chess_vector_engine/

uci.rs

use chess::{Board, ChessMove, Color};
use std::collections::HashMap;
use std::io::{self, BufRead, Write};
use std::str::FromStr;
use std::thread;
use std::time::{Duration, Instant};

use crate::{ChessVectorEngine, HybridConfig, TacticalConfig};

/// UCI (Universal Chess Interface) protocol implementation for the chess vector engine
pub struct UCIEngine {
    engine: ChessVectorEngine,
    board: Board,
    debug: bool,
    engine_name: String,
    engine_author: String,
    options: HashMap<String, UCIOption>,
    thinking: bool,
    stop_search: bool,
    pondering: bool,
    ponder_move: Option<ChessMove>,
    ponder_board: Option<Board>,
}

/// UCI option types
#[derive(Debug, Clone)]
pub enum UCIOption {
    Check {
        default: bool,
        value: bool,
    },
    Spin {
        default: i32,
        min: i32,
        max: i32,
        value: i32,
    },
    Combo {
        default: String,
        options: Vec<String>,
        value: String,
    },
    Button,
    String {
        default: String,
        value: String,
    },
}

/// Search information for UCI info command
#[derive(Debug, Clone)]
pub struct SearchInfo {
    depth: u32,
    #[allow(dead_code)]
    seldepth: Option<u32>,
    time: u64, // milliseconds
    nodes: u64,
    nps: u64, // nodes per second
    #[allow(dead_code)]
    score: SearchScore,
    #[allow(dead_code)]
    pv: Vec<ChessMove>, // principal variation
    #[allow(dead_code)]
    currmove: Option<ChessMove>,
    #[allow(dead_code)]
    currmovenumber: Option<u32>,
}

#[derive(Debug, Clone)]
pub enum SearchScore {
    Centipawns(i32),
    Mate(i32), // moves to mate (positive if we're winning)
}

impl UCIEngine {
    pub fn new() -> Self {
        let mut engine = ChessVectorEngine::new_lightweight(1024);

        // Enable fast features for UCI compliance - no auto-loading
        engine.enable_opening_book();
        engine.enable_tactical_search_default();
        engine.configure_hybrid_evaluation(HybridConfig::default());

        // Enable strategic motifs for instant master-level pattern recognition
        let _ = engine.enable_strategic_motifs();

        // Skip auto-loading for UCI fast startup - data can be loaded on demand

        let mut options = HashMap::new();

        // Standard UCI options
        options.insert(
            "Hash".to_string(),
            UCIOption::Spin {
                default: 128,
                min: 1,
                max: 2048,
                value: 128,
            },
        );

        options.insert(
            "Threads".to_string(),
            UCIOption::Spin {
                default: 1,
                min: 1,
                max: 64,
                value: 1,
            },
        );

        options.insert(
            "MultiPV".to_string(),
            UCIOption::Spin {
                default: 1,
                min: 1,
                max: 10,
                value: 1,
            },
        );

        // Chess Vector Engine specific options
        options.insert(
            "Pattern_Weight".to_string(),
            UCIOption::Spin {
                default: 60,
                min: 0,
                max: 100,
                value: 60,
            },
        );

        options.insert(
            "Tactical_Depth".to_string(),
            UCIOption::Spin {
                default: 3,
                min: 1,
                max: 10,
                value: 3,
            },
        );

        options.insert(
            "Pattern_Confidence_Threshold".to_string(),
            UCIOption::Spin {
                default: 75,
                min: 0,
                max: 100,
                value: 75,
            },
        );

        options.insert(
            "Enable_LSH".to_string(),
            UCIOption::Check {
                default: true,
                value: true,
            },
        );

        options.insert(
            "Enable_GPU".to_string(),
            UCIOption::Check {
                default: true,
                value: true,
            },
        );

        options.insert(
            "Ponder".to_string(),
            UCIOption::Check {
                default: true,
                value: true,
            },
        );

        options.insert("Load_Position_Data".to_string(), UCIOption::Button);

