// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program 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.

// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.

use crate::{multihash::Multihash, PeerId};
use bytes::Bytes;
use libp2p_kad::RecordKey as Libp2pKey;
use litep2p::protocol::libp2p::kademlia::{Record as Litep2pRecord, RecordKey as Litep2pKey};
use std::{error::Error, fmt, time::Instant};

/// The (opaque) key of a record.
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct Key(Bytes);

impl Key {
	/// Creates a new key from the bytes of the input.
	pub fn new<K: AsRef<[u8]>>(key: &K) -> Self {
		Key(Bytes::copy_from_slice(key.as_ref()))
	}

	/// Copies the bytes of the key into a new vector.
	pub fn to_vec(&self) -> Vec<u8> {
		self.0.to_vec()
	}
}

impl AsRef<[u8]> for Key {
	fn as_ref(&self) -> &[u8] {
		&self.0[..]
	}
}

impl From<Vec<u8>> for Key {
	fn from(v: Vec<u8>) -> Key {
		Key(Bytes::from(v))
	}
}

impl From<Multihash> for Key {
	fn from(m: Multihash) -> Key {
		Key::from(m.to_bytes())
	}
}

impl From<Litep2pKey> for Key {
	fn from(key: Litep2pKey) -> Self {
		Self::from(key.to_vec())
	}
}

impl From<Key> for Litep2pKey {
	fn from(key: Key) -> Self {
		Self::from(key.to_vec())
	}
}

impl From<Libp2pKey> for Key {
	fn from(key: Libp2pKey) -> Self {
		Self::from(key.to_vec())
	}
}

impl From<Key> for Libp2pKey {
	fn from(key: Key) -> Self {
		Self::from(key.to_vec())
	}
}

/// A record stored in the DHT.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Record {
	/// Key of the record.
	pub key: Key,
	/// Value of the record.
	pub value: Vec<u8>,
	/// The (original) publisher of the record.
	pub publisher: Option<PeerId>,
	/// The expiration time as measured by a local, monotonic clock.
	pub expires: Option<Instant>,
}

impl Record {
	/// Creates a new record for insertion into the DHT.
	pub fn new(key: Key, value: Vec<u8>) -> Self {
		Record { key, value, publisher: None, expires: None }
	}

	/// Checks whether the record is expired w.r.t. the given `Instant`.
	pub fn is_expired(&self, now: Instant) -> bool {
		self.expires.map_or(false, |t| now >= t)
	}
}

impl From<libp2p_kad::Record> for Record {
	fn from(out: libp2p_kad::Record) -> Self {
		let vec: Vec<u8> = out.key.to_vec();
		let key: Key = vec.into();
		let publisher = out.publisher.map(Into::into);
		Record { key, value: out.value, publisher, expires: out.expires }
	}
}

impl From<Record> for Litep2pRecord {
	fn from(val: Record) -> Self {
		let vec: Vec<u8> = val.key.to_vec();
		let key: Litep2pKey = vec.into();
		let publisher = val.publisher.map(Into::into);
		Litep2pRecord { key, value: val.value, publisher, expires: val.expires }
	}
}

impl From<Record> for libp2p_kad::Record {
	fn from(a: Record) -> libp2p_kad::Record {
		let peer = a.publisher.map(Into::into);
		libp2p_kad::Record {
			key: a.key.to_vec().into(),
			value: a.value,
			publisher: peer,
			expires: a.expires,
		}
	}
}

/// A record either received by the given peer or retrieved from the local
/// record store.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PeerRecord {
	/// The peer from whom the record was received. `None` if the record was
	/// retrieved from local storage.
	pub peer: Option<PeerId>,
	pub record: Record,
}

impl From<libp2p_kad::PeerRecord> for PeerRecord {
	fn from(out: libp2p_kad::PeerRecord) -> Self {
		let peer = out.peer.map(Into::into);
		let record = out.record.into();
		PeerRecord { peer, record }
	}
}

/// An error during signing of a message.
#[derive(Debug)]
pub struct SigningError {
	msg: String,
	source: Option<Box<dyn Error + Send + Sync>>,
}

/// An error during encoding of key material.
#[allow(dead_code)]
impl SigningError {
	pub(crate) fn new<S: ToString>(msg: S) -> Self {
		Self { msg: msg.to_string(), source: None }
	}

	pub(crate) fn source(self, source: impl Error + Send + Sync + 'static) -> Self {
		Self { source: Some(Box::new(source)), ..self }
	}
}

impl fmt::Display for SigningError {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		write!(f, "Key signing error: {}", self.msg)
	}
}

impl Error for SigningError {
	fn source(&self) -> Option<&(dyn Error + 'static)> {
		self.source.as_ref().map(|s| &**s as &dyn Error)
	}
}