// Copyright (C) Parity Technologies (UK) Ltd.

// This file is part of Polkadot.

// Polkadot is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

// Polkadot is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.

use crate::MAX_XCM_DECODE_DEPTH;

use alloc::vec::Vec;

use codec::{Decode, DecodeLimit, Encode};

/// Wrapper around the encoded and decoded versions of a value.

/// Caches the decoded value once computed.

#[codec(encode_bound())]

#[codec(decode_bound())]

#[scale_info(bounds(), skip_type_params(T))]

#[scale_info(replace_segment("staging_xcm", "xcm"))]

#[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]

pub struct DoubleEncoded<T> {

	encoded: Vec<u8>,

	#[codec(skip)]

	decoded: Option<T>,

}

impl<T> Clone for DoubleEncoded<T> {

}

impl<T> PartialEq for DoubleEncoded<T> {

}

impl<T> Eq for DoubleEncoded<T> {}

impl<T> core::fmt::Debug for DoubleEncoded<T> {

}

impl<T> From<Vec<u8>> for DoubleEncoded<T> {

}

impl<T> DoubleEncoded<T> {

	/// Provides an API similar to `AsRef` that provides access to the inner value.

	/// `AsRef` implementation would expect an `&Option<T>` return type.

	/// Access the encoded data.

}

impl<T: Decode> DoubleEncoded<T> {

	/// Decode the inner encoded value and store it.

	/// Returns a reference to the value in case of success and `Err(())` in case the decoding

	/// fails.

	/// Move the decoded value out or (if not present) decode `encoded`.

	/// Provides an API similar to `TryInto` that allows fallible conversion to the inner value

	/// type. `TryInto` implementation would collide with std blanket implementation based on

	/// `TryFrom`.

}

#[cfg(test)]

mod tests {

	use super::*;

	#[test]

	fn ensure_decoded_works() {

		let val: u64 = 42;

		let mut encoded: DoubleEncoded<_> = Encode::encode(&val).into();

		assert_eq!(encoded.ensure_decoded(), Ok(&val));

	}

	#[test]

	fn take_decoded_works() {

		let val: u64 = 42;

		let mut encoded: DoubleEncoded<_> = Encode::encode(&val).into();

		assert_eq!(encoded.take_decoded(), Ok(val));

	}

	#[test]

	fn try_into_works() {

		let val: u64 = 42;

		let encoded: DoubleEncoded<_> = Encode::encode(&val).into();

		assert_eq!(encoded.try_into(), Ok(val));

	}

}