# frozen_string_literal: true

# rubocop:disable Metrics/AbcSize

# Note: The ABC size is large here because we have a method generating test cases with
#       multiple nested contexts. This shouldn't count as a violation.
module CycleAnalyticsHelpers
  module TestGeneration
    # Generate the most common set of specs that all cycle analytics phases need to have.
    #
    # Arguments:
    #
    #                  phase: Which phase are we testing? Will call `CycleAnalytics.new.send(phase)` for the final assertion
    #                data_fn: A function that returns a hash, constituting initial data for the test case
    #  start_time_conditions: An array of `conditions`. Each condition is an tuple of `condition_name` and `condition_fn`. `condition_fn` is called with
    #                         `context` (no lexical scope, so need to do `context.create` for factories, for example) and `data` (from the `data_fn`).
    #                         Each `condition_fn` is expected to implement a case which consitutes the start of the given cycle analytics phase.
    #    end_time_conditions: An array of `conditions`. Each condition is an tuple of `condition_name` and `condition_fn`. `condition_fn` is called with
    #                         `context` (no lexical scope, so need to do `context.create` for factories, for example) and `data` (from the `data_fn`).
    #                         Each `condition_fn` is expected to implement a case which consitutes the end of the given cycle analytics phase.
    #          before_end_fn: This function is run before calling the end time conditions. Used for setup that needs to be run between the start and end conditions.
    #                post_fn: Code that needs to be run after running the end time conditions.

    def generate_cycle_analytics_spec(phase:, data_fn:, start_time_conditions:, end_time_conditions:, before_end_fn: nil, post_fn: nil)
      combinations_of_start_time_conditions = (1..start_time_conditions.size).flat_map { |size| start_time_conditions.combination(size).to_a }
      combinations_of_end_time_conditions = (1..end_time_conditions.size).flat_map { |size| end_time_conditions.combination(size).to_a }

      scenarios = combinations_of_start_time_conditions.product(combinations_of_end_time_conditions)
      scenarios.each do |start_time_conditions, end_time_conditions|
        let_it_be(:other_project) { create(:project, :repository) }

        before do
          other_project.add_developer(self.user)
        end

        context "start condition: #{start_time_conditions.map(&:first).to_sentence}" do
          context "end condition: #{end_time_conditions.map(&:first).to_sentence}" do
            it "finds the median of available durations between the two conditions", :sidekiq_might_not_need_inline do
              time_differences = Array.new(5) do |index|
                data = data_fn[self]
                start_time = (index * 10).days.from_now
                end_time = start_time + rand(1..5).days

                start_time_conditions.each do |condition_name, condition_fn|
                  Timecop.freeze(start_time) { condition_fn[self, data] }
                end

                # Run `before_end_fn` at the midpoint between `start_time` and `end_time`
                Timecop.freeze(start_time + (end_time - start_time) / 2) { before_end_fn[self, data] } if before_end_fn

                end_time_conditions.each do |condition_name, condition_fn|
                  Timecop.freeze(end_time) { condition_fn[self, data] }
                end

                Timecop.freeze(end_time + 1.day) { post_fn[self, data] } if post_fn

                end_time - start_time
              end

              median_time_difference = time_differences.sort[2]
              expect(subject[phase].project_median).to be_within(5).of(median_time_difference)
            end

            context "when the data belongs to another project" do
              it "returns nil" do
                # Use a stub to "trick" the data/condition functions
                # into using another project. This saves us from having to
                # define separate data/condition functions for this particular
                # test case.
                allow(self).to receive(:project) { other_project }

                data = data_fn[self]
                start_time = Time.now
                end_time = rand(1..10).days.from_now

                start_time_conditions.each do |condition_name, condition_fn|
                  Timecop.freeze(start_time) { condition_fn[self, data] }
                end

                end_time_conditions.each do |condition_name, condition_fn|
                  Timecop.freeze(end_time) { condition_fn[self, data] }
                end

                Timecop.freeze(end_time + 1.day) { post_fn[self, data] } if post_fn

                # Turn off the stub before checking assertions
                allow(self).to receive(:project).and_call_original

                expect(subject[phase].project_median).to be_nil
              end
            end

            context "when the end condition happens before the start condition" do
              it 'returns nil' do
                data = data_fn[self]
                start_time = Time.now
                end_time = start_time + rand(1..5).days

                # Run `before_end_fn` at the midpoint between `start_time` and `end_time`
                Timecop.freeze(start_time + (end_time - start_time) / 2) { before_end_fn[self, data] } if before_end_fn

                end_time_conditions.each do |condition_name, condition_fn|
                  Timecop.freeze(start_time) { condition_fn[self, data] }
                end

                start_time_conditions.each do |condition_name, condition_fn|
                  Timecop.freeze(end_time) { condition_fn[self, data] }
                end

                Timecop.freeze(end_time + 1.day) { post_fn[self, data] } if post_fn

                expect(subject[phase].project_median).to be_nil
              end
            end
          end
        end

        context "start condition NOT PRESENT: #{start_time_conditions.map(&:first).to_sentence}" do
          context "end condition: #{end_time_conditions.map(&:first).to_sentence}" do
            it "returns nil" do
              data = data_fn[self]
              end_time = rand(1..10).days.from_now

              end_time_conditions.each_with_index do |(_condition_name, condition_fn), index|
                Timecop.freeze(end_time + index.days) { condition_fn[self, data] }
              end

              Timecop.freeze(end_time + 1.day) { post_fn[self, data] } if post_fn

              expect(subject[phase].project_median).to be_nil
            end
          end
        end

        context "start condition: #{start_time_conditions.map(&:first).to_sentence}" do
          context "end condition NOT PRESENT: #{end_time_conditions.map(&:first).to_sentence}" do
            it "returns nil" do
              data = data_fn[self]
              start_time = Time.now

              start_time_conditions.each do |condition_name, condition_fn|
                Timecop.freeze(start_time) { condition_fn[self, data] }
              end

              post_fn[self, data] if post_fn

              expect(subject[phase].project_median).to be_nil
            end
          end
        end
      end

      context "when none of the start / end conditions are matched" do
        it "returns nil" do
          expect(subject[phase].project_median).to be_nil
        end
      end
    end
  end
end
