from __future__ import annotations

import hashlib
from pathlib import Path


FORBIDDEN_REFERENCE_ROOT = Path("/Users/yoilun/AI-train/zhengxin-vlm-0413")


def resolve_path(path: str | Path, *, base_dir: Path | None = None) -> Path:
    candidate = Path(path).expanduser()
    if not candidate.is_absolute() and base_dir is not None:
        candidate = base_dir / candidate
    return candidate.resolve(strict=False)


def _is_relative_to(path: Path, parent: Path) -> bool:
    try:
        path.relative_to(parent)
        return True
    except ValueError:
        return False


def validate_output_dir(
    input_dir: str | Path,
    output_dir: str | Path,
    *,
    forbidden_root: Path = FORBIDDEN_REFERENCE_ROOT,
) -> Path:
    resolved_input = resolve_path(input_dir)
    resolved_output = resolve_path(output_dir)
    resolved_forbidden = resolve_path(forbidden_root)

    if resolved_output == resolved_input:
        raise ValueError("output dir must not equal input dir")
    if _is_relative_to(resolved_output, resolved_forbidden):
        raise ValueError(
            f"output dir must not be inside forbidden reference dir: {resolved_forbidden}"
        )
    return resolved_output


def stable_video_id(path: str | Path) -> str:
    resolved = str(resolve_path(path))
    digest = hashlib.sha1(resolved.encode("utf-8")).hexdigest()[:16]
    return f"video-{digest}"


def hik_cloud_download_path(
    output_dir: str | Path,
    device_serial: str,
    channel_no: int | str,
    time_begin: int,
    time_end: int,
) -> Path:
    safe_device = _safe_path_component(device_serial)
    safe_channel = _safe_path_component(str(channel_no))
    filename = f"{safe_device}_ch{safe_channel}_{int(time_begin)}_{int(time_end)}.mp4"
    return (
        resolve_path(output_dir)
        / "downloads"
        / "hik_cloud"
        / safe_device
        / f"ch{safe_channel}"
        / filename
    )


def _safe_path_component(value: str) -> str:
    return "".join(char if char.isalnum() or char in "._-" else "_" for char in value)