local Token = require 'utils.global_token'
local Event = require 'utils.event'

local Gui = {}

global.Gui_data = {}

local click_handlers

function Gui.uid_name()
    return tostring(Token.uid())
end

-- Associates data with the LuaGuiElement. If data is nil then removes the data
function Gui.set_data(element, data)
    global.Gui_data[element.player_index .. ',' .. element.index] = data
end

-- Gets the Associated data with this LuaGuiElement if any.
function Gui.get_data(element)
    return global.Gui_data[element.player_index .. ',' .. element.index]
end

-- Removes data associated with LuaGuiElement and its children recursivly.
function Gui.remove_data_recursivly(element)
    Gui.set_data(element, nil)

    local children = element.children

    if not children then
        return
    end

    for _, child in ipairs(children) do
        if child.valid then
            Gui.remove_data_recursivly(child)
        end
    end
end

local function on_click(event)
    local element = event.element
    if not element or not element.valid then
        return
    end

    local player = game.players[event.player_index]
    if not player or not player.valid then
        return
    end
    event.player = player

    local handler = click_handlers[element.name]
    if not handler then
        return
    end

    handler(event)
end

-- Register a handler for the on_gui_click event for LuaGuiElements with element_name.
-- Can only have one handler per element name.
-- Guarantees that the element and the player are valid when calling the handler.
-- Adds a player field to the event table.
function Gui.on_click(element_name, handler)
    if not click_handlers then
        click_handlers = {}
        Event.add(defines.events.on_gui_click, on_click)
    end

    click_handlers[element_name] = handler
end

return Gui