defmodule Mobilizon.Actors do
  @moduledoc """
  The Actors context.
  """

  import Ecto.Query, warn: false
  alias Mobilizon.Repo

  alias Mobilizon.Actors.{Actor, Bot, Member, Follower, User}

  alias Mobilizon.Service.ActivityPub
  import Exgravatar

  @doc false
  def data() do
    Dataloader.Ecto.new(Repo, query: &query/2)
  end

  @doc false
  def query(queryable, _params) do
    queryable
  end

  @doc """
  Returns the list of actors.

  ## Examples

      iex> Mobilizon.Actors.list_actors()
      [%Mobilizon.Actors.Actor{}]

  """
  @spec list_actors() :: list()
  def list_actors do
    Repo.all(Actor)
  end

  @doc """
  Gets a single actor.

  Raises `Ecto.NoResultsError` if the Actor does not exist.

  ## Examples

      iex> get_actor!(123)
      %Mobilizon.Actors.Actor{}

      iex> get_actor!(456)
      ** (Ecto.NoResultsError)

  """
  @spec get_actor!(integer()) :: Actor.t()
  def get_actor!(id) do
    Repo.get!(Actor, id)
  end

  @doc """
  Returns the associated actor for an user, either the default set one or the first found
  """
  @spec get_actor_for_user(Mobilizon.Actors.User.t()) :: Mobilizon.Actors.Actor.t()
  def get_actor_for_user(%Mobilizon.Actors.User{} = user) do
    with %User{default_actor: actor} = user when not is_nil(user) and not is_nil(actor) <-
           Repo.preload(user, [:default_actor]) do
      actor
    end
  end

  def get_actor_with_everything!(id) do
    actor = Repo.get!(Actor, id)
    Repo.preload(actor, [:organized_events, :followers, :followings])
  end

  @doc """
  Creates a actor.

  ## Examples

      iex> create_actor(%{preferred_username: "test"})
      {:ok, %Mobilizon.Actors.Actor{preferred_username: "test"}}

      iex> create_actor(%{preferred_username: nil})
      {:error, %Ecto.Changeset{}}

  """
  def create_actor(attrs \\ %{}) do
    %Actor{}
    |> Actor.changeset(attrs)
    |> Repo.insert()
  end

  @doc """
  Updates a actor.

  ## Examples

      iex> update_actor(%Actor{preferred_username: "toto"}, %{preferred_username: "tata"})
      {:ok, %Mobilizon.Actors.Actor{preferred_username: "tata"}}

      iex> update_actor(%Actor{preferred_username: "toto"}, %{preferred_username: nil})
      {:error, %Ecto.Changeset{}}

  """
  def update_actor(%Actor{} = actor, attrs) do
    actor
    |> Actor.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a Actor.

  ## Examples

      iex> delete_actor(%Actor{})
      {:ok, %Mobilizon.Actors.Actor{}}

      iex> delete_actor(nil)
      {:error, %Ecto.Changeset{}}

  """
  @spec delete_actor(Actor.t()) :: {:ok, Actor.t()} | {:error, Ecto.Changeset.t()}
  def delete_actor(%Actor{} = actor) do
    Repo.delete(actor)
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking actor changes.

  ## Examples

      iex> change_actor(%Actor{})
      %Ecto.Changeset{data: %Mobilizon.Actors.Actor{}}

  """
  def change_actor(%Actor{} = actor) do
    Actor.changeset(actor, %{})
  end

  @doc """
  List the groups
  """
  def list_groups do
    Repo.all(from(a in Actor, where: a.type == ^:Group))
  end

  def get_group_by_name(name) do
    case String.split(name, "@") do
      [name] ->
        Repo.get_by(Actor, preferred_username: name, type: :Group)

      [name, domain] ->
        Repo.get_by(Actor, preferred_username: name, domain: domain, type: :Group)
    end
  end

  @doc """
  Creates a group.

  ## Examples

      iex> create_group(%{name: "group name"})
      {:ok, %Mobilizon.Actors.Actor{}}

      iex> create_group(%{name: nil})
      {:error, %Ecto.Changeset{}}

  """
  def create_group(attrs \\ %{}) do
    %Actor{}
    |> Actor.group_creation(attrs)
    |> Repo.insert()
  end

  alias Mobilizon.Actors.User

  @doc """
  Returns the list of users.

