hooks = class(function(self)
    self.events = {}
end)

function hooks:on(event, callback)
    if not self.events[event] then
        self.events[event] = {}
    end

    table.insert(self.events[event], callback)
end

function hooks:once(event, callback)
    local wrapper
    wrapper = function(...)
        callback(...)
        self:off(event, wrapper)
    end

    self:on(event, wrapper)
end

function hooks:off(event, callback)
    local list = self.events[event]
    if not list then return end
    for i, cb in ipairs(list) do
        if cb == callback then
            table.remove(list, i)
            return
        end
    end
end

function hooks:emit(event, ...)
    local list = self.events[event]
    if not list then return end
    for _, cb in ipairs(list) do
        cb(...)
    end
end

local Hooks = hooks()
return Hooks