"""
Emitter — convenience wrappers around the singleton EventBus.

Deprecated-ish: prefer using `bus.emit(EventType.X, ...)` directly.
These helpers exist for backward compatibility with older callers
and for the CLI's `stream` command which expects simple event shapes.
"""

from backend.events.bus import EventBus
from backend.events.schema import EventType

# Process-wide singleton bus. Import this instead of constructing your own
# unless you really need an isolated bus (e.g. for tests).
BUS = EventBus()


async def emit_pipeline(action, state, node, **extra):
    """Emit a pipeline/task event. `action` may be a dict (action spec)
    or a string (action name)."""
    action_name = action["name"] if isinstance(action, dict) else action
    node_name = node["name"] if isinstance(node, dict) else node
    BUS.emit(
        EventType.TASK_UPDATE,
        action=action_name,
        node=node_name,
        state=state,
        **extra,
    )


async def emit_node(node, **extra):
    """Emit a node state update."""
    node_name = node["name"] if isinstance(node, dict) else node
    BUS.emit(
        EventType.NODE_UPDATE,
        node=node_name,
        **extra,
    )


async def emit_cache(action, state, node=None, **extra):
    """Emit a cache hit/miss event."""
    action_name = action["name"] if isinstance(action, dict) else action
    BUS.emit(
        EventType.CACHE_UPDATE,
        action=action_name,
        node=node,
        state=state,
        **extra,
    )


async def emit_failure(action, reason, node=None, **extra):
    """Emit a failure event."""
    action_name = action["name"] if isinstance(action, dict) else action
    BUS.emit(
        EventType.FAILURE,
        action=action_name,
        node=node,
        state="failed",
        reason=reason,
        **extra,
    )


async def emit_policy(key, value):
    """Emit a policy change event."""
    BUS.emit(
        EventType.PIPELINE_UPDATE,  # closest existing type
        action=None,
        node=None,
        state="policy",
        meta={"key": key, "value": value},
    )