# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.ApplicationRequirements do
  @moduledoc """
  The module represents the collection of validations to runs before start server.
  """

  defmodule VerifyError, do: defexception([:message])

  alias Pleroma.Config
  alias Pleroma.Helpers.MediaHelper

  import Ecto.Query

  require Logger

  @spec verify!() :: :ok | VerifyError.t()
  def verify! do
    :ok
    |> check_system_commands!()
    |> check_confirmation_accounts!()
    |> check_migrations_applied!()
    |> check_welcome_message_config!()
    |> check_rum!()
    |> handle_result()
  end

  defp handle_result(:ok), do: :ok
  defp handle_result({:error, message}), do: raise(VerifyError, message: message)

  defp check_welcome_message_config!(:ok) do
    if Pleroma.Config.get([:welcome, :email, :enabled], false) and
         not Pleroma.Emails.Mailer.enabled?() do
      Logger.error("""
      To send welcome email do you need to enable mail.
      \nconfig :pleroma, Pleroma.Emails.Mailer, enabled: true
      """)

      {:error, "The mail disabled."}
    else
      :ok
    end
  end

  defp check_welcome_message_config!(result), do: result

  # Checks account confirmation email
  #
  def check_confirmation_accounts!(:ok) do
    if Pleroma.Config.get([:instance, :account_activation_required]) &&
         not Pleroma.Config.get([Pleroma.Emails.Mailer, :enabled]) do
      Logger.error(
        "Account activation enabled, but no Mailer settings enabled.\n" <>
          "Please set config :pleroma, :instance, account_activation_required: false\n" <>
          "Otherwise setup and enable Mailer."
      )

      {:error,
       "Account activation enabled, but Mailer is disabled. Cannot send confirmation emails."}
    else
      :ok
    end
  end

  def check_confirmation_accounts!(result), do: result

  # Checks for pending migrations.
  #
  def check_migrations_applied!(:ok) do
    unless Pleroma.Config.get(
             [:i_am_aware_this_may_cause_data_loss, :disable_migration_check],
             false
           ) do
      {_, res, _} =
        Ecto.Migrator.with_repo(Pleroma.Repo, fn repo ->
          down_migrations =
            Ecto.Migrator.migrations(repo)
            |> Enum.reject(fn
              {:up, _, _} -> true
              {:down, _, _} -> false
            end)

          if length(down_migrations) > 0 do
            down_migrations_text =
              Enum.map(down_migrations, fn {:down, id, name} -> "- #{name} (#{id})\n" end)

            Logger.error(
              "The following migrations were not applied:\n#{down_migrations_text}" <>
                "If you want to start Pleroma anyway, set\n" <>
                "config :pleroma, :i_am_aware_this_may_cause_data_loss, disable_migration_check: true"
            )

            {:error, "Unapplied Migrations detected"}
          else
            :ok
          end
        end)

      res
    else
      :ok
    end
  end

  def check_migrations_applied!(result), do: result

  # Checks for settings of RUM indexes.
  #
  defp check_rum!(:ok) do
    {_, res, _} =
      Ecto.Migrator.with_repo(Pleroma.Repo, fn repo ->
        migrate =
          from(o in "columns",
            where: o.table_name == "objects",
            where: o.column_name == "fts_content"
          )
          |> repo.exists?(prefix: "information_schema")

        setting = Pleroma.Config.get([:database, :rum_enabled], false)

        do_check_rum!(setting, migrate)
      end)

    res
  end

  defp check_rum!(result), do: result

  defp do_check_rum!(setting, migrate) do
    case {setting, migrate} do
      {true, false} ->
        Logger.error(
          "Use `RUM` index is enabled, but were not applied migrations for it.\n" <>
            "If you want to start Pleroma anyway, set\n" <>
            "config :pleroma, :database, rum_enabled: false\n" <>
            "Otherwise apply the following migrations:\n" <>
            "`mix ecto.migrate --migrations-path priv/repo/optional_migrations/rum_indexing/`"
        )

        {:error, "Unapplied RUM Migrations detected"}

      {false, true} ->
        Logger.error(
          "Detected applied migrations to use `RUM` index, but `RUM` isn't enable in settings.\n" <>
            "If you want to use `RUM`, set\n" <>
            "config :pleroma, :database, rum_enabled: true\n" <>
            "Otherwise roll `RUM` migrations back.\n" <>
            "`mix ecto.rollback --migrations-path priv/repo/optional_migrations/rum_indexing/`"
        )

        {:error, "RUM Migrations detected"}

      _ ->
        :ok
    end
  end

  defp check_system_commands!(:ok) do
    filter_commands_statuses = [
      check_filter(Pleroma.Upload.Filters.Exiftool, "exiftool"),
      check_filter(Pleroma.Upload.Filters.Mogrify, "mogrify"),
      check_filter(Pleroma.Upload.Filters.Mogrifun, "mogrify")
    ]

    preview_proxy_commands_status =
      if !Config.get([:media_preview_proxy, :enabled]) or
           MediaHelper.missing_dependencies() == [] do
        true
      else
        Logger.error(
          "The following dependencies required by Media preview proxy " <>
            "(which is currently enabled) are not installed: " <>
            inspect(MediaHelper.missing_dependencies())
        )

        false
      end

    if Enum.all?([preview_proxy_commands_status | filter_commands_statuses], & &1) do
      :ok
    else
      {:error,
       "System commands missing. Check logs and see `docs/installation` for more details."}
    end
  end

  defp check_system_commands!(result), do: result

  defp check_filter(filter, command_required) do
    filters = Config.get([Pleroma.Upload, :filters])

    if filter in filters and not Pleroma.Utils.command_available?(command_required) do
      Logger.error(
        "#{filter} is specified in list of Pleroma.Upload filters, but the " <>
          "#{command_required} command is not found"
      )

      false
    else
      true
    end
  end
end