"""
任务管理模块 (task_manager)
模块: 服务端 / 任务管理
输入: init 请求 / 卷到达事件
输出: transfer 状态机

状态机: uploading -> storing -> done / failed
(零合并: 无 assembling/decrypting 阶段, 卷齐即入库)
transfer_id 生命周期贯穿接收->入库; 孤儿任务由清理逻辑回收 (见 server/data/tmp)。
"""

import uuid
from typing import Any

from db import ServerDB

STATUS_UPLOADING = "uploading"
STATUS_STORING = "storing"
STATUS_DONE = "done"
STATUS_FAILED = "failed"


class TaskManager:
    """transfer 生命周期管理 (基于 ServerDB)"""

    def __init__(self, db: ServerDB) -> None:
        self.db = db

    def create(self, init_json: dict[str, Any], user_id: str,
               dir_id: int | None = None) -> str:
        """POST /init: 建任务, 返回 transfer_id (输入清洗: 文件名/卷数上限)

        文件名只做可打印字符过滤 + 长度截断。不删 / \\ 等路径分隔符:
        加密文件名是 URL-safe base64 (可能含 - _ =), 路径安全由下载端 _safe_name 兜底
        """
        # 文件名字段清洗: 长度上限 + 去路径分隔符/控制字符
        raw = str(init_json.get("file_name", ""))
        clean = "".join(c for c in raw if c.isprintable())[:255]
        init_json["file_name"] = clean or "unnamed"
        # 卷数上限: 防超大清单放大 (1MB init / 120B 每卷 spec ≈ 8000)
        chunks = init_json.get("chunks") or []
        if len(chunks) > 10000:
            raise ValueError(f"卷数超上限: {len(chunks)} > 10000")
        init_json["chunk_count"] = len(chunks)
        transfer_id = uuid.uuid4().hex[:12]
        self.db.create_transfer(transfer_id, init_json, user_id, dir_id)
        return transfer_id

    def get(self, transfer_id: str) -> dict[str, Any] | None:
        return self.db.get_transfer(transfer_id)

    def chunk_spec(self, transfer_id: str, idx: int) -> dict[str, Any] | None:
        return self.db.get_chunk_spec(transfer_id, idx)

    def is_chunk_received(self, transfer_id: str, idx: int) -> bool:
        return self.db.is_chunk_received(transfer_id, idx)

    def mark_chunk_received(self, transfer_id: str, idx: int) -> None:
        """事件: 卷到达 (校验通过后)"""
        self.db.mark_chunk_received(transfer_id, idx)

    def received(self, transfer_id: str) -> set[int]:
        """已收卷集合 (GET /chunks 依据)"""
        return self.db.get_received_chunks(transfer_id)

    def set_status(self, transfer_id: str, status: str) -> None:
        self.db.set_status(transfer_id, status)