        Self {
            engine,
            board: Board::default(),
            debug: false,
            engine_name: "Chess Vector Engine".to_string(),
            engine_author: "Chess Vector Engine Team".to_string(),
            options,
            thinking: false,
            stop_search: false,
            pondering: false,
            ponder_move: None,
            ponder_board: None,
        }
    }

    /// Main UCI loop
    pub fn run(&mut self) {
        let stdin = io::stdin();
        let mut stdout = io::stdout();

        for line in stdin.lock().lines() {
            match line {
                Ok(command) => {
                    let response = self.process_command(command.trim());
                    if !response.is_empty() {
                        let _ = writeln!(stdout, "{response}");
                        let _ = stdout.flush();
                    }

                    if command.trim() == "quit" {
                        break;
                    }
                }
                Err(e) => {
                    if self.debug {
                        let _ = writeln!(stdout, "Error reading input: {e}");
                    }
                    break;
                }
            }
        }
    }

    /// Process UCI command and return response
    fn process_command(&mut self, command: &str) -> String {
        let parts: Vec<&str> = command.split_whitespace().collect();
        if parts.is_empty() {
            return String::new();
        }

        match parts[0] {
            "uci" => self.handle_uci(),
            "debug" => self.handle_debug(&parts),
            "isready" => self.handle_isready(),
            "setoption" => self.handle_setoption(&parts),
            "register" => String::new(), // Not implemented
            "ucinewgame" => self.handle_ucinewgame(),
            "position" => self.handle_position(&parts),
            "go" => self.handle_go(&parts),
            "stop" => self.handle_stop(),
            "ponderhit" => self.handle_ponderhit(),
            "quit" => String::new(),
            _ => {
                if self.debug {
                    format!("Unknown command: {command}")
                } else {
                    String::new()
                }
            }
        }
    }

    fn handle_uci(&self) -> String {
        let mut response = String::new();
        response.push_str(&format!("id name {}\n", self.engine_name));
        response.push_str(&format!("id author {}\n", self.engine_author));

        // Send options
        for (name, option) in &self.options {
            match option {
                UCIOption::Check { default, .. } => {
                    response.push_str(&format!(
                        "option name {name} type check default {default}\n"
                    ));
                }
                UCIOption::Spin {
                    default, min, max, ..
                } => {
                    response.push_str(&format!(
                        "option name {name} type spin default {default} min {min} max {max}\n"
                    ));
                }
                UCIOption::Combo {
                    default, options, ..
                } => {
                    let combo_options = options.join(" var ");
                    response.push_str(&format!(
                        "option name {name} type combo default {default} var {combo_options}\n"
                    ));
                }
                UCIOption::Button => {
                    response.push_str(&format!("option name {name} type button\n"));
                }
                UCIOption::String { default, .. } => {
                    response.push_str(&format!(
                        "option name {name} type string default {default}\n"
                    ));
                }
            }
        }

        response.push_str("uciok");
        response
    }

    fn handle_debug(&mut self, parts: &[&str]) -> String {
        if parts.len() >= 2 {
            match parts[1] {
                "on" => self.debug = true,
                "off" => self.debug = false,
                _ => {}
            }
        }
        String::new()
    }

    fn handle_isready(&self) -> String {
        "readyok".to_string()
    }

    fn handle_setoption(&mut self, parts: &[&str]) -> String {
        // Parse: setoption name <name> value <value>
        if parts.len() >= 4 && parts[1] == "name" {
            let mut name_parts = Vec::new();
            let mut value_parts = Vec::new();
            let mut in_value = false;

            for &part in &parts[2..] {
                if part == "value" {
                    in_value = true;
                } else if in_value {
                    value_parts.push(part);
                } else {
                    name_parts.push(part);
                }
            }

            let name = name_parts.join(" ");
            let value = value_parts.join(" ");

