rust-mc-status 2.0.0

//! Client for querying Minecraft server status.
//!
//! This module provides the [`McClient`] struct for performing server status queries.
//! It supports both Java Edition and Bedrock Edition servers with automatic SRV record
//! lookup, DNS caching, and batch queries.
//!
//! # Examples
//!
//! ## Basic Usage
//!
//! ```no_run
//! use rust_mc_status::{McClient, ServerEdition};
//! use std::time::Duration;
//!
//! # #[tokio::main]
//! # async fn main() -> Result<(), Box<dyn std::error::Error>> {
//! let client = McClient::new()
//!     .with_timeout(Duration::from_secs(5))
//!     .with_max_parallel(10);
//!
//! // Ping a Java server (automatically uses SRV lookup if port not specified)
//! let status = client.ping("mc.hypixel.net", ServerEdition::Java).await?;
//! println!("Server is online: {}", status.online);
//! # Ok(())
//! # }
//! ```
//!
//! ## Batch Queries
//!
//! ```no_run
//! use rust_mc_status::{McClient, ServerEdition, ServerInfo};
//!
//! # #[tokio::main]
//! # async fn main() -> Result<(), Box<dyn std::error::Error>> {
//! let client = McClient::new();
//! let servers = vec![
//!     ServerInfo {
//!         address: "mc.hypixel.net".to_string(),
//!         edition: ServerEdition::Java,
//!     },
//!     ServerInfo {
//!         address: "geo.hivebedrock.network:19132".to_string(),
//!         edition: ServerEdition::Bedrock,
//!     },
//! ];
//!
//! let results = client.ping_many(&servers).await;
//! for (server, result) in results {
//!     match result {
//!         Ok(status) => println!("{}: Online ({}ms)", server.address, status.latency),
//!         Err(e) => println!("{}: Error - {}", server.address, e),
//!     }
//! }
//! # Ok(())
//! # }
//! ```
//!
//! ## SRV Record Lookup
//!
//! When pinging Java servers without an explicit port, the library automatically
//! performs an SRV DNS lookup for `_minecraft._tcp.{hostname}`. This mimics the
//! behavior of the official Minecraft client.
//!
//! ```no_run
//! use rust_mc_status::{McClient, ServerEdition};
//!
//! # #[tokio::main]
//! # async fn main() -> Result<(), Box<dyn std::error::Error>> {
//! let client = McClient::new();
//!
//! // This will perform SRV lookup for _minecraft._tcp.example.com
//! let status = client.ping("example.com", ServerEdition::Java).await?;
//!
//! // This will skip SRV lookup and use port 25565 directly
//! let status = client.ping("example.com:25565", ServerEdition::Java).await?;
//! # Ok(())
//! # }
//! ```

use std::io::Cursor;
use std::net::{SocketAddr, ToSocketAddrs};
use std::sync::Arc;
use std::time::{Duration, SystemTime};

use dashmap::DashMap;
use once_cell::sync::Lazy;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::net::{TcpStream, UdpSocket};
use tokio::sync::OnceCell;
use tokio::time::timeout;
use trust_dns_resolver::{
    config::{ResolverConfig, ResolverOpts},
    TokioAsyncResolver,
};

use crate::error::McError;
use crate::models::*;

/// Default timeout for server queries (10 seconds).
const DEFAULT_TIMEOUT: Duration = Duration::from_secs(10);

/// Default maximum number of parallel queries (10).
const DEFAULT_MAX_PARALLEL: usize = 10;

/// DNS cache TTL in seconds (5 minutes).
const DNS_CACHE_TTL: u64 = 300;

/// Default Java Edition port.
const JAVA_DEFAULT_PORT: u16 = 25565;

/// Default Bedrock Edition port.
const BEDROCK_DEFAULT_PORT: u16 = 19132;

/// Protocol version for status requests (legacy protocol).
const PROTOCOL_VERSION: i32 = 47;

/// Handshake packet ID.
const HANDSHAKE_PACKET_ID: i32 = 0x00;

/// Status request packet ID.
const STATUS_REQUEST_PACKET_ID: i32 = 0x00;

/// Status response packet ID.
const STATUS_RESPONSE_PACKET_ID: i32 = 0x00;

/// Maximum VarInt size (35 bits).
const MAX_VARINT_SHIFT: u32 = 35;

/// Initial buffer capacity for packets.
const INITIAL_PACKET_CAPACITY: usize = 64;

/// Initial response buffer capacity.
const INITIAL_RESPONSE_CAPACITY: usize = 1024;

/// Read buffer size.
const READ_BUFFER_SIZE: usize = 4096;

/// Bedrock ping packet size.
const BEDROCK_PING_PACKET_SIZE: usize = 35;

/// Minimum Bedrock response size.
const BEDROCK_MIN_RESPONSE_SIZE: usize = 35;

/// DNS resolution cache.
///
/// Maps `"{host}:{port}"` to `(SocketAddr, timestamp)`.
static DNS_CACHE: Lazy<DashMap<String, (SocketAddr, SystemTime)>> = Lazy::new(DashMap::new);

/// SRV record cache.
///
/// Maps `"srv:{host}"` to `((target_host, port), timestamp)`.
static SRV_CACHE: Lazy<DashMap<String, ((String, u16), SystemTime)>> = Lazy::new(DashMap::new);

/// Global DNS resolver for SRV lookups.
///
/// Initialized lazily on first use and reused for all subsequent lookups.
/// This improves performance by avoiding resolver creation overhead.
static RESOLVER: OnceCell<Arc<TokioAsyncResolver>> = OnceCell::const_new();

/// Initialize the global DNS resolver.
///
/// Creates a resolver with default configuration optimized for performance.
async fn get_resolver() -> Arc<TokioAsyncResolver> {
    RESOLVER
        .get_or_init(|| async {
            let config = ResolverConfig::default();
            let mut opts = ResolverOpts::default();
            // Optimize for performance
            opts.cache_size = 1000;
            opts.positive_min_ttl = Some(Duration::from_secs(60));
            opts.negative_min_ttl = Some(Duration::from_secs(10));
            
