defmodule ToweropsWeb.Api.V1.SchedulesController do
  @moduledoc """
  API controller for managing on-call schedules.

  All endpoints require API token authentication and operations are scoped
  to the organization associated with the token.
  """
  use ToweropsWeb, :controller

  import ToweropsWeb.Api.ErrorHelpers, only: [translate_errors: 1]

  alias Towerops.OnCall
  alias Towerops.OnCall.Layer
  alias Towerops.OnCall.LayerMember
  alias Towerops.OnCall.Override
  alias Towerops.OnCall.Schedule
  alias Towerops.Repo
  alias ToweropsWeb.ScopedResource

  require Logger

  # --- Schedule CRUD ---

  @doc "GET /api/v1/schedules"
  def index(conn, _params) do
    organization_id = conn.assigns.current_organization_id

    schedules =
      organization_id
      |> OnCall.list_schedules()
      |> Enum.map(&format_schedule/1)

    json(conn, %{schedules: schedules})
  end

  @doc "POST /api/v1/schedules"
  def create(conn, %{"schedule" => schedule_params}) do
    organization_id = conn.assigns.current_organization_id
    attrs = Map.put(schedule_params, "organization_id", organization_id)

    case OnCall.create_schedule(attrs) do
      {:ok, schedule} ->
        conn
        |> put_status(:created)
        |> json(format_schedule(schedule))

      {:error, %Ecto.Changeset{} = changeset} ->
        conn
        |> put_status(:unprocessable_entity)
        |> json(%{errors: translate_errors(changeset)})
    end
  end

  def create(conn, _params) do
    conn
    |> put_status(:bad_request)
    |> json(%{error: "Missing 'schedule' parameter"})
  end

  @doc "GET /api/v1/schedules/:id"
  def show(conn, %{"id" => id}) do
    organization_id = conn.assigns.current_organization_id

    case ScopedResource.fetch_preload(Schedule, id, organization_id,
           overrides: :user,
           layers: [members: :user]
         ) do
      {:ok, schedule} ->
        json(conn, format_schedule_detail(schedule))

      {:error, :forbidden} ->
        conn
        |> put_status(:forbidden)
        |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn
        |> put_status(:not_found)
        |> json(%{error: "Schedule not found"})
    end
  end

  @doc "PATCH /api/v1/schedules/:id"
  def update(conn, %{"id" => id, "schedule" => schedule_params}) do
    organization_id = conn.assigns.current_organization_id

    case ScopedResource.fetch(Schedule, id, organization_id) do
      {:ok, schedule} ->
        case OnCall.update_schedule(schedule, schedule_params) do
          {:ok, updated} ->
            json(conn, format_schedule(updated))

          {:error, %Ecto.Changeset{} = changeset} ->
            conn
            |> put_status(:unprocessable_entity)
            |> json(%{errors: translate_errors(changeset)})
        end

      {:error, :forbidden} ->
        conn
        |> put_status(:forbidden)
        |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn
        |> put_status(:not_found)
        |> json(%{error: "Schedule not found"})
    end
  end

  def update(conn, _params) do
    conn
    |> put_status(:bad_request)
    |> json(%{error: "Missing 'schedule' parameter"})
  end

  @doc "DELETE /api/v1/schedules/:id"
  def delete(conn, %{"id" => id}) do
    organization_id = conn.assigns.current_organization_id

    case ScopedResource.fetch(Schedule, id, organization_id) do
      {:ok, schedule} ->
        case OnCall.delete_schedule(schedule) do
          {:ok, _} ->
            json(conn, %{success: true})

          {:error, %Ecto.Changeset{} = changeset} ->
            conn
            |> put_status(:unprocessable_entity)
            |> json(%{errors: translate_errors(changeset)})
        end

      {:error, :forbidden} ->
        conn
        |> put_status(:forbidden)
        |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn
        |> put_status(:not_found)
        |> json(%{error: "Schedule not found"})
    end
  end

  # --- On-Call Resolution ---

  @doc "GET /api/v1/schedules/:id/on_call"
  def on_call(conn, %{"id" => id}) do
    organization_id = conn.assigns.current_organization_id

    case ScopedResource.fetch(Schedule, id, organization_id) do
      {:ok, _schedule} ->
        user = OnCall.who_is_on_call(id)
        json(conn, %{on_call: format_user(user)})

      {:error, :forbidden} ->
        conn
        |> put_status(:forbidden)
        |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn
        |> put_status(:not_found)
        |> json(%{error: "Schedule not found"})
    end
  end

