"""
marcus_odometry.py — Precise Distance & Position Module
=========================================================
Project  : Marcus | YS Lootah Technology
Hardware : Unitree G1 EDU + Jetson Orin NX
Purpose  : Track robot position precisely and execute accurate movements.

Two sources (priority order):
  1. ROS2 /dog_odom — joint encoder data → ±2cm accuracy
  2. Dead reckoning — velocity × time integration → ±10cm accuracy

Import in marcus_brain.py
--------------------------
  from marcus_odometry import Odometry
  odom = Odometry()
  odom.start(zmq_sock=sock)     ← pass existing ZMQ socket

  odom.walk_distance(1.0)       ← walk exactly 1 meter
  odom.turn_degrees(90)         ← turn exactly 90° left
  odom.turn_degrees(-90)        ← turn exactly 90° right
  odom.get_position()           ← {x, y, heading, source}
  odom.reset()                  ← zero at current location

Standalone test
---------------
  conda run -n marcus python3 Navigation/marcus_odometry.py

Date     : April 2026
"""

import os
import sys
import time
import math
import json
import threading
import zmq


# ══════════════════════════════════════════════════════════════════════════════
# CONFIGURATION — loaded from Config/config_Odometry.json
# ══════════════════════════════════════════════════════════════════════════════

_PROJECT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
if _PROJECT_DIR not in sys.path:
    sys.path.insert(0, _PROJECT_DIR)
try:
    from Core.config_loader import load_config
    _cfg = load_config("Odometry")
except Exception:
    _cfg = {}

ZMQ_HOST         = str(_cfg.get("zmq_host",          "127.0.0.1"))
ZMQ_PORT         = int(_cfg.get("zmq_port",          5556))
ROS2_ODOM_TOPIC  = str(_cfg.get("ros2_odom_topic",   "/dog_odom"))
ODOM_INTERFACE   = str(_cfg.get("odom_interface",    "eth0"))

# Movement defaults
DEFAULT_WALK_SPEED  = float(_cfg.get("default_walk_speed",  0.25))  # m/s — slower = more accurate
DEFAULT_TURN_SPEED  = float(_cfg.get("default_turn_speed",  0.25))  # rad/s
DIST_TOLERANCE      = float(_cfg.get("dist_tolerance",      0.05))  # meters — stop within 5cm
ANGLE_TOLERANCE     = float(_cfg.get("angle_tolerance",     2.0))   # degrees — stop within 2°
SAFETY_TIMEOUT_MULT = float(_cfg.get("safety_timeout_mult", 3.0))   # timeout = (distance/speed) × this
ODOM_STALE_WARN     = 1.0       # warn if odom not updated for this many seconds (internal only)

# Dead reckoning
DR_UPDATE_HZ   = int(_cfg.get("dr_update_hz", 20))                   # integration rate


# ══════════════════════════════════════════════════════════════════════════════
# ODOMETRY CLASS
# ══════════════════════════════════════════════════════════════════════════════

class Odometry:
    """
    Precise robot position tracking and movement control.

    Thread-safe. Start with odom.start(zmq_sock).
    If ROS2 is not available, falls back to dead reckoning automatically.

    Usage:
        odom = Odometry()
        odom.start(zmq_sock=sock)
        odom.walk_distance(1.0)
        odom.turn_degrees(90)
        pos = odom.get_position()
    """

    def __init__(self):
        self._lock      = threading.Lock()
        self._alive     = [False]
        self._sock      = None          # ZMQ PUB socket (shared from marcus_brain)

        # Position state
        self._x       = 0.0            # meters from start
        self._y       = 0.0            # meters from start
        self._heading = 0.0            # degrees — 0=start, +left, -right
        self._vx      = 0.0            # current velocity (for dead reckoning)
        self._vy      = 0.0
        self._vyaw    = 0.0
        self._source  = "none"         # "ros2" or "dead_reckoning"
        self._last_update = 0.0        # timestamp of last position update

        # Start position snapshot (for return_to_start)
        self._start_x = 0.0
        self._start_y = 0.0
        self._start_heading = 0.0

        # Running flag
        self._running = False

    # ── STARTUP ───────────────────────────────────────────────────────────────

    def start(self, zmq_sock=None) -> bool:
        """
        Start odometry tracking in background thread.

