defmodule Ecto.ActiveSchema do
  require Ecto.Query

  @date_atoms [:date, :time, :naive_datetime, :utc_datetime]

  defmacro __using__(_opts) do
    quote do
      import Ecto.ActiveSchema
      import Ecto.Schema, except: [schema: 2]

      @primary_key nil
      @timestamps_opts []
      @foreign_key_type :id
      @schema_prefix nil
      @field_source_mapper fn x -> x end

      Module.register_attribute(__MODULE__, :ecto_primary_keys, accumulate: true)
      Module.register_attribute(__MODULE__, :ecto_fields, accumulate: true)
      Module.register_attribute(__MODULE__, :ecto_field_sources, accumulate: true)
      Module.register_attribute(__MODULE__, :ecto_assocs, accumulate: true)
      Module.register_attribute(__MODULE__, :ecto_embeds, accumulate: true)
      Module.register_attribute(__MODULE__, :ecto_raw, accumulate: true)
      Module.register_attribute(__MODULE__, :ecto_autogenerate, accumulate: true)
      Module.register_attribute(__MODULE__, :ecto_autoupdate, accumulate: true)
      Module.put_attribute(__MODULE__, :ecto_autogenerate_id, nil)
    end
  end

  defmacro schema(source, do: block) do
    model_ref = __CALLER__.module

    field_definitions =
      block
      |> Tuple.to_list()
      |> tl()
      |> tl()
      |> hd()
      |> get_fields()
      |> Enum.map(fn field ->
        generate(field, model_ref)
      end)

    quote do
      Ecto.Schema.schema unquote(source) do
        unquote(block)
      end

      unquote(
        quote do
          def unquote(:by_id)(id) do
            from(q in unquote(model_ref), where: q.id == ^id)
          end

          def unquote(:by_id)(query, id) do
            from(q in query, where: q.id == ^id)
          end
        end
      )

      unquote(
        Enum.map(field_definitions, fn field_def ->
          quote do
            unquote(field_def)
          end
        end)
      )
    end
  end

  defp get_fields(fields) do
    fields
    |> Enum.map(fn field ->
      field_list = Tuple.to_list(field)
      type = Enum.at(field_list, 0)
      entry = Enum.at(field_list, 2)

      if type == :timestamps || is_list(entry) do
        Map.merge(%{type: type}, get_data_map(entry))
      else
        nil
      end
    end)
    |> Enum.reject(&is_nil/1)
  end

  # Assembles the name and data type fields
  defp get_data_map(entry) do
    field_name = Enum.at(entry, 0)
    data_type = Enum.at(entry, 1)

    Map.merge(%{name: field_name}, get_data_type(data_type))
  end

  # Get the data type for the currently being processed field
  defp get_data_type({:__aliases__, _, [:Ecto, :DateTime]}) do
    %{data_type: :datetime}
  end

  defp get_data_type(data) when data in @date_atoms do
    %{data_type: :datetime}
  end

  defp get_data_type({:__aliases__, _, arr}) when is_list(arr) do
    %{data_type: Enum.join(arr, ".")}
  end

  defp get_data_type({:array, _}) do
    %{data_type: :array}
  end

  defp get_data_type([{:through, arr}]) do
    %{data_type: :through, through_name: List.last(arr)}
  end

  defp get_data_type(type) do
    %{data_type: type}
  end

  defp to_name(field_name) when is_nil(field_name) do
    nil
  end

  defp to_name(field_name) when is_atom(field_name) do
    Atom.to_string(field_name)
  end

  # datetime fields
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :field, data_type: :datetime, name: field_name}, structure) do
    name = to_name(field_name)

    quote do
      def unquote(:"by_#{name}")(val) when is_nil(val) do
        unquote(structure) |> unquote(:"by_#{name}")(val)
      end

      def unquote(:"by_#{name}")(query, val) when is_nil(val) do
        from(q in query, where: is_nil(q.unquote(field_name)))
      end

      def unquote(:"by_#{name}")(val) do
        unquote(structure) |> unquote(:"by_#{name}")(val)
      end

      def unquote(:"by_#{name}")(query, val) do
        from(q in query, where: q.unquote(field_name) == ^val)
      end

      def unquote(:"#{name}_after")(date) do
        unquote(structure) |> unquote(:"#{name}_after")(date)
      end

      def unquote(:"#{name}_after")(query, date) do
        from(q in query, where: q.unquote(field_name) >= ^date)
      end

      def unquote(:"#{name}_before")(date) do
        unquote(structure) |> unquote(:"#{name}_before")(date)
      end

      def unquote(:"#{name}_before")(query, date) do
        from(q in query, where: q.unquote(field_name) <= ^date)
      end
    end
  end

