"""分片上传会话 ORM：支撑断点续传。"""

from __future__ import annotations

import json
import logging
from datetime import datetime, timezone
from typing import Any

from sqlalchemy import DateTime, ForeignKey, Integer, String, Text, TypeDecorator
from sqlalchemy.orm import Mapped, mapped_column

from ..database import Base

logger = logging.getLogger("audio2text.models")


def _now() -> datetime:
    return datetime.now(timezone.utc)


class _IntList(TypeDecorator):
    """把 list[int] 存成 JSON 字符串。SQLite 没有 ARRAY 类型。"""

    impl = Text
    cache_ok = True

    def process_bind_param(self, value: Any, dialect) -> str | None:
        return json.dumps(value) if value is not None else None

    def process_result_value(self, value: Any, dialect) -> list[int]:
        if not value:
            return []
        try:
            return json.loads(value)
        except (json.JSONDecodeError, TypeError):
            # DB 脏数据（手工修改/并发写截断）不应让整行读取失败
            logger.warning("uploaded_chunks JSON 解析失败，回退空列表：%r", value[:80])
            return []


class UploadSession(Base):
    __tablename__ = "upload_session"

    upload_id: Mapped[str] = mapped_column(String(64), primary_key=True)
    filename: Mapped[str] = mapped_column(String(512), nullable=False)
    size_bytes: Mapped[int] = mapped_column(Integer, nullable=False)
    chunk_size: Mapped[int] = mapped_column(Integer, nullable=False)
    total_chunks: Mapped[int] = mapped_column(Integer, nullable=False)
    uploaded_chunks: Mapped[list[int]] = mapped_column(_IntList, default=list)
    # pending → completed（complete 成功）| abandoned（reaper 清理）
    status: Mapped[str] = mapped_column(String(32), nullable=False, default="pending", index=True)
    # 拼接完成后的视频相对 upload_dir 路径
    final_path: Mapped[str | None] = mapped_column(String(1024), nullable=True)
    # complete 后关联的 Task.id。ondelete=SET NULL：Task 被删时 session 保留（task_id 置空）
    task_id: Mapped[int | None] = mapped_column(
        ForeignKey("task.id", ondelete="SET NULL"), nullable=True
    )

    created_at: Mapped[datetime] = mapped_column(DateTime, default=_now, index=True)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=_now, onupdate=_now)