            self.set_option(&name, &value);
        }

        String::new()
    }

    fn set_option(&mut self, name: &str, value: &str) {
        if let Some(option) = self.options.get_mut(name) {
            match option {
                UCIOption::Check {
                    value: ref mut val, ..
                } => {
                    *val = value == "true";
                }
                UCIOption::Spin {
                    value: ref mut val,
                    min,
                    max,
                    ..
                } => {
                    if let Ok(new_val) = value.parse::<i32>() {
                        if new_val >= *min && new_val <= *max {
                            *val = new_val;
                        }
                    }
                }
                UCIOption::Combo {
                    value: ref mut val,
                    options,
                    ..
                } => {
                    if options.contains(&value.to_string()) {
                        *val = value.to_string();
                    }
                }
                UCIOption::String {
                    value: ref mut val, ..
                } => {
                    *val = value.to_string();
                }
                UCIOption::Button => {
                    // Handle button press
                    if name == "Load_Position_Data" {
                        // Load position data on demand
                        let _ = self.engine.auto_load_training_data();
                    }
                }
            }
        }

        // Apply engine-specific options
        self.apply_options();
    }

    fn apply_options(&mut self) {
        if let Some(UCIOption::Spin {
            value: pattern_weight,
            ..
        }) = self.options.get("Pattern_Weight")
        {
            let weight = (*pattern_weight as f32) / 100.0;
            let config = HybridConfig {
                pattern_weight: weight,
                ..HybridConfig::default()
            };
            self.engine.configure_hybrid_evaluation(config);
        }

        if let Some(UCIOption::Spin { value: depth, .. }) = self.options.get("Tactical_Depth") {
            let config = TacticalConfig {
                max_depth: *depth as u32,
                ..TacticalConfig::default()
            };
            self.engine.enable_tactical_search(config);
        }

        if let Some(UCIOption::Spin {
            value: threshold, ..
        }) = self.options.get("Pattern_Confidence_Threshold")
        {
            let config = HybridConfig {
                pattern_confidence_threshold: (*threshold as f32) / 100.0,
                ..HybridConfig::default()
            };
            self.engine.configure_hybrid_evaluation(config);
        }

        if let Some(UCIOption::Check {
            value: enable_lsh, ..
        }) = self.options.get("Enable_LSH")
        {
            if *enable_lsh && !self.engine.is_lsh_enabled() {
                self.engine.enable_lsh(8, 16);
            }
        }
    }

    fn handle_ucinewgame(&mut self) -> String {
        self.board = Board::default();
        // Could reset engine state here if needed
        String::new()
    }

    fn handle_position(&mut self, parts: &[&str]) -> String {
        if parts.len() < 2 {
            return String::new();
        }

        let mut board = if parts[1] == "startpos" {
            Board::default()
        } else if parts[1] == "fen" && parts.len() >= 8 {
            let fen = parts[2..8].join(" ");
            match Board::from_str(&fen) {
                Ok(board) => board,
                Err(_) => {
                    if self.debug {
                        return "info string Invalid FEN".to_string();
                    }
                    return String::new();
                }
            }
        } else {
            return String::new();
        };

        // Apply moves if present
        if let Some(moves_idx) = parts.iter().position(|&x| x == "moves") {
            for move_str in &parts[moves_idx + 1..] {
                if let Ok(chess_move) = ChessMove::from_str(move_str) {
                    if board.legal(chess_move) {
                        board = board.make_move_new(chess_move);
                    } else if self.debug {
                        return format!("info string Illegal move: {move_str}");
                    }
                }
            }
        }

        self.board = board;
        String::new()
    }

    fn handle_go(&mut self, parts: &[&str]) -> String {
        if self.thinking {
            return String::new();
        }

        // Parse go command parameters
        let mut wtime = None;
        let mut btime = None;
        let mut _winc: Option<u64> = None;
        let mut _binc: Option<u64> = None;
        let mut movestogo = None;
        let mut depth = None;
        let mut _nodes: Option<u64> = None;
        let mut movetime = None;
        let mut infinite = false;
        let mut ponder = false;

