//! Tests for synchronous distributed key generation.

extern crate env_logger;
extern crate hbbft;
extern crate pairing;
extern crate rand;

use std::collections::BTreeMap;

use hbbft::crypto::{PublicKey, SecretKey};
use hbbft::sync_key_gen::{ProposeOutcome, SyncKeyGen};

fn test_sync_key_gen_with(threshold: usize, node_num: usize) {
    // Generate individual key pairs for encryption. These are not suitable for threshold schemes.
    let sec_keys: Vec<SecretKey> = (0..node_num).map(|_| rand::random()).collect();
    let pub_keys: BTreeMap<usize, PublicKey> = sec_keys
        .iter()
        .map(|sk| sk.public_key())
        .enumerate()
        .collect();

    // Create the `SyncKeyGen` instances and initial proposals.
    let mut nodes = Vec::new();
    let proposals: Vec<_> = sec_keys
        .into_iter()
        .enumerate()
        .map(|(id, sk)| {
            let (sync_key_gen, proposal) = SyncKeyGen::new(&id, sk, pub_keys.clone(), threshold);
            nodes.push(sync_key_gen);
            proposal
        })
        .collect();

    // Handle the first `threshold + 1` proposals. Those should suffice for key generation.
    let mut accepts = Vec::new();
    for (sender_id, proposal) in proposals[..=threshold].iter().enumerate() {
        for (node_id, node) in nodes.iter_mut().enumerate() {
            let proposal = proposal.clone().expect("proposal");
            let accept = match node.handle_propose(&sender_id, proposal) {
                Some(ProposeOutcome::Valid(accept)) => accept,
                _ => panic!("invalid proposal"),
            };
            // Only the first `threshold + 1` manage to commit their `Accept`s.
            if node_id <= 2 * threshold {
                accepts.push((node_id, accept));
            }
        }
    }

    // Handle the `Accept`s from `2 * threshold + 1` nodes.
    for (sender_id, accept) in accepts {
        for node in &mut nodes {
            assert!(!node.is_ready()); // Not enough `Accept`s yet.
            node.handle_accept(&sender_id, accept.clone());
        }
    }

    // Compute the keys and test a threshold signature.
    let msg = "Help I'm trapped in a unit test factory";
    let pub_key_set = nodes[0].generate().0;
    let sig_shares: BTreeMap<_, _> = nodes
        .iter()
        .enumerate()
        .map(|(idx, node)| {
            assert!(node.is_ready());
            let (pks, opt_sk) = node.generate();
            let sk = opt_sk.expect("new secret key");
            assert_eq!(pks, pub_key_set);
            let sig = sk.sign(msg);
            assert!(pks.public_key_share(idx as u64).verify(&sig, msg));
            (idx as u64, sig)
        })
        .collect();
    let sig = pub_key_set
        .combine_signatures(sig_shares.iter().take(threshold + 1))
        .expect("signature shares match");
    assert!(pub_key_set.public_key().verify(&sig, msg));
}

#[test]
fn test_sync_key_gen() {
    // This returns an error in all but the first test.
    let _ = env_logger::try_init();

    for &node_num in &[1, 2, 3, 4, 8, 15] {
        let threshold = (node_num - 1) / 3;
        test_sync_key_gen_with(threshold, node_num);
    }
}