if not modalWindows then
    modalWindows = {
        modalWindowConstructor = ModalWindow,
        nextFreeId = 500,

        windows = {}
    }
end

local MT = {}
MT.__index = MT

function ModalWindow(...)
    local args = {...}
    if type(args[1]) == 'table' then
        local self = setmetatable(args[1], MT)
        local id = modalWindows.nextFreeId
        self.id = id
        self.buttons = {}
        self.choices = {}
        self.players = {}
        self.created = false

        modalWindows.nextFreeId = id + 1
        table.insert(modalWindows.windows, self)
        return self
    end

    return modalWindows.modalWindowConstructor(...)
end

function MT:setDefaultCallback(callback)
    self.defaultCallback = callback
end

function MT:addButton(text, callback)
    local button = {text = tostring(text), callback = callback}
    table.insert(self.buttons, button)
    return button
end

function MT:addButtons(...)
    for _, text in ipairs({...}) do
        table.insert(self.buttons, {text = tostring(text)})
    end
end

function MT:addChoice(text)
    local choice = {text = tostring(text)}
    table.insert(self.choices, choice)
    return choice
end

function MT:addChoices(...)
    for _, text in ipairs({...}) do
        table.insert(self.choices, {text = tostring(text)})
    end
end

function MT:setDefaultEnterButton(text)
    self.defaultEnterButton = text
end

function MT:setDefaultEscapeButton(text)
    self.defaultEscapeButton = text
end

function MT:setTitle(title)
    self.title = tostring(title)
end

function MT:setMessage(message)
    self.message = tostring(message)
end

local buttonOrder = {
    [4] = {3, 4, 2, 1},
    [3] = {2, 3, 1},
    [2] = {1, 2},
    [1] = {1}
}
function MT:create()
    local modalWindow = modalWindows.modalWindowConstructor(self.id, self.title, self.message)
    local order = buttonOrder[math.min(#self.buttons, 4)]

    if order then
        for _, i in ipairs(order) do
            local button = self.buttons[i]
            modalWindow:addButton(i, button.text)
            button.id = i

            if button.text == self.defaultEnterButton then
                modalWindow:setDefaultEnterButton(i)
            elseif button.text == self.defaultEscapeButton then
                modalWindow:setDefaultEscapeButton(i)
            end
        end
    end

    for _, choice in ipairs(self.choices) do
        modalWindow:addChoice(_, choice.text)
        choice.id = _
    end

    self.modalWindow = modalWindow
end

function MT:sendToPlayer(player)
    if not self.modalWindow then
        self:create()
    end

    player:registerEvent('ModalWindowHelper')
    self.players[player:getId()] = true
    return self.modalWindow:sendToPlayer(player)
end