local startingPosition = { x = 0, y = 0, z = 0}

local blocksExplored = {}
local blockQueue = {}
local logMessages = {}

local dirWorld = "north"

term.write("Enable debug output mode?: ")
local debugOn = true
if(io.read("*l") == "false") then
	debugOn = false
end
term.write("Enter turtle's x coordinate: ")
startingPosition.x = io.read("*l")
term.write("Enter turtle's y coordinate: ")
startingPosition.y = io.read("*l")
term.write("Enter turtle's z coordinate: ")
startingPosition.z = io.read("*l")
local currentPosition = startingPosition

local function tableString(tbl)
	local str = "{"
	for k,v in pairs(tbl) do
		str = str .. k .. "=" .. v
	end
	str = str .. "}"
	return str
end

local function consumeFuel()
	for i = 1, 16, 1 do
		local fuelDifference = turtle.getFuelLimit() - turtle.getFuelLevel()
		if(fuelDifference < (80 * 64)) then
			turtle.refuel()
		end
	end
	term.write("[CaveEX]: New fuel amount is " .. turtle.getFuelLevel() .. " actions/moves.")
end

local function compactPosition()
	return "x: " .. currentPosition.x .. ", y: " .. currentPosition.y .. ", z: " .. currentPosition.z
end

local function logMessage(msg)
	logMessages[#logMessages + 1] = tostring(msg)
	if(debugOn) then print(msg) end
end

local function updatePosition()
	if(dirWorld == "north") then
		startingPosition.z = startingPosition.z + 1
	elseif(dirWorld == "south") then
		startingPosition.z = startingPosition.z - 1
	elseif(dirWorld == "west") then
		startingPosition.x = startingPosition.x - 1
	elseif(dirWorld == "east") then
		startingPosition.x = startingPosition.x + 1
	end
end

local function forward(n)
	for i = 1, n, 1 do
		turtle.forward()
		updatePosition()
	end
end

local function noDuplicate(newEntry)
	for i, v in pairs(blocksExplored) do
		if(v == newEntry) then
			return false
		end
	end

	for i, v in pairs(blockQueue) do
		if(v == newEntry) then
			return false
		end
	end

	return true
end

local function dirToOffset()
	if(dirWorld == "north") then
		return 0, 1
	elseif(dirWorld == "south") then
		return 0, -1
	elseif(dirWorld == "west") then
		return -1, 0
	elseif(dirWorld == "east") then
		return 1, 0
	end
end

local function leftTurn()
	if(dirWorld == "north") then
		dirWorld = "west"
	elseif(dirWorld == "west") then
		dirWorld = "south"
	elseif(dirWorld == "south") then
		dirWorld = "east"
	elseif(dirWorld == "east") then
		dirWorld = "north"
	end
end

local function addIfAirFront()
	consumeFuel()
	if(not turtle.detect()) then
		local x0, z0 = dirToOffset()
		local newEntry = { x = currentPosition.x + x0, y = currentPosition.y, z = currentPosition.z + z0 }
		if(noDuplicate(newEntry)) then
			blockQueue[#blockQueue + 1] = newEntry
			logMessage("[CaveEX]: blockQueue += " .. tableString(blockQueue[#blockQueue]))
		end
	else
		local x0, z0 = dirToOffset()
		local success, data = turtle.inspect()
		local newEntry = { x = currentPosition.x + x0, y = currentPosition.y, z = currentPosition.z + z0, name = data.name, meta = data.metadata }
		if(noDuplicate(newEntry)) then
			blocksExplored[#blocksExplored + 1] = newEntry
			logMessage("[CaveEX]: blocksExplored += " .. tableString(blocksExplored[#blocksExplored]))
		end
	end
	turtle.turnLeft()
	leftTurn()
end

local function addIfAir()
	if(not turtle.detectDown()) then
		local newEntry = { x = currentPosition.x, y = currentPosition.y - 1, z = currentPosition.z }
		if(noDuplicate(newEntry)) then
			blockQueue[#blockQueue + 1] = newEntry
			logMessage("[CaveEX]: blockQueue += " .. tableString(blockQueue[#blockQueue]))
		end
	else
		local success, data = turtle.inspectDown()
		local newEntry = { x = currentPosition.x, y = currentPosition.y - 1, z = currentPosition.z, name = data.name, meta = data.metadata }
		if(noDuplicate(newEntry)) then
			blocksExplored[#blocksExplored + 1] = newEntry
			logMessage("[CaveEX]: blocksExplored += " .. tableString(blocksExplored[#blocksExplored]))
		end
	end

	if(not turtle.detectUp()) then
		local newEntry = { x = currentPosition.x, y = currentPosition.y + 1, z = currentPosition.z }
		if(noDuplicate(newEntry)) then
			blockQueue[#blockQueue + 1] = newEntry
			logMessage("[CaveEX]: blockQueue += " .. tableString(blockQueue[#blockQueue]))
		end
	else
		local success, data = turtle.inspectUp()
		local newEntry = { x = currentPosition.x, y = currentPosition.y + 1, z = currentPosition.z, name = data.name, meta = data.metadata }
		if(noDuplicate(newEntry)) then
			blocksExplored[#blocksExplored + 1] = newEntry
			logMessage("[CaveEX]: blocksExplored += " .. tableString(blocksExplored[#blocksExplored]))
		end
	end

	addIfAirFront()
	addIfAirFront()
	addIfAirFront()
	addIfAirFront()
end

term.write("CaveEX starting from " .. compactPosition())

consumeFuel()

-- Populate blockQueue with the blocks around us.

addIfAir()