defmodule AshSqlite.Repo do
  @moduledoc """
  Resources that use `AshSqlite.DataLayer` use a `Repo` to access the database.

  This repo is a thin wrapper around an `Ecto.Repo`.

  You can use `Ecto.Repo`'s `init/2` to configure your repo like normal, but
  instead of returning `{:ok, config}`, use `super(config)` to pass the
  configuration to the `AshSqlite.Repo` implementation.
  """

  @doc "Use this to inform the data layer about what extensions are installed"
  @callback installed_extensions() :: [String.t()]

  @doc """
  Use this to inform the data layer about the oldest potential sqlite version it will be run on.

  Must be an integer greater than or equal to 13.
  """
  @callback min_pg_version() :: integer()

  @doc "The path where your migrations are stored"
  @callback migrations_path() :: String.t() | nil
  @doc "Allows overriding a given migration type for *all* fields, for example if you wanted to always use :timestamptz for :utc_datetime fields"
  @callback override_migration_type(atom) :: atom

  defmacro __using__(opts) do
    quote bind_quoted: [opts: opts] do
      otp_app = opts[:otp_app] || raise("Must configure OTP app")

      use Ecto.Repo,
        adapter: Ecto.Adapters.SQLite3,
        otp_app: otp_app

      @behaviour AshSqlite.Repo

      defoverridable insert: 2, insert: 1, insert!: 2, insert!: 1

      def installed_extensions, do: []
      def migrations_path, do: nil
      def override_migration_type(type), do: type
      def min_pg_version, do: 10

      def init(_, config) do
        new_config =
          config
          |> Keyword.put(:installed_extensions, installed_extensions())
          |> Keyword.put(:migrations_path, migrations_path())
          |> Keyword.put(:case_sensitive_like, :on)

        {:ok, new_config}
      end

      def insert(struct_or_changeset, opts \\ []) do
        struct_or_changeset
        |> to_ecto()
        |> then(fn value ->
          repo = get_dynamic_repo()

          Ecto.Repo.Schema.insert(
            __MODULE__,
            repo,
            value,
            Ecto.Repo.Supervisor.tuplet(repo, prepare_opts(:insert, opts))
          )
        end)
        |> from_ecto()
      end

      def insert!(struct_or_changeset, opts \\ []) do
        struct_or_changeset
        |> to_ecto()
        |> then(fn value ->
          repo = get_dynamic_repo()

          Ecto.Repo.Schema.insert!(
            __MODULE__,
            repo,
            value,
            Ecto.Repo.Supervisor.tuplet(repo, prepare_opts(:insert, opts))
          )
        end)
        |> from_ecto()
      end

      def from_ecto({:ok, result}), do: {:ok, from_ecto(result)}
      def from_ecto({:error, _} = other), do: other

      def from_ecto(nil), do: nil

      def from_ecto(value) when is_list(value) do
        Enum.map(value, &from_ecto/1)
      end

      def from_ecto(%resource{} = record) do
        if Spark.Dsl.is?(resource, Ash.Resource) do
          empty = struct(resource)

          resource
          |> Ash.Resource.Info.relationships()
          |> Enum.reduce(record, fn relationship, record ->
            case Map.get(record, relationship.name) do
              %Ecto.Association.NotLoaded{} ->
                Map.put(record, relationship.name, Map.get(empty, relationship.name))

              value ->
                Map.put(record, relationship.name, from_ecto(value))
            end
          end)
        else
          record
        end
      end

      def from_ecto(other), do: other

      def to_ecto(nil), do: nil

      def to_ecto(value) when is_list(value) do
        Enum.map(value, &to_ecto/1)
      end

      def to_ecto(%resource{} = record) do
        if Spark.Dsl.is?(resource, Ash.Resource) do
          resource
          |> Ash.Resource.Info.relationships()
          |> Enum.reduce(record, fn relationship, record ->
            value =
              case Map.get(record, relationship.name) do
                %Ash.NotLoaded{} ->
                  %Ecto.Association.NotLoaded{
                    __field__: relationship.name,
                    __cardinality__: relationship.cardinality
                  }

                value ->
                  to_ecto(value)
              end

            Map.put(record, relationship.name, value)
          end)
        else
          record
        end
      end

      def to_ecto(other), do: other

      defoverridable init: 2,
                     installed_extensions: 0,
                     override_migration_type: 1,
                     min_pg_version: 0
    end
  end
end