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//! Utility functions for the MPC specification.

use crate::broadcast::BroadcastRelay;
use crate::messages::Message;
use crate::party::ChannelConfig;
use std::sync::mpsc::{channel, Receiver, Sender};

/// Set up channel configurations for parties. Returns a vector of Channel Configurations.
pub fn set_up_channels(n: usize) -> (BroadcastRelay, Vec<ChannelConfig>) {
    let party_channels = (0..n)
        .map(|id| (id, channel()))
        .collect::<Vec<(usize, (Sender<Message>, Receiver<Message>))>>();

    let parties_tx: Vec<Sender<Message>> = party_channels
        .iter()
        .map(|(_, (tx, _))| tx.clone())
        .collect();

    let evaluator = party_channels[0].1 .0.clone();
    let (broadcast_sender, broadcast_receiver) = channel::<Message>();

    let channel_configs: Vec<ChannelConfig> = party_channels
        .into_iter()
        .map(|(id, (_tx, rx))| ChannelConfig {
            id,
            listen: rx,
            parties: parties_tx.clone(),
            evaluator: evaluator.clone(),
            broadcast: broadcast_sender.clone(),
        })
        .collect();

    let broadcast_channels = BroadcastRelay::new(broadcast_receiver, parties_tx.clone());

    (broadcast_channels, channel_configs)
}

pub(crate) fn ith_bit(i: usize, bytes: &[u8]) -> bool {
    let byte_index = i / 8;
    let bit_index = 7 - i % 8;
    ((bytes[byte_index] >> bit_index) & 1u8) == 1u8
}