local ringbuffer = {}
ringbuffer.__index = ringbuffer

function Ringbuffer(...)
    local rb = {}
    rb.items = {...}
    rb.current = 1
    return setmetatable(rb, ringbuffer)
end

function ringbuffer:insert(item, ...)
    if not item then return end
    -- insert rest before self so order is restored, e.g.:
    -- {1,<2>,3}:insert(4,5) -> {1,<2>,3}:insert(5) -> {1,<2>,5,3} -> {1,<2>,4,5,3} 
    self:insert(...)
    table.insert(self.items, self.current+1, item)
end

function ringbuffer:add(item, ...)
    if not item then return end
    self.items[#self.items+1] = item
    self:add(...)
end

function ringbuffer:remove(k)
    table.remove(self.items, k)
end

function ringbuffer:removeCurrent()
    self:remove(self.current)
end

function ringbuffer:remove(k, ...)
end

function ringbuffer:get()
    return self.items[self.current]
end

function ringbuffer:size()
    return #self.items
end

function ringbuffer:next()
    self.current = self.current + 1
    if self.current > #self.items then
        self.current = 1
    end
    return self:get()
end

function ringbuffer:prev()
    self.current = self.current - 1
    if self.current < 1 then
        self.current = #self.items
    end
end