defmodule Ami.RecentActivity do
  use Ecto.Schema

  import Ecto.{
    Changeset,
    Query
  }

  alias Ami.{
    Repo,
    Community,
    CoursePeriod,
    User
  }

  schema "recent_activities" do
    @timestamps_opts [type: :naive_datetime_usec]
    
    field(:activity_time, :utc_datetime_usec)
    field(:update_count, :integer)

    belongs_to(:community, Community)
    belongs_to(:course_period, CoursePeriod)
    belongs_to(:user, User)
  end

  def track(%{"id" => community_id, "user_id" => user_id}) do
    case Repo.all(
           from(
             ra in __MODULE__,
             where: ra.community_id == ^community_id and ra.user_id == ^user_id,
             limit: 1
           )
         ) do
      [] -> create_activity(%{community_id: community_id, user_id: user_id})
      [activity] -> update_activity(activity)
    end

    AmiWeb.Endpoint.broadcast!("community_activity_room:#{community_id}", "new_track", %{
      "communityId" => community_id
    })
  end

  def track(%{"course_period_id" => course_period_id, "user_id" => user_id}) do
    case Repo.all(
           from(
             ra in __MODULE__,
             where: ra.course_period_id == ^course_period_id and ra.user_id == ^user_id,
             limit: 1
           )
         ) do
      [] -> create_activity(%{course_period_id: course_period_id, user_id: user_id})
      [activity] -> update_activity(activity)
    end

    AmiWeb.Endpoint.broadcast!("studygroup_activity_room:#{course_period_id}", "new_track", %{
      "coursePeriodId" => course_period_id
    })
  end

  def create_activity(%{community_id: _community_id, user_id: _user_id} = params) do
    %__MODULE__{}
    |> cast(params, [:community_id, :user_id])
    |> cast(%{activity_time: DateTime.utc_now()}, [:activity_time])
    |> Repo.insert()
  end

  def create_activity(%{course_period_id: _course_period_id, user_id: _user_id} = params) do
    %__MODULE__{}
    |> cast(params, [:course_period_id, :user_id])
    |> cast(%{activity_time: DateTime.utc_now()}, [:activity_time])
    |> Repo.insert()
  end

  def update_activity(activity) do
    change(activity, activity_time: DateTime.utc_now(), update_count: activity.update_count + 1)
    |> Repo.update()
  end

  def member_of_the_month(%{community: community_id}) do
    start_period = Timex.beginning_of_month(Timex.shift(DateTime.utc_now(), months: -1))
    end_period = Timex.end_of_month(Timex.shift(DateTime.utc_now(), months: -1))

    from(
      r in Ami.RecentActivity,
      where: r.community_id == ^community_id,
      where: r.activity_time >= ^start_period and r.activity_time <= ^end_period,
      order_by: [desc: r.update_count, desc: r.activity_time],
      select: r.user_id,
      limit: 1
    )
    |> Repo.all()
    |> List.first()
  end

  def member_of_the_month(%{course_period: course_period_id}) do
    start_period = Timex.beginning_of_month(Timex.shift(DateTime.utc_now(), months: -1))
    end_period = Timex.end_of_month(Timex.shift(DateTime.utc_now(), months: -1))

    from(
      r in Ami.RecentActivity,
      where: r.course_period_id == ^course_period_id,
      where: r.activity_time >= ^start_period and r.activity_time <= ^end_period,
      order_by: [desc: r.update_count, desc: r.activity_time],
      select: r.user_id,
      limit: 1
    )
    |> Repo.all()
    |> List.first()
  end

  def active_members_count(%Community{} = community) do
    from(
      r in Ami.RecentActivity,
      where: r.community_id == ^community.id,
      select: count(r.user_id, :distinct)
    )
    |> Repo.one()
  end

  def active_members_count(%CoursePeriod{} = course_period) do
    from(
      r in Ami.RecentActivity,
      where: r.course_period_id == ^course_period.id,
      select: count(r.user_id, :distinct)
    )
    |> Repo.one()
  end
end