        let mut i = 1;
        while i < parts.len() {
            match parts[i] {
                "wtime" if i + 1 < parts.len() => {
                    wtime = parts[i + 1].parse().ok();
                    i += 2;
                }
                "btime" if i + 1 < parts.len() => {
                    btime = parts[i + 1].parse().ok();
                    i += 2;
                }
                "winc" if i + 1 < parts.len() => {
                    _winc = parts[i + 1].parse().ok();
                    i += 2;
                }
                "binc" if i + 1 < parts.len() => {
                    _binc = parts[i + 1].parse().ok();
                    i += 2;
                }
                "movestogo" if i + 1 < parts.len() => {
                    movestogo = parts[i + 1].parse().ok();
                    i += 2;
                }
                "depth" if i + 1 < parts.len() => {
                    depth = parts[i + 1].parse().ok();
                    i += 2;
                }
                "nodes" if i + 1 < parts.len() => {
                    _nodes = parts[i + 1].parse().ok();
                    i += 2;
                }
                "movetime" if i + 1 < parts.len() => {
                    movetime = parts[i + 1].parse().ok();
                    i += 2;
                }
                "infinite" => {
                    infinite = true;
                    i += 1;
                }
                "ponder" => {
                    ponder = true;
                    i += 1;
                }
                _ => i += 1,
            }
        }

        // Calculate search time
        let search_time = if let Some(mt) = movetime {
            Duration::from_millis(mt)
        } else if infinite {
            Duration::from_secs(3600) // 1 hour max
        } else {
            // Simple time management
            let our_time = if self.board.side_to_move() == Color::White {
                wtime.unwrap_or(30000)
            } else {
                btime.unwrap_or(30000)
            };

            let moves_left = movestogo.unwrap_or(30);
            let time_per_move = our_time / moves_left.max(1);
            Duration::from_millis(time_per_move.min(our_time / 2))
        };

        // Start search in separate thread
        if ponder {
            self.start_ponder_search(search_time, depth);
        } else {
            self.start_search(search_time, depth);
        }

        String::new()
    }

    fn start_search(&mut self, _max_time: Duration, _max_depth: Option<u32>) {
        self.thinking = true;
        self.stop_search = false;

        let board = self.board;
        let mut engine = self.engine.clone(); // Clone the engine for threaded evaluation
        let start_time = Instant::now();

        // Get MultiPV setting
        let multi_pv = if let Some(UCIOption::Spin { value, .. }) = self.options.get("MultiPV") {
            *value as usize
        } else {
            1
        };

        // Spawn search thread
        thread::spawn(move || {
            let mut search_info = SearchInfo {
                depth: 1,
                seldepth: None,
                time: 0,
                nodes: 0,
                nps: 0,
                score: SearchScore::Centipawns(0),
                pv: Vec::new(),
                currmove: None,
                currmovenumber: None,
            };

            // PROPER CHESS ENGINE SEARCH: evaluate all legal moves using hybrid system
            let legal_moves: Vec<ChessMove> = chess::MoveGen::new_legal(&board).collect();

            if legal_moves.is_empty() {
                println!("bestmove 0000"); // No legal moves - game over
                return;
            }

            let mut move_evaluations: Vec<(ChessMove, f32)> = Vec::new();
            let mut nodes_searched = 0;

            // Evaluate each legal move by making it and evaluating the resulting position
            for chess_move in &legal_moves {
                let temp_board = board.make_move_new(*chess_move);
                nodes_searched += 1;

                // Use the engine's hybrid evaluation system (opening book + patterns + tactical)
                if let Some(position_eval) = engine.evaluate_position(&temp_board) {
                    // Flip evaluation for opponent's perspective
                    let eval_for_us = if board.side_to_move() == chess::Color::White {
                        position_eval
                    } else {
                        -position_eval
                    };

                    move_evaluations.push((*chess_move, eval_for_us));
                }
            }

            // Sort moves by evaluation (best first)
            move_evaluations
                .sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal));

            // Get the best move for the final output
            let (best_move, _) = if !move_evaluations.is_empty() {
                move_evaluations[0]
            } else {
                // Fallback: no evaluations worked, use first legal move
                (legal_moves[0], 0.0)
            };

            // Update common search info
            search_info.time = start_time.elapsed().as_millis() as u64;
            search_info.nodes = nodes_searched;
            search_info.nps = if search_info.time > 0 {
                (search_info.nodes * 1000) / search_info.time
            } else {
                0
            };

