--
-- Helper functions
--

boats = {}

function boats.is_water(pos)
	local nn = minetest.get_node(pos).name
	return minetest.get_item_group(nn, "water") ~= 0
end

function boats.get_sign(i)
	if i == 0 then
		return 0
	else
		return i / math.abs(i)
	end
end

function boats.get_velocity(v, yaw, y)
	local x = -math.sin(yaw) * v
	local z =  math.cos(yaw) * v
	return {x = x, y = y, z = z}
end

function boats.get_v(v)
	return math.sqrt(v.x ^ 2 + v.z ^ 2)
end

boats.register_boat = function(parameters)
	local boat = {
		physical = true,
		collisionbox = {-0.6, -0.4, -0.6, 0.6, 0.3, 0.6},
		visual = "mesh",
		mesh = "boat.x",
		textures = {parameters.texture or "default_wood.png"},
		driver = nil,
		v = 0,
		last_v = 0,
		removed = false
	}

	function boat.on_rightclick(self, clicker)
		if not clicker or not clicker:is_player() then
			return
		end
		local name = clicker:get_player_name()
		if self.driver and clicker == self.driver then
			self.driver = nil
			clicker:set_detach()
			default.player_attached[name] = false
			default.player_set_animation(clicker, "stand" , 30)
		elseif not self.driver then
			self.driver = clicker
			clicker:set_attach(self.object, "", {x = 0, y = 11, z = -3}, {x = 0, y = 0, z = 0})
			default.player_attached[name] = true
			minetest.after(0.2, function()
				default.player_set_animation(clicker, "sit" , 30)
			end)
			self.object:setyaw(clicker:get_look_yaw() - math.pi / 2)
		end
	end

	function boat.on_activate(self, staticdata, dtime_s)
		self.object:set_armor_groups({immortal = 1})
		if staticdata then
			self.v = tonumber(staticdata)
		end
		self.last_v = self.v
	end

	function boat.get_staticdata(self)
		return tostring(self.v)
	end

	function boat.on_punch(self, puncher, time_from_last_punch, tool_capabilities, direction)
		if not puncher or not puncher:is_player() or self.removed then
			return
		end
		puncher:set_detach()
		default.player_attached[puncher:get_player_name()] = false
		self.removed = true
		-- delay remove to ensure player is detached
		minetest.after(0.1, function()
			self.object:remove()
		end)
		if not minetest.setting_getbool("creative_mode") then
			puncher:get_inventory():add_item("main", "boats:" .. parameters.name)
		end
	end

	function boat.on_step(self, dtime)
		self.v = boats.get_v(self.object:getvelocity()) * boats.get_sign(self.v)
		if self.driver then
			local ctrl = self.driver:get_player_control()
			local yaw = self.object:getyaw()
			if ctrl.up then
				self.v = self.v + parameters.controls.up or 0.1
			end
			if ctrl.down then
				self.v = self.v - parameters.controls.down or 0.08
			end
			if ctrl.left then
				if ctrl.down then
					self.object:setyaw(yaw - (1 + dtime) * (0.03 * (parameters.controls.rotate or 1)))
				else
					self.object:setyaw(yaw + (1 + dtime) * (0.03 * (parameters.controls.rotate or 1)))
				end
			end
			if ctrl.right then
				if ctrl.down then
					self.object:setyaw(yaw + (1 + dtime) * (0.03 * (parameters.controls.rotate or 1)))
				else
					self.object:setyaw(yaw - (1 + dtime) * (0.03 * (parameters.controls.rotate or 1)))
				end
			end
		end
		local velo = self.object:getvelocity()
		if self.v == 0 and velo.x == 0 and velo.y == 0 and velo.z == 0 then
			return
		end
		local s = boats.get_sign(self.v)
		self.v = self.v - 0.02 * s
		if s ~= boats.get_sign(self.v) then
			self.object:setvelocity({x = 0, y = 0, z = 0})
			self.v = 0
			return
		end
		if math.abs(self.v) > 4.5 then
			self.v = 4.5 * boats.get_sign(self.v)
		end

