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use serde::{Deserialize, Serialize};
use sha2::Digest;
use crate::{BlockData, BlockHash, BlockId, BlockNonce, BlockTime};
#[derive(Clone, Debug, Deserialize, Hash, PartialEq, Serialize)]
pub struct Block {
pub id: BlockId,
pub data: BlockData,
pub hash: BlockHash,
pub nonce: BlockNonce,
pub previous: BlockHash,
pub timestamp: BlockTime,
}
impl Block {
pub fn new(data: BlockData, id: BlockId, previous: BlockHash) -> Self {
let timestamp = crate::utils::timestamp();
let (nonce, hash) = create_block(data.clone(), id, previous.clone(), timestamp.clone());
Self { id, data, hash, nonce, previous, timestamp }
}
pub fn consensus(&self, data: BlockData, id: BlockId, previous: BlockHash, timestamp: BlockTime) -> (BlockNonce, BlockHash) {
create_block(data, id, previous, timestamp)
}
}
pub fn compute_hash_binary_repr(hash: &[u8]) -> String {
let mut res: String = String::default();
for c in hash {
res.push_str(&format!("{:b}", c));
}
res
}
pub fn determine_block_validity(block: &Block, previous_block: &Block) -> bool {
if block.previous != previous_block.hash {
log::warn!("block with id: {} has wrong previous hash", block.id);
return false;
} else if !compute_hash_binary_repr(
&hex::decode(&block.hash).expect("can decode from hex"),
)
.starts_with(crate::DIFFICULTY_PREFIX)
{
log::warn!("block with id: {} has invalid difficulty", block.id);
return false;
} else if block.id != previous_block.id + 1 {
log::warn!(
"block with id: {} is not the next block after the latest: {}",
block.id, previous_block.id
);
return false;
} else if hex::encode(compute_hash(
block.id.clone(),
block.timestamp.clone(),
block.previous.clone(),
block.data.clone(),
block.nonce.clone(),
)) != block.hash
{
log::warn!("block with id: {} has invalid hash", block.id);
return false;
}
true
}
pub fn determine_chain_validity(chain: &[Block]) -> bool {
for i in 0..chain.len() {
if i == 0 {
continue;
}
let first = chain.get(i - 1).expect("has to exist");
let second = chain.get(i).expect("has to exist");
if !determine_block_validity(second, first) {
return false;
}
}
true
}
pub fn create_block(data: BlockData, id: BlockId, previous: BlockHash, timestamp: BlockTime) -> (BlockNonce, BlockHash) {
log::info!("Creating a new block...");
let mut nonce = 0;
loop {
if nonce % 100000 == 0 {
log::info!("nonce: {}", nonce);
}
let hash = compute_hash(id, timestamp, previous.clone(), data.clone(), nonce);
let binary_hash = compute_hash_binary_repr(&hash);
if binary_hash.starts_with(crate::DIFFICULTY_PREFIX) {
log::info!(
"mined! nonce: {}, hash: {}, binary hash: {}",
nonce,
hex::encode(&hash),
binary_hash
);
return (nonce, hex::encode(hash));
}
nonce += 1;
}
}
pub fn compute_hash(id: BlockId, timestamp: BlockTime, previous: BlockHash, data: BlockData, nonce: BlockNonce) -> Vec<u8> {
let data = serde_json::json!({
"id": id,
"previous": previous,
"data": data,
"timestamp": timestamp,
"nonce": nonce
});
let mut hasher = sha2::Sha256::new();
hasher.update(data.to_string().as_bytes());
hasher.finalize().as_slice().to_owned()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_curate_block() {
let id = 0;
let previous_hash = "".to_string();
let data = "".to_string();
let block = Block::new(data.clone(), id, previous_hash.clone());
println!("{:#?}", &block);
assert_eq!(&block, &block)
}
}