        Args:
            zmq_sock : existing ZMQ PUB socket from marcus_brain.py.
                       If None, creates its own socket on ZMQ_PORT.
                       Passing the shared socket avoids port conflicts.

        Returns:
            True always — runs in either ROS2 or dead reckoning mode.

        Edge cases:
            - ZMQ port already in use → catches and warns
            - Called twice → second call is no-op with warning
            - ROS2 not sourced → falls back to dead reckoning automatically
        """
        if self._running:
            print("  [Odom] ⚠️  Already running — ignoring duplicate start()")
            return True

        # Wire up ZMQ socket
        if zmq_sock is not None:
            self._sock = zmq_sock
        else:
            self._init_own_zmq()

        if self._sock is None:
            print("  [Odom] ⚠️  No ZMQ socket — movement functions disabled")
            return False

        # Reset position
        self._reset_state()
        self._alive[0] = True
        self._running  = True

        # Try ROS2 first
        ros2_ok = self._try_start_ros2()
        if not ros2_ok:
            # Fall back to dead reckoning
            threading.Thread(
                target=self._dead_reckoning_loop,
                daemon=True,
                name="odom-dr"
            ).start()
            print("  [Odom] Dead reckoning mode — accuracy ±10cm")
        else:
            print("  [Odom] ROS2 /dog_odom mode — accuracy ±2cm")

        time.sleep(0.5)
        return True

    def stop(self):
        """Stop odometry tracking."""
        self._alive[0] = False
        self._running  = False
        print("  [Odom] Stopped")

    def _init_own_zmq(self):
        """Create own ZMQ socket if no shared socket provided."""
        try:
            ctx = zmq.Context()
            sock = ctx.socket(zmq.PUB)
            sock.bind(f"tcp://{ZMQ_HOST}:{ZMQ_PORT}")
            self._sock = sock
            time.sleep(0.5)
        except zmq.ZMQError as e:
            if "Address already in use" in str(e):
                print(f"  [Odom] ⚠️  ZMQ port {ZMQ_PORT} already in use.")
                print("  [Odom]    Pass zmq_sock=sock from marcus_brain.py instead.")
            else:
                print(f"  [Odom] ⚠️  ZMQ error: {e}")
            self._sock = None

    def _reset_state(self):
        """Reset position to zero."""
        with self._lock:
            self._x = self._y = self._heading = 0.0
            self._vx = self._vy = self._vyaw = 0.0
            self._start_x = self._start_y = self._start_heading = 0.0
            self._last_update = time.time()

    # ── ROS2 ODOMETRY ─────────────────────────────────────────────────────────

    def _try_start_ros2(self) -> bool:
        """
        Try to subscribe to /dog_odom via ROS2.
        Returns True if ROS2 is available, False otherwise.

        Edge cases:
            - ROS2 not installed → ImportError caught
            - ROS2 not sourced → caught
            - Topic not publishing → timeout after 2s
        """
        try:
            import rclpy
            # Skip ROS2 on this system — DDS init causes bad_alloc
            # due to memory conflict with Holosoma + YOLO
            # Dead reckoning fallback is used instead
            return False
            rclpy.init()
        except Exception:
            return False

        # Quick check: can we create a node?
        try:
            from rclpy.node import Node
            from nav_msgs.msg import Odometry as OdomMsg

            class _OdomNode(Node):
                def __init__(self, parent):
                    super().__init__("marcus_odom")
                    self._parent = parent
                    self.create_subscription(
                        OdomMsg, ROS2_ODOM_TOPIC,
                        self._callback, 10
                    )

                def _callback(self, msg):
                    pos   = msg.pose.pose.position
                    ori   = msg.pose.pose.orientation
                    twist = msg.twist.twist

