-- Represents a collection of drawable entities.  Each gamestate holds one of these.

local Entities = {
  active = true,
  world = nil,
  entityList = {}
}

function Entities:enter(world)
  self:clear()

  self.world = world
end

function Entities:add(entity)
  table.insert(self.entityList, entity)
end

function Entities:addMany(entities)
  for k, entity in pairs(entities) do
    table.insert(self.entityList, entity)
  end
end

function Entities:remove(entity)
  for i, e in ipairs(self.entityList) do
    if e == entity then
      table.remove(self.entityList, i)
      return
    end
  end
end

function Entities:removeAt(index)
  table.remove(self.entityList, index)
end

function Entities:clear()
  self.world = nil
  self.entityList = {}
end

function Entities:draw()
  for i, e in ipairs(self.entityList) do
    e:draw(i)
  end
end

function Entities:update(dt)
  for i, e in ipairs(self.entityList) do
    e:update(dt, i)
  end
end

return Entities