--!native
--!optimize 2

local ChunkBuilder = {}

local Chunk = require("./Chunk")
local BlockManager = require("./BlockManager")
local util = require("../Util")

local objects = script.Parent.Parent.Parent.Objects

local RunService = game:GetService("RunService")

local ChunkBorderFolder = game:GetService("Workspace"):FindFirstChildOfClass("Terrain")
local DEBUG_GHOST = true

local NEIGHBOR_OFFSETS = {
	{-1, 0, 0}, {1, 0, 0},
	{0, -1, 0}, {0, 1, 0},
	{0, 0, -1}, {0, 0, 1}
}

-- TODO: Move to Chunk
type BlockData = {
	id: number,
	state: {
		[typeof("")]: string | boolean | number
	}
}

local function placeBorder(a,b,c)
	local pos = util.ChunkPosToCFrame(Vector3.new(a,b,c),Vector3.new(1,1,1)).Position - Vector3.new(2,2,2)
	local d = objects.ChunkLoading:Clone()
	d:PivotTo(CFrame.new(pos))
	d.Parent = ChunkBorderFolder
	return d
end

local function Swait(l)
	for i = 1,l do
		RunService.Stepped:Wait()
	end
end

local function propogateNeighboringBlockChanges(cx, cy, cz, x, y, z)
	--warn("propogateNeighboringBlockChanges",cx,cy,cz,x,y,z)
	-- updates block in another chunk
	local c = Chunk.AllChunks[`{cx},{cy},{cz}`]
	if not c then return end

	local d = c.data[`{x},{y},{z}`]
	if not d then return end

	if c:IsBlockRenderable(x, y, z) then
		if c.instance:FindFirstChild(`{x},{y},{z}`) then return end
		task.synchronize()
		local block = BlockManager:GetBlockRotated(d.id, util.RotationStringToNormalId(d.state["r"] or "f"), d.state)
		block.Name = `{x},{y},{z}`
		block:PivotTo(util.ChunkPosToCFrame(c.pos, Vector3.new(x, y, z)))
		block.Parent = c.instance
		task.desynchronize()
	else
		local existing = c.instance:FindFirstChild(`{x},{y},{z}`)
		if existing then
			task.synchronize()
			existing:Destroy()
			task.desynchronize()
		end
	end
end

function ChunkBuilder:BuildChunk(c: typeof(Chunk.new(0,0,0)),parent: Instance?)

	if c.loaded then
		return c.instance
	end

	local blocks = c.data
	local newcache = {} :: {[typeof("")]: BlockData}

	local finished = false


	local ch = Instance.new("Folder")
	ch.Parent = parent
	ch.Name = `{c.pos.X},{c.pos.Y},{c.pos.Z}`

	local conn = c.UpdateBlockBindableL.Event:Connect(function(x: number, y: number, z: number, d: BlockData)
		task.desynchronize()
		if finished == false then
			newcache[`{x},{y},{z}`] = d
			return
		end
		task.synchronize()
		for _, o in pairs(NEIGHBOR_OFFSETS) do
			--warn("propogate",o[1],o[2],o[3])
			-- Adjust for chunk boundaries
			local b = {x = x + o[1], y = y + o[2], z = z + o[3]}
			local ch = {x = c.pos.X, y = c.pos.Y, z = c.pos.Z}

			if b.x < 1 then ch.x = c.pos.X - 1 b.x = 8 end
			if b.x > 8 then ch.x = c.pos.X + 1 b.x = 1 end
			if b.y < 1 then ch.y = c.pos.Y - 1 b.y = 8 end
			if b.y > 8 then ch.y = c.pos.Y + 1 b.y = 1 end
			if b.z < 1 then ch.z = c.pos.Z - 1 b.z = 8 end
			if b.z > 8 then ch.z = c.pos.Z + 1 b.z = 1 end

			propogateNeighboringBlockChanges(ch.x, ch.y, ch.z, b.x, b.y, b.z)
			--BlockManager:GetBlock(ch.x)
		end

