"""Safe, movement-only bridge from legacy navigation to protocol 777."""
import threading
import time
import traceback


def start(global_state):
    """Start the legacy path-following physics, without legacy job/game packets."""
    g = global_state
    g.protocol_version = 777
    g.time = 0.0
    g.path = []
    g.look_at = None
    g.y_v = 0.0
    g.y_a = 0.0
    g.crawling = False
    g.afk_timeout = 0.0
    g.objects = g.get('objects') or {}
    g.players = g.get('players') or {}
    g.breaking = None
    g.break_time = 0.0
    g.correction_count = g.get('correction_count', 0)
    g.yaw = float(g.get('yaw', 0.0) or 0.0)
    g.pitch = float(g.get('pitch', 0.0) or 0.0)
    g.chunks.loading = False
    # Local navigation only needs nearby chunks; waiting for the entire view
    # radius can stall on servers that stream chunks gradually.
    g.physics_render_distance = 2
    g.movement_paused = False
    g.movement_status = 'idle'
    g.movement_error = None
    # Inventory, interaction, and job packets remain disabled until migrated.
    g.job = None
    g.game = None

    def run():
        from mosfet import bot, utils
        loaded_since = None

        while (g.get('running', True) and g.get('connection') and
               g.connection.connected):
            started = time.monotonic()
            now = time.monotonic()
            if g.chunks.check_loaded(g.physics_render_distance):
                if loaded_since is None:
                    loaded_since = now
            else:
                loaded_since = None
            # Let the initial position correction and first chunk batch settle
            # before allowing any client-originated movement.
            movement_ready = loaded_since is not None and now - loaded_since >= 0.5
            if g.get('movement_paused'):
                g.movement_status = 'paused'
            elif g.path and not movement_ready:
                g.movement_status = 'waiting_for_chunks'
            elif g.path and movement_ready:
                g.movement_status = 'following_path'
                try:
                    bot.tick(g)
                except Exception:
                    traceback.print_exc()
                    g.movement_error = traceback.format_exc()
                    g.path = []
                    g.movement_status = 'error'
                    print('[26.3 movement] stopped after navigation error',
                          flush=True)
                    return
            elif not g.path and not g.get('movement_paused'):
                g.movement_status = 'idle'
            delay = max(0.0, utils.TICK - (time.monotonic() - started))
            time.sleep(delay)

    worker = threading.Thread(target=run, name='mosfet-26.3-movement',
                              daemon=True)
    g.movement_thread = worker
    worker.start()
    return worker