  # --- Layers ---

  @doc "POST /api/v1/schedules/:id/layers"
  def create_layer(conn, %{"id" => schedule_id, "layer" => layer_params}) do
    organization_id = conn.assigns.current_organization_id

    case ScopedResource.fetch(Schedule, schedule_id, organization_id) do
      {:ok, _schedule} ->
        attrs = Map.put(layer_params, "schedule_id", schedule_id)

        case OnCall.create_layer(attrs) do
          {:ok, layer} ->
            conn
            |> put_status(:created)
            |> json(format_layer(layer))

          {:error, %Ecto.Changeset{} = changeset} ->
            conn
            |> put_status(:unprocessable_entity)
            |> json(%{errors: translate_errors(changeset)})
        end

      {:error, :forbidden} ->
        conn
        |> put_status(:forbidden)
        |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn
        |> put_status(:not_found)
        |> json(%{error: "Schedule not found"})
    end
  end

  @doc "PATCH /api/v1/schedules/:id/layers/:layer_id"
  def update_layer(conn, %{"id" => schedule_id, "layer_id" => layer_id, "layer" => layer_params}) do
    organization_id = conn.assigns.current_organization_id

    with {:ok, _schedule} <- ScopedResource.fetch(Schedule, schedule_id, organization_id),
         {:ok, layer} <- fetch_layer(layer_id, schedule_id) do
      case OnCall.update_layer(layer, layer_params) do
        {:ok, updated} ->
          json(conn, format_layer(updated))

        {:error, %Ecto.Changeset{} = changeset} ->
          conn
          |> put_status(:unprocessable_entity)
          |> json(%{errors: translate_errors(changeset)})
      end
    else
      {:error, :forbidden} ->
        conn |> put_status(:forbidden) |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Schedule not found"})

      {:error, :layer_not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Layer not found"})
    end
  end

  @doc "DELETE /api/v1/schedules/:id/layers/:layer_id"
  def delete_layer(conn, %{"id" => schedule_id, "layer_id" => layer_id}) do
    organization_id = conn.assigns.current_organization_id

    with {:ok, _schedule} <- ScopedResource.fetch(Schedule, schedule_id, organization_id),
         {:ok, layer} <- fetch_layer(layer_id, schedule_id) do
      {:ok, _} = OnCall.delete_layer(layer)
      json(conn, %{success: true})
    else
      {:error, :forbidden} ->
        conn |> put_status(:forbidden) |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Schedule not found"})

      {:error, :layer_not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Layer not found"})
    end
  end

  # --- Members ---

  @doc "POST /api/v1/schedules/:id/layers/:layer_id/members"
  def create_member(conn, %{"id" => schedule_id, "layer_id" => layer_id, "member" => member_params}) do
    organization_id = conn.assigns.current_organization_id

    with {:ok, _schedule} <- ScopedResource.fetch(Schedule, schedule_id, organization_id),
         {:ok, _layer} <- fetch_layer(layer_id, schedule_id) do
      attrs = Map.put(member_params, "layer_id", layer_id)

      case OnCall.add_layer_member(attrs) do
        {:ok, member} ->
          conn
          |> put_status(:created)
          |> json(format_member(member))

        {:error, %Ecto.Changeset{} = changeset} ->
          conn
          |> put_status(:unprocessable_entity)
          |> json(%{errors: translate_errors(changeset)})
      end
    else
      {:error, :forbidden} ->
        conn |> put_status(:forbidden) |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Schedule not found"})

      {:error, :layer_not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Layer not found"})
    end
  end

  @doc "DELETE /api/v1/schedules/:id/layers/:layer_id/members/:member_id"
  def delete_member(conn, %{"id" => schedule_id, "layer_id" => layer_id, "member_id" => member_id}) do
    organization_id = conn.assigns.current_organization_id

    with {:ok, _schedule} <- ScopedResource.fetch(Schedule, schedule_id, organization_id),
         {:ok, _layer} <- fetch_layer(layer_id, schedule_id),
         {:ok, member} <- fetch_member(member_id, layer_id) do
      {:ok, _} = OnCall.remove_layer_member(member)
      json(conn, %{success: true})
    else
      {:error, :forbidden} ->
        conn |> put_status(:forbidden) |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Schedule not found"})

      {:error, :layer_not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Layer not found"})

      {:error, :member_not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Member not found"})
    end
  end

