"""
回复队列执行记录
================
待回复队列本身只存"现在还欠谁一条回复"，不留痕迹：任务一完成就被删掉，出了
问题事后完全看不出它经历过什么。排查"为什么这个客户没收到回复"、"为什么同一
句话回了三遍"时，缺的就是这条时间线。

这里按时间顺序记下每个会话在队列里的每一步：入队、开始处理、生成回复、已发送、
完成、跳过、失败。机器人线程写、界面线程读，所以写入走临时文件加原子替换，
界面永远不会读到写了一半的 JSON。
"""

import json
import os
import tempfile
import threading
import time

from runtime_paths import application_data_dir

# 队列事件
ENQUEUED = "入队"
OPENED = "开始处理"
GENERATED = "生成回复"
SENT = "已发送"
DONE = "完成"
SKIPPED = "跳过"
FAILED = "失败"


class QueueLog:
    """回复队列的执行流水。"""

    # 只留最近这么多条。这是给人看的排查线索，不是审计账本；
    # 无上限的话跑上几天，界面每次刷新都要读一个几十兆的文件
    MAX_EVENTS = 500

    def __init__(self, path: str = ""):
        self.path = str(path or os.path.join(application_data_dir(), "queue_events.json"))
        self._lock = threading.Lock()

    # ── 写 ───────────────────────────────────────────────────────────────────
    def append(
        self,
        session_id: str,
        name: str,
        event: str,
        detail: str = "",
    ) -> bool:
        """记一步。写失败绝不能影响回复，所以吞掉异常只返回 False。"""
        entry = {
            "ts": time.time(),
            "session_id": str(session_id or "")[:32],
            "name": str(name or ""),
            "event": str(event or ""),
            "detail": str(detail or "")[:200],
        }
        with self._lock:
            try:
                events = self._read_unlocked()
                events.append(entry)
                if len(events) > self.MAX_EVENTS:
                    events = events[-self.MAX_EVENTS:]
                self._write_unlocked(events)
                return True
            except Exception:
                return False

    def clear(self) -> bool:
        with self._lock:
            try:
                self._write_unlocked([])
                return True
            except Exception:
                return False

    # ── 读 ───────────────────────────────────────────────────────────────────
    def recent(self, limit: int = 200) -> list[dict]:
        """最近的事件，最新的排在前面。"""
        with self._lock:
            try:
                events = self._read_unlocked()
            except Exception:
                return []
        count = max(0, int(limit))
        return list(reversed(events[-count:])) if count else []

    # ── 落盘 ─────────────────────────────────────────────────────────────────
    def _read_unlocked(self) -> list[dict]:
        if not os.path.exists(self.path):
            return []
        try:
            with open(self.path, encoding="utf-8") as handle:
                data = json.load(handle)
        except (OSError, ValueError):
            # 文件损坏时从头开始，总好过让界面和机器人一起崩
            return []
        if isinstance(data, dict):
            data = data.get("events", [])
        return [item for item in data if isinstance(item, dict)]

    def _write_unlocked(self, events: list) -> None:
        directory = os.path.dirname(os.path.abspath(self.path)) or "."
        os.makedirs(directory, exist_ok=True)
        handle = tempfile.NamedTemporaryFile(
            "w",
            encoding="utf-8",
            dir=directory,
            prefix=".queue_events_",
            suffix=".tmp",
            delete=False,
        )
        try:
            with handle:
                json.dump({"events": events}, handle, ensure_ascii=False, indent=2)
            # 原子替换：界面随时可能在读，不能让它撞上写了一半的文件
            os.replace(handle.name, self.path)
        except Exception:
            try:
                os.unlink(handle.name)
            except OSError:
                pass
            raise