    local bFull = true
    local nTotalItems = 0
    for n=1,16 do
        local nCount = turtle.getItemCount(n)
        if nCount == 0 then
            bFull = false
        end
        nTotalItems = nTotalItems + nCount
    end

    if nTotalItems > collected then
        collected = nTotalItems
        if math.fmod(collected + unloaded, 50) == 0 then
            printr( "Mined "..(collected + unloaded).." items." )
        end
    end

    if bFull then
        printr( "No empty slots left." )
        return false
    end
    return true
end

function refuel( ammount )
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" then
        return true
    end

    local needed = ammount or (xPos + zPos + depth + 2)
    if turtle.getFuelLevel() < needed then
        local fueled = false
        for n=1,16 do
            if turtle.getItemCount(n) > 0 then
                turtle.select(n)
                if turtle.refuel(1) then
                    while turtle.getItemCount(n) > 0 and turtle.getFuelLevel() < needed do
                        turtle.refuel(1)
                    end
                    if turtle.getFuelLevel() >= needed then
                        turtle.select(1)
                        return true
                    end
                end
            end
        end
        turtle.select(1)
        return false
    end

    return true
end

local function checkInv()
    for n=1,16 do
        if turtle.getItemCount(n) > 0 then
            if turtle.getItemDetail(n).name == "minecraft:cobblestone" then
                turtle.select(n)
                turtle.dropUp(64)
            end
        end
    end
    organize()
end

local function tryForwards()
    if not refuel() then
        printr( "Not enough Fuel" )
        returnSupplies()
    end

    while not turtle.forward() do
        if turtle.detect() then
            if turtle.dig() then
                if not collect() then
                    checkInv()
                    if not collect() then
                        returnSupplies()
                    end
                end
            else
                return false
            end
        end
    end

    triggerDfs(Dir.Front)
    triggerDfs(Dir.Up)
    triggerDfs(Dir.Down)

    xPos = xPos + xDir
    zPos = zPos + zDir
    return true
end

local function tryDown()
    if not refuel() then
        printr( "Not enough Fuel" )
        returnSupplies()
    end

    while not turtle.down() do
        if turtle.detectDown() then
            if turtle.digDown() then
                if not collect() then
                    checkInv()
                    if not collect() then
                        returnSupplies()
                    end
                end
            else
                return false
            end
        end
    end

    depth = depth + 1
    if math.fmod( depth, 10 ) == 0 then
        printr( "Descended "..depth.." metres." )
    end

    return true
end

local function turnLeft()
    turtle.turnLeft()
    xDir, zDir = -zDir, xDir
end

local function turnRight()
    turtle.turnRight()
    xDir, zDir = zDir, -xDir
end

function goTo( x, y, z, xd, zd )
    while depth > y do
        if turtle.up() then
            depth = depth - 1
        elseif turtle.digUp() then
            collect()
        else
            sleep( 0.5 )
        end
    end

    if xPos > x then
        while xDir ~= -1 do
            turnLeft()
        end
        while xPos > x do
            if turtle.forward() then
                xPos = xPos - 1
            elseif turtle.dig() then
                collect()
            else
                sleep( 0.5 )
            end
        end
    elseif xPos < x then
        while xDir ~= 1 do
            turnLeft()
        end
        while xPos < x do
            if turtle.forward() then
                xPos = xPos + 1
            elseif turtle.dig() then
                collect()
            else
                sleep( 0.5 )
            end
        end
    end

    if zPos > z then
        while zDir ~= -1 do
            turnLeft()
        end
        while zPos > z do
            if turtle.forward() then
                zPos = zPos - 1
            elseif turtle.dig() then
                collect()
            else
                sleep( 0.5 )
            end
        end
    elseif zPos < z then
        while zDir ~= 1 do
            turnLeft()
        end
        while zPos < z do
            if turtle.forward() then
                zPos = zPos + 1
            elseif turtle.dig()then
                collect()
            else
                sleep( 0.5 )
            end
        end
    end

    while depth < y do
        if turtle.down() then
            depth = depth + 1
        elseif turtle.digDown()then
            collect()
        else
            sleep( 0.5 )
        end
    end

    while zDir ~= zd or xDir ~= xd do
        turnLeft()
    end
end

if not refuel() then
    printr( "Out of Fuel" )
    return
end

rednet.open("left")

goTo( 0,0,0,0,-1 )
unload( false )
goTo( 0,0,0,0,1 )

printr( "Excavating..." )

local alternate = 0
local done = false
while not done do
    for n = 1, size do
        for m = 1, size - 1 do
            if not tryForwards() then
                done = true
                break
            end
        end
        if done then
            break
        end
        if n < size then
            if math.fmod(n + alternate, 2) == 0 then
                turnLeft()
                if not tryForwards() then
                    done = true
                    break
                end
                turnLeft()
            else
                turnRight()
                if not tryForwards() then
                    done = true
                    break
                end
                turnRight()
            end
        end
    end
    if done then
        break
    end

    if size > 1 then
        if math.fmod(size, 2) == 0 then
            turnRight()
        else
            if alternate == 0 then
                turnLeft()
            else
                turnRight()
            end
            alternate = 1 - alternate
        end
    end

    if not tryDown() then
        done = true
        break
    end
end

printr( "Returning to surface..." )

-- Return to where we started
goTo( 0,0,0,0,-1 )
unload( false )
goTo( 0,0,0,0,1 )

printr( "Mined "..(collected + unloaded).." items total." )