"""
转写进度追踪器（内存级 + DB 状态）

为每个问诊维护：
- stage (preparing | uploading | transcribing | extracting | generating | done | error)
- percent (0-100)
- message (人类可读描述)
- engine (实际使用的引擎名称)
- updated_at

提供线程安全的更新与查询接口，供前端轮询。
"""

import threading
import time
from dataclasses import dataclass, asdict
from typing import Optional


@dataclass
class ProgressState:
    """单个问诊的进度状态"""

    consultation_id: str
    stage: str = "preparing"          # preparing | uploading | transcribing | extracting | generating | done | error
    percent: int = 0                  # 0-100
    message: str = "准备中"             # 人类可读
    engine: str = "xunfei_llm"        # 当前实际使用的引擎
    error: Optional[str] = None       # 错误信息（如有）
    updated_at: float = 0.0           # 上次更新时间戳


class ProgressTracker:
    """内存级进度追踪器（线程安全）"""

    def __init__(self) -> None:
        self._states: dict[str, ProgressState] = {}
        self._lock = threading.Lock()

    def init(self, consultation_id: str, engine: str = "xunfei_llm") -> ProgressState:
        """初始化/重置一个问诊的进度"""
        with self._lock:
            state = ProgressState(
                consultation_id=consultation_id,
                stage="preparing",
                percent=0,
                message="准备中…",
                engine=engine,
                updated_at=time.time(),
            )
            self._states[consultation_id] = state
            return state

    def update(
        self,
        consultation_id: str,
        *,
        stage: Optional[str] = None,
        percent: Optional[int] = None,
        message: Optional[str] = None,
        error: Optional[str] = None,
    ) -> ProgressState:
        """更新进度状态"""
        with self._lock:
            state = self._states.get(consultation_id)
            if state is None:
                state = ProgressState(consultation_id=consultation_id)
                self._states[consultation_id] = state
            if stage is not None:
                state.stage = stage
            if percent is not None:
                state.percent = max(state.percent, min(percent, 100))
            if message is not None:
                state.message = message
            if error is not None:
                state.error = error
                state.stage = "error"
            state.updated_at = time.time()
            return state

    def get(self, consultation_id: str) -> Optional[dict]:
        """获取进度状态（用于 API 返回）"""
        with self._lock:
            state = self._states.get(consultation_id)
            if state is None:
                return None
            return asdict(state)

    def clear(self, consultation_id: str) -> None:
        """清理进度记录"""
        with self._lock:
            self._states.pop(consultation_id, None)


# ================================================================
# 全局单例
# ================================================================
_tracker: Optional[ProgressTracker] = None


def get_progress_tracker() -> ProgressTracker:
    """获取全局进度追踪器（单例）"""
    global _tracker
    if _tracker is None:
        _tracker = ProgressTracker()
    return _tracker