-- Minetest: builtin/item.lua (override falling entity with new features)

local function add_fall_damage(node, damage)

	if minetest.registered_nodes[node] then

		local group = minetest.registered_nodes[node].groups

		group.falling_node_damage = damage

		minetest.override_item(node, {groups = group})
	else
		print (node .. " not found to add falling_node_damage to")
	end
end

-- override falling nodes to add damage
minetest.after(1.0, function()

	add_fall_damage("default:sand", 1)
	add_fall_damage("default:desert_sand", 1)
	add_fall_damage("default:silver_sand", 1)
	add_fall_damage("default:gravel", 2)
	add_fall_damage("caverealms:coal_dust", 1)
	add_fall_damage("tnt:tnt_burning", 2)
end)

-- variables and settings
local node_fall_hurt = minetest.settings:get_bool("node_fall_hurt") ~= false
local delay = 0.1 -- used to simulate lag
local gravity = tonumber(core.settings:get("movement_gravity")) or 9.81
local builtin_shared = ...
local SCALE = 0.667

local facedir_to_euler = {
	{y = 0, x = 0, z = 0},
	{y = -math.pi/2, x = 0, z = 0},
	{y = math.pi, x = 0, z = 0},
	{y = math.pi/2, x = 0, z = 0},
	{y = math.pi/2, x = -math.pi/2, z = math.pi/2},
	{y = math.pi/2, x = math.pi, z = math.pi/2},
	{y = math.pi/2, x = math.pi/2, z = math.pi/2},
	{y = math.pi/2, x = 0, z = math.pi/2},
	{y = -math.pi/2, x = math.pi/2, z = math.pi/2},
	{y = -math.pi/2, x = 0, z = math.pi/2},
	{y = -math.pi/2, x = -math.pi/2, z = math.pi/2},
	{y = -math.pi/2, x = math.pi, z = math.pi/2},
	{y = 0, x = 0, z = math.pi/2},
	{y = 0, x = -math.pi/2, z = math.pi/2},
	{y = 0, x = math.pi, z = math.pi/2},
	{y = 0, x = math.pi/2, z = math.pi/2},
	{y = math.pi, x = math.pi, z = math.pi/2},
	{y = math.pi, x = math.pi/2, z = math.pi/2},
	{y = math.pi, x = 0, z = math.pi/2},
	{y = math.pi, x = -math.pi/2, z = math.pi/2},
	{y = math.pi, x = math.pi, z = 0},
	{y = -math.pi/2, x = math.pi, z = 0},
	{y = 0, x = math.pi, z = 0},
	{y = math.pi/2, x = math.pi, z = 0}
}

--
-- Falling stuff
--

core.register_entity(":__builtin:falling_node", {

	initial_properties = {
		visual = "item",
		visual_size = vector.new(SCALE, SCALE, SCALE),
		textures = {},
		physical = true,
		is_visible = false,
		collide_with_objects = true,
		collisionbox = {-0.5, -0.5, -0.5, 0.5, 0.5, 0.5},
	},

	node = {},
	meta = {},
	floats = false,

	set_node = function(self, node, meta)

		node.param2 = node.param2 or 0
		self.node = node
		meta = meta or {}

		if type(meta.to_table) == "function" then
			meta = meta:to_table()
		end

		for _, list in pairs(meta.inventory or {}) do

			for i, stack in pairs(list) do

				if type(stack) == "userdata" then
					list[i] = stack:to_string()
				end
			end
		end

		local def = core.registered_nodes[node.name]

		if not def then

			-- Don't allow unknown nodes to fall
			core.log("info",
				"Unknown falling node removed at "..
				core.pos_to_string(self.object:get_pos()))

			self.object:remove()

			return
		end

		self.meta = meta

		-- Cache whether we're supposed to float on water
		self.floats = core.get_item_group(node.name, "float") ~= 0

