defmodule Plausible.FunnelsTest do
  use Plausible.DataCase
  @moduletag :ee_only

  on_ee do
    alias Plausible.Goals
    alias Plausible.Funnels
    alias Plausible.Stats
    alias Plausible.Stats.QueryBuilder

    setup do
      site = new_site()

      {:ok, g1} = Goals.create(site, %{"page_path" => "/go/to/blog/**"})
      {:ok, g2} = Goals.create(site, %{"event_name" => "Signup"})
      {:ok, g3} = Goals.create(site, %{"page_path" => "/checkout"})
      {:ok, g4} = Goals.create(site, %{"event_name" => "Leave feedback"})
      {:ok, g5} = Goals.create(site, %{"page_path" => "/recommend"})
      {:ok, g6} = Goals.create(site, %{"event_name" => "Extra event"})
      {:ok, g7} = Goals.create(site, %{"event_name" => "Extra event 2"})
      {:ok, g8} = Goals.create(site, %{"event_name" => "Extra event 3"})
      {:ok, g9} = Goals.create(site, %{"event_name" => "Extra event 4"})

      {:ok,
       %{
         site: site,
         goals: [g1, g2, g3],
         steps: [g1, g2, g3, g4, g5, g6, g7, g8, g9] |> Enum.map(&%{"goal_id" => &1.id})
       }}
    end

    describe "Common context" do
      test "create and store a funnel given a set of goals", %{
        site: site,
        steps: [g1, g2, g3 | _]
      } do
        {:ok, funnel} =
          Funnels.create(
            site,
            "From blog to signup and purchase",
            [g1, g2, g3]
          )

        assert funnel.inserted_at
        assert funnel.name == "From blog to signup and purchase"
        assert funnel.strict_order == false
        assert [fg1, fg2, fg3] = funnel.steps

        assert fg1.goal_id == g1["goal_id"]
        assert fg2.goal_id == g2["goal_id"]
        assert fg3.goal_id == g3["goal_id"]

        assert fg1.step_order == 1
        assert fg2.step_order == 2
        assert fg3.step_order == 3
      end

      test "update funnel", %{site: site, steps: [g1, g2, g3, g4, g5 | _]} do
        {:ok, funnel1} =
          Funnels.create(
            site,
            "Sample funnel",
            [g1, g2, g3]
          )

        {:ok, funnel2} = Funnels.update(funnel1, "Updated funnel", [g4, g5])

        assert funnel2.name == "Updated funnel"
        assert [fg1, fg2] = funnel2.steps

        assert fg1.goal_id == g4["goal_id"]
        assert fg2.goal_id == g5["goal_id"]

        assert fg1.step_order == 1
        assert fg2.step_order == 2

        assert funnel1.id == funnel2.id
      end

      test "update funnel strict_order", %{site: site, steps: [g1, g2, g3 | _]} do
        {:ok, funnel} =
          Funnels.create(
            site,
            "Sample funnel",
            [g1, g2]
          )

        assert funnel.strict_order == false

        {:ok, strict_funnel} =
          Funnels.update(
            funnel,
            "Sample funnel",
            [g1, g2, g3],
            strict_order?: true
          )

        assert strict_funnel.strict_order == true

        {:ok, preserved_funnel} =
          Funnels.update(
            strict_funnel,
            "Sample funnel",
            [g1, g2]
          )

        assert preserved_funnel.strict_order == true
      end

      test "retrieve a funnel by id and site, get steps in order", %{
        site: site,
        steps: [g1, g2, g3 | _]
      } do
        {:ok, funnel} =
          Funnels.create(
            site,
            "Lorem ipsum",
            [g3, g1, g2]
          )

        assert funnel = Funnels.get(site, funnel.id)
        assert funnel.name == "Lorem ipsum"
        assert [%{step_order: 1}, %{step_order: 2}, %{step_order: 3}] = funnel.steps
      end

      test "funnels can be deleted by id and a site", %{site: site, steps: [g1, g2 | _]} do
        {:ok, funnel} =
          Funnels.create(
            site,
            "Sample funnel",
            [g1, g2]
          )

        assert :ok = Funnels.delete(site, funnel.id)
        # deletion is idempotent
        assert :ok = Funnels.delete(site, funnel.id)
        refute Funnels.get(site, funnel.id)
      end

      test "a funnel cannot be made of < 2 steps", %{site: site, steps: [g1 | _]} do
        assert {:error, :invalid_funnel_size} =
                 Funnels.create(
                   site,
                   "Lorem ipsum",
                   [g1]
                 )
      end

