Each post is created with a role, which represents a data type. A user can only access certain data types another user shared with him. Each type of data is assigned a binary code for permission, which is assigned with a group where user can decides permissions. One user can belong to multiple groups of another user. self.for_user is trying to f…

post.rb

class Post < ActiveRecord::Base

    attr_accessible :user, :description, :role, :guid, :created_at, :group, :gpoint

	belongs_to :user
	has_many :notifications, :as => :notifiable

	has_data_fields [:gpoint, :group]

	validates_presence_of :user_id, :description
	validates_uniqueness_of :guid, :scope => :user_id, :if => Proc.new{|x| !x.guid.blank? }

	attr_accessible :post_type, :description, :user_id, :location

	def as_json(options={})
		{
			:description => description,
			:created_at => created_at,
			:post_type => post_type,
			:group => group,
			:gpoint => gpoint,
			:user => user
		}
	end

	def todays_post_of_same_type_exists
		Post.where(:user_id => user.id, :post_type => post_type).each do |post|
			if post.created_at.to_date == Date.today
				self.errors.add(:base, "Post of today already exists")
			end
		end
	end

	def self.for_user(user)
	    role_matchers = user.cumulative_roles.map do |user_id, cr|
	    	[user_id, cr.split('').map{|role| role == "1" ? "#{[0,1]}" : "0"}.join('')]
	    end

	    query_operator = Rails.env.production? ? "~" : "REGEXP"

	    query = role_matchers.map do |user_id, matcher|
	      "(user_id = #{user_id} and role #{query_operator} '#{matcher}')"
	    end
	    query << "(user_id = #{user.id})"

	    Post.where(query.join(" OR ")).order("updated_at DESC")
	end

end