"""
Fester backend — core API facade.

This module exposes a single `bus`, `registry`, `observability`, `ws_stream`,
plus thin wrapper functions for the API layer. It used to be broken
(referenced `bus` before creation, imported nonexistent `_endpoint` symbols,
duplicated CauseGraphEngine setup). It now wires everything cleanly.
"""

from backend.events.bus import EventBus
from backend.metrics.observability import ObservabilityHub
from backend.metrics.node_state import NodeStateRegistry
from backend.analysis.cause_graph import CauseGraphEngine

# =========================================================
# GLOBAL CORE SYSTEM INITIALIZATION (SINGLETON LAYER)
# =========================================================

bus = EventBus()
registry = NodeStateRegistry()
observability = ObservabilityHub(registry, bus)
observability.attach_bus()

# Cause graph — subscribes ONCE, no recursion (ingest only)
cause_graph = CauseGraphEngine()
cause_graph.attach_bus(bus)
bus.subscribe(cause_graph.ingest)

# WebSocket stream — attached lazily by main.py when FastAPI starts,
# because the WS layer needs the running app's connection registry.
ws_stream = None  # set by backend.main when app boots


def attach_ws_stream(stream):
    """Called by backend.main during startup to bind a WebSocketStream."""
    global ws_stream
    ws_stream = stream
    ws_stream.attach_bus(bus)


# =========================================================
# API REGISTRATION LAYER
# Thin wrappers so Cockpit / external callers can bind cleanly.
# =========================================================

# These imports are deliberately placed AFTER the singletons above are
# initialized, because some api/* modules may want to import `bus` etc.
from backend.api import build as build_api
from backend.api import nodes as nodes_api
from backend.api import replay as replay_api
from backend.api import debugger as debugger_api
from backend.api import timeline as timeline_api
from backend.api import metrics as metrics_api
from backend.api import autopsy as autopsy_api
from backend.api import pipeline_control as pipeline_control_api
from backend.api import cause as cause_api


def build(spec, nodes, cluster=None, intelligence=None):
    return build_api.build_endpoint(spec, nodes, cluster, intelligence)


def replay(session_id):
    return replay_api.replay_endpoint(session_id, registry)


def debugger(session_id):
    return debugger_api.debugger_endpoint(session_id, registry, bus)


def timeline(session_id):
    return timeline_api.timeline_endpoint(session_id)


def nodes():
    return nodes_api.nodes_endpoint(registry)


def metrics():
    return metrics_api.metrics_endpoint(registry)


def autopsy(session_id):
    return autopsy_api.autopsy_endpoint(session_id)


def pipeline_control(action, payload=None):
    return pipeline_control_api.pipeline_control_endpoint(action, payload, bus)


__all__ = [
    "bus",
    "registry",
    "observability",
    "ws_stream",
    "cause_graph",
    "attach_ws_stream",

    "build",
    "replay",
    "debugger",
    "timeline",
    "nodes",
    "metrics",
    "autopsy",
    "pipeline_control",
]