#include <string>
#include <chrono>

struct Block {
    int index;
    std::string previousHash;
    std::string hash;
    std::chrono::system_clock::time_point timestamp;
    int nonce;
    std::vector<Transaction> transactions;
};

class Transaction {
public:
    std::string sender;
    std::string receiver;
    float amount;
    std::string timestamp;

    Transaction(std::string sender, std::string receiver, float amount) : sender(sender), receiver(receiver), amount(amount) {
        // Generate timestamp for the transaction
        std::time_t now = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
        timestamp = std::ctime(&now);
    }
};

std::string calculateProofOfWork(const std::string& data, int difficulty) {
    int nonce = 0;
    std::string hash;

    do {
        hash = sha256(data + std::to_string(nonce));
        nonce++;
    } while (!isValidProof(hash, difficulty));

    return hash;
}

Block createBlock(int index, std::string previousHash, std::vector<Transaction> transactions, int difficulty) {
    Block block;
    block.index = index;
    block.previousHash = previousHash;
    block.timestamp = std::chrono::system_clock::now();
    block.transactions = transactions;

    std::string data = std::to_string(index) + previousHash + block.timestamp + transactionsToString(transactions);
    block.hash = calculateProofOfWork(data, difficulty);

    return block;
}

void addBlock(std::vector<Block>& blockchain, Block newBlock) {
    blockchain.push_back(newBlock);
}

int main() {
    std::vector<Block> blockchain;
    int difficulty = 4; // Number of leading zeros required for Proof of Work

    // Create genesis block
    std::vector<Transaction> genesisTransactions;
    genesisTransactions.push_back(Transaction("Genesis", "Alice", 100));
    Block genesisBlock = createBlock(0, "0", genesisTransactions, difficulty);
    addBlock(blockchain, genesisBlock);

    // Create new transaction and add to a new block
    std::vector<Transaction> transactions;
    transactions.push_back(Transaction("Alice", "Bob", 50));
    Block newBlock = createBlock(blockchain.size(), blockchain.back().hash, transactions, difficulty);
    addBlock(blockchain, newBlock);

    return 0;
}