local S = minetest.get_translator("mcl_potions")
-- Time in seconds after which a stuck arrow is deleted
local ARROW_TIMEOUT = 60
-- Time after which stuck arrow is rechecked for being stuck
local STUCK_RECHECK_TIME = 5

local GRAVITY = 9.81

local YAW_OFFSET = -math.pi/2

local dir_to_pitch = function(dir)
	local dir2 = vector.normalize(dir)
	local xz = math.abs(dir.x) + math.abs(dir.z)
	return -math.atan2(-dir.y, xz)
end

local function arrow_image(colorstring, opacity)
	if not opacity then
		opacity = 127
	end
	return {"mcl_bows_arrow.png^[transformFX^(mcl_bows_arrow_overlay.png^[transformFX^[colorize:"..colorstring..":"..tostring(opacity)..")",
			"mcl_bows_arrow.png^[transformFX^(mcl_bows_arrow_overlay.png^[transformFX^[colorize:"..colorstring..":"..tostring(opacity)..")",
			"mcl_bows_arrow_back.png^[colorize:"..colorstring..":"..tostring(opacity),
			"mcl_bows_arrow_front.png^[colorize:"..colorstring..":"..tostring(opacity),
			"mcl_bows_arrow.png^(mcl_bows_arrow_overlay.png^[colorize:"..colorstring..":"..tostring(opacity)..")",
			"mcl_bows_arrow.png^[transformFX^(mcl_bows_arrow_overlay.png^[transformFX^[colorize:"..colorstring..":"..tostring(opacity)..")"}

end

local how_to_shoot = minetest.registered_items["mcl_bows:arrow"]._doc_items_usagehelp

local mod_awards = minetest.get_modpath("awards") and minetest.get_modpath("mcl_achievements")
local mod_button = minetest.get_modpath("mesecons_button")

function mcl_potions.register_arrow(name, desc, color, def)

	local longdesc = def.longdesc or ""
	minetest.register_craftitem("mcl_potions:"..name.."_arrow", {
		description = desc,
		_tt_help = S("Ammunition").."\n"..S("Damage from bow: 1-10").."\n"..S("Damage from dispenser: 3").."\n"..def.tt,
		_doc_items_longdesc = S("Arrows are ammunition for bows and dispensers.").."\n"..
			S("An arrow fired from a bow has a regular damage of 1-9. At full charge, there's a 20% chance of a critical hit dealing 10 damage instead. An arrow fired from a dispenser always deals 3 damage.").."\n"..
			S("Arrows might get stuck on solid blocks and can be retrieved again. They are also capable of pushing wooden buttons.").."\n"..
			S("This particular arrow is tipped and will give an effect when it hits a player or mob.").."\n"..
			longdesc,
		_doc_items_usagehelp = how_to_shoot,
		inventory_image = "mcl_bows_arrow_inv.png^(mcl_potions_arrow_inv.png^[colorize:"..color..":100)",
		groups = { ammo=1, ammo_bow=1, brewitem=1},
		_on_dispense = function(itemstack, dispenserpos, droppos, dropnode, dropdir)
			-- Shoot arrow
			local shootpos = vector.add(dispenserpos, vector.multiply(dropdir, 0.51))
			local yaw = math.atan2(dropdir.z, dropdir.x) + YAW_OFFSET
			mcl_bows.shoot_arrow(itemstack:get_name(), shootpos, dropdir, yaw, nil, 19, 3)
		end,
	})


	-- This is a fake node, used as model for the arrow entity.
	-- It's not supposed to be usable as item or real node.
	-- TODO: Use a proper mesh for the arrow entity
	minetest.register_node("mcl_potions:"..name.."_arrow_box", {
		drawtype = "nodebox",
		is_ground_content = false,
		node_box = {
			type = "fixed",
			fixed = {
				-- Shaft
				{-6.5/17, -1.5/17, -1.5/17, -4.5/17, 1.5/17, 1.5/17},
				{-4.5/17, -0.5/17, -0.5/17, 5.5/17, 0.5/17, 0.5/17},
				{5.5/17, -1.5/17, -1.5/17, 6.5/17, 1.5/17, 1.5/17},
				-- Tip
				{-4.5/17, 2.5/17, 2.5/17, -3.5/17, -2.5/17, -2.5/17},
				{-8.5/17, 0.5/17, 0.5/17, -6.5/17, -0.5/17, -0.5/17},
				-- Fletching
				{6.5/17, 1.5/17, 1.5/17, 7.5/17, 2.5/17, 2.5/17},
				{7.5/17, -2.5/17, 2.5/17, 6.5/17, -1.5/17, 1.5/17},
				{7.5/17, 2.5/17, -2.5/17, 6.5/17, 1.5/17, -1.5/17},
				{6.5/17, -1.5/17, -1.5/17, 7.5/17, -2.5/17, -2.5/17},

