data_chain 0.1.1

// Copyright 2015 MaidSafe.net limited.
//
// This SAFE Network Software is licensed to you under (1) the MaidSafe.net
// Commercial License,
// version 1.0 or later, or (2) The General Public License (GPL), version 3,
// depending on which
// licence you accepted on initial access to the Software (the "Licences").
//
// By contributing code to the SAFE Network Software, or to this project
// generally, you agree to be
// bound by the terms of the MaidSafe Contributor Agreement, version 1.0.
// This, along with the
// Licenses can be found in the root directory of this project at LICENSE,
// COPYING and CONTRIBUTOR.
//
// Unless required by applicable law or agreed to in writing, the SAFE Network
// Software distributed
// under the GPL Licence is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
// OR CONDITIONS OF ANY
// KIND, either express or implied.
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// Please review the Licences for the specific language governing permissions
// and limitations
// relating to use of the SAFE Network Software.

use maidsafe_utilities::serialisation;
use sodiumoxide::crypto::sign::{Signature, PublicKey, SecretKey};
use sodiumoxide::crypto;
use block_identifier::{BlockIdentifier, LinkDescriptor};
use error::Error;

/// Descriptor is the xored group members starting with base of 0000..:32
/// This process is faster than hash and means group can be unordered
/// which is beneficial under heavy churn and out of order links being sent.
pub fn create_link_descriptor(group: &[PublicKey]) -> LinkDescriptor {
    let mut base = [0u8; 32];
    for key in group.iter() {
        for item in key.0.iter().cloned().enumerate() {
            base[item.0] ^= item.1
        }
    }
    base
}


/// Proof as provided by a close group member
#[derive(RustcEncodable, RustcDecodable, PartialEq, Debug, Clone)]
pub struct NodeBlockProof {
    key: PublicKey,
    sig: Signature,
}

impl NodeBlockProof {
    /// cstr
    pub fn new(key: PublicKey, sig: Signature) -> NodeBlockProof {
        NodeBlockProof {
            key: key,
            sig: sig,
        }
    }

    /// getter
    pub fn key(&self) -> &PublicKey {
        &self.key
    }

    /// getter
    pub fn sig(&self) -> &Signature {
        &self.sig
    }
}

/// If data block then this is sent by any group member when data is `Put`, `Post` or `Delete`.
/// If this is a link then it is sent with a `churn` event.
/// A `Link` is a nodeblock that each member must send each other in times of churn.
/// These will not accumulate but be `ManagedNode`  to `ManagedNode` messages in the routing layer
#[derive(RustcEncodable, RustcDecodable, PartialEq, Debug, Clone)]
pub struct NodeBlock {
    identifier: BlockIdentifier,
    proof: NodeBlockProof,
}

impl NodeBlock {
    /// Create a Block (used by nodes in network to send to holders of `DataChains`)
    pub fn new(pub_key: &PublicKey,
               secret_key: &SecretKey,
               data_identifier: BlockIdentifier)
               -> Result<NodeBlock, Error> {
        let signature =
            crypto::sign::sign_detached(&try!(serialisation::serialise(&data_identifier))[..],
                                        secret_key);

        Ok(NodeBlock {
            identifier: data_identifier,
            proof: NodeBlockProof::new(*pub_key, signature),
        })

    }

    /// Getter
    pub fn identifier(&self) -> &BlockIdentifier {
        &self.identifier
    }
    /// Getter
    pub fn proof(&self) -> &NodeBlockProof {
        &self.proof
    }

    /// validate signed correctly
    pub fn validate(&self) -> bool {
        let data = if let Ok(data) = serialisation::serialise(&self.identifier) {
            data
        } else {
            return false;
        };
        crypto::sign::verify_detached(self.proof.sig(), &data[..], self.proof.key())
    }

    /// validate signed correctly
    pub fn validate_detached(&self, identifier: BlockIdentifier) -> bool {
        let data = if let Ok(data) = serialisation::serialise(&identifier) {
            data
        } else {
            return false;
        };
        crypto::sign::verify_detached(self.proof.sig(), &data[..], self.proof.key())
    }
}

#[cfg(test)]

mod tests {
    use super::*;
    use block_identifier::BlockIdentifier;
    use sodiumoxide::crypto;
    use sodiumoxide::crypto::hash::sha256;

    #[test]
    fn node_block_comparisons() {
        ::sodiumoxide::init();
        let keys = crypto::sign::gen_keypair();
        let test_data1 = BlockIdentifier::Link(sha256::hash(b"1").0);
        let test_data2 = BlockIdentifier::Link(sha256::hash(b"1").0);
        let test_data3 = BlockIdentifier::ImmutableData(sha256::hash(b"1"));
        let test_node_data_block1 = NodeBlock::new(&keys.0, &keys.1, test_data1).expect("fail1");
        let test_node_data_block2 = NodeBlock::new(&keys.0, &keys.1, test_data2).expect("fail2");
        let test_node_data_block3 = NodeBlock::new(&keys.0, &keys.1, test_data3).expect("fail3");
        assert!(test_node_data_block1.validate());
        assert!(test_node_data_block2.validate());
        assert!(test_node_data_block3.validate());
        assert_eq!(test_node_data_block1.clone(), test_node_data_block2.clone());
        assert!(test_node_data_block1 != test_node_data_block3.clone());
        assert!(test_node_data_block2 != test_node_data_block3);

    }
}