                    # Quaternion → yaw
                    siny = 2.0 * (ori.w * ori.z + ori.x * ori.y)
                    cosy = 1.0 - 2.0 * (ori.y**2 + ori.z**2)
                    yaw  = math.degrees(math.atan2(siny, cosy))

                    with self._parent._lock:
                        self._parent._x       = pos.x
                        self._parent._y       = pos.y
                        self._parent._heading = yaw
                        self._parent._vx      = twist.linear.x
                        self._parent._vy      = twist.linear.y
                        self._parent._vyaw    = twist.angular.z
                        self._parent._source  = "ros2"
                        self._parent._last_update = time.time()

            node = _OdomNode(self)

            def _spin():
                while self._alive[0]:
                    rclpy.spin_once(node, timeout_sec=0.02)

            # Start spin thread and wait 2s for first message
            t = threading.Thread(target=_spin, daemon=True, name="odom-ros2")
            t.start()

            deadline = time.time() + 2.0
            while time.time() < deadline:
                time.sleep(0.1)
                if self._source == "ros2":
                    return True

            # No message received — ROS2 available but topic silent
            print("  [Odom] ⚠️  /dog_odom topic not publishing — using dead reckoning")
            return False

        except Exception as e:
            return False

    # ── DEAD RECKONING ────────────────────────────────────────────────────────

    def _dead_reckoning_loop(self):
        """
        Estimate position by integrating velocity × time.
        Updates position at DR_UPDATE_HZ.

        Edge cases:
            - Very large dt (system sleep) → capped at 0.5s to avoid jumps
            - Heading wrap-around at 360°/0° → handled by modulo
        """
        dt_target = 1.0 / DR_UPDATE_HZ
        t_last    = time.time()

        while self._alive[0]:
            time.sleep(dt_target)
            now = time.time()
            dt  = min(now - t_last, 0.5)   # cap at 0.5s to prevent position jumps
            t_last = now

            with self._lock:
                heading_rad = math.radians(self._heading)
                vx  = self._vx
                vy  = self._vy
                vyaw = self._vyaw

                # World-frame position update
                self._x += (vx * math.cos(heading_rad) - vy * math.sin(heading_rad)) * dt
                self._y += (vx * math.sin(heading_rad) + vy * math.cos(heading_rad)) * dt
                self._heading = (self._heading + math.degrees(vyaw) * dt) % 360

                self._source      = "dead_reckoning"
                self._last_update = now

    # ── VELOCITY CONTROL ──────────────────────────────────────────────────────

    def _send_vel(self, vx: float = 0.0, vy: float = 0.0, vyaw: float = 0.0):
        """Send velocity to Holosoma. Also updates dead reckoning velocity state."""
        if self._sock:
            try:
                self._sock.send_string(json.dumps({"vel": {"vx": vx, "vy": vy, "vyaw": vyaw}}))
            except Exception as e:
                print(f"  [Odom] ⚠️  ZMQ send error: {e}")

        # Update dead reckoning state
        with self._lock:
            self._vx   = vx
            self._vy   = vy
            self._vyaw = vyaw

    def _gradual_stop(self, steps: int = 20):
        """Smooth stop — 20 zero-velocity messages over ~1 second."""
        for _ in range(steps):
            self._send_vel(0.0, 0.0, 0.0)
            time.sleep(0.05)

    def _check_stale(self):
        """Warn if odometry hasn't been updated recently."""
        if time.time() - self._last_update > ODOM_STALE_WARN:
            print(f"  [Odom] ⚠️  Position data may be stale (>{ODOM_STALE_WARN:.0f}s since last update)")

    # ── PUBLIC MOVEMENT API ───────────────────────────────────────────────────

    def get_position(self) -> dict:
        """
        Return current robot position.

