"""
events.py — Canonical event schema for Purpose Agent v3.0.

Every action in the framework emits a PAEvent. Events are:
  - Typed (EventKind enum)
  - Ordered (per-lane sequence numbers)
  - Scoped (visibility: public/internal/debug)
  - Immutable (frozen dataclass)
  - Serializable (to_dict → JSON/JSONL)

Safety: reasoning.summary is allowed. Raw hidden chain-of-thought is NOT.
"""
from __future__ import annotations

import time
import uuid
from dataclasses import dataclass, field
from enum import Enum
from typing import Any


class Visibility(str, Enum):
    """Who can see this event."""
    PUBLIC = "public"       # Safe for UI, logs, external consumers
    INTERNAL = "internal"   # Framework internals (memory ops, optimization)
    DEBUG = "debug"         # Verbose debug info, never in production streams


class EventKind(str, Enum):
    """All possible event types in the Purpose Agent runtime."""

    # Run lifecycle
    RUN_STARTED = "run.started"
    RUN_FINISHED = "run.finished"
    RUN_ERROR = "run.error"

    # Agent lifecycle
    AGENT_STARTED = "agent.started"
    AGENT_PROGRESS = "agent.progress"
    AGENT_FINISHED = "agent.finished"
    AGENT_ERROR = "agent.error"

    # Reasoning (safe summaries only — NO raw chain-of-thought)
    REASONING_SUMMARY = "reasoning.summary"

    # Model calls
    MODEL_REQUEST = "model.request"
    MODEL_RESPONSE = "model.response"

    # Text streaming
    TEXT_DELTA = "text.delta"
    TEXT_DONE = "text.done"

    # Tool execution
    TOOL_STARTED = "tool.started"
    TOOL_ARGS = "tool.args"
    TOOL_RESULT = "tool.result"
    TOOL_ERROR = "tool.error"

    # State management
    STATE_SNAPSHOT = "state.snapshot"
    STATE_DELTA = "state.delta"

    # Checkpointing
    CHECKPOINT_SAVED = "checkpoint.saved"

    # Human-in-the-loop
    HUMAN_APPROVAL_REQUESTED = "human.approval.requested"
    HUMAN_APPROVAL_RECEIVED = "human.approval.received"

    # Memory lifecycle
    MEMORY_CANDIDATE = "memory.candidate"
    MEMORY_PROMOTED = "memory.promoted"
    MEMORY_ARCHIVED = "memory.archived"

    # Skill lifecycle
    SKILL_SELECTED = "skill.selected"
    SKILL_UPDATED = "skill.updated"
    SKILL_ROLLBACK = "skill.rollback"


# Events that MUST NOT contain raw chain-of-thought
_PRIVATE_KINDS = frozenset()  # No kind is inherently private; visibility controls this

# Events that should always be delivered even under backpressure
TERMINAL_KINDS = frozenset({
    EventKind.RUN_FINISHED,
    EventKind.RUN_ERROR,
    EventKind.AGENT_FINISHED,
    EventKind.AGENT_ERROR,
})


@dataclass(frozen=True)
class PAEvent:
    """
    Canonical event emitted by the Purpose Agent runtime.

    Every observable action produces one or more PAEvents.
    Events are immutable, ordered, and typed.

    Fields:
        run_id: Unique ID for this execution run
        session_id: Groups related runs (e.g., a conversation)
        lane_id: Identifies parallel execution lane (for swarm/parallel)
        span_id: Unique ID for this specific event
        parent_span_id: Parent event (for nesting: run → agent → tool)
        seq: Monotonically increasing sequence number within a lane
        ts: Unix timestamp
        kind: What happened (EventKind enum)
        visibility: Who should see this (public/internal/debug)
        payload: Event-specific data
    """
    run_id: str
    session_id: str = ""
    lane_id: str = "main"
    span_id: str = field(default_factory=lambda: uuid.uuid4().hex[:12])
    parent_span_id: str | None = None
    seq: int = 0
    ts: float = field(default_factory=time.time)
    kind: EventKind = EventKind.AGENT_PROGRESS
    visibility: Visibility = Visibility.PUBLIC
    payload: dict[str, Any] = field(default_factory=dict)

    def to_dict(self) -> dict[str, Any]:
        """Serialize to dictionary (JSON-safe)."""
        return {
            "run_id": self.run_id,
            "session_id": self.session_id,
            "lane_id": self.lane_id,
            "span_id": self.span_id,
            "parent_span_id": self.parent_span_id,
            "seq": self.seq,
            "ts": self.ts,
            "kind": self.kind.value,
            "visibility": self.visibility.value,
            "payload": self.payload,
        }

    @classmethod
    def from_dict(cls, d: dict[str, Any]) -> "PAEvent":
        """Deserialize from dictionary."""
        return cls(
            run_id=d["run_id"],
            session_id=d.get("session_id", ""),
            lane_id=d.get("lane_id", "main"),
            span_id=d.get("span_id", uuid.uuid4().hex[:12]),
            parent_span_id=d.get("parent_span_id"),
            seq=d.get("seq", 0),
            ts=d.get("ts", time.time()),
            kind=EventKind(d["kind"]),
            visibility=Visibility(d.get("visibility", "public")),
            payload=d.get("payload", {}),
        )

    @property
    def is_terminal(self) -> bool:
        """Is this a terminal event that must always be delivered?"""
        return self.kind in TERMINAL_KINDS

    @property
    def is_error(self) -> bool:
        return self.kind in (EventKind.RUN_ERROR, EventKind.AGENT_ERROR, EventKind.TOOL_ERROR)

    def has_hidden_cot(self) -> bool:
        """Check if payload contains raw chain-of-thought (safety violation)."""
        forbidden_keys = {"hidden_chain_of_thought", "raw_cot", "internal_reasoning", "think_content"}
        return bool(forbidden_keys & set(self.payload.keys()))


def create_event(
    run_id: str,
    kind: EventKind,
    lane_id: str = "main",
    seq: int = 0,
    parent_span_id: str | None = None,
    visibility: Visibility = Visibility.PUBLIC,
    **payload,
) -> PAEvent:
    """Factory helper for creating events with less boilerplate."""
    return PAEvent(
        run_id=run_id,
        lane_id=lane_id,
        span_id=uuid.uuid4().hex[:12],
        parent_span_id=parent_span_id,
        seq=seq,
        kind=kind,
        visibility=visibility,
        payload=payload,
    )