How to Integrate :missed Days with :level Days?

This is a multi-faceted question that leads to the same problem:

How to integrate t.integer :missed with t.integer :level so that when a User checks off he missed a day he gets a strike and has to make up the day before moving onto the next level?

Each habit has 5 levels before hitting mastery!

class Habit < ActiveRecord::Base
        belongs_to :user
        before_save :set_level
        acts_as_taggable
        serialize :committed, Array

scope :missed, -> { where(missed: 1) }

        def levels
          committed_wdays = committed.map { |day| Date::DAYNAMES.index(day.titleize) }
          n_days = ((date_started.to_date)..Date.today).count { |date| committed_wdays.include? date.wday }

  case n_days     
          when 0..9
            1
          when 10..24
            2
          when 25..44
            3
          when 45..69
            4
          when 70..99
            5
          else
            "Mastery"
                end
        end

protected
        def set_level
         self.level = levels
        end     
end

Here's a Question Breakdown:

If a User checks off a box how can we save it?

If a User checks off a box how can we add +1 day to the level?

If a User checks off a box how can we add an additional box using AJAX?

If a User checks off 3 boxes in a level (aka 3 strikes you're out) how can we restart him in that level? Ex, if he's on day 66 and checked off :missed three times in Level 4 as shown below how can we recalculate the day to be 45 again?

If a User succeeds to the next level (aka not getting 3 strikes) then how can we show the following level using AJAX?

Form Layout Example:

         Missed:
Level 1: [ ]
Level 2: [√] [√] [ ]
Level 3: [√] [ ]
Level 4: [√] [√] [√] [ ]
*Level 5: [ ]
*Mastered!
         *Not shown to User yet bc we'll assume he hasn't completed level 4.

Controller

class HabitsController < ApplicationController
  before_action :set_habit, only: [:show, :edit, :update, :destroy]
  before_action :logged_in_user, only: [:create, :destroy]

  def index
    if params[:tag]
      @habits = Habit.tagged_with(params[:tag])
    else
      @habits = Habit.all.order("date_started DESC")
      @habits = current_user.habits
    end
  end

  def show
  end

  def new
    @habit = current_user.habits.build
  end

  def edit
  end

  def create
    @habit = current_user.habits.build(habit_params)
    if  @habit.save
        redirect_to @habit, notice: 'Habit was successfully created.'
    else
        @feed_items = []
        render 'pages/home'
    end
  end

  def update
    if @habit.update(habit_params)
      redirect_to @habit, notice: 'Habit was successfully updated.'
    else
      render action: 'edit'
    end
  end

  def destroy
    @habit.destroy
    redirect_to habits_url
  end

  private
    def set_habit
      @habit = Habit.find(params[:id])
    end

    def correct_user
      @habit = current_user.habits.find_by(id: params[:id])
      redirect_to habits_path, notice: "Not authorized to edit this habit" if @habit.nil?
    end

    def habit_params
      params.require(:habit).permit(:missed, :left, :level, :date_started, :trigger, :target, :positive, :negative, :tag_list, :committed => [])
    end
end

Github: http://ift.tt/1yCWXeU

I know this is a tall order so any help would be greatly appreciated!