        Returns:
            {"x": float, "y": float, "heading": float,
             "source": "ros2"|"dead_reckoning"|"none"}

        x, y in meters from start position.
        heading in degrees (0 = start direction, +left, -right, 0-360).
        """
        with self._lock:
            return {
                "x":       round(self._x, 4),
                "y":       round(self._y, 4),
                "heading": round(self._heading, 2),
                "source":  self._source,
            }

    def get_distance_from_start(self) -> float:
        """Return Euclidean distance in meters from the starting position."""
        with self._lock:
            dx = self._x - self._start_x
            dy = self._y - self._start_y
        return round(math.sqrt(dx**2 + dy**2), 3)

    def reset(self):
        """
        Reset odometry to zero at current physical location.
        Use when robot is at a known reference point.
        """
        with self._lock:
            self._x = self._y = self._heading = 0.0
            self._start_x = self._start_y = self._start_heading = 0.0
        print("  [Odom] ✅ Reset to (0, 0, 0°)")

    def is_running(self) -> bool:
        return self._running

    def status_str(self) -> str:
        """Return formatted status string for display."""
        pos = self.get_position()
        return (f"x={pos['x']:.2f}m  y={pos['y']:.2f}m  "
                f"heading={pos['heading']:.1f}°  source={pos['source']}")

    def walk_distance(self, meters: float, speed: float = None,
                      direction: str = "forward") -> bool:
        """
        Walk a precise distance using odometry feedback.

        Args:
            meters    : distance in meters (must be > 0)
            speed     : m/s (default DEFAULT_WALK_SPEED = 0.25)
            direction : "forward" or "backward"

        Returns:
            True if target reached within tolerance.
            False if timeout, invalid input, or odometry not running.

        Edge cases:
            - meters <= 0 → rejected
            - speed <= 0 or > 0.5 → clamped with warning
            - Odometry not running → time-based fallback with warning
            - Safety timeout = (meters / speed) × SAFETY_TIMEOUT_MULT
            - Keyboard interrupt → gradual_stop then re-raise
        """
        # Validate inputs
        if meters <= 0:
            print(f"  [Odom] ⚠️  Invalid distance: {meters}m — must be positive")
            return False

        if speed is None:
            speed = DEFAULT_WALK_SPEED

        if speed <= 0:
            print(f"  [Odom] ⚠️  Speed must be positive — using default {DEFAULT_WALK_SPEED}")
            speed = DEFAULT_WALK_SPEED
        elif speed > 0.5:
            print(f"  [Odom] ⚠️  Speed {speed} exceeds safe limit — clamping to 0.4 m/s")
            speed = 0.4

        if not self._running:
            print("  [Odom] ⚠️  Odometry not started — using time-based fallback")
            return self._time_based_walk(meters, speed, direction)

        self._check_stale()

        vx = speed if direction == "forward" else -speed

        with self._lock:
            start_x = self._x
            start_y = self._y

        timeout = (meters / speed) * SAFETY_TIMEOUT_MULT
        t0      = time.time()

        print(f"  [Odom] Walking {meters:.2f}m {direction} at {speed:.2f} m/s "
              f"(timeout: {timeout:.1f}s)")

        try:
            while time.time() - t0 < timeout:
                with self._lock:
                    dx = self._x - start_x
                    dy = self._y - start_y
                covered = math.sqrt(dx**2 + dy**2)

                if covered >= meters - DIST_TOLERANCE:
                    self._gradual_stop()
                    print(f"  [Odom] ✅ Walked {covered:.3f}m (target {meters:.2f}m)")
                    return True

                self._send_vel(vx=vx)
                time.sleep(0.05)

        except KeyboardInterrupt:
            print("  [Odom] Walk interrupted by user")
            self._gradual_stop()
            raise