            Arc::new(TokioAsyncResolver::tokio(config, opts))
        })
        .await
        .clone()
}

/// Minecraft server status client.
///
/// This client provides methods for querying Minecraft server status with
/// support for both Java Edition and Bedrock Edition servers.
///
/// # Features
///
/// - Automatic SRV record lookup for Java servers
/// - DNS caching for improved performance
/// - Configurable timeouts and concurrency limits
/// - Batch queries for multiple servers
///
/// # Example
///
/// ```no_run
/// use rust_mc_status::{McClient, ServerEdition};
/// use std::time::Duration;
///
/// # #[tokio::main]
/// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let client = McClient::new()
///     .with_timeout(Duration::from_secs(5))
///     .with_max_parallel(10);
///
/// let status = client.ping("mc.hypixel.net", ServerEdition::Java).await?;
/// println!("Server is online: {}", status.online);
/// # Ok(())
/// # }
/// ```
#[derive(Clone)]
pub struct McClient {
    /// Request timeout.
    timeout: Duration,
    /// Maximum number of parallel queries.
    max_parallel: usize,
}

impl Default for McClient {
    fn default() -> Self {
        Self {
            timeout: DEFAULT_TIMEOUT,
            max_parallel: DEFAULT_MAX_PARALLEL,
        }
    }
}

impl McClient {
    /// Create a new client with default settings.
    ///
    /// Default settings:
    /// - Timeout: 10 seconds
    /// - Max parallel: 10 queries
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// let client = McClient::new();
    /// ```
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the request timeout.
    ///
    /// This timeout applies to all network operations including DNS resolution,
    /// connection establishment, and response reading.
    ///
    /// # Arguments
    ///
    /// * `timeout` - Maximum time to wait for a server response
    ///   - Default: 10 seconds
    ///   - Recommended: 5-10 seconds for most use cases
    ///   - Use shorter timeouts (1-3 seconds) for quick checks
    ///
    /// # Returns
    ///
    /// Returns `Self` for method chaining.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    /// use std::time::Duration;
    ///
    /// // Quick timeout for fast checks
    /// let fast_client = McClient::new()
    ///     .with_timeout(Duration::from_secs(2));
    ///
    /// // Longer timeout for reliable queries
    /// let reliable_client = McClient::new()
    ///     .with_timeout(Duration::from_secs(10));
    /// ```
    #[must_use]
    pub fn with_timeout(mut self, timeout: Duration) -> Self {
        self.timeout = timeout;
        self
    }

    /// Set the maximum number of parallel queries.
    ///
    /// This limit controls how many servers can be queried simultaneously
    /// when using [`ping_many`](Self::ping_many). Higher values increase
    /// throughput but consume more resources.
    ///
    /// # Arguments
    ///
    /// * `max_parallel` - Maximum number of concurrent server queries
    ///   - Default: 10
    ///   - Recommended: 5-20 for most use cases
    ///   - Higher values (50-100) for batch processing
    ///   - Lower values (1-5) for resource-constrained environments
    ///
    /// # Returns
    ///
    /// Returns `Self` for method chaining.
    ///
    /// # Performance
    ///
    /// - Higher values = faster batch processing but more memory/CPU usage
    /// - Lower values = slower but more resource-friendly
    /// - DNS and SRV caches are shared across all parallel queries
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::{McClient, ServerEdition, ServerInfo};
    ///
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// // High concurrency for batch processing
    /// let batch_client = McClient::new()
    ///     .with_max_parallel(50);
    ///
    /// // Low concurrency for resource-constrained environments
    /// let limited_client = McClient::new()
    ///     .with_max_parallel(3);
    /// # Ok(())
    /// # }
    /// ```
    #[must_use]
    pub fn with_max_parallel(mut self, max_parallel: usize) -> Self {
        self.max_parallel = max_parallel;
        self
    }

    /// Get the maximum number of parallel queries.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// let client = McClient::new().with_max_parallel(20);
    /// assert_eq!(client.max_parallel(), 20);
    /// ```
    #[must_use]
    pub fn max_parallel(&self) -> usize {
        self.max_parallel
    }

    /// Get the request timeout.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    /// use std::time::Duration;
    ///
    /// let client = McClient::new().with_timeout(Duration::from_secs(5));
    /// assert_eq!(client.timeout(), Duration::from_secs(5));
    /// ```
    #[must_use]
    pub fn timeout(&self) -> Duration {
        self.timeout
    }

    /// Clear DNS cache.
    ///
    /// This method clears all cached DNS resolutions. Useful when you need to
    /// force fresh DNS lookups or free memory.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// # #[tokio::main]
    /// # async fn main() {
    /// let client = McClient::new();
    /// client.clear_dns_cache();
    /// # }
    /// ```
    pub fn clear_dns_cache(&self) {
        DNS_CACHE.clear();
    }

    /// Clear SRV record cache.
    ///
    /// This method clears all cached SRV record lookups. Useful when you need to
    /// force fresh SRV lookups or free memory.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// # #[tokio::main]
    /// # async fn main() {
    /// let client = McClient::new();
    /// client.clear_srv_cache();
    /// # }
    /// ```
    pub fn clear_srv_cache(&self) {
        SRV_CACHE.clear();
    }

    /// Clear all caches (DNS and SRV).
    ///
    /// This method clears both DNS and SRV caches. Useful when you need to
    /// force fresh lookups or free memory.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// # #[tokio::main]
    /// # async fn main() {
    /// let client = McClient::new();
    /// client.clear_all_caches();
    /// # }
    /// ```
    pub fn clear_all_caches(&self) {
        self.clear_dns_cache();
        self.clear_srv_cache();
    }

