import gleam/option.{None, Option, Some}
import validator/common.{Validator}

fn is_some_check(
		maybe: Option(value),
	) -> Option(value) {

	case maybe {
		None -> None
		Some(value) -> Some(value)
	}
}

/// Validate that a value is not None.
/// Returns the value if Some.
///
/// ## Example
///
///	type PersonInput { PersonInput(name: Option(String)) }
///
///	type PersonValid { PersonValid(name: String) }
///
///	let validator = fn(person) {
///		v.build1(PersonValid)
///		|> v.validate(person.name, option.is_some("Name is null"))
///	}
///
pub fn is_some(error: e) -> Validator(Option(i),i,e) {
	common.custom(error, is_some_check)
}

/// Validate an optional value.
///
/// Run the validator only if the value is Some.
/// If the value is None then just return None back.
///
/// ## Example
///
///	let validator = fn(person) {
///		v.build1(PersonValid)
///		|> v.validate(
///			person.name,
///			option.optional(string.min_length("Short", 3))
///		)
///	}
///
pub fn optional(
		validator: Validator(input, input, error)
	) {

	fn(maybe: Option(input)) {
		case maybe {
			None ->
				Ok(maybe)

			Some(value) ->
				case validator(value) {
					Ok(_) -> Ok(maybe)
					Error(error) -> Error(error)
				}
		}
	}
}