				{7.5/17, 2.5/17, 2.5/17, 8.5/17, 3.5/17, 3.5/17},
				{8.5/17, -3.5/17, 3.5/17, 7.5/17, -2.5/17, 2.5/17},
				{8.5/17, 3.5/17, -3.5/17, 7.5/17, 2.5/17, -2.5/17},
				{7.5/17, -2.5/17, -2.5/17, 8.5/17, -3.5/17, -3.5/17},
			}
		},
		tiles = arrow_image(color, 100),
		paramtype = "light",
		paramtype2 = "facedir",
		sunlight_propagates = true,
		groups = {not_in_creative_inventory=1, dig_immediate=3},
		drop = "",
		node_placement_prediction = "",
		on_construct = function(pos)
			minetest.log("error", "[mcl_potions] Trying to construct mcl_potions:"..name.."arrow_box at "..minetest.pos_to_string(pos))
			minetest.remove_node(pos)
		end,
	})


	local ARROW_ENTITY={
		physical = true,
		visual = "wielditem",
		visual_size = {x=0.4, y=0.4},
		textures = {"mcl_potions:"..name.."_arrow_box"},
		collisionbox = {-0.19, -0.125, -0.19, 0.19, 0.125, 0.19},
		collide_with_objects = false,

		_lastpos={},
		_startpos=nil,
		_damage=1,	-- Damage on impact
		_stuck=false,   -- Whether arrow is stuck
		_stucktimer=nil,-- Amount of time (in seconds) the arrow has been stuck so far
		_stuckrechecktimer=nil,-- An additional timer for periodically re-checking the stuck status of an arrow
		_stuckin=nil,	--Position of node in which arow is stuck.
		_shooter=nil,	-- ObjectRef of player or mob who shot it

		_viscosity=0,   -- Viscosity of node the arrow is currently in
		_deflection_cooloff=0, -- Cooloff timer after an arrow deflection, to prevent many deflections in quick succession
	}

	-- Destroy arrow entity self at pos and drops it as an item
	local spawn_item = function(self, pos)
		if not minetest.is_creative_enabled("") then
			local item = minetest.add_item(pos, "mcl_potions:"..name.."_arrow")
			item:set_velocity({x=0, y=0, z=0})
			item:set_yaw(self.object:get_yaw())
		end
		self.object:remove()
	end

	ARROW_ENTITY.on_step = function(self, dtime)
		local pos = self.object:get_pos()
		local dpos = table.copy(pos) -- digital pos
		dpos = vector.round(dpos)
		local node = minetest.get_node(dpos)

		if self._stuck then
			self._stucktimer = self._stucktimer + dtime
			self._stuckrechecktimer = self._stuckrechecktimer + dtime
			if self._stucktimer > ARROW_TIMEOUT then
				self.object:remove()
				return
			end
			-- Drop arrow as item when it is no longer stuck
			-- FIXME: Arrows are a bit slow to react and continue to float in mid air for a few seconds.
			if self._stuckrechecktimer > STUCK_RECHECK_TIME then
				local stuckin_def
				if self._stuckin then
					stuckin_def = minetest.registered_nodes[minetest.get_node(self._stuckin).name]
				end
				-- TODO: In MC, arrow just falls down without turning into an item
				if stuckin_def and stuckin_def.walkable == false then
					spawn_item(self, pos)
					return
				end
				self._stuckrechecktimer = 0
			end
			-- Pickup arrow if player is nearby (not in Creative Mode)
			local objects = minetest.get_objects_inside_radius(pos, 1)
			for _,obj in ipairs(objects) do
				if obj:is_player() then
					if not minetest.is_creative_enabled(obj:get_player_name()) then
						if obj:get_inventory():room_for_item("main", "mcl_potions:"..name.."_arrow") then
							obj:get_inventory():add_item("main", "mcl_potions:"..name.."_arrow")
							minetest.sound_play("item_drop_pickup", {
								pos = pos,
								max_hear_distance = 16,
								gain = 1.0,
							}, true)
						end
					end
					self.object:remove()
					return
				end
			end

		-- Check for object "collision". Done every tick (hopefully this is not too stressing)
		else
			-- We just check for any hurtable objects nearby.
			-- The radius of 3 is fairly liberal, but anything lower than than will cause
			-- arrow to hilariously go through mobs often.
			-- TODO: Implement an ACTUAL collision detection (engine support needed).
			local objs = minetest.get_objects_inside_radius(pos, 1.5)
			local closest_object
			local closest_distance

			if self._deflection_cooloff > 0 then
				self._deflection_cooloff = self._deflection_cooloff - dtime
			end