  # --- Overrides ---

  @doc "POST /api/v1/schedules/:id/overrides"
  def create_override(conn, %{"id" => schedule_id, "override" => override_params}) do
    organization_id = conn.assigns.current_organization_id

    case ScopedResource.fetch(Schedule, schedule_id, organization_id) do
      {:ok, _schedule} ->
        attrs = Map.put(override_params, "schedule_id", schedule_id)

        case OnCall.create_override(attrs) do
          {:ok, override} ->
            conn
            |> put_status(:created)
            |> json(format_override(override))

          {:error, %Ecto.Changeset{} = changeset} ->
            conn
            |> put_status(:unprocessable_entity)
            |> json(%{errors: translate_errors(changeset)})
        end

      {:error, :forbidden} ->
        conn |> put_status(:forbidden) |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Schedule not found"})
    end
  end

  @doc "DELETE /api/v1/schedules/:id/overrides/:override_id"
  def delete_override(conn, %{"id" => schedule_id, "override_id" => override_id}) do
    organization_id = conn.assigns.current_organization_id

    with {:ok, _schedule} <- ScopedResource.fetch(Schedule, schedule_id, organization_id),
         {:ok, override} <- fetch_override(override_id, schedule_id) do
      case OnCall.delete_override(override) do
        {:ok, _} ->
          json(conn, %{success: true})

        {:error, reason} ->
          Logger.error("Failed to delete override #{override_id}: #{inspect(reason)}")
          conn |> put_status(:internal_server_error) |> json(%{error: "Failed to delete override"})
      end
    else
      {:error, :forbidden} ->
        conn |> put_status(:forbidden) |> json(%{error: "Access denied to this schedule"})

      {:error, :not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Schedule not found"})

      {:error, :override_not_found} ->
        conn |> put_status(:not_found) |> json(%{error: "Override not found"})
    end
  end

  # --- Private helpers ---

  defp fetch_layer(layer_id, schedule_id) do
    case Repo.get(Layer, layer_id) do
      %Layer{schedule_id: ^schedule_id} = layer -> {:ok, layer}
      _ -> {:error, :layer_not_found}
    end
  end

  defp fetch_member(member_id, layer_id) do
    case Repo.get(LayerMember, member_id) do
      %LayerMember{layer_id: ^layer_id} = member -> {:ok, member}
      _ -> {:error, :member_not_found}
    end
  end

  defp fetch_override(override_id, schedule_id) do
    case Repo.get(Override, override_id) do
      %Override{schedule_id: ^schedule_id} = override -> {:ok, override}
      _ -> {:error, :override_not_found}
    end
  end

  defp format_schedule(schedule) do
    %{
      id: schedule.id,
      name: schedule.name,
      description: schedule.description,
      timezone: schedule.timezone,
      inserted_at: schedule.inserted_at
    }
  end

  defp format_schedule_detail(schedule) do
    %{
      id: schedule.id,
      name: schedule.name,
      description: schedule.description,
      timezone: schedule.timezone,
      inserted_at: schedule.inserted_at,
      layers: Enum.map(schedule.layers, &format_layer_detail/1),
      overrides: Enum.map(schedule.overrides, &format_override_detail/1)
    }
  end

  defp format_layer(layer) do
    %{
      id: layer.id,
      name: layer.name,
      position: layer.position,
      rotation_type: layer.rotation_type,
      rotation_interval: layer.rotation_interval,
      handoff_time: layer.handoff_time,
      handoff_day: layer.handoff_day,
      start_date: layer.start_date,
      inserted_at: layer.inserted_at
    }
  end

  defp format_layer_detail(layer) do
    layer
    |> format_layer()
    |> Map.put(:members, Enum.map(layer.members, &format_member_detail/1))
  end

  defp format_member(member) do
    %{
      id: member.id,
      position: member.position,
      user_id: member.user_id,
      layer_id: member.layer_id,
      inserted_at: member.inserted_at
    }
  end

  defp format_member_detail(member) do
    %{
      id: member.id,
      position: member.position,
      user_id: member.user_id,
      user: format_user(member.user)
    }
  end

  defp format_override(override) do
    %{
      id: override.id,
      start_time: override.start_time,
      end_time: override.end_time,
      user_id: override.user_id,
      schedule_id: override.schedule_id,
      inserted_at: override.inserted_at
    }
  end

  defp format_override_detail(override) do
    %{
      id: override.id,
      start_time: override.start_time,
      end_time: override.end_time,
      user_id: override.user_id,
      user: format_user(override.user)
    }
  end

  defp format_user(nil), do: nil

  defp format_user(user) do
    %{
      id: user.id,
      email: user.email
    }
  end
end