"""Manifest loading and validation — Issue #2."""
import yaml
from typing import Optional


def validate_profile(profile: dict) -> dict:
    """Validate and normalize a single manifest profile entry.

    Required fields: id, name, model_path.
    Optional field: flags (defaults to {}).
    """
    for field in ("id", "name", "model_path"):
        if field not in profile:
            raise ValueError(f"Missing required field: {field}")

    return {
        "id": profile["id"],
        "name": profile["name"],
        "model_path": profile["model_path"],
        "flags": profile.get("flags", {}),
    }


def load_manifest(path: str) -> Optional[list]:
    """Load and validate profiles from a YAML manifest file.

    Returns a list of validated profile dicts, or None on any error.
    """
    try:
        with open(path, "r") as f:
            content = f.read()
    except (FileNotFoundError, OSError):
        return None

    if not content.strip():
        return []

    try:
        data = yaml.safe_load(content)
    except yaml.YAMLError:
        return None

    if data is None or data == []:
        return []

    if not isinstance(data, list):
        return None

    profiles = []
    for item in data:
        try:
            profiles.append(validate_profile(item))
        except ValueError:
            # Skip invalid profiles rather than failing the whole manifest
            continue

    return profiles