    /// Get cache statistics.
    ///
    /// Returns the number of entries in DNS and SRV caches.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// # #[tokio::main]
    /// # async fn main() {
    /// let client = McClient::new();
    /// let stats = client.cache_stats();
    /// println!("DNS cache entries: {}", stats.dns_entries);
    /// println!("SRV cache entries: {}", stats.srv_entries);
    /// # }
    /// ```
    #[must_use]
    pub fn cache_stats(&self) -> CacheStats {
        CacheStats {
            dns_entries: DNS_CACHE.len(),
            srv_entries: SRV_CACHE.len(),
        }
    }

    /// Resolve DNS and measure resolution time.
    ///
    /// This method resolves a hostname to an IP address and returns both
    /// the resolved address and the time taken for resolution. Useful for
    /// measuring cache effectiveness and DNS performance.
    ///
    /// # Arguments
    ///
    /// * `host` - Hostname to resolve (e.g., `"mc.hypixel.net"` or `"192.168.1.1"`)
    /// * `port` - Port number (e.g., `25565` for Java, `19132` for Bedrock)
    ///
    /// # Returns
    ///
    /// Returns `Ok((SocketAddr, f64))` where:
    /// - `SocketAddr`: Resolved IP address and port
    /// - `f64`: Resolution time in milliseconds
    ///
    /// # Errors
    ///
    /// Returns [`McError::DnsError`] if DNS resolution fails.
    ///
    /// # Performance Notes
    ///
    /// - First resolution (cold cache): Typically 10-100ms
    /// - Subsequent resolutions (warm cache): Typically <1ms
    /// - Cache TTL: 5 minutes
    /// - Use [`clear_dns_cache`](Self::clear_dns_cache) to force fresh lookups
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// let client = McClient::new();
    ///
    /// // First resolution (cold cache - actual DNS lookup)
    /// let (addr1, time1) = client.resolve_dns_timed("mc.hypixel.net", 25565).await?;
    /// println!("First resolution: {:.2} ms", time1);
    /// println!("Resolved to: {}", addr1);
    ///
    /// // Second resolution (warm cache - from cache)
    /// let (addr2, time2) = client.resolve_dns_timed("mc.hypixel.net", 25565).await?;
    /// println!("Cached resolution: {:.2} ms", time2);
    /// println!("Cache speedup: {:.1}x faster", time1 / time2);
    /// println!("Time saved: {:.2} ms", time1 - time2);
    /// # Ok(())
    /// # }
    /// ```
    pub async fn resolve_dns_timed(&self, host: &str, port: u16) -> Result<(SocketAddr, f64), McError> {
        let start = std::time::Instant::now();
        let addr = self.resolve_dns(host, port).await?;
        let elapsed = start.elapsed().as_secs_f64() * 1000.0;
        Ok((addr, elapsed))
    }

    /// Ping a server and get its status.
    ///
    /// This is a convenience method that dispatches to either [`ping_java`](Self::ping_java)
    /// or [`ping_bedrock`](Self::ping_bedrock) based on the server edition.
    ///
    /// # Arguments
    ///
    /// * `address` - Server address in one of the following formats:
    ///   - `"hostname"` - Hostname without port (uses default port for edition)
    ///   - `"hostname:port"` - Hostname with explicit port
    ///   - `"192.168.1.1"` - IP address without port (uses default port)
    ///   - `"192.168.1.1:25565"` - IP address with explicit port
    /// * `edition` - Server edition: `ServerEdition::Java` or `ServerEdition::Bedrock`
    ///
    /// # Returns
    ///
    /// Returns a [`ServerStatus`] struct containing:
    /// - `online`: Whether the server is online
    /// - `ip`: Resolved IP address
    /// - `port`: Server port number
    /// - `hostname`: Original hostname used for query
    /// - `latency`: Response time in milliseconds
    /// - `dns`: Optional DNS information (A records, CNAME, TTL)
    /// - `data`: Edition-specific server data (version, players, plugins, etc.)
    ///
    /// # Errors
    ///
    /// Returns [`McError`] if:
    /// - DNS resolution fails ([`McError::DnsError`])
    /// - Connection cannot be established ([`McError::ConnectionError`])
    /// - Request times out ([`McError::Timeout`])
    /// - Server returns invalid response ([`McError::InvalidResponse`])
    /// - Invalid port number in address ([`McError::InvalidPort`])
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::{McClient, ServerEdition};
    ///
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// let client = McClient::new();
    ///
    /// // Ping Java server (automatic SRV lookup)
    /// let status = client.ping("mc.hypixel.net", ServerEdition::Java).await?;
    /// println!("Server is online: {}", status.online);
    /// println!("Latency: {:.2}ms", status.latency);
    ///
    /// // Ping Bedrock server
    /// let status = client.ping("geo.hivebedrock.network:19132", ServerEdition::Bedrock).await?;
    /// println!("Players: {}/{}", status.players().unwrap_or((0, 0)).0, status.players().unwrap_or((0, 0)).1);
    /// # Ok(())
    /// # }
    /// ```
    pub async fn ping(&self, address: &str, edition: ServerEdition) -> Result<ServerStatus, McError> {
        match edition {
            ServerEdition::Java => self.ping_java(address).await,
            ServerEdition::Bedrock => self.ping_bedrock(address).await,
        }
    }

