# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0

"""External media path helpers."""

from __future__ import annotations

import getpass
import os
import platform
from pathlib import Path

from utils.paths.sensitive import (
    contains_sensitive_path_component,
    is_sensitive_path_component,
)


def _is_linux_media_mount_path(path: str, media_root: Path | str) -> bool:
    normalized = os.path.normpath(os.path.realpath(os.path.expanduser(path)))
    root = os.path.normpath(os.path.realpath(os.path.expanduser(str(media_root))))
    try:
        rel = os.path.relpath(normalized, root)
    except ValueError:
        return False
    if rel == "." or rel == ".." or rel.startswith(f"..{os.sep}"):
        return False
    parts = [part for part in rel.split(os.sep) if part]
    return len(parts) >= 2 and all(part not in (".", "..") for part in parts[:2])


def is_linux_run_media_path(path: str) -> bool:
    """True for Linux removable-media paths under /run/media/<user>/<volume>."""
    if platform.system() != "Linux":
        return False
    return _is_linux_media_mount_path(path, "/run/media")


def _current_username() -> str | None:
    try:
        user = getpass.getuser().strip()
    except Exception:
        return None
    return user or None


def _contains_sensitive_media_component(path: Path, media_root: Path) -> bool:
    try:
        rel = path.relative_to(media_root)
    except ValueError:
        rel = path
    return contains_sensitive_path_component(str(rel))


def linux_run_media_mount_roots(
    base: Path | str = "/run/media", *, user: str | None = None
) -> list[Path]:
    """Readable /run/media/<user>/<volume> roots for the folder browser."""
    if platform.system() != "Linux":
        return []
    user = user or _current_username()
    if not user or user in (".", "..") or os.sep in user:
        return []
    base_path = Path(base)
    try:
        resolved_base = base_path.resolve()
    except (OSError, RuntimeError, ValueError):
        return []

    roots: list[Path] = []
    seen: set[str] = set()
    user_dir = base_path / user
    try:
        if not user_dir.is_dir():
            return []
        volume_dirs = list(user_dir.iterdir())
    except (OSError, RuntimeError, ValueError):
        return []
    for volume_dir in volume_dirs:
        if is_sensitive_path_component(volume_dir.name):
            continue
        try:
            resolved = volume_dir.resolve()
        except (OSError, RuntimeError, ValueError):
            continue
        if not _is_linux_media_mount_path(str(resolved), resolved_base):
            continue
        if _contains_sensitive_media_component(resolved, resolved_base):
            continue
        key = os.path.normcase(os.path.realpath(str(resolved)))
        if key in seen:
            continue
        try:
            is_dir = resolved.is_dir()
        except OSError:
            continue
        if is_dir and os.access(resolved, os.R_OK | os.X_OK):
            seen.add(key)
            roots.append(resolved)
    return roots