        self._gradual_stop()
        with self._lock:
            dx = self._x - start_x
            dy = self._y - start_y
        covered = math.sqrt(dx**2 + dy**2)
        print(f"  [Odom] ⚠️  Timeout — walked {covered:.3f}m of {meters:.2f}m")
        return False

    def _time_based_walk(self, meters: float, speed: float,
                         direction: str = "forward") -> bool:
        """
        Time-based fallback when odometry is not running.
        Accuracy ~±10cm.
        """
        print(f"  [Odom]    Time-based fallback: {meters:.2f}m ≈ {meters/speed:.1f}s")
        vx = speed if direction == "forward" else -speed
        duration = meters / speed
        t0 = time.time()
        try:
            while time.time() - t0 < duration:
                self._send_vel(vx=vx)
                time.sleep(0.05)
        except KeyboardInterrupt:
            self._gradual_stop()
            raise
        self._gradual_stop()
        print(f"  [Odom] ✅ Time-based walk complete (~{meters:.2f}m)")
        return True

    def turn_degrees(self, degrees: float, speed: float = None) -> bool:
        """
        Turn a precise number of degrees using odometry feedback.

        Args:
            degrees : degrees to turn.
                      Positive = left (counter-clockwise)
                      Negative = right (clockwise)
            speed   : angular speed in rad/s (default DEFAULT_TURN_SPEED)

        Returns:
            True if reached target within tolerance.
            False if invalid input, timeout, or odometry not running.

        Edge cases:
            - degrees == 0 → no-op
            - |degrees| > 360 → clamped to 360 with warning
            - speed <= 0 → default
            - speed > 0.5 → clamped
            - Handles 0°/360° wrap-around correctly
            - Keyboard interrupt → graceful stop
        """
        if degrees == 0:
            print("  [Odom] ⚠️  Turn 0° — nothing to do")
            return True

        if abs(degrees) > 360:
            print(f"  [Odom] ⚠️  Turn {degrees}° > 360 — clamping to {360 * (1 if degrees > 0 else -1)}°")
            degrees = 360.0 * (1 if degrees > 0 else -1)

        if speed is None:
            speed = DEFAULT_TURN_SPEED

        if speed <= 0:
            speed = DEFAULT_TURN_SPEED
        elif speed > 0.5:
            print(f"  [Odom] ⚠️  Turn speed clamped to 0.4 rad/s")
            speed = 0.4

        if not self._running:
            print("  [Odom] ⚠️  Odometry not started — using time-based fallback")
            return self._time_based_turn(degrees, speed)

        self._check_stale()

        vyaw = speed if degrees > 0 else -speed
        target_abs = abs(degrees)

        with self._lock:
            start_heading = self._heading

        timeout = (target_abs / math.degrees(speed)) * SAFETY_TIMEOUT_MULT
        t0      = time.time()

        direction = "left" if degrees > 0 else "right"
        print(f"  [Odom] Turning {degrees:.1f}° {direction} at {math.degrees(speed):.1f}°/s "
              f"(timeout: {timeout:.1f}s)")

        try:
            while time.time() - t0 < timeout:
                with self._lock:
                    current = self._heading

                # Compute angular delta — handle wrap-around
                delta = abs(current - start_heading)
                if delta > 180:
                    delta = 360 - delta

                if delta >= target_abs - ANGLE_TOLERANCE:
                    self._gradual_stop()
                    print(f"  [Odom] ✅ Turned {delta:.1f}° (target {target_abs:.1f}°)")
                    return True

                self._send_vel(vyaw=vyaw)
                time.sleep(0.05)

        except KeyboardInterrupt:
            print("  [Odom] Turn interrupted by user")
            self._gradual_stop()
            raise

        self._gradual_stop()
        print(f"  [Odom] ⚠️  Timeout on turn")
        return False