    /// Ping a Java Edition server and get its status.
    ///
    /// This method automatically performs an SRV DNS lookup if no port is specified
    /// in the address. The lookup follows the Minecraft client behavior:
    /// - Queries `_minecraft._tcp.{hostname}` for SRV records
    /// - Uses the target host and port from the SRV record if found
    /// - Falls back to the default port (25565) if no SRV record exists
    /// - Skips SRV lookup if port is explicitly specified
    ///
    /// # Arguments
    ///
    /// * `address` - Server address in one of the following formats:
    ///   - `"hostname"` - Hostname without port (performs SRV lookup, defaults to 25565)
    ///   - `"hostname:25565"` - Hostname with explicit port (skips SRV lookup)
    ///   - `"192.168.1.1"` - IP address without port (uses port 25565)
    ///   - `"192.168.1.1:25565"` - IP address with explicit port
    ///
    /// # Returns
    ///
    /// Returns a [`ServerStatus`] with `ServerData::Java` containing:
    /// - Version information (name, protocol version)
    /// - Player information (online count, max players, sample list)
    /// - Server description (MOTD)
    /// - Optional favicon (base64-encoded PNG)
    /// - Optional plugins list
    /// - Optional mods list
    /// - Additional metadata (map, gamemode, software)
    ///
    /// # Errors
    ///
    /// Returns [`McError`] if:
    /// - DNS resolution fails ([`McError::DnsError`])
    /// - SRV lookup fails (non-critical, falls back to default port)
    /// - Connection cannot be established ([`McError::ConnectionError`])
    /// - Request times out ([`McError::Timeout`])
    /// - Server returns invalid response ([`McError::InvalidResponse`])
    /// - JSON parsing fails ([`McError::JsonError`])
    /// - Invalid port number ([`McError::InvalidPort`])
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// let client = McClient::new();
    ///
    /// // Automatic SRV lookup (queries _minecraft._tcp.mc.hypixel.net)
    /// let status = client.ping_java("mc.hypixel.net").await?;
    /// if let rust_mc_status::ServerData::Java(java) = &status.data {
    ///     println!("Version: {}", java.version.name);
    ///     println!("Players: {}/{}", java.players.online, java.players.max);
    ///     println!("Description: {}", java.description);
    /// }
    ///
    /// // Skip SRV lookup (uses port 25565 directly)
    /// let status = client.ping_java("mc.hypixel.net:25565").await?;
    /// # Ok(())
    /// # }
    /// ```
    pub async fn ping_java(&self, address: &str) -> Result<ServerStatus, McError> {
        let start = SystemTime::now();
        let (host, port) = Self::parse_address(address, JAVA_DEFAULT_PORT)?;

        // Check for SRV record first (mimics Minecraft's server address field behavior)
        // Only perform SRV lookup if port was not explicitly specified in address
        let port_explicit = address.contains(':');
        let (actual_host, actual_port) = if port_explicit {
            // Port was explicitly specified, skip SRV lookup
            (host.to_string(), port)
        } else {
            // No port specified, check for SRV record
            self.lookup_srv_record(host, port).await?
        };

        let resolved = self.resolve_dns(&actual_host, actual_port).await?;
        let dns_info = self.get_dns_info(host).await.ok(); // DNS info is optional

        let mut stream = timeout(self.timeout, TcpStream::connect(resolved))
            .await
            .map_err(|_| McError::Timeout)?
            .map_err(|e| McError::ConnectionError(e.to_string()))?;

        stream.set_nodelay(true).map_err(McError::IoError)?;

        // Send handshake - use original host and actual port in handshake packet
        // (Minecraft protocol expects original hostname in handshake, but actual port)
        self.send_handshake(&mut stream, host, actual_port).await?;

        // Send status request
        self.send_status_request(&mut stream).await?;

        // Read and parse response
        let response = self.read_response(&mut stream).await?;
        let (json, latency) = self.parse_java_response(response, start)?;

        // Build result
        Ok(ServerStatus {
            online: true,
            ip: resolved.ip().to_string(),
            port: resolved.port(),
            hostname: host.to_string(),
            latency,
            dns: dns_info,
            data: ServerData::Java(self.parse_java_json(&json)?),
        })
    }

    /// Ping a Bedrock Edition server and get its status.
    ///
    /// Bedrock Edition servers use UDP protocol and typically run on port 19132.
    /// This method sends a UDP ping packet and parses the response.
    ///
    /// # Arguments
    ///
    /// * `address` - Server address in one of the following formats:
    ///   - `"hostname"` - Hostname without port (uses default port 19132)
    ///   - `"hostname:19132"` - Hostname with explicit port
    ///   - `"192.168.1.1"` - IP address without port (uses port 19132)
    ///   - `"192.168.1.1:19132"` - IP address with explicit port
    ///
    /// # Returns
    ///
    /// Returns a [`ServerStatus`] with `ServerData::Bedrock` containing:
    /// - Edition information (e.g., "MCPE")
    /// - Version information
    /// - Player counts (online and max)
    /// - Message of the day (MOTD)
    /// - Protocol version
    /// - Server UID
    /// - Game mode information
    /// - Port information (IPv4 and IPv6)
    /// - Optional map name and software
    ///
    /// # Errors
    ///
    /// Returns [`McError`] if:
    /// - DNS resolution fails ([`McError::DnsError`])
    /// - Connection cannot be established ([`McError::ConnectionError`])
    /// - Request times out ([`McError::Timeout`])
    /// - Server returns invalid response ([`McError::InvalidResponse`])
    /// - Invalid port number ([`McError::InvalidPort`])
    /// - UTF-8 conversion fails ([`McError::Utf8Error`])
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::McClient;
    ///
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// let client = McClient::new();
    /// let status = client.ping_bedrock("geo.hivebedrock.network:19132").await?;
    ///
    /// if let rust_mc_status::ServerData::Bedrock(bedrock) = &status.data {
    ///     println!("Edition: {}", bedrock.edition);
    ///     println!("Version: {}", bedrock.version);
    ///     println!("Players: {}/{}", bedrock.online_players, bedrock.max_players);
    ///     println!("MOTD: {}", bedrock.motd);
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn ping_bedrock(&self, address: &str) -> Result<ServerStatus, McError> {
        let start = SystemTime::now();
        let (host, port) = Self::parse_address(address, BEDROCK_DEFAULT_PORT)?;
        let resolved = self.resolve_dns(host, port).await?;
        let dns_info = self.get_dns_info(host).await.ok(); // DNS info is optional

        let socket = UdpSocket::bind("0.0.0.0:0").await.map_err(McError::IoError)?;

        // Send ping packet
        let ping_packet = self.create_bedrock_ping_packet();
        timeout(self.timeout, socket.send_to(&ping_packet, resolved))
            .await
            .map_err(|_| McError::Timeout)?
            .map_err(McError::IoError)?;