            // Output multiple PV lines
            let pv_count = move_evaluations.len().min(multi_pv);
            for (pv_index, (chess_move, eval)) in move_evaluations.iter().take(pv_count).enumerate()
            {
                let score_cp = (*eval * 100.0) as i32;

                // Send UCI info for this PV line
                if multi_pv == 1 {
                    // Single PV (standard format)
                    println!(
                        "info depth {} score cp {} time {} nodes {} nps {} pv {}",
                        search_info.depth,
                        score_cp,
                        search_info.time,
                        search_info.nodes,
                        search_info.nps,
                        chess_move
                    );
                } else {
                    // Multi-PV format (include multipv field)
                    println!(
                        "info depth {} multipv {} score cp {} time {} nodes {} nps {} pv {}",
                        search_info.depth,
                        pv_index + 1,
                        score_cp,
                        search_info.time,
                        search_info.nodes,
                        search_info.nps,
                        chess_move
                    );
                }
            }

            // Send best move
            println!("bestmove {best_move}");
        });
    }

    /// Start pondering search (thinking on opponent's time)
    fn start_ponder_search(&mut self, _max_time: Duration, _max_depth: Option<u32>) {
        // Check if pondering is enabled
        if let Some(UCIOption::Check { value, .. }) = self.options.get("Ponder") {
            if !value {
                return; // Pondering disabled
            }
        } else {
            return; // No ponder option
        }

        self.pondering = true;
        self.thinking = true;
        self.stop_search = false;

        // Find a likely opponent move to ponder on
        if let Some(ponder_move) = self.get_expected_opponent_move() {
            self.ponder_move = Some(ponder_move);
            self.ponder_board = Some(self.board.make_move_new(ponder_move));

            if self.debug {
                println!("info string Pondering on {ponder_move}");
            }

            // Start pondering in background thread
            let ponder_board = self.ponder_board.unwrap();
            let mut engine = self.engine.clone();
            let debug = self.debug;

            thread::spawn(move || {
                // Perform deep search on pondered position
                if let Some(eval) = engine.evaluate_position(&ponder_board) {
                    if debug {
                        println!("info string Ponder evaluation: {eval:.2}");
                    }
                }

                // In a full implementation, we would:
                // 1. Run full tactical search on ponder position
                // 2. Analyze multiple candidate moves
                // 3. Store results for quick retrieval on ponderhit
                // 4. Continue until stop or ponderhit
            });
        }
    }

    /// Get the most likely opponent move for pondering
    fn get_expected_opponent_move(&mut self) -> Option<ChessMove> {
        use chess::MoveGen;

        // Simple strategy: pick the first legal move
        // In a real engine, this would use:
        // - Principal variation from previous search
        // - Opening book moves
        // - Most common moves in this position
        let legal_moves: Vec<ChessMove> = MoveGen::new_legal(&self.board).collect();

        if !legal_moves.is_empty() {
            // Use engine evaluation to pick most likely move
            let mut best_move = legal_moves[0];
            let mut best_eval = f32::NEG_INFINITY;

            for chess_move in legal_moves.iter().take(5) {
                // Check top 5 moves
                let new_board = self.board.make_move_new(*chess_move);
                if let Some(eval) = self.engine.evaluate_position(&new_board) {
                    // From opponent's perspective (flip evaluation)
                    let opponent_eval = -eval;
                    if opponent_eval > best_eval {
                        best_eval = opponent_eval;
                        best_move = *chess_move;
                    }
                }
            }

            Some(best_move)
        } else {
            None
        }
    }

    /// Handle ponderhit command (opponent played the expected move)
    fn handle_ponderhit(&mut self) -> String {
        if self.pondering {
            self.pondering = false;

            if self.debug {
                println!("info string Ponderhit received - converting ponder to normal search");
            }

            // Convert pondering to normal search
            // In a full implementation, we would:
            // 1. Use cached ponder results
            // 2. Continue search with time limits
            // 3. Output bestmove when search completes

