class CourseSessionController < ApplicationController
  def index
    @sessions = CourseSession
      .search(params[:q])
      .by_course_type(params[:course_type_id])
      .by_role(params[:role_id])
      .paginate(page_params)
      .order(ordering_params)
  end
end

class CourseSessionController < ApplicationController
  def index
    @sessions = rubanok_process(
      # pass input
      CourseSession.all,
      # pass params
      params,
      # provide a processor to use
      with: CourseSessionsProcessor
    )
  end
end

class CourseSessionController < ApplicationController
  def index
    @sessions = rubanok_process(CourseSession.all)
  end
end

gem "rubanok"

class CourseSessionsProcessor < Rubanok::Processor
  # You can map keys
  map :q do |q:|
    # `raw` is an accessor for input data
    raw.search(q)
  end
end

# The following code
CourseSessionsProcessor.call(CourseSession.all, q: "xyz")

# is equal to
CourseSession.all.search("xyz")

class CourseSessionsProcessor < Rubanok::Processor
  DEFAULT_PAGE_SIZE = 25

  map :page, :per_page do |page:, per_page: DEFAULT_PAGE_SIZE|
    raw.paginate(page: page, per_page: per_page)
  end
end

class CourseSessionsProcessor < Rubanok::Processor
  SORT_ORDERS = %w[asc desc].freeze
  SORTABLE_FIELDS = %w[id name created_at].freeze

  match :sort_by, :sort do
    having "course_id", "desc" do
      raw.joins(:courses).order("courses.id desc nulls last")
    end

    having "course_id", "asc" do
      raw.joins(:courses).order("courses.id asc nulls first")
    end

    # Match any value for the second arg
    having "type" do |sort: "asc"|
      # Prevent SQL injections
      raise "Possible injection: #{sort}" unless SORT_ORDERS.include?(sort)
      raw.joins(:course_type).order("course_types.name #{sort}")
    end

    # Match any value
    default do |sort_by:, sort: "asc"|
      raise "Possible injection: #{sort}" unless SORT_ORDERS.include?(sort)
      raise "The field is not sortable: #{sort_by}" unless SORTABLE_FIELDS.include?(sort_by)
      raw.order(sort_by => sort)
    end
  end

  # strict matching; if Processor will not match parameter, it will raise Rubanok::UnexpectedInputError
  # You can handle it in controller, for example, with sending 422 Unprocessable Entity to client
  match :filter, fail_when_no_matches: true do
    having "active" do
      raw.active
    end

    having "finished" do
      raw.finished
    end
  end
end

class CourseSessionsProcessor < Rubanok::Processor
  process :filter do
    match :status do
      having "draft" do
        raw.where(draft: true)
      end

      having "deleted" do
        raw.where.not(deleted_at: nil)
      end
    end

    # You can also use .map or even .process here
  end
end

class CourseSearchQueryProcessor < Rubanok::Processor
  prepare do
    next if raw&.dig(:query, :bool)

    {query: {bool: {filters: []}}}
  end

  map :ids do |ids:|
    raw.dig(:query, :bool, :filters) << {terms: {id: ids}}
    raw
  end
end

CourseSearchQueryProcessor.call(nil, {}) #=> nil

# But
CourseSearchQueryProcessor.call(nil, {ids: [1]}) #=> {query {bool: {filters: [{terms: {ids: [1]}}]}}}

# Note that we can omit the first argument altogether
CourseSearchQueryProcessor.call({ids: [1]})

class CourseSessionController < ApplicationController
  def index
    @sessions = rubanok_process(CourseSession.all)
    # Returns the Hash of params recognized by the CourseSessionProcessor.
    # For example:
    #
    #    params == {q: "search", role_id: 2, date: "2019-08-22"}
    #    @session_filter == {q: "search", role_id: 2}
    @sessions_filter = rubanok_scope(
      params.permit(:q, :role_id),
      with: CourseSessionProcessor
    )

    # You can omit all the arguments
    @sessions_filter = rubanok_scope #=> equals to rubanok_scope(params, with: implicit_rubanok_class)
  end
end

# Always apply the rule; use default values for keyword args
map :page, :per_page, activate_always: true do |page: 1, per_page: 2|
  raw.page(page).per(per_page)
end

# Only require `sort_by` to be preset to activate sorting rule
match :sort_by, :sort, activate_on: :sort_by do
 # ...
end

class PostsProcessor < Rubanok::Processor
  # We can pass a Proc
  map :ids, filter_with: ->(vals) { vals.reject(&:blank?).presence } do |ids:|
    raw.where(id: ids)
  end

  # or define a class method
  def self.non_empty_array(val)
    non_blank = val.reject(&:blank?)
    return if non_blank.empty?

    non_blank
  end

  # and pass its name as a filter_with value
  map :ids, filter_with: :non_empty_array do |ids:|
    raw.where(id: ids)
  end
end

# Filtered values are used in rules
PostsProcessor.call(Post.all, {ids: ["1", ""]}) == Post.where(id: ["1"])

# When filter returns empty value, the rule is not applied
PostsProcessor.call(Post.all, {ids: [nil, ""]}) == Post.all

# For example, with RSpec
RSpec.describe CourseSessionsProcessor do
  let(:input) { CourseSession.all }
  let(:params) { {} }

  subject { described_class.call(input, params) }

  specify "searching" do
    params[:q] = "wood"

    expect(subject).to eq input.search("wood")
  end
end

RSpec.describe CourseSessionController do
  subject { get :index }

  specify do
    expect { subject }.to have_rubanok_processed(CourseSession.all)
      .with(CourseSessionsProcessor)
  end
end

require "rubanok/rspec"

class ApplicationController < ActionController::Smth
  # override the `implicit_rubanok_class` method
  def implicit_rubanok_class
    "#{controller_path.classify.pluralize}Scoper".safe_constantize
  end
end

class CourseSessionsController < ApplicationController
  def index
    @sessions = rubanok_process(CourseSession.all, params)
    # which equals to
    @sessions = CourseSessionsScoper.call(CourseSession.all, params.to_unsafe_h)
  end
end

class MyProcessor < Rubanok::Processor
  map :q do |q:|
    # @type self : Rubanok::Processor
    raw
  end

  match :sort_by, :sort, activate_on: :sort_by do
    # @type self : Rubanok::DSL::Matching::Rule
    having "status", "asc" do
      # @type self : Rubanok::Processor
      raw
    end

    # @type self : Rubanok::DSL::Matching::Rule
    default do |sort_by:, sort: "asc"|
      # @type self : Rubanok::Processor
      raw
    end
  end
end