        // Receive response
        let mut buf = [0u8; READ_BUFFER_SIZE];
        let (len, _) = timeout(self.timeout, socket.recv_from(&mut buf))
            .await
            .map_err(|_| McError::Timeout)?
            .map_err(McError::IoError)?;

        if len < BEDROCK_MIN_RESPONSE_SIZE {
            return Err(McError::InvalidResponse("Response too short".to_string()));
        }

        let latency = start
            .elapsed()
            .map_err(|_| McError::InvalidResponse("Time error".to_string()))?
            .as_secs_f64()
            * 1000.0;

        let pong_data = String::from_utf8_lossy(&buf[BEDROCK_PING_PACKET_SIZE..len]).to_string();

        Ok(ServerStatus {
            online: true,
            ip: resolved.ip().to_string(),
            port: resolved.port(),
            hostname: host.to_string(),
            latency,
            dns: dns_info,
            data: ServerData::Bedrock(self.parse_bedrock_response(&pong_data)?),
        })
    }

    /// Quick check if a server is online.
    ///
    /// This method performs a minimal connection check without retrieving
    /// full server status. It's faster than `ping()` but provides less information.
    /// Use this method when you only need to know if a server is reachable.
    ///
    /// # Arguments
    ///
    /// * `address` - Server address in one of the following formats:
    ///   - `"hostname"` - Hostname without port (uses default port for edition)
    ///   - `"hostname:port"` - Hostname with explicit port
    ///   - `"192.168.1.1"` - IP address without port (uses default port)
    ///   - `"192.168.1.1:25565"` - IP address with explicit port
    /// * `edition` - Server edition: `ServerEdition::Java` or `ServerEdition::Bedrock`
    ///
    /// # Returns
    ///
    /// Returns `true` if the server is reachable and responds to ping requests,
    /// `false` if the server is offline, unreachable, or times out.
    ///
    /// # Performance
    ///
    /// This method is faster than `ping()` because it:
    /// - Doesn't parse full server status
    /// - Doesn't retrieve player information
    /// - Doesn't parse JSON responses (for Java servers)
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::{McClient, ServerEdition};
    ///
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// let client = McClient::new();
    ///
    /// // Quick check without full status
    /// if client.is_online("mc.hypixel.net", ServerEdition::Java).await {
    ///     println!("Server is online!");
    ///     // Now get full status if needed
    ///     let status = client.ping("mc.hypixel.net", ServerEdition::Java).await?;
    ///     println!("Players: {}/{}", status.players().unwrap_or((0, 0)).0, status.players().unwrap_or((0, 0)).1);
    /// } else {
    ///     println!("Server is offline or unreachable");
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn is_online(&self, address: &str, edition: ServerEdition) -> bool {
        self.ping(address, edition).await.is_ok()
    }

    /// Ping multiple servers in parallel.
    ///
    /// This method queries multiple servers concurrently with a configurable
    /// concurrency limit. Results are returned in the same order as input.
    /// The concurrency limit is controlled by [`with_max_parallel`](Self::with_max_parallel).
    ///
    /// # Arguments
    ///
    /// * `servers` - Slice of [`ServerInfo`] structures containing:
    ///   - `address`: Server address (hostname or IP, optionally with port)
    ///   - `edition`: Server edition (`ServerEdition::Java` or `ServerEdition::Bedrock`)
    ///
    /// # Returns
    ///
    /// Returns a `Vec<(ServerInfo, Result<ServerStatus, McError>)>` where:
    /// - Each tuple contains the original `ServerInfo` and the query result
    /// - Results are in the same order as the input slice
    /// - `Ok(ServerStatus)` contains full server status information
    /// - `Err(McError)` contains error information (timeout, DNS error, etc.)
    ///
    /// # Performance
    ///
    /// - Queries are executed in parallel up to the configured limit
    /// - DNS and SRV caches are shared across all queries
    /// - Failed queries don't block other queries
    /// - Use `with_max_parallel()` to control resource usage
    ///
    /// # Example
    ///
    /// ```no_run
    /// use rust_mc_status::{McClient, ServerEdition, ServerInfo};
    ///
    /// # #[tokio::main]
    /// # async fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// let client = McClient::new()
    ///     .with_max_parallel(5)  // Process up to 5 servers concurrently
    ///     .with_timeout(std::time::Duration::from_secs(5));
    ///
    /// let servers = vec![
    ///     ServerInfo {
    ///         address: "mc.hypixel.net".to_string(),
    ///         edition: ServerEdition::Java,
    ///     },
    ///     ServerInfo {
    ///         address: "geo.hivebedrock.network:19132".to_string(),
    ///         edition: ServerEdition::Bedrock,
    ///     },
    /// ];
    ///
    /// let results = client.ping_many(&servers).await;
    /// for (server, result) in results {
    ///     match result {
    ///         Ok(status) => {
    ///             println!("{}: ✅ Online ({}ms)", server.address, status.latency);
    ///             if let Some((online, max)) = status.players() {
    ///                 println!("  Players: {}/{}", online, max);
    ///             }
    ///         }
    ///         Err(e) => println!("{}: ❌ Error - {}", server.address, e),
    ///     }
    /// }
    /// # Ok(())
    /// # }
    /// ```
    pub async fn ping_many(&self, servers: &[ServerInfo]) -> Vec<(ServerInfo, Result<ServerStatus, McError>)> {
        use futures::stream::StreamExt;
        use tokio::sync::Semaphore;

        let semaphore = Arc::new(Semaphore::new(self.max_parallel));
        let client = self.clone();

        let futures = servers.iter().map(|server| {
            let server = server.clone();
            let semaphore = semaphore.clone();
            let client = client.clone();

            async move {
                let _permit = semaphore.acquire().await;
                let result = client.ping(&server.address, server.edition).await;
                (server, result)
            }
        });

        futures::stream::iter(futures)
            .buffer_unordered(self.max_parallel)
            .collect()
            .await
    }