  # boolean fields
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :field, data_type: :boolean, name: field_name}, structure) do
    name = to_name(field_name)

    quote do
      def unquote(:"where_#{name}")(val, params) when is_list(params) do
        unquote(structure) |> unquote(:"where_#{name}")(val, params)
      end

      def unquote(:"where_#{name}")(query, val, params) when is_list(params) do
        unquote(:"where_#{name}")(query, val, Enum.into(params, %{}, fn entry -> entry end))
      end

      def unquote(:"where_#{name}")(query, val, params) when is_map(params) do
        query
        |> unquote(:"where_#{name}")(val)
        |> Ecto.ActiveSchema.order_by(params)
        |> Ecto.ActiveSchema.limit(params)
      end

      def unquote(:"where_#{name}")(val) when is_nil(val) do
        unquote(structure) |> unquote(:"where_#{name}")(val)
      end

      def unquote(:"where_#{name}")(query, val) when is_nil(val) do
        from(q in query, where: is_nil(q.unquote(field_name)))
      end

      def unquote(:"where_#{name}")(val) do
        unquote(structure) |> unquote(:"where_#{name}")(val)
      end

      def unquote(:"where_#{name}")(query, val) do
        from(q in query, where: q.unquote(field_name) == ^val)
      end
    end
  end

  # array fields
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :field, data_type: :array, name: field_name}, structure) do
    name = to_name(field_name)

    quote do
      # the empty array will be interpreted as query for an empty array
      def unquote(:"by_#{name}")(val, params) when params == [] do
        from(q in val, where: q.unquote(field_name) == ^params)
      end

      def unquote(:"by_#{name}")(val, params) when is_list(params) do
        # we need to figure out if params is used for ecto seting or a query
        pass_through_params =
          params
          |> Enum.all?(fn element ->
            case element do
              {k, _v} -> k in [:order_by, :limit]
              _ -> false
            end
          end)

        if pass_through_params do
          unquote(structure) |> unquote(:"by_#{name}")(val, params)
        else
          from(q in val, where: q.unquote(field_name) == ^params)
        end
      end

      def unquote(:"by_#{name}")(query, val, params) when is_list(params) do
        unquote(:"by_#{name}")(query, val, Enum.into(params, %{}, fn entry -> entry end))
      end

      def unquote(:"by_#{name}")(query, val, params) when is_map(params) do
        query
        |> unquote(:"by_#{name}")(val)
        |> Ecto.ActiveSchema.order_by(params)
        |> Ecto.ActiveSchema.limit(params)
      end

      def unquote(:"by_#{name}")(val) when is_nil(val) do
        unquote(structure) |> unquote(:"by_#{name}")(val)
      end

      def unquote(:"by_#{name}")(query, val) when is_nil(val) do
        from(q in query, where: is_nil(q.unquote(field_name)))
      end

      def unquote(:"by_#{name}")(val) do
        unquote(structure) |> unquote(:"by_#{name}")(val)
      end

      def unquote(:"by_#{name}")(query, val) do
        from(q in query, where: q.unquote(field_name) == ^val)
      end
    end
  end

  # all other fields
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :field, data_type: _, name: field_name}, structure) do
    name = to_name(field_name)

    quote do
      def unquote(:"by_#{name}")(val, params) when is_list(params) do
        unquote(structure) |> unquote(:"by_#{name}")(val, params)
      end

      def unquote(:"by_#{name}")(query, val, params) when is_list(params) do
        unquote(:"by_#{name}")(query, val, Enum.into(params, %{}, fn entry -> entry end))
      end

      def unquote(:"by_#{name}")(query, val, params) when is_map(params) do
        query
        |> unquote(:"by_#{name}")(val)
        |> Ecto.ActiveSchema.order_by(params)
        |> Ecto.ActiveSchema.limit(params)
      end

      def unquote(:"by_#{name}")(val) when is_nil(val) do
        unquote(structure) |> unquote(:"by_#{name}")(val)
      end

      def unquote(:"by_#{name}")(query, val) when is_nil(val) do
        from(q in query, where: is_nil(q.unquote(field_name)))
      end

      def unquote(:"by_#{name}")(val) do
        unquote(structure) |> unquote(:"by_#{name}")(val)
      end

      def unquote(:"by_#{name}")(query, val) do
        from(q in query, where: q.unquote(field_name) == ^val)
      end
    end
  end

  # belongs_to associations
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :belongs_to, data_type: _, name: field_name}, structure) do
    name = to_name(field_name)

    quote do
      def unquote(:"by_#{name}_id")(id) do
        unquote(structure) |> unquote(:"by_#{name}_id")(id)
      end

      def unquote(:"by_#{name}_id")(query, id) do
        from(q in query, where: q.unquote(:"#{name}_id") == ^id)
      end

      def unquote(:"with_#{name}")(query) do
        from(
          q in query,
          left_join: s in assoc(q, unquote(:"#{name}")),
          preload: [{unquote(field_name), s}]
        )
      end

      def unquote(:"with_#{name}")() do
        from(
          q in unquote(structure),
          left_join: s in assoc(q, unquote(:"#{name}")),
          preload: [{unquote(field_name), s}]
        )
      end
    end
  end

