--
-- Parachute mod
-- By webdesigner97(No license?)
-- Tweaked by Kaadmy, for Pixture
--

function a(v)
   local m = 80    -- Weight of player, kg
   local g = -9.81 -- Earth Acceleration, m/s^2
   local cw = 1.33 -- Drag coefficient
   local rho = 1.2 -- Density of air (on ground, not accurate), kg/m^3
   local A = 25    -- Surface of the parachute, m^2

   return ((m * g + 0.5 * cw * rho * A * v * v) / m)
end

minetest.register_craftitem(
   "parachute:parachute", {
      description = "Parachute",
      inventory_image = "parachute_inventory.png",
      wield_image = "parachute_inventory.png",
      stack_max = 1,
      on_use = function(itemstack, player, pointed_thing)
         local pos = player:getpos()

         local on = minetest.get_node({x = pos.x, y = pos.y - 1, z = pos.z})

         if default.player_attached[player:get_player_name()] then
            return
         end

         if on.name == "air" then
            -- Spawn parachute
            pos.y = pos.y + 3

            local ent = minetest.add_entity(pos, "parachute:entity")

            ent:setvelocity({x = 0, y = player:get_player_velocity().y, z = 0})

            player:set_attach(ent, "", {x = 0, y = -8, z = 0}, {x = 0, y = 0, z = 0})

            ent:setyaw(player:get_look_yaw() - (math.pi / 2))
            ent = ent:get_luaentity()
            ent.attached = player

            default.player_attached[player:get_player_name()] = true

            itemstack:take_item()
            return itemstack
         else
            minetest.chat_send_player(
               player:get_player_name(),
               "Cannot open parachute on ground!")
         end
      end
})

minetest.register_entity(
   "parachute:entity",
   {
      visual = "mesh",
      mesh = "parachute.b3d",
      textures = {"parachute_mesh.png"},
      collisionbox = {0, 0, 0, 0, 0, 0},
      automatic_face_movement_dir = -90,
      attached = nil,
      on_step = function(self, dtime)
         local pos = self.object:getpos()
         local under = minetest.get_node({x = pos.x, y = pos.y - 1, z = pos.z})

         if self.attached ~= nil then
            local vel = self.object:getvelocity()

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

            local lookyaw = self.attached:get_look_yaw()

            local s = math.sin((math.pi * 0.5) - lookyaw)
            local c = math.cos((math.pi * 0.5) - lookyaw)

            local sr = math.sin(((math.pi * 0.5) - lookyaw) + (math.pi / 2))
            local cr = math.cos(((math.pi * 0.5) - lookyaw) + (math.pi / 2))

            local controls = self.attached:get_player_control()

            local speed = 3.0

            if controls.up then
               accel.x = s * speed
               accel.z = c * speed
            elseif controls.down then
               accel.x = s * -speed
               accel.z = c * -speed
            end

            if controls.right then
               accel.x = sr * speed
               accel.z = cr * speed
            elseif controls.left then
               accel.x = sr * -speed
               accel.z = cr * -speed
            end

            accel.y = accel.y + a(vel.y) * 0.25

            self.object:setacceleration(accel)

            if under.name ~= "air" then
               default.player_attached[self.attached:get_player_name()] = false
            end
         end

         if under.name ~= "air" then
            default.player_attached[self.attached:get_player_name()] = false

            self.object:set_detach()
            self.object:remove()
         end
      end
})

minetest.register_craft(
   {
      output = "parachute:parachute",
      recipe = {
	 {"group:fuzzy", "group:fuzzy", "group:fuzzy"},
	 {"default:rope", "", "default:rope"},
	 {"", "default:stick", ""}
      }
})

-- Achievements

achievements.register_achievement(
   "sky_diver",
   {
      title = "Sky Diver",
      description = "Craft 5 parachutes.",
      times = 5,
      craftitem = "parachute:parachute",
})

default.log("mod:parachute", "loaded")