lighttroupe/luz

module EngineButtons
    include Callbacks

    attr_reader :seen_buttons_list

    def init_buttons
        @button_down = Hash.new(false)
        @button_down_frame_number = Hash.new
        @button_up_frame_number = Hash.new
        @button_press_count = Hash.new(0)
        @seen_buttons_list = []
    end

    #
    # button press/release response
    #
    # returns whether button was eaten by a grab
    def on_button_down(name, frame_offset = 0)
        return false unless name
        on_new_button(name)

        # Some input devices don't send "button up" events, so we force it here (NOTE: of course user can still only use the button-down moment)
        on_button_up(name, frame_offset-1) if @button_down[name]        # TODO: is the -1 here correct?

        @button_down[name] = true
        @button_down_frame_number[name] = @frame_number + frame_offset

        # NOTE: press counts is useful for 'toggle' style inputs and selecting from lists
        #@button_press_count[name] ||= 0
        @button_press_count[name] += 1

        # Send signal if GUI is listening for button presses
        if @button_grab_proc
            @button_grab_proc.call(name)
            @button_grab_proc = nil        # TODO: should we only remove handler if proc returns true/false ?
            true        # eaten
        else
            false        # not eaten
        end
    end

    def on_button_up(name, frame_offset=0)
        return unless @button_down[name]        # ignore calls when button is not down

        $env[:last_message_bus_activity_at] = $env[:frame_time]        # TODO: move elsewhere?

        on_new_button(name)
        @button_up_frame_number[name] = @frame_number + frame_offset
        @button_down[name] = false
    end

    # Button (binary) Input
    def button_grab(&proc)
        @button_grab_proc = proc
    end

    #
    # button status API
    #
    def button_down?(name)
        return false unless name
        on_new_button(name)
        @button_down[name]        # || false  # NOTE: can be nil if unseen
    end

    def button_press_count(name)
        return 0 unless name
        on_new_button(name)
        @button_press_count[name]
    end

    def button_pressed_this_frame?(name)
        return false unless name
        on_new_button(name)
        @button_down_frame_number[name] == @frame_number
    end

    def button_released_this_frame?(name)
        return false unless name
        on_new_button(name)
        @button_up_frame_number[name] == @frame_number
    end

private

    def on_new_button(name)
        return if @seen_buttons_list.include?(name)
        raise ArgumentError unless name
        @seen_buttons_list << name
        @seen_buttons_list.sort!
    end
end