gasless 0.1.3

Gasless Transactions in Rust for SKALE Network
Documentation 
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use node_bindgen::derive::node_bindgen;
use alloy_primitives::{hex, Address, B256, U256};
use rand::Rng;
use std::time::{Instant, Duration};

#[node_bindgen(name = "mineGasForTransaction")]
pub async fn mine_gas_for_transaction(gas_amount: u32, address: String, nonce: u32) -> Result<MiningOutput, String> {
    // Function implementation remains the same
    // Validate and parse input
    if !is_address(&address) {
        return Err("Invalid Address".to_string());
    }
    
    let address = Address::parse_checksummed(&address, None)
        .map_err(|_| "Invalid address format".to_string())?;
    
    // Perform mining
    let result = mine_free_gas(gas_amount, address, nonce).unwrap();
    
    Ok(MiningOutput {
        duration: result.0.as_secs_f64() * 1000.0, // Convert to milliseconds
        gas_price: format!("0x{}", hex::encode(result.1.to_be_bytes::<32>())),
    })
}

// Export struct with JavaScript-friendly name
#[node_bindgen]
pub struct MiningOutput {
    pub duration: f64,
    pub gas_price: String,
}

// Helper functions remain the same
fn is_address(value: &str) -> bool {
    if !value.starts_with("0x") || value.len() != 42 {
        return false;
    }
    value[2..].chars().all(|c| c.is_ascii_hexdigit())
}

fn mine_free_gas(gas_amount: u32, address: Address, nonce: u32) -> Result<(Duration, U256), String> {
    // Implementation remains the same
    // Calculate nonce hash
    let nonce_bytes = U256::from(nonce).to_be_bytes::<32>();
    let nonce_hash = U256::from_be_bytes(B256::from(keccak256(&nonce_bytes)).0);
    
    // Calculate address hash
    let address_hash = U256::from_be_bytes(B256::from(keccak256(address.as_slice())).0);
    
    // XOR nonce and address hashes
    let nonce_address_xor = nonce_hash ^ address_hash;
    
    // Max U256 value
    let div_constant = U256::MAX;
    
    let start = Instant::now();
    let mut rng = rand::thread_rng();
    let mut iterations = 0;
    
    // Mining loop
    loop {
        // Generate random candidate
        let mut candidate_bytes = [0u8; 32];
        rng.fill(&mut candidate_bytes);
        let candidate = U256::from_be_bytes(candidate_bytes);
        
        // Calculate candidate hash
        let candidate_hash = U256::from_be_bytes(B256::from(keccak256(&candidate.to_be_bytes::<32>())).0);
        
        // XOR with previous result
        let result_hash = nonce_address_xor ^ candidate_hash;
        
        // Avoid division by zero
        if result_hash == U256::ZERO {
            continue;
        }
        
        // Calculate external gas
        let external_gas = div_constant / result_hash;
        
        // Check if we found a solution
        if external_gas >= U256::from(gas_amount) {
            let duration = start.elapsed();
            return Ok((duration, candidate));
        }
        
        // Yield to the event loop every 5000 iterations
        iterations += 1;
        if iterations % 5000 == 0 {
            std::thread::yield_now();
        }
    }
}

fn keccak256(data: impl AsRef<[u8]>) -> [u8; 32] {
    use sha3::{Digest, Keccak256};
    let mut hasher = Keccak256::new();
    hasher.update(data);
    hasher.finalize().into()
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_is_address() {
        assert!(is_address("0x1234567890123456789012345678901234567890"));
        assert!(!is_address("0x12345"));
        assert!(!is_address("not_an_address"));
    }
    
    #[test]
    fn test_basic_mining() {
        let address = Address::parse_checksummed("0x1234567890123456789012345678901234567890", None).unwrap();
        let result = mine_free_gas(21000, address, 1);
        assert!(result.is_ok());
    }
    
    #[tokio::test]
    async fn test_skale_pow_mining() {
        let from_address = Address::parse_checksummed("0x742d35Cc6634C0532925a3b844Bc454e4438f44e", None).unwrap();
        let nonce = 42;
        let gas = 21000;
        
        println!("Testing SKALE PoW gas mining");
        
        let start = Instant::now();
        let result = mine_free_gas(gas, from_address, nonce).unwrap();
        
        let elapsed = start.elapsed();
        println!("Mining completed successfully!");
        println!("Gas price: 0x{}", hex::encode(result.1.to_be_bytes::<32>()));
        println!("Mining took: {} seconds", result.0.as_secs_f64());
        println!("Actual elapsed time: {:.2} seconds", elapsed.as_secs_f64());
        
        assert!(result.0.as_secs_f64() > 0.0, "Duration should be positive");
    }
}