		-- Save liquidtype for falling water
		self.liquidtype = def.liquidtype

		-- Set entity visuals
		if def.drawtype == "torchlike" or def.drawtype == "signlike" then

			local textures

			if def.tiles and def.tiles[1] then

				local tile = def.tiles[1]

				if type(tile) == "table" then
					tile = tile.name
				end

				if def.drawtype == "torchlike" then
					textures = { "("..tile..")^[transformFX", tile }
				else
					textures = { tile, "("..tile..")^[transformFX" }
				end
			end

			local vsize

			if def.visual_scale then

				local s = def.visual_scale

				vsize = vector.new(s, s, s)
			end

			self.object:set_properties({
				is_visible = true,
				visual = "upright_sprite",
				visual_size = vsize,
				textures = textures,
				glow = def.light_source,
			})

		elseif def.drawtype ~= "airlike" then

			local itemstring = node.name

			if core.is_colored_paramtype(def.paramtype2) then
				itemstring = core.itemstring_with_palette(itemstring, node.param2)
			end

			-- FIXME: solution needed for paramtype2 == "leveled"
			-- Calculate size of falling node
			local s = {}
			s.x = (def.visual_scale or 1) * SCALE
			s.y = s.x
			s.z = s.x

			-- Compensate for wield_scale
			if def.wield_scale then
				s.x = s.x / def.wield_scale.x
				s.y = s.y / def.wield_scale.y
				s.z = s.z / def.wield_scale.z
			end

			self.object:set_properties({
				is_visible = true,
				wield_item = itemstring,
				visual_size = s,
				glow = def.light_source,
			})
		end

		-- Set collision box (certain nodeboxes only for now)
		local nb_types = {fixed=true, leveled=true, connected=true}

		if def.drawtype == "nodebox" and def.node_box and

			nb_types[def.node_box.type] and def.node_box.fixed then

			local box = table.copy(def.node_box.fixed)

			if type(box[1]) == "table" then
				box = #box == 1 and box[1] or nil -- We can only use a single box
			end

			if box then

				if def.paramtype2 == "leveled" and (self.node.level or 0) > 0 then
					box[5] = -0.5 + self.node.level / 64
				end

				self.object:set_properties({
					collisionbox = box
				})
			end
		end

		-- Rotate entity
		if def.drawtype == "torchlike" then

			if (def.paramtype2 == "wallmounted" or def.paramtype2 == "colorwallmounted")
					and node.param2 % 8 == 7 then
				self.object:set_yaw(-math.pi*0.25)
			else
				self.object:set_yaw(math.pi*0.25)
			end

		elseif ((node.param2 ~= 0 or def.drawtype == "nodebox" or def.drawtype == "mesh")
				and (def.wield_image == "" or def.wield_image == nil))
				or def.drawtype == "signlike"
				or def.drawtype == "mesh"
				or def.drawtype == "normal"
				or def.drawtype == "nodebox" then

			if (def.paramtype2 == "facedir" or def.paramtype2 == "colorfacedir") then

				local fdir = node.param2 % 32 % 24

				-- Get rotation from a precalculated lookup table
				local euler = facedir_to_euler[fdir + 1]

				if euler then
					self.object:set_rotation(euler)
				end

			elseif (def.paramtype2 == "4dir" or def.paramtype2 == "color4dir") then

				local fdir = node.param2 % 4

				-- Get rotation from a precalculated lookup table
				local euler = facedir_to_euler[fdir + 1]

				if euler then
					self.object:set_rotation(euler)
				end

			elseif (def.drawtype ~= "plantlike" and def.drawtype ~= "plantlike_rooted" and
					(def.paramtype2 == "wallmounted" or def.paramtype2 == "colorwallmounted" or def.drawtype == "signlike")) then

				local rot = node.param2 % 8

				if (def.drawtype == "signlike" and def.paramtype2 ~= "wallmounted" and def.paramtype2 ~= "colorwallmounted") then
					-- Change rotation to "floor" by default for non-wallmounted paramtype2
					rot = 1
				end

				local pitch, yaw, roll = 0, 0, 0

				if def.drawtype == "nodebox" or def.drawtype == "mesh" then

					if rot == 0 then
						pitch, yaw = math.pi/2, 0
					elseif rot == 1 then
						pitch, yaw = -math.pi/2, math.pi
					elseif rot == 2 then
						pitch, yaw = 0, math.pi/2
					elseif rot == 3 then
						pitch, yaw = 0, -math.pi/2
					elseif rot == 4 then
						pitch, yaw = 0, math.pi
					elseif rot == 6 then
						pitch, yaw = math.pi/2, 0
					elseif rot == 7 then
						pitch, yaw = -math.pi/2, math.pi
					end
				else
					if rot == 1 then
						pitch, yaw = math.pi, math.pi
					elseif rot == 2 then
						pitch, yaw = math.pi/2, math.pi/2
					elseif rot == 3 then
						pitch, yaw = math.pi/2, -math.pi/2
					elseif rot == 4 then
						pitch, yaw = math.pi/2, math.pi
					elseif rot == 5 then
						pitch, yaw = math.pi/2, 0
					elseif rot == 6 then
						pitch, yaw = math.pi, -math.pi/2
					elseif rot == 7 then
						pitch, yaw = 0, -math.pi/2
					end
				end

