-- Based on: https://github.com/minetest/minetest_game/blob/master/mods/boats/init.lua

local function 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

local function get_v(v, speed)
  return math.sqrt(v.x ^ 2 + v.z ^ 2) * speed
end

local class = {
  driver = nil,
  v = 0,
  last_v = 0,
  removed = false,
  auto = false,
  speed = 1
}

function class:on_rightclick(clicker)
  if not clicker or not clicker:is_player() then
    return
  end

  local name = clicker:get_player_name()
  if self.driver and name == self.driver then
    clicker:set_detach()

    local pos = clicker:get_pos()
    pos = {x = pos.x, y = pos.y + 0.2, z = pos.z}
    core.after(0.1, function()
      clicker:set_pos(pos)
    end)
  elseif not self.driver then
    clicker:set_attach(self.object, "",
    {x = 0.5, y = 1, z = -3}, {x = 0, y = 0, z = 0})

    self.driver = name

    clicker:set_look_horizontal(self.object:get_yaw())
  end
end

function class:on_detach_child(child)
  if child and child:get_player_name() == self.driver then
    self.driver = nil
    self.auto = false
  end
end

function class:on_activate(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 class:get_staticdata()
  return tostring(self.v)
end

function class:on_punch(puncher)
  if not puncher or not puncher:is_player() or self.removed then
    return
  end

  local name = puncher:get_player_name()
  if self.driver and name == self.driver then
    self.driver = nil
    puncher:set_detach()
  end
  if not self.driver then
    self.removed = true
    local inv = puncher:get_inventory()
    if not core.is_creative_enabled(name)
      or not inv:contains_item("main", self.name) then

      local leftover = inv:add_item("main", self.name)
      if not leftover:is_empty() then
        core.add_item(self.object:get_pos(), leftover)
      end
    end

    core.after(0.1, function()
      self.object:remove()
    end)
  end
end

function class:on_step(dtime)
  self.v = get_v(self.object:get_velocity(), self.speed) * math.sign(self.v)
  if self.driver then
    local driver_objref = core.get_player_by_name(self.driver)
    if driver_objref then
      local ctrl = driver_objref:get_player_control()
      if ctrl.up and ctrl.down then
        if not self.auto then
          self.auto = true
          core.chat_send_player(self.driver, Translate("Auto mode on"))
        end
      elseif ctrl.down then
        self.v = self.v - dtime * 2.0
        if self.auto then
          self.auto = false
          core.chat_send_player(self.driver, Translate("Auto mode off"))
        end
      elseif ctrl.up or self.auto then
        self.v = self.v + dtime * 2.0
      end
      if ctrl.left then
        if self.v < -0.001 then
          self.object:set_yaw(self.object:get_yaw() - dtime * 0.9)
        else
          self.object:set_yaw(self.object:get_yaw() + dtime * 0.9)
        end
      elseif ctrl.right then
        if self.v < -0.001 then
          self.object:set_yaw(self.object:get_yaw() + dtime * 0.9)
        else
          self.object:set_yaw(self.object:get_yaw() - dtime * 0.9)
        end
      end
    end
  end
  local velo = self.object:get_velocity()
  if not self.driver and
    self.v == 0 and velo.x == 0 and velo.y == 0 and velo.z == 0 then
    self.object:set_pos(self.object:get_pos())
    return
  end
  -- We need to preserve velocity sign to properly apply drag force
  -- while moving backward
  local drag = dtime * math.sign(self.v) * (0.01 + 0.0796 * self.v * self.v)
  -- If drag is larger than velocity, then stop horizontal movement
  if math.abs(self.v) <= math.abs(drag) then
    self.v = 0
  else
    self.v = self.v - drag
  end

  local p = self.object:get_pos()
  p.y = p.y - 0.5
  local new_velo
  local new_acce = {x = 0, y = 0, z = 0}
  p.y = p.y + 1
  local y = self.object:get_velocity().y
  if y >= 5 then
    y = 5
  end
  new_velo = get_velocity(self.v, self.object:get_yaw(), y, self.speed)
  self.object:set_pos(self.object:get_pos())
  self.object:set_velocity(new_velo)
  self.object:set_acceleration(new_acce)
end

PyuTest.create_vehicle = function(name, desc, speed, properties, image, craft)
  local options = setmetatable(properties, { __index = class})
  options.name = name
  options.speed = speed

  core.register_entity(name, properties)

  PyuTest.make_item(name, desc, {
    vehicle = 1
  }, image, {
    liquids_pointable = true,
    on_place = function (itemstack, placer, pointed_thing)
      local under = pointed_thing.under
      local node = core.get_node(under)
      local udef = core.registered_nodes[node.name]
      if udef and udef.on_rightclick and
        not (placer and placer:is_player() and
        placer:get_player_control().sneak) then
        return udef.on_rightclick(under, node, placer, itemstack,
        pointed_thing) or itemstack
      end

      if pointed_thing.type ~= "node" then
        return itemstack
      end

      pointed_thing.under.y = pointed_thing.under.y + 0.5
      local vehicle = core.add_entity(pointed_thing.under, name)
      if vehicle then
        if placer then
          vehicle:set_yaw(placer:get_look_horizontal())
        end
        local player_name = placer and placer:get_player_name() or ""
        if not core.is_creative_enabled(player_name) then
          itemstack:take_item()
        end
      end
      return itemstack
    end
  })

  if craft then
    core.register_craft({
      output = name,
      recipe = craft
    })
  end
end