defmodule ArcadiaCloudWeb.CatalogController do
  @moduledoc """
  Pricing catalog. The list endpoints (`plans`, `addons`) are readable by
  any authenticated tenant — that's what they pick a plan from.

  The write endpoints are operator-only (platform-admin). Pricing is
  versioned: you never edit a published plan in place. `create_version`
  always makes a new DRAFT version; `publish_version` activates it and
  retires the prior active one. Existing subscriptions keep the version
  they were signed on until explicitly migrated.
  """

  use ArcadiaCloudWeb, :controller

  alias ArcadiaCloud.Catalog

  # ---- reads ----------------------------------------------------------------

  def plans(conn, _params) do
    plans =
      Catalog.list_plans()
      |> Enum.map(fn plan -> shape_plan(plan, Catalog.active_version(plan)) end)

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

  def addons(conn, _params) do
    json(conn, %{addons: Enum.map(Catalog.list_addons(), &shape_addon/1)})
  end

  @doc "Full plan detail incl. every version (draft/active/retired). Operator-only."
  def show(conn, %{"id" => id}) do
    with :ok <- require_platform_admin(conn) do
      case Catalog.get_plan(id) do
        nil ->
          conn |> put_status(:not_found) |> json(%{error: "not_found"})

        plan ->
          json(conn, %{
            plan: %{
              id: plan.id,
              code: plan.code,
              name: plan.name,
              description: plan.description,
              active: plan.active,
              versions: Enum.map(plan.versions, &shape_version/1)
            }
          })
      end
    end
  end

  # ---- writes (operator-only) -----------------------------------------------

  def create_plan(conn, params) do
    with :ok <- require_platform_admin(conn) do
      case Catalog.create_plan(params) do
        {:ok, plan} ->
          conn |> put_status(:created) |> json(%{plan: shape_plan_bare(plan)})

        {:error, changeset} ->
          conn |> put_status(:unprocessable_entity) |> json(%{error: errors(changeset)})
      end
    end
  end

  def create_version(conn, %{"plan_id" => plan_id} = params) do
    with :ok <- require_platform_admin(conn) do
      attrs = Map.take(params, ["base_price_cents", "currency"])
      items = params["items"] || []

      case Catalog.create_plan_version(plan_id, attrs, items) do
        {:ok, version} ->
          conn |> put_status(:created) |> json(%{version: shape_version(version)})

        {:error, changeset} ->
          conn |> put_status(:unprocessable_entity) |> json(%{error: errors(changeset)})
      end
    end
  end

  def publish_version(conn, %{"id" => id}) do
    with :ok <- require_platform_admin(conn) do
      case Catalog.get_version(id) do
        nil ->
          conn |> put_status(:not_found) |> json(%{error: "not_found"})

        %{status: "retired"} ->
          conn
          |> put_status(:unprocessable_entity)
          |> json(%{error: "cannot publish a retired version"})

        version ->
          {:ok, published} = Catalog.publish_version(version)
          json(conn, %{version: shape_version(Catalog.get_version!(published.id))})
      end
    end
  end

  def create_addon(conn, params) do
    with :ok <- require_platform_admin(conn) do
      case Catalog.create_addon(params) do
        {:ok, addon} ->
          conn |> put_status(:created) |> json(%{addon: shape_addon(addon)})

        {:error, changeset} ->
          conn |> put_status(:unprocessable_entity) |> json(%{error: errors(changeset)})
      end
    end
  end

  # ---- shaping --------------------------------------------------------------

  defp shape_plan_bare(plan) do
    %{id: plan.id, code: plan.code, name: plan.name, description: plan.description, active: plan.active}
  end

  defp shape_plan(plan, nil) do
    %{id: plan.id, code: plan.code, name: plan.name, description: plan.description, active_version: nil}
  end

  defp shape_plan(plan, version) do
    %{
      id: plan.id,
      code: plan.code,
      name: plan.name,
      description: plan.description,
      active_version: shape_version(version)
    }
  end

  defp shape_version(v) do
    %{
      id: v.id,
      version: v.version,
      status: v.status,
      base_price_cents: v.base_price_cents,
      currency: v.currency,
      published_at: v.published_at,
      items: Enum.map(v.items, &shape_item/1)
    }
  end

  defp shape_item(i) do
    %{
      resource_kind: i.resource_kind,
      included_qty: i.included_qty,
      overage_unit: i.overage_unit,
      overage_price_cents: i.overage_price_cents,
      hard_cap_qty: i.hard_cap_qty
    }
  end

  defp shape_addon(a) do
    %{
      code: a.code,
      name: a.name,
      resource_kind: a.resource_kind,
      qty: a.qty,
      price_cents: a.price_cents,
      currency: a.currency
    }
  end

  # ---- helpers --------------------------------------------------------------

  defp require_platform_admin(conn) do
    identity = conn.assigns.current_identity

    if is_list(identity.roles) and "platform-admin" in identity.roles do
      :ok
    else
      conn
      |> put_status(:forbidden)
      |> json(%{error: "platform_admin_required"})
      |> halt()
    end
  end

  defp errors(changeset) do
    Ecto.Changeset.traverse_errors(changeset, fn {msg, opts} ->
      Enum.reduce(opts, msg, fn {k, v}, acc -> String.replace(acc, "%{#{k}}", to_string(v)) end)
    end)
  end
end