  ## Examples

      iex> list_users()
      [%Mobilizon.Actors.User{}]

  """
  def list_users do
    Repo.all(User)
  end

  def insert_or_update_actor(data, preload \\ false) do
    cs = Actor.remote_actor_creation(data)

    {:ok, actor} =
      Repo.insert(
        cs,
        on_conflict: [
          set: [
            keys: data.keys,
            avatar_url: data.avatar_url,
            banner_url: data.banner_url,
            name: data.name
          ]
        ],
        conflict_target: [:preferred_username, :domain]
      )

    if preload, do: {:ok, Repo.preload(actor, [:followers])}, else: {:ok, actor}
  end

  #  def increase_event_count(%Actor{} = actor) do
  #    event_count = (actor.info["event_count"] || 0) + 1
  #    new_info = Map.put(actor.info, "note_count", note_count)
  #
  #    cs = info_changeset(actor, %{info: new_info})
  #
  #    update_and_set_cache(cs)
  #  end

  def count_users() do
    Repo.one(
      from(
        u in User,
        select: count(u.id)
      )
    )
  end

  @doc """
  Gets a single user.

  Raises `Ecto.NoResultsError` if the User does not exist.

  ## Examples

      iex> get_user!(123)
      %Mobilizon.Actors.User{}

      iex> get_user!(456)
      ** (Ecto.NoResultsError)

  """
  def get_user!(id), do: Repo.get!(User, id)

  @doc """
  Get an user with it's actors

  Raises `Ecto.NoResultsError` if the User does not exist.
  """
  @spec get_user_with_actors!(integer()) :: User.t()
  def get_user_with_actors!(id) do
    user = Repo.get!(User, id)
    Repo.preload(user, :actors)
  end

  @spec get_user_with_actors(integer()) :: User.t()
  def get_user_with_actors(id) do
    case Repo.get(User, id) do
      nil -> {:error, "User with ID #{id} not found"}
      user -> {:ok, Repo.preload(user, :actors)}
    end
  end

  @doc """
  Get an actor by it's URL (ActivityPub ID). The `:preload` option allows preloading the Followers relation.

  Raises `Ecto.NoResultsError` if the Actor does not exist.

  ## Examples
      iex> get_actor_by_url("https://mastodon.server.tld/users/user")
      {:ok, %Mobilizon.Actors.Actor{preferred_username: "user"}}

      iex> get_actor_by_url("https://mastodon.server.tld/users/user", true)
      {:ok, %Mobilizon.Actors.Actor{preferred_username: "user", followers: []}}

      iex> get_actor_by_url("non existent")
      {:error, :actor_not_found}

  """
  @spec get_actor_by_url(String.t(), boolean()) :: {:ok, Actor.t()} | {:error, :actor_not_found}
  def get_actor_by_url(url, preload \\ false) do
    case Repo.get_by(Actor, url: url) do
      nil ->
        {:error, :actor_not_found}

      actor ->
        if preload, do: {:ok, Repo.preload(actor, [:followers])}, else: {:ok, actor}
    end
  end

  @doc """
  Get an actor by it's URL (ActivityPub ID). The `:preload` option allows preloading the Followers relation.

  Raises `Ecto.NoResultsError` if the Actor does not exist.

  ## Examples
      iex> get_actor_by_url!("https://mastodon.server.tld/users/user")
      %Mobilizon.Actors.Actor{}

      iex> get_actor_by_url!("https://mastodon.server.tld/users/user", true)
      {:ok, %Mobilizon.Actors.Actor{preferred_username: "user", followers: []}}

      iex> get_actor_by_url!("non existent")
      ** (Ecto.NoResultsError)

  """
  @spec get_actor_by_url!(String.t(), boolean()) :: struct()
  def get_actor_by_url!(url, preload \\ false) do
    actor = Repo.get_by!(Actor, url: url)
    if preload, do: Repo.preload(actor, [:followers]), else: actor
  end