    // === Private Helper Methods ===

    /// Parse server address into host and port.
    ///
    /// # Arguments
    ///
    /// * `address` - Server address string
    /// * `default_port` - Default port to use if not specified
    ///
    /// # Returns
    ///
    /// Tuple of `(host, port)`.
    ///
    /// # Errors
    ///
    /// Returns an error if the port cannot be parsed as a `u16`.
    fn parse_address(address: &str, default_port: u16) -> Result<(&str, u16), McError> {
        if let Some((host, port_str)) = address.split_once(':') {
            let port = port_str
                .parse::<u16>()
                .map_err(|e| McError::InvalidPort(e.to_string()))?;
            Ok((host, port))
        } else {
            Ok((address, default_port))
        }
    }

    /// Lookup SRV record for Minecraft Java server.
    ///
    /// This method mimics Minecraft's server address field behavior by querying
    /// `_minecraft._tcp.{host}` for SRV records. Results are cached for 5 minutes.
    ///
    /// # Arguments
    ///
    /// * `host` - Hostname to lookup
    /// * `port` - Default port to use if no SRV record is found
    ///
    /// # Returns
    ///
    /// Tuple of `(target_host, port)` from SRV record or original values.
    ///
    /// # Errors
    ///
    /// Returns an error if DNS resolution fails critically (timeouts are handled gracefully).
    async fn lookup_srv_record(&self, host: &str, port: u16) -> Result<(String, u16), McError> {
        let cache_key = format!("srv:{}", host);

        // Check cache with TTL validation
        if let Some(entry) = SRV_CACHE.get(&cache_key) {
            let ((cached_host, cached_port), timestamp) = entry.value();
            if timestamp
                .elapsed()
                .map(|d| d.as_secs() < DNS_CACHE_TTL)
                .unwrap_or(false)
            {
                return Ok((cached_host.clone(), *cached_port));
            }
        }

        // Build SRV record name: _minecraft._tcp.{host}
        let srv_name = format!("_minecraft._tcp.{}", host);

        // Try to resolve SRV record using cached resolver
        let resolver = get_resolver().await;

        match timeout(self.timeout, resolver.srv_lookup(&srv_name)).await {
            Ok(Ok(srv_lookup)) => {
                // Get the first SRV record (sorted by priority and weight)
                if let Some(srv) = srv_lookup.iter().next() {
                    let target = srv.target().to_string().trim_end_matches('.').to_string();
                    let srv_port = srv.port();

                    // Cache and return SRV result
                    let result = (target, srv_port);
                    SRV_CACHE.insert(cache_key, (result.clone(), SystemTime::now()));
                    return Ok(result);
                }
            }
            Ok(Err(_)) => {
                // SRV record not found - this is normal, use original values
            }
            Err(_) => {
                // Timeout - use original values
            }
        }

        // No SRV record found or error occurred, use original host and port
        let result = (host.to_string(), port);
        SRV_CACHE.insert(cache_key, (result.clone(), SystemTime::now()));
        Ok(result)
    }

    /// Resolve hostname to IP address with caching.
    ///
    /// DNS resolutions are cached for 5 minutes to improve performance.
    ///
    /// # Arguments
    ///
    /// * `host` - Hostname to resolve
    /// * `port` - Port number
    ///
    /// # Returns
    ///
    /// Resolved `SocketAddr`.
    ///
    /// # Errors
    ///
    /// Returns an error if DNS resolution fails.
    async fn resolve_dns(&self, host: &str, port: u16) -> Result<SocketAddr, McError> {
        let cache_key = format!("{}:{}", host, port);

        // Check cache with TTL validation
        if let Some(entry) = DNS_CACHE.get(&cache_key) {
            let (addr, timestamp) = *entry.value();
            if timestamp
                .elapsed()
                .map(|d| d.as_secs() < DNS_CACHE_TTL)
                .unwrap_or(false)
            {
                return Ok(addr);
            }
        }

        // Resolve and cache
        let addrs: Vec<SocketAddr> = format!("{}:{}", host, port)
            .to_socket_addrs()
            .map_err(|e| McError::DnsError(e.to_string()))?
            .collect();

        let addr = addrs
            .iter()
            .find(|a| a.is_ipv4())
            .or_else(|| addrs.first())
            .copied()
            .ok_or_else(|| McError::DnsError("No addresses resolved".to_string()))?;

        DNS_CACHE.insert(cache_key, (addr, SystemTime::now()));
        Ok(addr)
    }

    /// Get DNS information for a hostname.
    ///
    /// This is a simplified implementation that retrieves A records.
    /// More advanced DNS queries (e.g., CNAME) would require additional DNS library features.
    ///
    /// # Arguments
    ///
    /// * `host` - Hostname to query
    ///
    /// # Returns
    ///
    /// DNS information or an error if resolution fails.
    async fn get_dns_info(&self, host: &str) -> Result<DnsInfo, McError> {
        let addrs: Vec<SocketAddr> = format!("{}:0", host)
            .to_socket_addrs()
            .map_err(|e| McError::DnsError(e.to_string()))?
            .collect();

        Ok(DnsInfo {
            a_records: addrs.iter().map(|a| a.ip().to_string()).collect(),
            cname: None, // This would require proper DNS queries
            ttl: DNS_CACHE_TTL as u32,
        })
    }

    /// Send handshake packet to Java server.
    ///
    /// # Arguments
    ///
    /// * `stream` - TCP stream to write to
    /// * `host` - Hostname (used in handshake packet)
    /// * `port` - Port number (used in handshake packet)
    ///
    /// # Errors
    ///
    /// Returns an error if writing to the stream fails or times out.
    async fn send_handshake(&self, stream: &mut TcpStream, host: &str, port: u16) -> Result<(), McError> {
        let mut handshake = Vec::with_capacity(INITIAL_PACKET_CAPACITY);
        write_var_int(&mut handshake, HANDSHAKE_PACKET_ID);
        write_var_int(&mut handshake, PROTOCOL_VERSION);
        write_string(&mut handshake, host);
        handshake.extend_from_slice(&port.to_be_bytes());
        write_var_int(&mut handshake, 1); // Next state: status

        let mut packet = Vec::with_capacity(handshake.len() + 5);
        write_var_int(&mut packet, handshake.len() as i32);
        packet.extend_from_slice(&handshake);

        timeout(self.timeout, stream.write_all(&packet))
            .await
            .map_err(|_| McError::Timeout)?
            .map_err(McError::IoError)
    }