    def _time_based_turn(self, degrees: float, speed: float) -> bool:
        """Time-based turn fallback. ~±5° accuracy."""
        target_abs = abs(degrees)
        vyaw       = speed if degrees > 0 else -speed
        duration   = target_abs / math.degrees(speed)
        print(f"  [Odom]    Time-based fallback: {degrees:.1f}° ≈ {duration:.1f}s")
        t0 = time.time()
        try:
            while time.time() - t0 < duration:
                self._send_vel(vyaw=vyaw)
                time.sleep(0.05)
        except KeyboardInterrupt:
            self._gradual_stop()
            raise
        self._gradual_stop()
        print(f"  [Odom] ✅ Time-based turn complete (~{degrees:.1f}°)")
        return True

    def navigate_to(self, target_x: float, target_y: float,
                    target_heading: float = None,
                    speed: float = None) -> bool:
        """
        Navigate to absolute coordinates.

        Steps:
            1. Rotate to face target direction
            2. Walk straight-line distance to target
            3. Optionally rotate to target_heading

        Args:
            target_x, target_y : destination in meters (same frame as odometry)
            target_heading      : final heading in degrees (None = don't adjust)
            speed               : walk speed in m/s

        Edge cases:
            - Already at target → skip walk, only rotate if needed
            - Odometry not running → time-based fallback (imprecise)
            - target_heading None → skip final rotation
        """
        with self._lock:
            curr_x = self._x
            curr_y = self._y
            curr_h = self._heading

        dx   = target_x - curr_x
        dy   = target_y - curr_y
        dist = math.sqrt(dx**2 + dy**2)

        print(f"  [Odom] Navigate to ({target_x:.2f}, {target_y:.2f}) — "
              f"dist={dist:.2f}m")

        if dist < DIST_TOLERANCE:
            print("  [Odom] Already at target position")
        else:
            # Rotate to face target
            angle_to_target = math.degrees(math.atan2(dy, dx))
            rotation_needed = angle_to_target - curr_h
            # Normalize to -180..180
            while rotation_needed >  180: rotation_needed -= 360
            while rotation_needed < -180: rotation_needed += 360

            if abs(rotation_needed) > ANGLE_TOLERANCE:
                self.turn_degrees(rotation_needed, speed=DEFAULT_TURN_SPEED)
                time.sleep(0.3)

            self.walk_distance(dist, speed=speed)
            time.sleep(0.3)

        # Rotate to final heading if specified
        if target_heading is not None:
            with self._lock:
                curr_h = self._heading
            final_rot = target_heading - curr_h
            while final_rot >  180: final_rot -= 360
            while final_rot < -180: final_rot += 360
            if abs(final_rot) > ANGLE_TOLERANCE:
                self.turn_degrees(final_rot)

        print(f"  [Odom] ✅ Arrived at ({target_x:.2f}, {target_y:.2f})")
        return True

    def return_to_start(self, speed: float = None) -> bool:
        """
        Navigate back to the position where start() was called.

        Edge cases:
            - Already at start → no movement
            - Odometry not running → cannot navigate (warn)
        """
        if not self._running:
            print("  [Odom] ⚠️  Cannot return to start — odometry not running")
            return False
        print("  [Odom] Returning to start position...")
        return self.navigate_to(
            self._start_x, self._start_y,
            self._start_heading, speed=speed
        )

    def patrol_route(self, waypoints: list,
                     speed: float = None,
                     loop: bool = False) -> bool:
        """
        Walk through a list of waypoints in order.

        Args:
            waypoints : list of dicts with keys x, y, heading (all optional)
                        e.g. [{"x": 1.0, "y": 0.0, "heading": 90}]
            speed     : travel speed in m/s
            loop      : if True, return to first waypoint after last

        Returns:
            True if all waypoints reached.

