package gs.config.v0.source

import cats.Applicative
import cats.effect.Sync
import gs.config.v0.ConfigKey

/** Interface for loading raw configuration values.
  *
  * This interface is **not** intended to be used with sensitive information. Do
  * not use this interface for loading passwords, encryption keys, or any other
  * sensitive information.
  */
trait ConfigSource[F[_]]:
  /** Retrieve the value for the specified key.
    *
    * @param key
    *   The key which defines the piece of configuration.
    * @return
    *   The raw value, or an error if no value can be retrieved.
    */
  def getValue(key: ConfigKey[?]): F[Option[String]]

  /** @return
    *   The name of this source.
    */
  def name: String

object ConfigSource:

  def inMemory[F[_]: Applicative](
    configs: Map[String, String]
  ): ConfigSource[F] =
    new MemoryConfigSource[F](configs)

  def environment[F[_]: Sync]: ConfigSource[F] =
    new EnvironmentConfigSource[F]

  def empty[F[_]: Applicative]: ConfigSource[F] =
    new Empty[F]

  final class Empty[F[_]: Applicative] extends ConfigSource[F]:

    /** @inheritDocs
      */
    override def getValue(key: ConfigKey[?]): F[Option[String]] =
      Applicative[F].pure(None)

    /** @inheritDocs
      */
    override val name: String = "empty"

end ConfigSource