defmodule Selecto.DB.PostgreSQL do
  @moduledoc """
  PostgreSQL adapter for Selecto.
  """

  @behaviour Selecto.DB.Adapter

  @impl true
  def name, do: :postgresql

  @impl true
  def connect({:pool, _} = pool_ref), do: {:ok, pool_ref}
  def connect(connection) when is_pid(connection) or is_atom(connection), do: {:ok, connection}
  def connect(opts) when is_map(opts), do: connect(Map.to_list(opts))

  def connect(opts) when is_list(opts) do
    case Postgrex.start_link(opts) do
      {:ok, conn} -> {:ok, conn}
      {:error, reason} -> {:error, reason}
    end
  end

  def connect(other), do: {:error, {:invalid_connection_options, other}}

  @impl true
  def execute({:pool, pool_ref}, query, params, opts) do
    case Selecto.ConnectionPool.execute(pool_ref, normalize_query(query), params, opts) do
      {:ok, result} -> {:ok, normalize_result(result)}
      {:error, reason} -> {:error, reason}
    end
  end

  def execute(connection, query, params, opts) when is_pid(connection) or is_atom(connection) do
    case Postgrex.query(connection, normalize_query(query), params, opts) do
      {:ok, result} -> {:ok, normalize_result(result)}
      {:error, reason} -> {:error, reason}
    end
  end

  def execute(connection, _query, _params, _opts), do: {:error, {:invalid_connection, connection}}

  @impl true
  def placeholder(index), do: ["$", Integer.to_string(index)]

  @impl true
  def quote_identifier(identifier) when is_binary(identifier) do
    escaped = String.replace(identifier, "\"", "\"\"")
    "\"#{escaped}\""
  end

  def quote_identifier(identifier), do: identifier |> to_string() |> quote_identifier()

  @impl true
  def supports?(feature) do
    feature in [:cte, :jsonb, :array_ops, :returning, :window_functions, :lateral_join, :prefix]
  end

  defp normalize_query(query) when is_binary(query), do: query
  defp normalize_query(query), do: IO.iodata_to_binary(query)

  defp normalize_result(%{rows: rows, columns: columns}) do
    %{
      rows: rows || [],
      columns: Enum.map(columns || [], &to_string/1)
    }
  end
end