posts_controller.rb

class PostsController < ApplicationController
  def index
    render cell: :index, model: posts
  end

  def show
    post_view_registrar.commit_view
    show_post_page
  end

  private

  def posts
    Posts::Filter.new(params)
      .filtered_posts
      .includes(:related_posts, :categories)
      .include_voted_by_user(current_user)
  end

  def post_view_registrar
    @_post_view_registrar ||=
      PostViewRegistrar.new(post: post, user: current_user, user_ip: request.remote_ip)
  end

  def show_post_page
    if post.show_internally?
      render cell: :show, model: post, layout: "post_layout"
    else
      redirect_to post.link
    end
  end

  def post
    @_post ||= Post.include_voted_by_user(current_user).find(params[:id])
  end
end

posts_filter.rb

class Posts::Filter
  def initialize(params)
    @params = Params.new(params)
  end

  def filtered_posts
    filters.reduce(all_posts) do |posts, filter|
      filter.call(posts)
    end
  end

  private

  attr_reader :params

  def all_posts
    ::Post.all
  end

  def filters
    [page_filter, time_filter, sorting_filter, source_filter, search_filter, category_filter]
  end

  def page_filter
    ->(posts) { posts.paginate(page: params.page) }
  end

  def time_filter
    if params.all_time?
      ->(posts) { posts }
    else
      ->(posts) { posts.published_later_than(beginning_time_from_params) }
    end
  end

  def beginning_time_from_params
    case params.time.to_sym
    when :hourly
      1.hour.ago
    when :daily
      1.day.ago
    when :weekly
      7.days.ago
    when :monthly
      1.month.ago
    when :annually
      1.year.ago
    end
  end

  def sorting_filter
    case params.set.to_sym
    when :new
      ->(posts) { posts.ordered_by_date }
    when :most_read
      ->(posts) { posts.ordered_by_views_count.ordered_by_date }
    when :highly_voted
      ->(posts) { posts.ordered_by_voting_result.ordered_by_date }
    when :most_reviewed
      ->(posts) { posts.order_by_review_rating.ordered_by_date }
    when :most_covered
      ->(posts) { posts.ordered_by_coverage.ordered_by_voting_result.ordered_by_date }
    end
  end

  def source_filter
    if params.sources.present?
      ->(posts) { posts.source_posts(params.sources) }
    else
      ->(posts) { posts }
    end
  end

  def search_filter
    if params.q.present?
      ->(posts) { posts.for_search_query(params.q) }
    else
      ->(posts) { posts }
    end
  end

  def category_filter
    if params.categories.present?
      ->(posts) { posts.for_categories(params.categories) }
    else
      ->(posts) { posts }
    end
  end
end

posts_filter_params.rb

class Posts::Filter::Params
  extend ActiveModel::Naming
  extend Enumerize

  def initialize(raw_params)
    @page = raw_params[:page]
    @q = raw_params[:q]
    @set = raw_params[:set] || :highly_voted
    @time = raw_params[:time] || :daily
    @sources = raw_params[:sources]
    @categories = raw_params[:categories]
  end

  attr_reader :page, :q, :sources, :categories

  enumerize :set, in: [:new, :most_read, :highly_voted, :most_reviewed, :most_covered], default: :highly_voted

  enumerize :time, in: [:hourly, :daily, :weekly, :monthly, :annually, :all_time], default: :daily, predicates: true
end