    /// Send status request packet to Java server.
    ///
    /// # Arguments
    ///
    /// * `stream` - TCP stream to write to
    ///
    /// # Errors
    ///
    /// Returns an error if writing to the stream fails or times out.
    async fn send_status_request(&self, stream: &mut TcpStream) -> Result<(), McError> {
        let mut status_request = Vec::with_capacity(5);
        write_var_int(&mut status_request, STATUS_REQUEST_PACKET_ID);

        let mut status_packet = Vec::with_capacity(status_request.len() + 5);
        write_var_int(&mut status_packet, status_request.len() as i32);
        status_packet.extend_from_slice(&status_request);

        timeout(self.timeout, stream.write_all(&status_packet))
            .await
            .map_err(|_| McError::Timeout)?
            .map_err(McError::IoError)
    }

    /// Read response from Java server.
    ///
    /// This method reads the complete response packet, handling variable-length
    /// packets correctly.
    ///
    /// # Arguments
    ///
    /// * `stream` - TCP stream to read from
    ///
    /// # Returns
    ///
    /// Complete response packet as bytes.
    ///
    /// # Errors
    ///
    /// Returns an error if reading fails, times out, or no data is received.
    async fn read_response(&self, stream: &mut TcpStream) -> Result<Vec<u8>, McError> {
        let mut response = Vec::with_capacity(INITIAL_RESPONSE_CAPACITY);
        let mut buf = [0u8; READ_BUFFER_SIZE];
        let mut expected_length = None;

        loop {
            let n = timeout(self.timeout, stream.read(&mut buf))
                .await
                .map_err(|_| McError::Timeout)?
                .map_err(McError::IoError)?;

            if n == 0 {
                break;
            }

            response.extend_from_slice(&buf[..n]);

            // Check if we have enough data to determine packet length
            if expected_length.is_none() && response.len() >= 5 {
                let mut cursor = Cursor::new(&response);
                if let Ok(packet_length) = read_var_int(&mut cursor) {
                    expected_length = Some(cursor.position() as usize + packet_length as usize);
                }
            }

            if let Some(expected) = expected_length {
                if response.len() >= expected {
                    break;
                }
            }
        }

        if response.is_empty() {
            return Err(McError::InvalidResponse("No response from server".to_string()));
        }

        Ok(response)
    }

    /// Parse Java server response.
    ///
    /// Extracts JSON data and calculates latency from the response packet.
    ///
    /// # Arguments
    ///
    /// * `response` - Complete response packet
    /// * `start` - Start time for latency calculation
    ///
    /// # Returns
    ///
    /// Tuple of `(JSON value, latency in milliseconds)`.
    ///
    /// # Errors
    ///
    /// Returns an error if the packet is malformed or contains invalid data.
    fn parse_java_response(&self, response: Vec<u8>, start: SystemTime) -> Result<(serde_json::Value, f64), McError> {
        let mut cursor = Cursor::new(&response);
        let packet_length = read_var_int(&mut cursor)
            .map_err(|e| McError::InvalidResponse(format!("Failed to read packet length: {}", e)))?;

        let total_expected = cursor.position() as usize + packet_length as usize;
        if response.len() < total_expected {
            return Err(McError::InvalidResponse(format!(
                "Incomplete packet: expected {}, got {}",
                total_expected, response.len()
            )));
        }

        let packet_id = read_var_int(&mut cursor)
            .map_err(|e| McError::InvalidResponse(format!("Failed to read packet ID: {}", e)))?;

        if packet_id != STATUS_RESPONSE_PACKET_ID {
            return Err(McError::InvalidResponse(format!("Unexpected packet ID: {}", packet_id)));
        }

        let json_length = read_var_int(&mut cursor)
            .map_err(|e| McError::InvalidResponse(format!("Failed to read JSON length: {}", e)))?;

        if cursor.position() as usize + json_length as usize > response.len() {
            return Err(McError::InvalidResponse("JSON data truncated".to_string()));
        }

        let json_buf = &response[cursor.position() as usize..cursor.position() as usize + json_length as usize];
        let json_str = String::from_utf8(json_buf.to_vec()).map_err(McError::Utf8Error)?;

        let json: serde_json::Value = serde_json::from_str(&json_str).map_err(McError::JsonError)?;

        let latency = start
            .elapsed()
            .map_err(|_| McError::InvalidResponse("Time error".to_string()))?
            .as_secs_f64()
            * 1000.0;

        Ok((json, latency))
    }

    /// Parse Java server JSON response.
    ///
    /// Extracts structured data from the JSON response, including version info,
    /// players, plugins, mods, and more.
    ///
    /// # Arguments
    ///
    /// * `json` - JSON value from server response
    ///
    /// # Returns
    ///
    /// Parsed `JavaStatus` structure.
    ///
    /// # Errors
    ///
    /// Returns an error if required fields are missing or malformed.
    fn parse_java_json(&self, json: &serde_json::Value) -> Result<JavaStatus, McError> {
        let version = JavaVersion {
            name: json["version"]["name"]
                .as_str()
                .unwrap_or("Unknown")
                .to_string(),
            protocol: json["version"]["protocol"].as_i64().unwrap_or(0),
        };

        let players = JavaPlayers {
            online: json["players"]["online"].as_i64().unwrap_or(0),
            max: json["players"]["max"].as_i64().unwrap_or(0),
            sample: if let Some(sample) = json["players"]["sample"].as_array() {
                Some(
                    sample
                        .iter()
                        .filter_map(|p| {
                    Some(JavaPlayer {
                        name: p["name"].as_str()?.to_string(),
                        id: p["id"].as_str()?.to_string(),
                    })
                        })
                        .collect(),
                )
            } else {
                None
            },
        };

