// Copyright 2017 Parity Technologies (UK) Ltd.
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//! The `peerstore` crate allows one to store information about a peer.
//!
//! `peerstore` is a key-value database, where the keys are multihashes (which usually corresponds
//! to the hash of the public key of the peer, but that is not enforced by this crate) and the
//! values are the public key and a list of multiaddresses. Additionally, the multiaddresses stored
//! by the `peerstore` have a time-to-live after which they disappear.
//!
//! This crate consists of a generic `Peerstore` trait and the follow implementations:
//!
//! - `JsonPeerstore`: Stores the information in a single JSON file.
//! - `MemoryPeerstore`: Stores the information in memory.
//!
//! Note that the peerstore implementations do not consider information inside a peer store to be
//! critical. In case of an error (eg. corrupted file, disk error, etc.) they will prefer to lose
//! data rather than returning the error.
//!
//! # Example
//! 
//! ```
//! extern crate multiaddr;
//! extern crate libp2p_peerstore;
//! 
//! # fn main() {
//! use libp2p_peerstore::memory_peerstore::MemoryPeerstore;
//! use libp2p_peerstore::{PeerId, Peerstore, PeerAccess};
//! use multiaddr::Multiaddr;
//! use std::time::Duration;
//! 
//! // In this example we use a `MemoryPeerstore`, but you can easily swap it for another backend.
//! let mut peerstore = MemoryPeerstore::empty();
//! let peer_id = PeerId::from_public_key(&[1, 2, 3, 4]);
//! 
//! // Let's write some information about a peer.
//! {
//!     // `peer_or_create` mutably borrows the peerstore, so we have to do it in a local scope.
//!     let mut peer = peerstore.peer_or_create(&peer_id);
//!     peer.add_addr("/ip4/10.11.12.13/tcp/20000".parse::<Multiaddr>().unwrap(),
//!                   Duration::from_millis(5000));
//! }
//! 
//! // Now let's load back the info.
//! {
//!     let mut peer = peerstore.peer(&peer_id).expect("peer doesn't exist in the peerstore");
//!     assert_eq!(peer.addrs().collect::<Vec<_>>(),
//!                &["/ip4/10.11.12.13/tcp/20000".parse::<Multiaddr>().unwrap()]);
//! }
//! # }
//! ```

extern crate base58;
extern crate datastore;
extern crate futures;
extern crate multiaddr;
extern crate multihash;
extern crate owning_ref;
extern crate serde;
#[macro_use]
extern crate serde_derive;

use std::fmt;
use base58::ToBase58;

pub use self::peerstore::{Peerstore, PeerAccess};

#[macro_use]
mod peerstore_tests;

pub mod json_peerstore;
pub mod memory_peerstore;
mod peerstore;
mod peer_info;

pub type TTL = std::time::Duration;

/// Identifier of a peer of the network.
///
/// The data is a multihash of the public key of the peer.
// TODO: maybe keep things in decoded version?
#[derive(Clone, PartialEq, Eq, Hash)]
pub struct PeerId {
    multihash: Vec<u8>,
}

impl fmt::Debug for PeerId {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "PeerId({})", self.multihash.to_base58())
    }
}

impl PeerId {
    /// Builds a `PeerId` from a public key.
    #[inline]
    pub fn from_public_key(public_key: &[u8]) -> PeerId {
        let data = multihash::encode(multihash::Hash::SHA2256, public_key)
            .expect("sha2-256 is always supported");
        PeerId { multihash: data }
    }

    /// Checks whether `data` is a valid `PeerId`. If so, returns the `PeerId`. If not, returns
    /// back the data as an error.
    #[inline]
    pub fn from_bytes(data: Vec<u8>) -> Result<PeerId, Vec<u8>> {
        match multihash::decode(&data) {
            Ok(_) => Ok(PeerId { multihash: data }),
            Err(_) => Err(data),
        }
    }

    /// Returns a raw bytes representation of this `PeerId`.
    #[inline]
    pub fn into_bytes(self) -> Vec<u8> {
        self.multihash
    }

    /// Returns a raw bytes representation of this `PeerId`.
    #[inline]
    pub fn as_bytes(&self) -> &[u8] {
        &self.multihash
    }

    /// Returns the raw bytes of the hash of this `PeerId`.
    #[inline]
    pub fn hash(&self) -> &[u8] {
        let multihash::Multihash { digest, .. } = multihash::decode(&self.multihash)
            .expect("our inner value should always be valid");
        digest
    }

    /// Checks whether the public key passed as parameter matches the public key of this `PeerId`.
    pub fn is_public_key(&self, public_key: &[u8]) -> bool {
        let multihash::Multihash { alg, .. } = multihash::decode(&self.multihash)
            .expect("our inner value should always be valid");
        let compare = multihash::encode(alg, public_key)
            .expect("unsupported multihash algorithm");     // TODO: what to do here?
        compare == self.multihash
    }
}