            // Evaluate the pondered position and return best move
            if let Some(ponder_board) = self.ponder_board {
                let legal_moves: Vec<ChessMove> =
                    chess::MoveGen::new_legal(&ponder_board).collect();
                if !legal_moves.is_empty() {
                    // Use engine evaluation to find best move instead of simple fallback
                    let mut best_move = legal_moves[0];
                    let mut best_eval = f32::NEG_INFINITY;
                    
                    for chess_move in legal_moves.iter().take(5) {
                        let new_board = ponder_board.make_move_new(*chess_move);
                        if let Some(eval) = self.engine.evaluate_position(&new_board) {
                            if eval > best_eval {
                                best_eval = eval;
                                best_move = *chess_move;
                            }
                        }
                    }
                    thread::spawn(move || {
                        println!("bestmove {best_move}");
                    });
                }
            }

            self.ponder_move = None;
            self.ponder_board = None;
        }

        String::new()
    }

    fn handle_stop(&mut self) -> String {
        self.stop_search = true;
        self.thinking = false;

        // Stop pondering if active
        if self.pondering {
            self.pondering = false;
            self.ponder_move = None;
            self.ponder_board = None;

            if self.debug {
                println!("info string Pondering stopped");
            }
        }

        String::new()
    }
}

impl Default for UCIEngine {
    fn default() -> Self {
        Self::new()
    }
}

/// Configuration for the UCI engine
#[derive(Debug, Clone)]
pub struct UCIConfig {
    pub engine_name: String,
    pub engine_author: String,
    pub enable_debug: bool,
    pub default_hash_size: i32,
    pub default_threads: i32,
}

impl Default for UCIConfig {
    fn default() -> Self {
        Self {
            engine_name: "Chess Vector Engine".to_string(),
            engine_author: "Chess Vector Engine Team".to_string(),
            enable_debug: false,
            default_hash_size: 128,
            default_threads: 1,
        }
    }
}

/// Run the UCI engine with default configuration
pub fn run_uci_engine() {
    let mut engine = UCIEngine::new();
    engine.run();
}

/// Run the UCI engine with custom configuration
pub fn run_uci_engine_with_config(config: UCIConfig) {
    let mut engine = UCIEngine::new();
    engine.engine_name = config.engine_name;
    engine.engine_author = config.engine_author;
    engine.debug = config.enable_debug;

    // Apply configuration to options
    if let Some(UCIOption::Spin { value, .. }) = engine.options.get_mut("Hash") {
        *value = config.default_hash_size;
    }
    if let Some(UCIOption::Spin { value, .. }) = engine.options.get_mut("Threads") {
        *value = config.default_threads;
    }

    engine.run();
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::str::FromStr;

    #[test]
    fn test_uci_initialization() {
        let engine = UCIEngine::new();
        assert_eq!(engine.board, Board::default());
        assert!(!engine.debug);
        assert!(!engine.thinking);
    }

    #[test]
    fn test_uci_command() {
        let engine = UCIEngine::new();
        let response = engine.handle_uci();
        assert!(response.contains("id name"));
        assert!(response.contains("id author"));
        assert!(response.contains("uciok"));
    }

    #[test]
    fn test_isready_command() {
        let engine = UCIEngine::new();
        let response = engine.handle_isready();
        assert_eq!(response, "readyok");
    }

    #[test]
    fn test_position_startpos() {
        let mut engine = UCIEngine::new();
        let parts = vec!["position", "startpos"];
        engine.handle_position(&parts);
        assert_eq!(engine.board, Board::default());
    }

    #[test]
    fn test_position_with_moves() {
        let mut engine = UCIEngine::new();
        let parts = vec!["position", "startpos", "moves", "e2e4", "e7e5"];
        engine.handle_position(&parts);

        let expected_board = Board::default()
            .make_move_new(ChessMove::from_str("e2e4").unwrap())
            .make_move_new(ChessMove::from_str("e7e5").unwrap());

        assert_eq!(engine.board, expected_board);
    }

    #[test]
    fn test_option_setting() {
        let mut engine = UCIEngine::new();
        engine.set_option("Pattern_Weight", "80");

        if let Some(UCIOption::Spin { value, .. }) = engine.options.get("Pattern_Weight") {
            assert_eq!(*value, 80);
        } else {
            panic!("Option not found or wrong type");
        }
    }