  @doc """
  Get an actor by name

  ## Examples
      iex> get_actor_by_name("tcit")
      %Mobilizon.Actors.Actor{preferred_username: "tcit", domain: nil}

      iex> get_actor_by_name("tcit@social.tcit.fr")
      %Mobilizon.Actors.Actor{preferred_username: "tcit", domain: "social.tcit.fr"}

      iex> get_actor_by_name("tcit", :Group)
      nil

  """
  @spec get_actor_by_name(String.t(), atom() | nil) :: Actor.t()
  def get_actor_by_name(name, type \\ nil) do
    # Base query
    query = from(a in Actor)

    # If we have Person / Group information
    query =
      if type in [:Person, :Group] do
        from(a in query, where: a.type == ^type)
      else
        query
      end

    # If the name is a remote actor
    query =
      case String.split(name, "@") do
        [name] -> do_get_actor_by_name(query, name)
        [name, domain] -> do_get_actor_by_name(query, name, domain)
      end

    Repo.one(query)
  end

  # Get actor by username and domain is nil
  defp do_get_actor_by_name(query, name) do
    from(a in query, where: a.preferred_username == ^name and is_nil(a.domain))
  end

  # Get actor by username and domain
  defp do_get_actor_by_name(query, name, domain) do
    from(a in query, where: a.preferred_username == ^name and a.domain == ^domain)
  end

  def get_local_actor_by_name(name) do
    Repo.one(from(a in Actor, where: a.preferred_username == ^name and is_nil(a.domain)))
  end

  def get_local_actor_by_name_with_everything(name) do
    actor = Repo.one(from(a in Actor, where: a.preferred_username == ^name and is_nil(a.domain)))
    Repo.preload(actor, [:organized_events, :followers, :followings])
  end

  @spec get_actor_by_name_with_everything(String.t(), atom() | nil) :: Actor.t()
  def get_actor_by_name_with_everything(name, type \\ nil) do
    name
    |> get_actor_by_name(type)
    |> Repo.preload(:organized_events)
  end

  def get_or_fetch_by_url(url, preload \\ false) do
    with {:ok, actor} <- get_actor_by_url(url, preload) do
      {:ok, actor}
    else
      _ ->
        case ActivityPub.make_actor_from_url(url, preload) do
          {:ok, actor} ->
            {:ok, actor}

          _ ->
            {:error, "Could not fetch by AP id"}
        end
    end
  end

  def get_or_fetch_by_url!(url, preload \\ false) do
    with {:ok, actor} <- get_actor_by_url(url, preload) do
      actor
    else
      _ ->
        case ActivityPub.make_actor_from_url(url, preload) do
          {:ok, actor} ->
            actor

          _ ->
            raise "Could not fetch by AP id"
        end
    end
  end

  @doc """
  Find local users by it's username
  """
  def find_local_by_username(username) do
    actors =
      Repo.all(
        from(
          a in Actor,
          where:
            (ilike(a.preferred_username, ^like_sanitize(username)) or
               ilike(a.name, ^like_sanitize(username))) and is_nil(a.domain)
        )
      )

    Repo.preload(actors, :organized_events)
  end

  @doc """
  Find actors by their name or displayed name
  """
  @spec find_actors_by_username_or_name(String.t(), integer(), integer()) :: list(Actor.t())
  def find_actors_by_username_or_name(username, page \\ 1, limit \\ 10)
  def find_actors_by_username_or_name("", _page, _limit), do: []

  def find_actors_by_username_or_name(username, page, limit) do
    start = (page - 1) * limit

    Repo.all(
      from(
        a in Actor,
        limit: ^limit,
        offset: ^start,
        where:
          ilike(a.preferred_username, ^like_sanitize(username)) or
            ilike(a.name, ^like_sanitize(username))
      )
    )
  end

  # Sanitize the LIKE queries
  defp like_sanitize(value) do
    "%" <> String.replace(value, ~r/([\\%_])/, "\\1") <> "%"
  end

