"""跨平台路径工具：重点兼容 Windows UNC 网络路径（\\\\NAS\\share\\...）。"""
from __future__ import annotations

import os
import sys
from pathlib import Path, PureWindowsPath


def normalize_user_path(raw: str) -> str:
    """规范化用户输入的路径，保留 UNC 反斜杠格式。

    示例：
    - \\\\JIULUGNAS\\personal_folder\\Photos  -> 原样保留
    - //JIULUGNAS/personal_folder/Photos     -> 转为 UNC
    - D:/Pictures/Screenshots                -> D:\\Pictures\\Screenshots
    """
    raw = (raw or "").strip().strip('"').strip("'")
    if not raw:
        return raw

    if sys.platform == "win32":
        # //server/share -> \\server\share
        if raw.startswith("//") and not raw.startswith("///"):
            raw = "\\\\" + raw.lstrip("/").replace("/", "\\")
        elif raw.startswith("\\\\"):
            pass
        else:
            raw = raw.replace("/", "\\")
        return str(PureWindowsPath(raw))

    return str(Path(raw).expanduser())


def path_from_storage(stored: str) -> Path:
    """从数据库读出的路径转为 Path（修复历史 as_posix 导致的 //NAS/...）。"""
    if not stored:
        return Path(stored)
    if sys.platform == "win32":
        # 历史数据：//JIULUGNAS/foo/bar -> \\JIULUGNAS\foo\bar
        if stored.startswith("//") and not stored.startswith("///"):
            stored = "\\\\" + stored.lstrip("/").replace("/", "\\")
    return Path(stored)


def path_to_storage(path: Path | str) -> str:
    """写入数据库 / 比较用的路径字符串；Windows 下保留反斜杠。"""
    if isinstance(path, Path):
        if sys.platform == "win32":
            return str(path)
        return path.as_posix()
    return normalize_user_path(str(path)) if sys.platform == "win32" else str(path)


def is_accessible_dir(path: str | Path) -> bool:
    """目录是否可访问（UNC / 本地均适用）。"""
    try:
        return os.path.isdir(str(path))
    except OSError:
        return False


def is_accessible_file(path: str | Path) -> bool:
    """文件是否可访问。"""
    try:
        return os.path.isfile(str(path))
    except OSError:
        return False


def path_is_under(parent: str | Path, child: str | Path) -> bool:
    """判断 child 是否在 parent 目录下（用于敏感目录检测）。"""
    try:
        parent_norm = os.path.normcase(os.path.normpath(str(parent)))
        child_norm = os.path.normcase(os.path.normpath(str(child)))
        if not parent_norm.endswith(os.sep):
            parent_norm += os.sep
        return child_norm.startswith(parent_norm) or child_norm == parent_norm.rstrip(os.sep)
    except OSError:
        return False


def count_files_sample(root: str | Path, limit: int = 5) -> tuple[int, list[str]]:
    """快速抽样统计目录下图片数量（网络路径可能较慢，limit 控制遍历深度）。"""
    from app.services.thumbnail import is_supported

    root_p = path_from_storage(str(root)) if isinstance(root, str) else root
    total = 0
    samples: list[str] = []
    try:
        for dirpath, _, filenames in os.walk(str(root_p)):
            for name in filenames:
                p = Path(dirpath) / name
                if not is_supported(p):
                    continue
                total += 1
                if len(samples) < limit:
                    samples.append(path_to_storage(p))
            if total >= 1000:
                break
    except OSError:
        pass
    return total, samples