  # has_one associations
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :has_one, data_type: _, name: field_name}, structure) do
    name = to_name(field_name)

    quote do
      def unquote(:"by_#{name}_id")(id) do
        unquote(structure) |> unquote(:"by_#{name}_id")(id)
      end

      def unquote(:"by_#{name}_id")(query, id) do
        from(
          q in query,
          left_join: s in assoc(q, unquote(:"#{name}")),
          where: s.id == ^id
        )
      end

      def unquote(:"with_#{name}")(query) do
        from(
          q in query,
          left_join: s in assoc(q, unquote(:"#{name}")),
          preload: [{unquote(field_name), s}]
        )
      end

      def unquote(:"with_#{name}")() do
        from(
          q in unquote(structure),
          left_join: s in assoc(q, unquote(:"#{name}")),
          preload: [{unquote(field_name), s}]
        )
      end
    end
  end

  # has_many associations
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :has_many, data_type: _, name: field_name}, structure) do
    name = to_name(field_name)
    through_name = Inflex.singularize(name)

    quote do
      def unquote(:"by_#{through_name}_id")(id) do
        unquote(structure) |> unquote(:"by_#{through_name}_id")(id)
      end

      def unquote(:"by_#{through_name}_id")(query, id) do
        from(
          q in query,
          left_join: s in assoc(q, unquote(:"#{name}")),
          where: s.id == ^id
        )
      end

      def unquote(:"with_#{name}")(params) when is_list(params) do
        unquote(:"with_#{name}")(from(q in unquote(structure)), params)
      end

      def unquote(:"with_#{name}")(query, params)
          when (is_map(query) or is_atom(query)) and is_list(params) do
        unquote(:"with_#{name}")(query, Enum.into(params, %{}, fn entry -> entry end))
      end

      def unquote(:"with_#{name}")(query, params)
          when (is_map(query) or is_atom(query)) and is_map(params) do
        query
        |> unquote(:"with_#{name}")()
        |> Ecto.ActiveSchema.sub_order_by(unquote(field_name), params)
      end

      def unquote(:"with_#{name}")(query) when is_map(query) do
        from(
          q in query,
          left_join: s in assoc(q, unquote(:"#{name}")),
          preload: [{unquote(field_name), s}]
        )
      end

      def unquote(:"with_#{name}")() do
        from(
          q in unquote(structure),
          left_join: s in assoc(q, unquote(:"#{name}")),
          preload: [{unquote(field_name), s}]
        )
      end
    end
  end

  # timestamps
  # credo:disable-for-lines:2 Credo.Check.Refactor.ABCSize
  # credo:disable-for-next-line Credo.Check.Refactor.CyclomaticComplexity
  defp generate(%{type: :timestamps, data_type: _, name: _}, structure) do
    quote do
      def inserted_after(date) do
        from(q in unquote(structure), where: q.inserted_at >= ^date)
      end

      def inserted_after(query, date) do
        from(q in query, where: q.inserted_at >= ^date)
      end

      def inserted_before(date) do
        from(q in unquote(structure), where: q.inserted_at <= ^date)
      end

      def inserted_before(query, date) do
        from(q in query, where: q.inserted_at <= ^date)
      end

      def updated_after(date) do
        from(q in unquote(structure), where: q.updated_at >= ^date)
      end

      def updated_after(query, date) do
        from(q in query, where: q.updated_at >= ^date)
      end

      def updated_before(date) do
        from(q in unquote(structure), where: q.updated_at <= ^date)
      end

      def updated_before(query, date) do
        from(q in query, where: q.updated_at <= ^date)
      end
    end
  end

  def limit(query, %{limit: lim}) when is_number(lim) do
    Ecto.Query.limit(query, ^lim)
  end

  def limit(query, _) do
    query
  end

  def order_by(query, %{order_by: order}) when is_list(order) and length(order) > 0 do
    query
    |> Ecto.ActiveSchema.order_by(%{order_by: hd(order)})
    |> Ecto.ActiveSchema.order_by(%{order_by: tl(order)})
  end

  def order_by(query, %{order_by: order}) when is_tuple(order) do
    Ecto.Query.order_by(query, ^[order])
  end

  def order_by(query, _) do
    query
  end

  def sub_order_by(query, field_name, %{order_by: ordered_by})
      when is_list(ordered_by) and length(ordered_by) > 0 do
    query
    |> Ecto.ActiveSchema.sub_order_by(field_name, %{order_by: hd(ordered_by)})
    |> Ecto.ActiveSchema.sub_order_by(field_name, %{order_by: tl(ordered_by)})
  end

  def sub_order_by(query, field_name, %{order_by: ordered_by}) when is_tuple(ordered_by) do
    # Get the index we need to match against
    assoc = query.assocs[field_name]
    index = elem(assoc, 0)
    order_by_direction = elem(ordered_by, 0)
    order_by_field = elem(ordered_by, 1)

    Map.put(
      query,
      :order_bys,
      query.order_bys ++
        [
          %Ecto.Query.QueryExpr{
            expr: [
              {order_by_direction, {{:., [], [{:&, [], [index]}, order_by_field]}, [], []}}
            ]
          }
        ]
    )
  end

  def sub_order_by(query, _, _) do
    query
  end
end