		local blockName = `{x},{y},{z}`
		local existing = ch:FindFirstChild(blockName)
		if d == 0 then
			if c.delayedRemoval and c.delayedRemoval[blockName] then
				c.delayedRemoval[blockName] = nil
				if existing then
					task.defer(function()
						task.synchronize()
						RunService.RenderStepped:Wait()
						if existing.Parent then
							existing:Destroy()
						end
						task.desynchronize()
					end)
				elseif DEBUG_GHOST then
					print("[CHUNKBUILDER][GHOST] Delayed remove missing instance", c.pos, blockName)
				end
				return
			end
			if existing then
				task.synchronize()
				existing:Destroy()
				task.desynchronize()
			elseif DEBUG_GHOST then
				print("[CHUNKBUILDER][GHOST] Remove missing instance", c.pos, blockName)
			end
			return
		end
		if not c:IsBlockRenderable(x, y, z) then
			if existing then
				task.synchronize()
				existing:Destroy()
				task.desynchronize()
			end
			return
		end
		if existing then
			task.synchronize()
			existing:Destroy()
			task.desynchronize()
		end
		if not d then return end
		if d.id == 0 then return end
		local N = util.RotationStringToNormalId(d.state["r"] or "f")
		task.synchronize()
		local block = BlockManager:GetBlockRotated(d.id, N, d.state)
		block.Name = blockName
		block:PivotTo(util.ChunkPosToCFrame(c.pos, Vector3.new(x, y, z)))
		block.Parent = ch
		task.desynchronize()
	end)

	c.unloadChunkHook = function()
		conn:Disconnect()
		blocks = nil
		c = nil
	end

	task.defer(function()

		local p = 0

		task.synchronize()

		local hb = false

		for a,b in pairs(blocks) do
			hb = true
		end

		local border = Instance.new("Part")
		if hb == true then
			border:Destroy()
			border = placeBorder(c.pos.X, c.pos.Y, c.pos.Z)
		end

		for a,b in pairs(blocks) do
			task.desynchronize()
			local coords = util.BlockPosStringToCoords(a)
			if not c:IsBlockRenderable(coords.X, coords.Y, coords.Z) then
				if ch:FindFirstChild(a) then
					task.synchronize()
					ch:FindFirstChild(a):Destroy()
					task.desynchronize()
				end
				continue
			end
			task.desynchronize()
			local N = util.RotationStringToNormalId(b.state["r"] or "f")
			task.synchronize()
			local block = BlockManager:GetBlockRotated(b.id, N, b.state)
			if ch:FindFirstChild(a) then
				ch:FindFirstChild(a):Destroy()
			end
			block.Name = a
			block:PivotTo(util.ChunkPosToCFrame(c.pos, coords))
			block.Parent = ch
			p += 1
			if p == 15 then
				p = 0
				Swait(1)
			end
		end

		finished = true

		task.synchronize()
		border:Destroy()
		task.desynchronize()

		task.defer(function()
			task.synchronize()
			for key, data in pairs(newcache) do
				local coords = util.BlockPosStringToCoords(key)
				for _, o in pairs(NEIGHBOR_OFFSETS) do
					-- chunks are 8x8x8
					local nb = {x = coords.X + o[1], y = coords.Y + o[2], z = coords.Z + o[3]}
					local chCoords = {x = c.pos.X, y = c.pos.Y, z = c.pos.Z}
					if nb.x == 0 then chCoords.x = c.pos.X - 1 nb.x = 8 end
					if nb.x == 9 then chCoords.x = c.pos.X + 1 nb.x = 1 end

					if nb.y == 0 then chCoords.y = c.pos.Y - 1 nb.y = 8 end
					if nb.y == 9 then chCoords.y = c.pos.Y + 1 nb.y = 1 end

					if nb.z == 0 then chCoords.z = c.pos.Z - 1 nb.z = 8 end
					if nb.z == 9 then chCoords.z = c.pos.Z + 1 nb.z = 1 end

					propogateNeighboringBlockChanges(chCoords.x, chCoords.y, chCoords.z, nb.x, nb.y, nb.z)
				end

				local existing = ch:FindFirstChild(key)
				if data == 0 or (data and data.id == 0) then
					if existing then
						existing:Destroy()
					end
					continue
				end
				if not c:IsBlockRenderable(coords.X, coords.Y, coords.Z) then
					if existing then
						existing:Destroy()
					end
					continue
				end
				if existing then
					existing:Destroy()
				end
				if not data then
					continue
				end
				local N = util.RotationStringToNormalId(data.state["r"] or "f")
				local block = BlockManager:GetBlockRotated(data.id, N, data.state)
				block.Name = key
				block:PivotTo(util.ChunkPosToCFrame(c.pos, coords))
				block.Parent = ch
			end
			newcache = nil
			blocks = nil
		end)
		task.desynchronize()
	end)

	c.loaded = true

	return ch

end

return ChunkBuilder