    #[test]
    fn test_debug_toggle() {
        let mut engine = UCIEngine::new();

        engine.handle_debug(&["debug", "on"]);
        assert!(engine.debug);

        engine.handle_debug(&["debug", "off"]);
        assert!(!engine.debug);
    }

    #[test]
    fn test_pondering_option() {
        let engine = UCIEngine::new();

        // Check that Ponder option exists and is enabled by default
        if let Some(UCIOption::Check { value, .. }) = engine.options.get("Ponder") {
            assert!(*value); // Should be enabled by default
        } else {
            panic!("Ponder option should be available");
        }
    }

    #[test]
    fn test_ponder_command_parsing() {
        let mut engine = UCIEngine::new();

        // Test "go ponder" command
        let response = engine.process_command("go ponder");
        assert_eq!(response, ""); // Should return empty string

        // Pondering should be active (may be set asynchronously)
        // We don't assert on engine.pondering here due to threading
    }

    #[test]
    fn test_ponderhit_command() {
        let mut engine = UCIEngine::new();

        // Start pondering first
        engine.pondering = true;
        engine.ponder_move = Some(ChessMove::from_str("e2e4").unwrap());

        // Send ponderhit
        let response = engine.handle_ponderhit();
        assert_eq!(response, "");

        // Pondering should be stopped
        assert!(!engine.pondering);
        assert!(engine.ponder_move.is_none());
    }

    #[test]
    fn test_stop_during_pondering() {
        let mut engine = UCIEngine::new();

        // Start pondering
        engine.pondering = true;
        engine.ponder_move = Some(ChessMove::from_str("e2e4").unwrap());

        // Send stop command
        let response = engine.handle_stop();
        assert_eq!(response, "");

        // Pondering should be stopped
        assert!(!engine.pondering);
        assert!(!engine.thinking);
        assert!(engine.ponder_move.is_none());
    }

    #[test]
    fn test_expected_opponent_move() {
        let mut engine = UCIEngine::new();

        // Test getting expected opponent move from starting position
        let expected_move = engine.get_expected_opponent_move();
        assert!(expected_move.is_some());

        // Should be a legal move
        let legal_moves: Vec<ChessMove> = chess::MoveGen::new_legal(&engine.board).collect();
        if let Some(mv) = expected_move {
            assert!(legal_moves.contains(&mv));
        }
    }

    #[test]
    fn test_multi_pv_option() {
        let engine = UCIEngine::new();

        // Check that MultiPV option exists and has correct default
        if let Some(UCIOption::Spin {
            default,
            min,
            max,
            value,
        }) = engine.options.get("MultiPV")
        {
            assert_eq!(*default, 1);
            assert_eq!(*min, 1);
            assert_eq!(*max, 10);
            assert_eq!(*value, 1);
        } else {
            panic!("MultiPV option should be available");
        }
    }

    #[test]
    fn test_multi_pv_setting() {
        let mut engine = UCIEngine::new();

        // Test setting MultiPV option
        let response = engine.process_command("setoption name MultiPV value 3");
        assert_eq!(response, "");

        // Check that option was set
        if let Some(UCIOption::Spin { value, .. }) = engine.options.get("MultiPV") {
            assert_eq!(*value, 3);
        } else {
            panic!("MultiPV option should exist");
        }
    }

    #[test]
    fn test_single_pv_vs_multi_pv() {
        let mut engine = UCIEngine::new();

        // Test that engine accepts both single and multi-PV modes
        // (We can't easily test the actual output format in unit tests due to threading)

        // Set to single PV
        engine.process_command("setoption name MultiPV value 1");
        if let Some(UCIOption::Spin { value, .. }) = engine.options.get("MultiPV") {
            assert_eq!(*value, 1);
        }

        // Set to multi-PV
        engine.process_command("setoption name MultiPV value 5");
        if let Some(UCIOption::Spin { value, .. }) = engine.options.get("MultiPV") {
            assert_eq!(*value, 5);
        }
    }
}