				if def.drawtype == "signlike" then

					pitch = pitch - math.pi/2

					if rot == 0 then
						yaw = yaw + math.pi/2
					elseif rot == 1 then
						yaw = yaw - math.pi/2
					elseif rot == 6 then
						yaw = yaw - math.pi/2
						pitch = pitch + math.pi
					elseif rot == 7 then
						yaw = yaw + math.pi/2
						pitch = pitch + math.pi
					end

				elseif def.drawtype == "mesh" or def.drawtype == "normal" or def.drawtype == "nodebox" then
					if rot == 0 or rot == 1 then
						roll = roll + math.pi
					elseif rot == 6 or rot == 7 then
						if def.drawtype ~= "normal" then
							roll = roll - math.pi/2
						end
					else
						yaw = yaw + math.pi
					end
				end

				self.object:set_rotation({x=pitch, y=yaw, z=roll})

			elseif (def.drawtype == "mesh" and def.paramtype2 == "degrotate") then

				local p2 = (node.param2 - (def.place_param2 or 0)) % 240
				local yaw = (p2 / 240) * (math.pi * 2)

				self.object:set_yaw(yaw)

			elseif (def.drawtype == "mesh" and def.paramtype2 == "colordegrotate") then

				local p2 = (node.param2 % 32 - (def.place_param2 or 0) % 32) % 24
				local yaw = (p2 / 24) * (math.pi * 2)

				self.object:set_yaw(yaw)
			end
		end
	end,

	get_staticdata = function(self)

		local ds = {
			node = self.node,
			meta = self.meta,
		}
		return core.serialize(ds)
	end,

	on_activate = function(self, staticdata)

		self.object:set_armor_groups({immortal = 1})
		self.object:set_acceleration(vector.new(0, -gravity, 0))

		local ds = core.deserialize(staticdata)

		if ds and ds.node then
			self:set_node(ds.node, ds.meta)
		elseif ds then
			self:set_node(ds)
		elseif staticdata ~= "" then
			self:set_node({name = staticdata})
		end
	end,

	try_place = function(self, bcp, bcn)

		local bcd = core.registered_nodes[bcn.name]

		-- Add levels if dropped on same leveled node
		if bcd and bcd.paramtype2 == "leveled" and
				bcn.name == self.node.name then

			local addlevel = self.node.level

			if (addlevel or 0) <= 0 then
				addlevel = bcd.leveled
			end

			if core.add_node_level(bcp, addlevel) < addlevel then
				return true
			elseif bcd.buildable_to then
				-- Node level has already reached max, don't place anything
				return true
			end
		end

		-- Decide if we're replacing the node or placing on top
		-- This condition is very similar to the check in core.check_single_for_falling(p)
		local np = vector.copy(bcp)

		if bcd and bcd.buildable_to
				and -- Take "float" group into consideration:
				(
					-- Fall through non-liquids
					not self.floats or bcd.liquidtype == "none" or
					-- Only let sources fall through flowing liquids
					(self.floats and self.liquidtype ~= "none" and bcd.liquidtype ~= "source")
				) then

			core.remove_node(bcp)
		else
			np.y = np.y + 1
		end

		-- Check what's here
		local n2 = core.get_node(np)
		local nd = core.registered_nodes[n2.name]

		-- If it's not air or liquid, remove node and replace it with it's drops
		if n2.name ~= "air" and (not nd or nd.liquidtype ~= "source") then

			if nd and nd.buildable_to == false then

				nd.on_dig(np, n2, nil) -- pos, node, digger

				-- If it's still there, it might be protected
				if core.get_node(np).name == n2.name then
					return false
				end
			else
				core.remove_node(np)
			end
		end