			-- Iterate through all objects and remember the closest attackable object
			for k, obj in pairs(objs) do
				local ok = false
				-- Arrows can only damage players and mobs
				if obj ~= self._shooter and obj:is_player() then
					ok = true
				elseif obj:get_luaentity() ~= nil then
					if obj ~= self._shooter and obj:get_luaentity()._cmi_is_mob then
						ok = true
					end
				end

				if ok then
					local dist = vector.distance(pos, obj:get_pos())
					if not closest_object or not closest_distance then
						closest_object = obj
						closest_distance = dist
					elseif dist < closest_distance then
						closest_object = obj
						closest_distance = dist
					end
				end
			end

			-- If an attackable object was found, we will damage the closest one only
			if closest_object ~= nil then
				local obj = closest_object
				local is_player = obj:is_player()
				local lua = obj:get_luaentity()
				if obj ~= self._shooter and (is_player or (lua and lua._cmi_is_mob)) then

					if obj:get_hp() > 0 then
						-- Check if there is no solid node between arrow and object
						local ray = minetest.raycast(self.object:get_pos(), obj:get_pos(), true)
						for pointed_thing in ray do
							if pointed_thing.type == "object" and pointed_thing.ref == closest_object then
								-- Target reached! We can proceed now.
								break
							elseif pointed_thing.type == "node" then
								local nn = minetest.get_node(minetest.get_pointed_thing_position(pointed_thing)).name
								local nodedef = minetest.registered_nodes[nn]
								if (not nodedef) or nodedef.walkable then
									-- There's a node in the way. Delete arrow without damage
									self.object:remove()
									return
								end
							end
						end

						-- Punch target object but avoid hurting enderman.
						if lua then
							if lua.name ~= "mobs_mc:enderman" then
								obj:punch(self.object, 1.0, {
									full_punch_interval=1.0,
									damage_groups={fleshy=self._damage},
								}, nil)
								def.potion_fun(obj)
							end
						else
							obj:punch(self.object, 1.0, {
								full_punch_interval=1.0,
								damage_groups={fleshy=self._damage},
							}, nil)
							def.potion_fun(obj)
						end

						if is_player then
							if self._shooter and self._shooter:is_player() then
								-- “Ding” sound for hitting another player
								minetest.sound_play({name="mcl_bows_hit_player", gain=0.1}, {to_player=self._shooter}, true)
								def.potion_fun(obj)
							end
						end

						if lua then
							local entity_name = lua.name
							-- Achievement for hitting skeleton, wither skeleton or stray (TODO) with an arrow at least 50 meters away
							-- NOTE: Range has been reduced because mobs unload much earlier than that ... >_>
							-- TODO: This achievement should be given for the kill, not just a hit
							if self._shooter and self._shooter:is_player() and vector.distance(pos, self._startpos) >= 20 then
								if mod_awards and (entity_name == "mobs_mc:skeleton" or entity_name == "mobs_mc:stray" or entity_name == "mobs_mc:witherskeleton") then
									awards.unlock(self._shooter:get_player_name(), "mcl:snipeSkeleton")
								end
							end
						end
					end
					self.object:remove()
					return
				end
			end
		end

		-- Check for node collision
		if self._lastpos.x~=nil and not self._stuck then
			local nodedef = minetest.registered_nodes[node.name]
			local vel = self.object:get_velocity()
			-- Arrow has stopped in one axis, so it probably hit something.
			-- This detection is a bit clunky, but sadly, MT does not offer a direct collision detection for us. :-(
			if (math.abs(vel.x) < 0.0001) or (math.abs(vel.z) < 0.0001) or (math.abs(vel.y) < 0.00001) then
				-- Check for the node to which the arrow is pointing
				local dir
				if math.abs(vel.y) < 0.00001 then
					if self._lastpos.y < pos.y then
						dir = {x=0, y=1, z=0}
					else
						dir = {x=0, y=-1, z=0}
					end
				else
					dir = minetest.facedir_to_dir(minetest.dir_to_facedir(minetest.yaw_to_dir(self.object:get_yaw()-YAW_OFFSET)))
				end
				self._stuckin = vector.add(dpos, dir)
				local snode = minetest.get_node(self._stuckin)
				local sdef = minetest.registered_nodes[snode.name]

				-- If node is non-walkable, unknown or ignore, don't make arrow stuck.
				-- This causes a deflection in the engine.
				if not sdef or sdef.walkable == false or snode.name == "ignore" then
					self._stuckin = nil
					if self._deflection_cooloff <= 0 then
						-- Lose 1/3 of velocity on deflection
						local newvel = vector.multiply(vel, 0.6667)

						self.object:set_velocity(newvel)
						-- Reset deflection cooloff timer to prevent many deflections happening in quick succession
						self._deflection_cooloff = 1.0
					end
				else