  @email_regex ~r/^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/
  @spec search(String.t()) :: {:ok, list(Actor.t())} | {:ok, []} | {:error, any()}
  def search(name) do
    # find already saved accounts
    case find_actors_by_username_or_name(name) do
      [] ->
        # no accounts found, let's test if it's an username@domain.tld
        with true <- Regex.match?(@email_regex, name),
             # creating the actor in that case
             {:ok, actor} <- ActivityPub.find_or_make_actor_from_nickname(name) do
          {:ok, [actor]}
        else
          false ->
            {:ok, []}

          # error fingering the actor
          {:error, err} ->
            {:error, err}
        end

      actors = [_ | _] ->
        # actors already saved found !
        {:ok, actors}
    end
  end

  @doc """
  Authenticate user
  """
  def authenticate(%{user: user, password: password}) do
    # Does password match the one stored in the database?
    case Comeonin.Argon2.checkpw(password, user.password_hash) do
      true ->
        # Yes, create and return the token
        MobilizonWeb.Guardian.encode_and_sign(user)

      _ ->
        # No, return an error
        {:error, :unauthorized}
    end
  end

  @doc """
  Register user
  """
  @spec register(map()) :: {:ok, Actor.t()} | {:error, String.t()}
  def register(%{email: email, password: password, username: username}) do
    key = :public_key.generate_key({:rsa, 2048, 65_537})
    entry = :public_key.pem_entry_encode(:RSAPrivateKey, key)
    pem = [entry] |> :public_key.pem_encode() |> String.trim_trailing()

    with avatar <- gravatar(email),
         actor_changeset <-
           Mobilizon.Actors.Actor.registration_changeset(%Mobilizon.Actors.Actor{}, %{
             preferred_username: username,
             domain: nil,
             keys: pem,
             avatar_url: avatar
           }),
         {:ok, %Mobilizon.Actors.Actor{} = actor} <- Mobilizon.Repo.insert(actor_changeset),
         user_changeset <-
           Mobilizon.Actors.User.registration_changeset(%Mobilizon.Actors.User{}, %{
             email: email,
             password: password,
             default_actor: actor
           }),
         {:ok, %Mobilizon.Actors.User{} = user} <- Mobilizon.Repo.insert(user_changeset) do
      {:ok, Map.put(actor, :user, user)}
    else
      {:error, %Ecto.Changeset{} = changeset} ->
        handle_actor_user_changeset(changeset)
    end
  end

  @spec gravatar(String.t()) :: String.t() | nil
  defp gravatar(nil), do: nil

  defp gravatar(email) do
    avatar_url = gravatar_url(email, default: "404")

    case HTTPoison.get(avatar_url) do
      {:ok, %HTTPoison.Response{status_code: 200}} ->
        avatar_url

      _ ->
        nil
    end
  end

  @spec handle_actor_user_changeset(Ecto.Changeset.t()) :: {:error, String.t()}
  defp handle_actor_user_changeset(changeset) do
    changeset =
      Ecto.Changeset.traverse_errors(changeset, fn
        {msg, _opts} -> msg
        msg -> msg
      end)

    email_msg = Map.get(changeset, :email) || [:empty_email]
    {:error, hd(email_msg)}
  end

  def register_bot_account(%{name: name, summary: summary}) do
    key = :public_key.generate_key({:rsa, 2048, 65_537})
    entry = :public_key.pem_entry_encode(:RSAPrivateKey, key)
    pem = [entry] |> :public_key.pem_encode() |> String.trim_trailing()

    actor =
      Mobilizon.Actors.Actor.registration_changeset(%Mobilizon.Actors.Actor{}, %{
        preferred_username: name,
        domain: nil,
        keys: pem,
        summary: summary,
        type: :Service
      })

    try do
      Mobilizon.Repo.insert!(actor)
    rescue
      e in Ecto.InvalidChangesetError ->
        {:error, e.changeset}
    end
  end

  @doc """
  Creates a user.

