"""JSONL audit events + writer.

All RSA orchestrator state changes emit one event per JSON line. Schema is
documented in docs/superpowers/specs/2026-05-10-markovian-rsa-mlx-design.md.
"""
from __future__ import annotations
import dataclasses
import io
import json
import weakref
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Literal

from markovian_rsa_mlx.config import RSAConfig


@dataclass
class _BaseEvent:
    """Base for all audit events. Subclasses set EVENT_NAME."""
    EVENT_NAME: str = field(init=False, repr=False, default="")

    def to_dict(self) -> dict[str, Any]:
        d: dict[str, Any] = {"event": self.EVENT_NAME}
        for f in dataclasses.fields(self):
            if f.name == "EVENT_NAME":
                continue
            v = getattr(self, f.name)
            if isinstance(v, RSAConfig):
                v = dataclasses.asdict(v)
            d[f.name] = v
        return d


@dataclass
class RunStartEvent(_BaseEvent):
    run_id: str
    model_id: str
    quantization: str
    config: RSAConfig
    prompt: str
    created_at: str
    EVENT_NAME: str = field(init=False, default="run_start")


@dataclass
class GenerationStartEvent(_BaseEvent):
    run_id: str
    round: int
    trace_id: str
    seed: int
    prompt_token_count: int
    max_tokens: int
    parent_trace_ids: list[str]
    EVENT_NAME: str = field(init=False, default="generation_start")


@dataclass
class TraceCompleteEvent(_BaseEvent):
    run_id: str
    round: int
    trace_id: str
    text: str
    token_ids: list[int]
    generated_tokens: int
    finish_reason: Literal["eos", "max_tokens", "error"]
    elapsed_s: float
    EVENT_NAME: str = field(init=False, default="trace_complete")


@dataclass
class TailExtractedEvent(_BaseEvent):
    run_id: str
    round: int
    trace_id: str
    tail_token_ids: list[int]
    tail_text: str
    tail_tokens: int
    EVENT_NAME: str = field(init=False, default="tail_extracted")


@dataclass
class AggregationPromptEvent(_BaseEvent):
    run_id: str
    round: int
    trace_id: str
    selected_tail_trace_ids: list[str]
    prompt_text: str
    prompt_token_ids: list[int]
    EVENT_NAME: str = field(init=False, default="aggregation_prompt")


@dataclass
class RoundCompleteEvent(_BaseEvent):
    run_id: str
    round: int
    trace_ids: list[str]
    memory_estimate_bytes: int
    elapsed_s: float
    EVENT_NAME: str = field(init=False, default="round_complete")


@dataclass
class FinalEvent(_BaseEvent):
    run_id: str
    final_trace_id: str
    final_text: str
    all_final_trace_ids: list[str]
    answer_selection: str
    EVENT_NAME: str = field(init=False, default="final")


@dataclass
class RunEndEvent(_BaseEvent):
    run_id: str
    elapsed_s: float
    total_generated_tokens: int
    peak_memory_bytes: int
    EVENT_NAME: str = field(init=False, default="run_end")


@dataclass
class ErrorEvent(_BaseEvent):
    run_id: str
    stage: str
    message: str
    recoverable: bool
    EVENT_NAME: str = field(init=False, default="error")


class AuditWriter:
    """Streaming JSONL writer. No-op when path is None.

    Once `close()` is called, subsequent `write()` calls raise ValueError.
    Use as a context manager (`with AuditWriter(p) as w:`) for guaranteed close.
    """
    def __init__(self, path: Path | str | None, mode: Literal["w", "a"] = "w") -> None:
        self._path = Path(path) if path is not None else None
        self._enabled = self._path is not None
        self._closed = False
        self._fp: io.TextIOWrapper | None = None
        if self._path is not None:
            self._path.parent.mkdir(parents=True, exist_ok=True)
            self._fp = self._path.open(mode, encoding="utf-8")
        if self._fp is not None:
            weakref.finalize(self, self._fp.close)

    def write(self, event: _BaseEvent) -> None:
        if not self._enabled:
            return
        if self._closed:
            raise ValueError("AuditWriter is closed")
        assert self._fp is not None
        self._fp.write(json.dumps(event.to_dict(), ensure_ascii=False))
        self._fp.write("\n")
        self._fp.flush()  # flush per event so a crash mid-run preserves the audit trail

    def close(self) -> None:
        if self._closed:
            return
        self._closed = True
        if self._fp is not None:
            self._fp.close()
            self._fp = None

    def __enter__(self) -> "AuditWriter":
        return self

    def __exit__(self, exc_type, exc_val, exc_tb) -> None:
        self.close()