      test "a funnel can be made of 8 steps maximum", %{site: site, steps: too_many_steps} do
        assert {:ok, _} =
                 Funnels.create(
                   site,
                   "Lorem ipsum",
                   Enum.take(too_many_steps, 8)
                 )

        assert {:error, :invalid_funnel_size} =
                 Funnels.create(
                   site,
                   "Lorem ipsum",
                   too_many_steps
                 )
      end

      test "a goal can only appear once in a funnel", %{steps: [g1 | _], site: site} do
        {:error, _changeset} =
          Funnels.create(
            site,
            "Lorem ipsum",
            [g1, g1]
          )
      end

      test "funnels can be listed per site, starting from most recently added", %{
        site: site,
        steps: [g1, g2, g3 | _]
      } do
        Funnels.create(site, "Funnel 1", [g3, g1])
        Funnels.create(site, "Funnel 2", [g2, g1, g3])

        funnels_list = Funnels.list(site)

        assert [%{name: "Funnel 2", steps_count: 3}, %{name: "Funnel 1", steps_count: 2}] =
                 funnels_list
      end
    end

    describe "Plausible.Stats.Funnel" do
      test "funnels can be evaluated per site within a time range against an ephemeral definition",
           %{
             site: site,
             goals: [g1, g2, g3 | _]
           } do
        funnel_definition =
          Funnels.ephemeral_definition(
            site,
            "From blog to signup and purchase",
            [
              %{
                "goal_id" => "#{g1.id}",
                "goal" => %{
                  "id" => "#{g1.id}",
                  "event_name" => g1.event_name,
                  "page_path" => g1.page_path
                }
              },
              %{
                "goal_id" => g2.id,
                "goal" => %{
                  "id" => g2.id,
                  "event_name" => g2.event_name,
                  "page_path" => g2.page_path
                }
              },
              %{
                "goal_id" => g3.id,
                "goal" => %{
                  "id" => g3.id,
                  "event_name" => g3.event_name,
                  "page_path" => g3.page_path
                }
              }
            ]
          )

        populate_stats(site, [
          build(:pageview, pathname: "/irrelevant/page/not/in/funnel", user_id: 999),
          build(:pageview, pathname: "/go/to/blog/foo", user_id: 123),
          build(:event, name: "Signup", user_id: 123),
          build(:pageview, pathname: "/checkout", user_id: 123),
          build(:pageview, pathname: "/go/to/blog/bar", user_id: 666),
          build(:event, name: "Signup", user_id: 666)
        ])

        query = QueryBuilder.build!(site, input_date_range: :all)

        funnel_data = Stats.funnel(site, query, funnel_definition)

        assert {:ok,
                %{
                  all_visitors: 3,
                  entering_visitors: 2,
                  entering_visitors_percentage: "66.67",
                  never_entering_visitors: 1,
                  never_entering_visitors_percentage: "33.33",
                  steps: [
                    %{
                      label: "Visit /go/to/blog/**",
                      visitors: 2,
                      conversion_rate: "100",
                      conversion_rate_step: "0",
                      dropoff: 0,
                      dropoff_percentage: "0"
                    },
                    %{
                      label: "Signup",
                      visitors: 2,
                      conversion_rate: "100",
                      conversion_rate_step: "100",
                      dropoff: 0,
                      dropoff_percentage: "0"
                    },
                    %{
                      label: "Visit /checkout",
                      visitors: 1,
                      conversion_rate: "50",
                      conversion_rate_step: "50",
                      dropoff: 1,
                      dropoff_percentage: "50"
                    }
                  ]
                }} = funnel_data
      end

      test "funnels can be evaluated per site within a time range", %{
        site: site,
        steps: [g1, g2, g3 | _]
      } do
        {:ok, funnel} =
          Funnels.create(
            site,
            "From blog to signup and purchase",
            [g1, g2, g3]
          )

        populate_stats(site, [
          build(:pageview, pathname: "/go/to/blog/foo", user_id: 123),
          build(:event, name: "Signup", user_id: 123),
          build(:pageview, pathname: "/checkout", user_id: 123),
          build(:pageview, pathname: "/go/to/blog/bar", user_id: 666),
          build(:event, name: "Signup", user_id: 666)
        ])

        query = QueryBuilder.build!(site, input_date_range: :all)

        funnel_data = Stats.funnel(site, query, funnel.id)