  ## Examples

      iex> create_user(%{email: "test@test.tld"})
      {:ok, %Mobilizon.Actors.User{}}

      iex> create_user(%{email: "not an email"})
      {:error, %Ecto.Changeset{}}

  """
  def create_user(attrs \\ %{}) do
    %User{}
    |> User.registration_changeset(attrs)
    |> Repo.insert()
  end

  @doc """
  Gets an user by it's email

  ## Examples

      iex> get_user_by_email("test@test.tld", true)
      {:ok, %Mobilizon.Actors.User{}}

      iex> get_user_by_email("test@notfound.tld", false)
      {:error, :user_not_found}
  """
  def get_user_by_email(email, activated \\ nil) do
    query =
      case activated do
        nil -> from(u in User, where: u.email == ^email)
        true -> from(u in User, where: u.email == ^email and not is_nil(u.confirmed_at))
        false -> from(u in User, where: u.email == ^email and is_nil(u.confirmed_at))
      end

    case Repo.one(query) do
      nil -> {:error, :user_not_found}
      user -> {:ok, user}
    end
  end

  @spec get_user_by_activation_token(String.t()) :: Actor.t()
  def get_user_by_activation_token(token) do
    Repo.one(
      from(u in User,
        where: u.confirmation_token == ^token,
        preload: [:default_actor]
      )
    )
  end

  @doc """
  Updates a user.

  ## Examples

      iex> update_user(User{}, %{password: "coucou"})
      {:ok, %Mobilizon.Actors.User{}}

      iex> update_user(User{}, %{password: nil})
      {:error, %Ecto.Changeset{}}

  """
  def update_user(%User{} = user, attrs) do
    user
    |> User.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a User.

  ## Examples

      iex> delete_user(%User{email: "test@test.tld"})
      {:ok, %Mobilizon.Actors.User{}}

      iex> delete_user(%User{})
      {:error, %Ecto.Changeset{}}

  """
  def delete_user(%User{} = user) do
    Repo.delete(user)
  end

  # @doc """
  # Returns an `%Ecto.Changeset{}` for tracking user changes.

  # ## Examples

  #     iex> change_user(%Mobilizon.Actors.User{})
  #     %Ecto.Changeset{data: %Mobilizon.Actors.User{}}

  # """
  # def change_user(%User{} = user) do
  #   User.changeset(user, %{})
  # end

  alias Mobilizon.Actors.Member

  @doc """
  Gets a single member.

  Raises `Ecto.NoResultsError` if the Member does not exist.

  ## Examples

      iex> get_member!(123)
      %Mobilizon.Actors.Member{}

      iex> get_member!(456)
      ** (Ecto.NoResultsError)

  """
  def get_member!(id), do: Repo.get!(Member, id)

  @doc """
  Creates a member.

  ## Examples

      iex> create_member(%{actor: %Actor{}})
      {:ok, %Mobilizon.Actors.Member{}}

      iex> create_member(%{actor: nil})
      {:error, %Ecto.Changeset{}}

  """
  def create_member(attrs \\ %{}) do
    with {:ok, %Member{} = member} <-
           %Member{}
           |> Member.changeset(attrs)
           |> Repo.insert() do
      {:ok, Repo.preload(member, [:actor, :parent])}
    end
  end

  @doc """
  Updates a member.

  ## Examples

      iex> update_member(%Member{}, %{role: 3})
      {:ok, %Mobilizon.Actors.Member{}}

      iex> update_member(%Member{}, %{role: nil})
      {:error, %Ecto.Changeset{}}

  """
  def update_member(%Member{} = member, attrs) do
    member
    |> Member.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a Member.

  ## Examples

      iex> delete_member(%Member{})
      {:ok, %Mobilizon.Actors.Member{}}

      iex> delete_member(%Member{})
      {:error, %Ecto.Changeset{}}

  """
  def delete_member(%Member{} = member) do
    Repo.delete(member)
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking member changes.

  ## Examples

      iex> change_member(%Member{})
      %Ecto.Changeset{data: %Mobilizon.Actors.Member{}}

  """
  def change_member(%Member{} = member) do
    Member.changeset(member, %{})
  end

  def groups_for_actor(%Actor{id: id} = _actor) do
    Repo.all(
      from(
        m in Member,
        where: m.actor_id == ^id,
        preload: [:parent]
      )
    )
  end

  def members_for_group(%Actor{type: :Group, id: id} = _group) do
    Repo.all(
      from(
        m in Member,
        where: m.parent_id == ^id,
        preload: [:parent, :actor]
      )
    )
  end

  alias Mobilizon.Actors.Bot

  @doc """
  Returns the list of bots.