		local p = self.object:getpos()
		p.y = p.y - 0.5
		local new_velo = {x = 0, y = 0, z = 0}
		local new_acce = {x = 0, y = 0, z = 0}
		if not boats.is_water(p) then
			local nodedef = minetest.registered_nodes[minetest.get_node(p).name]
			if (not nodedef) or nodedef.walkable then
				self.v = 0
				new_acce = {x = 0, y = 1, z = 0}
			else
				new_acce = {x = 0, y = -9.8, z = 0} -- freefall in air -9.81
			end
			new_velo = boats.get_velocity(self.v, self.object:getyaw(), self.object:getvelocity().y)
		else
			p.y = p.y + 1
			if boats.is_water(p) then
				new_acce = {x = 0, y = 3, z = 0}
				local y = self.object:getvelocity().y
				if y > 2 then
					y = 2
				end
				if y < 0 then
					self.object:setacceleration({x = 0, y = 10, z = 0})
				end
				new_velo = boats.get_velocity(self.v, self.object:getyaw(), y)
			else
				new_acce = {x = 0, y = 0, z = 0}
				if math.abs(self.object:getvelocity().y) <= 2 then
					local pos = self.object:getpos()
					pos.y = math.floor(pos.y) + 0.5
					self.object:setpos(pos)
					new_velo = boats.get_velocity(self.v, self.object:getyaw(), 0)
				else
					new_velo = boats.get_velocity(self.v, self.object:getyaw(), self.object:getvelocity().y)
				end
			end
		end
		self.object:setvelocity(new_velo)
		self.object:setacceleration(new_acce)
	end

	minetest.register_entity("boats:"..parameters.name, boat)

	minetest.register_craftitem("boats:"..parameters.name, {
		description = parameters.description or "Boat",
		inventory_image = "boats_"..parameters.name.."_inventory.png",
		wield_image = "boats_"..parameters.name.."_wield.png",
		wield_scale = {x=2, y=2, z=1},
		liquids_pointable = true,
		
		on_place = function(itemstack, placer, pointed_thing)
			if pointed_thing.type ~= "node" then
				return
			end
			if not boats.is_water(pointed_thing.under) then
				return
			end
			pointed_thing.under.y = pointed_thing.under.y+0.5
			minetest.env:add_entity(pointed_thing.under, "boats:"..parameters.name)
			itemstack:take_item()
			return itemstack
		end,
	})
end

boats.register_boat({
	name = "boat",
	texture = "default_wood.png",
	controls = {
		up = 0.1,
		down = 0.08,
		rotate = 0.75
	},
	description = "Boat"
})

boats.register_boat({
	name = "race",
	texture = "default_gravel.png",
	controls = {
		up = 0.2,
		down = 0.18,
		rotate = 1
	},
	description = "Race boat"
})

boats.register_boat({
	name = "expert_race",
	texture = "default_desert_stone.png",
	controls = {
		up = 0.25,
		down = 0.25,
		rotate = 2
	},
	description = "Expert race boat"
})


boats.register_boat({
	name = "water",
	texture = "default_water.png",
	controls = {
		up = 0.3,
		down = 0.24,
		rotate = 4
	},
	description = "Water boat"
})

boats.register_boat({
	name = "moon",
	texture = "boats_moon.png",
	controls = {
		up = 0.5,
		down = 0.1,
		rotate = 8
	},
	description = "Moon boat"
})

-- Craft registrations

minetest.register_craft({
	output = "boats:moon",
	recipe = {
		{"default:obsidian", "", "default:obsidian"},
		{"default:dirt", "default:leaves", "default:dirt"},
	},
})

minetest.register_craft({
	output = "boats:expert_race",
	recipe = {
		{"default:desert_stone", "", "default:desert_stone"},
		{"default:desert_stone", "default:mese", "default:desert_stone"},
	},
})

minetest.register_craft({
	output = "boats:race",
	recipe = {
		{"default:gravel", "", "default:gravel"},
		{"default:gravel", "default:steelblock", "default:gravel"},
	},
})

minetest.register_craft({
	output = "boats:water",
	recipe = {
		{"default:glass", "", "default:glass"},
		{"default:glass", "bucket:bucket_water", "default:glass"},
	},
})

minetest.register_craft({
	output = "boats:boat",
	recipe = {
		{"group:wood", "", "group:wood"},
		{"group:wood", "group:wood", "group:wood"},
	},
})