local Point = require('point')
local Util  = require('util')

local os     = _G.os
local turtle = _G.turtle

local checkedNodes, nodes

local function addNode(node)

  for i = 0, 3 do
    local hi = turtle.getHeadingInfo(i)
    local testNode = { x = node.x + hi.xd, z = node.z + hi.zd }

    local key = table.concat({ testNode.x, testNode.z }, ':')
    if not checkedNodes[key] then
      nodes[key] = testNode
    end
  end
end

local function findObsidian()
  repeat
    local node = { x = turtle.point.x, z = turtle.point.z }
    local key = table.concat({ node.x, node.z }, ':')

    checkedNodes[key] = true
    nodes[key] = nil

    local _,b = turtle.inspectDown()
    if b and (b.name == 'minecraft:lava' or b.name == 'minecraft:flowing_lava') then
      if turtle.select('minecraft:water_bucket') then
        while true do
          if turtle.up() then
            break
          end
          print('stuck')
        end
        turtle.placeDown()
        os.sleep(2)
        turtle.placeDown()
        turtle.down()
        turtle.select(1)
        _, b = turtle.inspectDown()
      end
    end

    if turtle.getItemCount(16) > 0 then
      print('Inventory full')
      print('Enter to continue...')
      _G.read()
    end

    if b and b.name == 'minecraft:obsidian' then
      turtle.digDown()
      addNode(node)
    else
      turtle.digDown()
    end

    print(string.format('%d nodes remaining', Util.size(nodes)))

    if Util.size(nodes) == 0 then
      break
    end

    node = Point.closest(turtle.point, nodes)
    if not turtle.go(node) then
      break
    end
  until turtle.isAborted()
end

turtle.run(function()
  turtle.reset()
  turtle.set({ digPolicy = 'dig' })

  local s, m = pcall(function()
    repeat
      checkedNodes = { }
      nodes = { }

      local _,b = turtle.inspectDown()
      if not b or b.name ~= 'minecraft:obsidian' then
        break
      end

      findObsidian()
      if not turtle.select('minecraft:water_bucket') then
        break
      end
      turtle.go({ x = 0, z = 0 })
      turtle.placeDown()
      os.sleep(2)
      turtle.placeDown()
      turtle.down()
      turtle.select(1)
    until turtle.isAborted()
  end)

  if not s and m then
    error(m)
  end

  turtle.go({ x = 0, y = 0, z = 0, heading = 0 })
end)