        Edge cases:
            - Empty waypoints → warns
            - Waypoint missing x/y → skipped with warning
            - Keyboard interrupt → stops gracefully at current position
            - loop=True appends waypoint[0] to end of route
        """
        if not waypoints:
            print("  [Odom] ⚠️  patrol_route: empty waypoints list")
            return False

        route = list(waypoints)
        if loop:
            route.append(waypoints[0])

        print(f"  [Odom] Patrol route: {len(route)} waypoints | loop={loop}")

        try:
            for i, wp in enumerate(route, 1):
                if "x" not in wp or "y" not in wp:
                    print(f"  [Odom] ⚠️  Waypoint {i} missing x/y — skipping")
                    continue

                print(f"  [Odom] Waypoint {i}/{len(route)}: ({wp['x']:.2f}, {wp['y']:.2f})")
                heading = wp.get("heading", None)
                self.navigate_to(wp["x"], wp["y"], heading, speed=speed)
                time.sleep(0.5)

        except KeyboardInterrupt:
            print("\n  [Odom] Patrol route interrupted by user")
            self._gradual_stop()
            return False

        print("  [Odom] ✅ Patrol route complete")
        return True

    def __repr__(self):
        pos = self.get_position()
        return (f"Odometry(x={pos['x']:.2f}, y={pos['y']:.2f}, "
                f"h={pos['heading']:.1f}°, source={pos['source']}, "
                f"running={self._running})")


# ══════════════════════════════════════════════════════════════════════════════
# STANDALONE TEST
# ══════════════════════════════════════════════════════════════════════════════

if __name__ == "__main__":
    import sys

    print("Marcus Odometry — Standalone Test")
    print("===================================\n")

    odom = Odometry()
    ok   = odom.start()
    time.sleep(1.5)

    print(f"\nInitial state: {odom}")
    print()
    print("Commands:")
    print("  walk <m>       — walk precisely N meters")
    print("  back <m>       — walk backward N meters")
    print("  turn <deg>     — turn precisely N degrees (+left, -right)")
    print("  status         — current position")
    print("  reset          — zero position")
    print("  goto <x> <y>   — navigate to coordinates")
    print("  home           — return to start")
    print("  square         — walk 1m×1m square")
    print("  q              — quit")
    print()

    while True:
        try:
            raw = input("Odom: ").strip().lower()
        except (EOFError, KeyboardInterrupt):
            break

        if not raw:
            continue

        parts = raw.split()
        cmd   = parts[0]

        if cmd == "q":
            break

        elif cmd == "status":
            print(f"  {odom.status_str()}")
            print(f"  Distance from start: {odom.get_distance_from_start():.3f}m")

        elif cmd == "reset":
            odom.reset()

        elif cmd == "walk" and len(parts) >= 2:
            try:
                odom.walk_distance(float(parts[1]))
            except ValueError:
                print("  Usage: walk <meters>")

        elif cmd == "back" and len(parts) >= 2:
            try:
                odom.walk_distance(float(parts[1]), direction="backward")
            except ValueError:
                print("  Usage: back <meters>")

        elif cmd == "turn" and len(parts) >= 2:
            try:
                odom.turn_degrees(float(parts[1]))
            except ValueError:
                print("  Usage: turn <degrees>  (+left, -right)")

        elif cmd == "goto" and len(parts) >= 3:
            try:
                odom.navigate_to(float(parts[1]), float(parts[2]))
            except ValueError:
                print("  Usage: goto <x> <y>")

        elif cmd == "home":
            odom.return_to_start()

        elif cmd == "square":
            print("  Walking 1m × 1m square...")
            odom.walk_distance(1.0)
            odom.turn_degrees(90)
            odom.walk_distance(1.0)
            odom.turn_degrees(90)
            odom.walk_distance(1.0)
            odom.turn_degrees(90)
            odom.walk_distance(1.0)
            odom.turn_degrees(90)
            print("  ✅ Square complete")

        else:
            print(f"  Unknown: {raw}")

    odom.stop()
    print("Odometry stopped.")