defmodule ToweropsWeb.GraphQL.Resolvers.Member do
  @moduledoc "GraphQL resolvers for member and invitation management."

  alias Towerops.Organizations
  alias Towerops.Organizations.Invitation
  alias Towerops.Repo
  alias ToweropsWeb.GraphQL.Resolvers.Helpers
  alias ToweropsWeb.ScopedResource

  # Roles that are allowed to send invitations
  @invite_roles [:owner, :admin]
  # Role hierarchy for checking if inviter can assign a given role
  @role_rank %{owner: 0, admin: 1, executive: 2, technician: 3, member: 4, viewer: 5}

  def list(_parent, _args, %{context: %{organization_id: org_id}}) do
    members = Organizations.list_organization_members(org_id)
    {:ok, members}
  end

  def list(_parent, _args, _resolution), do: Helpers.authentication_error()

  def invite(_parent, %{email: email} = args, %{context: %{organization_id: org_id, user: user}}) do
    role = Map.get(args, :role, "technician")

    with {:ok, _membership} <- authorize_invite(org_id, user.id, role) do
      case Organizations.create_invitation(%{
             email: email,
             role: role,
             organization_id: org_id,
             invited_by_id: user.id
           }) do
        {:ok, invitation} -> {:ok, invitation}
        {:error, changeset} -> {:error, Helpers.format_changeset_errors(changeset)}
      end
    end
  end

  def invite(_parent, _args, _resolution), do: Helpers.authentication_error()

  defp authorize_invite(org_id, user_id, requested_role) do
    case Organizations.get_membership(org_id, user_id) do
      nil ->
        {:error, "not a member of this organization"}

      membership when membership.role not in @invite_roles ->
        {:error, "only admins and owners can send invitations"}

      membership ->
        authorize_role(membership, requested_role)
    end
  end

  defp authorize_role(membership, requested_role) do
    case parse_role(requested_role) do
      nil ->
        {:error, "invalid role: #{requested_role}"}

      requested_role_atom ->
        if @role_rank[membership.role] <= @role_rank[requested_role_atom] do
          {:ok, membership}
        else
          {:error, "cannot assign a role higher than your own"}
        end
    end
  end

  defp parse_role(role) when is_binary(role) do
    atom = String.to_existing_atom(role)

    if Map.has_key?(@role_rank, atom), do: atom
  rescue
    ArgumentError -> nil
  end

  def cancel_invitation(_parent, %{id: id}, %{context: %{organization_id: org_id}}) do
    with {:ok, invitation} <- fetch_org_invitation(id, org_id) do
      case Repo.delete(invitation) do
        {:ok, _} -> {:ok, %{success: true, message: "Invitation cancelled"}}
        {:error, _} -> {:ok, %{success: false, message: "Could not cancel invitation"}}
      end
    end
  end

  def cancel_invitation(_parent, _args, _resolution), do: Helpers.authentication_error()

  def remove(_parent, %{id: user_id}, %{context: %{organization_id: org_id}}) do
    case Organizations.remove_member(org_id, user_id) do
      {:ok, _} -> {:ok, %{success: true, message: "Member removed"}}
      {:error, :cannot_remove_owner} -> {:error, "Cannot remove owner"}
      {:error, :not_found} -> {:error, "Member not found"}
    end
  end

  def remove(_parent, _args, _resolution), do: Helpers.authentication_error()

  def update_role(_parent, %{id: user_id, role: role}, %{context: %{organization_id: org_id}}) do
    case Organizations.update_member_role(org_id, user_id, role) do
      {:ok, membership} ->
        membership = Repo.preload(membership, :user)
        {:ok, membership}

      {:error, :cannot_change_owner_role} ->
        {:error, "Cannot change owner role"}

      {:error, :not_found} ->
        {:error, "Member not found"}

      {:error, changeset} ->
        {:error, Helpers.format_changeset_errors(changeset)}
    end
  end

  def update_role(_parent, _args, _resolution), do: Helpers.authentication_error()

  defp fetch_org_invitation(id, org_id) do
    case ScopedResource.fetch(Invitation, id, org_id) do
      {:ok, invitation} -> {:ok, invitation}
      {:error, _reason} -> {:error, "Invitation not found"}
    end
  end
end