from __future__ import annotations

import sys
from pathlib import Path


def find_project_root(start_path: Path | None = None) -> Path:
    """Find the emotion_fusion_demo project root from a file or directory.

    A valid root contains app.py, config.py, and at least two of the core module
    directories. If detection fails, return the current working directory with a
    clear warning instead of raising.
    """
    start = Path(start_path) if start_path is not None else Path.cwd()
    try:
        start = start.resolve()
    except Exception:
        start = Path.cwd().resolve()

    if start.is_file():
        start = start.parent

    candidates = [start, *start.parents]
    for candidate in candidates:
        if _looks_like_project_root(candidate):
            return candidate

    print(
        "Warning: 未能自动识别项目根目录，请确认你在 emotion_fusion_demo 项目目录中运行。",
        file=sys.stderr,
    )
    return Path.cwd().resolve()


def _looks_like_project_root(path: Path) -> bool:
    if not (path / "app.py").is_file():
        return False
    if not (path / "config.py").is_file():
        return False

    core_dirs = ["face_module", "ecg_module", "fusion"]
    existing_count = sum(1 for dirname in core_dirs if (path / dirname).is_dir())
    return existing_count >= 2