		-- Create node
		local def = core.registered_nodes[self.node.name]

		if def then

			core.add_node(np, self.node)

			if self.meta then
				core.get_meta(np):from_table(self.meta)
			end

			if def.sounds and def.sounds.place then
				core.sound_play(def.sounds.place, {pos = np}, true)
			end
		end

		core.check_for_falling(np)

		return true
	end,

	-- incase falling entity is stuck, punching drops as item to recover
	on_punch = function(self, puncher, tflp, tool_caps, dir, damage)

		if puncher and puncher:is_player() then

			local drops = minetest.get_node_drops(self.node, "")

			for _, dropped_item in pairs(drops) do
				minetest.add_item(self.object:get_pos(), dropped_item)
			end

			self.object:remove()
		end
	end,

	on_step = function(self, dtime, moveresult)

		-- used to simulate a little lag
		self.timer = (self.timer or 0) + dtime

		if self.timer < delay then
			return
		end

		self.timer = 0

		local pos = self.object:get_pos()
		local bcp = pos:offset(0, -0.7, 0):round()
		local bcn = {}

		-- Fallback code since collision detection can't tell us
		-- about liquids (which do not collide)
		if self.floats then

			bcn = core.get_node(bcp)

			local bcd = core.registered_nodes[bcn.name]

			if bcd and bcd.liquidtype ~= "none" then

				if self:try_place(bcp, bcn) then
					self.object:remove()
					return
				end
			end
		end

		--  check if falling node has custom function set
		local custom = minetest.registered_items[self.node.name]
				and minetest.registered_items[self.node.name].falling_step

		if custom and custom(self, pos, dtime + delay) == false then
			return -- skip further checks if false
		end

		assert(moveresult)

		if not moveresult.collides then
			return -- Nothing to do :)
		end

		local player_collision

		if moveresult.touching_ground then

			for _, info in ipairs(moveresult.collisions) do

				if info.type == "object" then

					if info.axis == "y" and info.object:is_player() then

						player_collision = info

						if node_fall_hurt then

							local def = minetest.registered_nodes[self.node.name]
							local damage = def and def.groups and def.groups.falling_node_damage

							if damage and damage > 0 then
								info.object:punch(info.object, 4.0,
										{damage_groups = {fleshy = damage}}, nil)
							end
						end
					end

				elseif info.axis == "y" then
					bcp = info.node_pos
					bcn = core.get_node(bcp)
					break
				end
			end
		end

		if not bcp then

			-- We're colliding with something, but not the ground. Irrelevant to us.
			if player_collision then
				-- Continue falling through players by moving a little into
				-- their collision box
				-- TODO: this hack could be avoided in the future if objects
				--       could choose who to collide with
				local vel = self.object:get_velocity()

				self.object:set_velocity(vector.new(
					vel.x,
					player_collision.old_velocity.y,
					vel.z
				))

				self.object:set_pos(self.object:get_pos():offset(0, -0.5, 0))
			end

			return

		elseif bcn.name == "ignore" then

			-- Delete on contact with ignore at world edges
			self.object:remove()
			return
		end

		local failure = false

		local pos = self.object:get_pos()
		local distance = vector.apply(vector.subtract(pos, bcp), math.abs)

		if distance.x >= 1 or distance.z >= 1 then
			-- We're colliding with some part of a node that's sticking out
			-- Since we don't want to visually teleport, drop as item
			failure = true

		elseif distance.y >= 2 then
			-- Doors consist of a hidden top node and a bottom node that is
			-- the actual door. Despite the top node being solid, the moveresult
			-- almost always indicates collision with the bottom node.
			-- Compensate for this by checking the top node
			bcp.y = bcp.y + 1
			bcn = core.get_node(bcp)

			local def = core.registered_nodes[bcn.name]

			if not (def and def.walkable) then
				failure = true -- This is unexpected, fail
			end
		end

		-- Try to actually place ourselves
		if not failure then
			failure = not self:try_place(bcp, bcn)
		end

		if failure then

			local drops = core.get_node_drops(self.node, "")

			for _, item in pairs(drops) do
				core.add_item(pos, item)
			end
		end

		self.object:remove()
	end
})

--[[
minetest.override_item("default:gravel", {
	groups = {crumbly = 2, falling_node = 1, float = 1},
	light_source = 12,
	falling_step = function(self, pos, dtime)
		print ("Gravel falling!", dtime)
	end
})
]]

print("[MOD] Falling Item loaded")