					-- Node was walkable, make arrow stuck
					self._stuck = true
					self._stucktimer = 0
					self._stuckrechecktimer = 0

					self.object:set_velocity({x=0, y=0, z=0})
					self.object:set_acceleration({x=0, y=0, z=0})

					-- Push the button! Push, push, push the button!
					if mod_button and minetest.get_item_group(node.name, "button") > 0 and minetest.get_item_group(node.name, "button_push_by_arrow") == 1 then
						local bdir = minetest.wallmounted_to_dir(node.param2)
						-- Check the button orientation
						if vector.equals(vector.add(dpos, bdir), self._stuckin) then
							mesecon.push_button(dpos, node)
						end
					end
				end
			elseif (nodedef and nodedef.liquidtype ~= "none") then
				-- Slow down arrow in liquids
				local v = nodedef.liquid_viscosity
				if not v then
					v = 0
				end
				local old_v = self._viscosity
				self._viscosity = v
				local vpenalty = math.max(0.1, 0.98 - 0.1 * v)
				if math.abs(vel.x) > 0.001 then
					vel.x = vel.x * vpenalty
				end
				if math.abs(vel.z) > 0.001 then
					vel.z = vel.z * vpenalty
				end
				self.object:set_velocity(vel)
			end
		end

		-- Update yaw
		if not self._stuck then
			local vel = self.object:get_velocity()
			local yaw = minetest.dir_to_yaw(vel)+YAW_OFFSET
			local pitch = dir_to_pitch(vel)
			self.object:set_rotation({ x = 0, y = yaw, z = pitch })
		end

		-- Update internal variable
		self._lastpos={x=pos.x, y=pos.y, z=pos.z}
	end

	-- Force recheck of stuck arrows when punched.
	-- Otherwise, punching has no effect.
	ARROW_ENTITY.on_punch = function(self)
		if self._stuck then
			self._stuckrechecktimer = STUCK_RECHECK_TIME
		end
	end

	ARROW_ENTITY.get_staticdata = function(self)
		local out = {
			lastpos = self._lastpos,
			startpos = self._startpos,
			damage = self._damage,
			stuck = self._stuck,
			stuckin = self._stuckin,
		}
		if self._stuck then
			-- If _stucktimer is missing for some reason, assume the maximum
			if not self._stucktimer then
				self._stucktimer = ARROW_TIMEOUT
			end
			out.stuckstarttime = minetest.get_gametime() - self._stucktimer
		end
		if self._shooter and self._shooter:is_player() then
			out.shootername = self._shooter:get_player_name()
		end
		return minetest.serialize(out)
	end

	ARROW_ENTITY.on_activate = function(self, staticdata, dtime_s)
		local data = minetest.deserialize(staticdata)
		if data then
			self._stuck = data.stuck
			if data.stuck then
				if data.stuckstarttime then
					-- First, check if the stuck arrow is aleady past its life timer.
					-- If yes, delete it.
					self._stucktimer = minetest.get_gametime() - data.stuckstarttime
					if self._stucktimer > ARROW_TIMEOUT then
						self.object:remove()
						return
					end
				end

				-- Perform a stuck recheck on the next step.
				self._stuckrechecktimer = STUCK_RECHECK_TIME

				self._stuckin = data.stuckin
			end

			-- Get the remaining arrow state
			self._lastpos = data.lastpos
			self._startpos = data.startpos
			self._damage = data.damage
			if data.shootername then
				local shooter = minetest.get_player_by_name(data.shootername)
				if shooter and shooter:is_player() then
					self._shooter = shooter
				end
			end
		end
		self.object:set_armor_groups({ immortal = 1 })
	end

	minetest.register_entity("mcl_potions:"..name.."_arrow_entity", ARROW_ENTITY)

	if minetest.get_modpath("mcl_bows") then

		minetest.register_craft({
			output = 'mcl_potions:'..name..'_arrow 8',
			recipe = {
				{'mcl_bows:arrow','mcl_bows:arrow','mcl_bows:arrow'},
				{'mcl_bows:arrow','mcl_potions:'..name..'_lingering','mcl_bows:arrow'},
				{'mcl_bows:arrow','mcl_bows:arrow','mcl_bows:arrow'}
			}
		})

	end

	if minetest.get_modpath("doc_identifier") ~= nil then
		doc.sub.identifier.register_object("mcl_bows:arrow_entity", "craftitems", "mcl_bows:arrow")
	end

end