        assert {:ok,
                %{
                  all_visitors: 2,
                  entering_visitors: 2,
                  entering_visitors_percentage: "100",
                  never_entering_visitors: 0,
                  never_entering_visitors_percentage: "0",
                  steps: [
                    %{
                      label: "Visit /go/to/blog/**",
                      visitors: 2,
                      conversion_rate: "100",
                      conversion_rate_step: "0",
                      dropoff: 0
                    },
                    %{
                      label: "Signup",
                      visitors: 2,
                      conversion_rate: "100",
                      conversion_rate_step: "100",
                      dropoff: 0,
                      dropoff_percentage: "0"
                    },
                    %{
                      label: "Visit /checkout",
                      visitors: 1,
                      conversion_rate: "50",
                      conversion_rate_step: "50",
                      dropoff: 1,
                      dropoff_percentage: "50"
                    }
                  ]
                }} = funnel_data
      end

      test "strict-order funnels stop at intervention events", %{
        site: site,
        steps: [g1, g2, g3 | _]
      } do
        {:ok, non_strict_funnel} =
          Funnels.create(
            site,
            "From blog to signup and purchase",
            [g1, g2, g3]
          )

        {:ok, strict_funnel} =
          Funnels.create(
            site,
            "Strict from blog to signup and purchase",
            [g1, g2, g3],
            strict_order?: true
          )

        populate_stats(site, [
          build(:pageview,
            pathname: "/go/to/blog/foo",
            user_id: 123,
            timestamp: ~N[2021-01-01 00:00:00]
          ),
          build(:pageview,
            pathname: "/some/other/page",
            user_id: 123,
            timestamp: ~N[2021-01-01 00:00:01]
          ),
          build(:event,
            name: "Signup",
            user_id: 123,
            timestamp: ~N[2021-01-01 00:00:02]
          ),
          build(:pageview,
            pathname: "/checkout",
            user_id: 123,
            timestamp: ~N[2021-01-01 00:00:03]
          )
        ])

        query = QueryBuilder.build!(site, input_date_range: :all)

        {:ok, non_strict_funnel_data} = Stats.funnel(site, query, non_strict_funnel.id)
        {:ok, strict_funnel_data} = Stats.funnel(site, query, strict_funnel.id)

        assert Enum.at(non_strict_funnel_data.steps, 2).visitors == 1
        assert Enum.at(strict_funnel_data.steps, 2).visitors == 0
      end

      test "funnels can be evaluated even where there are no visits yet", %{
        site: site,
        steps: [g1, g2, g3 | _]
      } do
        {:ok, funnel} =
          Funnels.create(
            site,
            "From blog to signup and purchase",
            [g1, g2, g3]
          )

        query = QueryBuilder.build!(site, input_date_range: :all)

        funnel_data = Stats.funnel(site, query, funnel.id)

        assert {:ok,
                %{
                  all_visitors: 0,
                  entering_visitors: 0,
                  entering_visitors_percentage: "0",
                  never_entering_visitors: 0,
                  never_entering_visitors_percentage: "0",
                  steps: [
                    %{
                      label: "Visit /go/to/blog/**",
                      visitors: 0,
                      conversion_rate: "0",
                      conversion_rate_step: "0",
                      dropoff: 0,
                      dropoff_percentage: "0"
                    },
                    %{
                      label: "Signup",
                      visitors: 0,
                      conversion_rate: "0",
                      conversion_rate_step: "0",
                      dropoff: 0,
                      dropoff_percentage: "0"
                    },
                    %{
                      label: "Visit /checkout",
                      visitors: 0,
                      conversion_rate: "0",
                      conversion_rate_step: "0",
                      dropoff: 0,
                      dropoff_percentage: "0"
                    }
                  ]
                }} = funnel_data
      end

      @tag :slow
      test "sampling", %{site: site, steps: [g1, g2, g3 | _]} do
        {:ok, funnel} =
          Funnels.create(
            site,
            "From blog to signup and purchase",
            [g1, g2, g3]
          )

        stats =
          1..50_000
          |> Enum.flat_map(fn _ ->
            user_id = SipHash.hash!("0123456789ABCDEF", :crypto.strong_rand_bytes(64))

            [
              build(:pageview, pathname: "/go/to/blog/foo", user_id: user_id),
              build(:event, name: "Signup", user_id: user_id),
              build(:pageview, pathname: "/checkout", user_id: user_id)
            ]
          end)

        populate_stats(site, stats)

        query =
          Plausible.Stats.Query.from(site, %{"period" => "all", "sample_threshold" => "10000"})

        {:ok, funnel_data} = Stats.funnel(site, query, funnel.id)
        assert_in_delta funnel_data[:all_visitors], 50_000, 5000
      end
    end
  end
end