        let description = if let Some(desc) = json["description"].as_str() {
            desc.to_string()
        } else if let Some(text) = json["description"]["text"].as_str() {
            text.to_string()
        } else {
            "No description".to_string()
        };

        let favicon = json["favicon"].as_str().map(|s| s.to_string());
        let map = json["map"].as_str().map(|s| s.to_string());
        let gamemode = json["gamemode"].as_str().map(|s| s.to_string());
        let software = json["software"].as_str().map(|s| s.to_string());

        let plugins = if let Some(plugins_array) = json["plugins"].as_array() {
            Some(
                plugins_array
                    .iter()
                    .filter_map(|p| {
                Some(JavaPlugin {
                    name: p["name"].as_str()?.to_string(),
                    version: p["version"].as_str().map(|s| s.to_string()),
                })
                    })
                    .collect(),
            )
        } else {
            None
        };

        let mods = if let Some(mods_array) = json["mods"].as_array() {
            Some(
                mods_array
                    .iter()
                    .filter_map(|m| {
                Some(JavaMod {
                    modid: m["modid"].as_str()?.to_string(),
                    version: m["version"].as_str().map(|s| s.to_string()),
                })
                    })
                    .collect(),
            )
        } else {
            None
        };

        Ok(JavaStatus {
            version,
            players,
            description,
            favicon,
            map,
            gamemode,
            software,
            plugins,
            mods,
            raw_data: json.clone(),
        })
    }

    /// Create Bedrock ping packet.
    ///
    /// Returns a properly formatted UDP packet for querying Bedrock servers.
    fn create_bedrock_ping_packet(&self) -> Vec<u8> {
        let mut ping_packet = Vec::with_capacity(BEDROCK_PING_PACKET_SIZE);
        ping_packet.push(0x01);
        ping_packet.extend_from_slice(
            &(SystemTime::now()
            .duration_since(SystemTime::UNIX_EPOCH)
            .unwrap()
            .as_millis() as u64)
                .to_be_bytes(),
        );
        ping_packet.extend_from_slice(&[
            0x00, 0xFF, 0xFF, 0x00, 0xFE, 0xFE, 0xFE, 0xFE, 0xFD, 0xFD, 0xFD, 0xFD, 0x12, 0x34, 0x56, 0x78,
        ]);
        ping_packet.extend_from_slice(&[0x00; 8]);
        ping_packet
    }

    /// Parse Bedrock server response.
    ///
    /// Extracts structured data from the Bedrock server's UDP response.
    ///
    /// # Arguments
    ///
    /// * `pong_data` - Response data string from server
    ///
    /// # Returns
    ///
    /// Parsed `BedrockStatus` structure.
    ///
    /// # Errors
    ///
    /// Returns an error if the response is malformed or missing required fields.
    fn parse_bedrock_response(&self, pong_data: &str) -> Result<BedrockStatus, McError> {
        let parts: Vec<&str> = pong_data.split(';').collect();

        if parts.len() < 6 {
            return Err(McError::InvalidResponse("Invalid Bedrock response".to_string()));
        }

        Ok(BedrockStatus {
            edition: parts[0].to_string(),
            motd: parts[1].to_string(),
            protocol_version: parts[2].to_string(),
            version: parts[3].to_string(),
            online_players: parts[4].to_string(),
            max_players: parts[5].to_string(),
            server_uid: parts.get(6).map_or("", |s| *s).to_string(),
            motd2: parts.get(7).map_or("", |s| *s).to_string(),
            game_mode: parts.get(8).map_or("", |s| *s).to_string(),
            game_mode_numeric: parts.get(9).map_or("", |s| *s).to_string(),
            port_ipv4: parts.get(10).map_or("", |s| *s).to_string(),
            port_ipv6: parts.get(11).map_or("", |s| *s).to_string(),
            map: parts.get(12).map(|s| s.to_string()),
            software: parts.get(13).map(|s| s.to_string()),
            raw_data: pong_data.to_string(),
        })
    }
}

// === Protocol Helper Functions ===

/// Write a VarInt to a buffer.
///
/// VarInt is a variable-length integer encoding used in Minecraft protocol.
/// It uses 7 bits per byte, with the most significant bit indicating continuation.
///
/// # Arguments
///
/// * `buffer` - Buffer to write to
/// * `value` - Integer value to encode
fn write_var_int(buffer: &mut Vec<u8>, value: i32) {
    let mut value = value as u32;
    loop {
        let mut temp = (value & 0x7F) as u8;
        value >>= 7;
        if value != 0 {
            temp |= 0x80;
        }
        buffer.push(temp);
        if value == 0 {
            break;
        }
    }
}

/// Write a string to a buffer (VarInt length + UTF-8 bytes).
///
/// # Arguments
///
/// * `buffer` - Buffer to write to
/// * `s` - String to write
fn write_string(buffer: &mut Vec<u8>, s: &str) {
    write_var_int(buffer, s.len() as i32);
    buffer.extend_from_slice(s.as_bytes());
}

/// Read a VarInt from a reader.
///
/// # Arguments
///
/// * `reader` - Reader to read from
///
/// # Returns
///
/// Decoded integer value.
///
/// # Errors
///
/// Returns an error if:
/// - Reading fails
/// - VarInt is too large (exceeds 35 bits)
fn read_var_int(reader: &mut impl std::io::Read) -> Result<i32, String> {
    let mut result = 0i32;
    let mut shift = 0;
    loop {
        let mut byte = [0u8];
        reader.read_exact(&mut byte).map_err(|e| e.to_string())?;
        let value = byte[0] as i32;
        result |= (value & 0x7F) << shift;
        shift += 7;
        if shift > MAX_VARINT_SHIFT {
            return Err("VarInt too big".to_string());
        }
        if (value & 0x80) == 0 {
            break;
        }
    }
    Ok(result)
}