  ## Examples

      iex> list_bots()
      [%Mobilizon.Actors.Bot{}]

  """
  def list_bots do
    Repo.all(Bot)
  end

  @doc """
  Gets a single bot.

  Raises `Ecto.NoResultsError` if the Bot does not exist.

  ## Examples

      iex> get_bot!(123)
      %Mobilizon.Actors.Bot{}

      iex> get_bot!(456)
      ** (Ecto.NoResultsError)

  """
  def get_bot!(id), do: Repo.get!(Bot, id)

  @spec get_bot_by_actor(Actor.t()) :: Bot.t()
  def get_bot_by_actor(%Actor{} = actor) do
    Repo.get_by!(Bot, actor_id: actor.id)
  end

  @doc """
  Creates a bot.

  ## Examples

      iex> create_bot(%{source: "toto"})
      {:ok, %Mobilizon.Actors.Bot{}}

      iex> create_bot(%{source: nil})
      {:error, %Ecto.Changeset{}}

  """
  def create_bot(attrs \\ %{}) do
    %Bot{}
    |> Bot.changeset(attrs)
    |> Repo.insert()
  end

  @doc """
  Updates a bot.

  ## Examples

      iex> update_bot(%Bot{}, %{source: "new"})
      {:ok, %Mobilizon.Actors.Bot{}}

      iex> update_bot(%Bot{}, %{source: nil})
      {:error, %Ecto.Changeset{}}

  """
  def update_bot(%Bot{} = bot, attrs) do
    bot
    |> Bot.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a Bot.

  ## Examples

      iex> delete_bot(%Bot{})
      {:ok, %Mobilizon.Actors.Bot{}}

      iex> delete_bot(%Bot{})
      {:error, %Ecto.Changeset{}}

  """
  def delete_bot(%Bot{} = bot) do
    Repo.delete(bot)
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking bot changes.

  ## Examples

      iex> change_bot(%Bot{})
      %Ecto.Changeset{data: %Mobilizon.Actors.Bot{}}

  """
  def change_bot(%Bot{} = bot) do
    Bot.changeset(bot, %{})
  end

  alias Mobilizon.Actors.Follower

  @doc """
  Gets a single follower.

  Raises `Ecto.NoResultsError` if the Follower does not exist.

  ## Examples

      iex> get_follower!(123)
      %Mobilizon.Actors.Follower{}

      iex> get_follower!(456)
      ** (Ecto.NoResultsError)

  """
  def get_follower!(id) do
    Repo.get!(Follower, id)
    |> Repo.preload([:actor, :target_actor])
  end

  @doc """
  Creates a follower.

  ## Examples

      iex> create_follower(%{actor: %Actor{}})
      {:ok, %Mobilizon.Actors.Follower{}}

      iex> create_follower(%{actor: nil})
      {:error, %Ecto.Changeset{}}

  """
  def create_follower(attrs \\ %{}) do
    with {:ok, %Follower{} = follower} <-
           %Follower{}
           |> Follower.changeset(attrs)
           |> Repo.insert() do
      {:ok, Repo.preload(follower, [:actor, :target_actor])}
    end
  end

  @doc """
  Updates a follower.

  ## Examples

      iex> update_follower(Follower{}, %{approved: true})
      {:ok, %Mobilizon.Actors.Follower{}}

      iex> update_follower(Follower{}, %{approved: nil})
      {:error, %Ecto.Changeset{}}

  """
  def update_follower(%Follower{} = follower, attrs) do
    follower
    |> Follower.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a Follower.

  ## Examples

      iex> delete_follower(Follower{})
      {:ok, %Mobilizon.Actors.Follower{}}

      iex> delete_follower(Follower{})
      {:error, %Ecto.Changeset{}}

  """
  def delete_follower(%Follower{} = follower) do
    Repo.delete(follower)
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking follower changes.

  ## Examples

      iex> change_follower(Follower{})
      %Ecto.Changeset{data: %Mobilizon.Actors.Follower{}}

  """
  def change_follower(%Follower{} = follower) do
    Follower.changeset(follower, %{})
  end
end