from pathlib import Path
from typing import Optional

import yaml

from datadog_tools.config import (
    DEFAULT_DEFINITION_FILENAME,
)


def get_full_entity_definition_file_path(
    repository_path: str,
    entity_path: str,
    entity_definition_file_path: Optional[str] = None,
) -> Path:
    """
    Resolve the absolute path to an entity’s definition file.

    :param repository_path: The base directory of the whole repo.
    :param entity_path: The relative directory inside the repository where the entity lives.
    :param entity_definition_file_path: If supplied, this is interpreted as a path
        *relative to the entity's* base directory.

    :return: The absolute path to the entity definition file.
    """
    repository_path = Path(repository_path).resolve()

    if entity_definition_file_path:
        return Path(repository_path / entity_definition_file_path)
    else:
        return Path(repository_path / entity_path / DEFAULT_DEFINITION_FILENAME)


def get_entity_kind_from_entity_definition_file(
    entity_definition_file_path: Path,
) -> Optional[str]:
    """
    Extract the kind field from a YAML definition file. Throws if the file
    cannot be read or parsed.

    :param entity_definition_file_path: The absolute path to the YAML file.
    :return: The kind of the entity, lowercased. If the kind is missing or not a
        string, returns ``None``.
    """
    with entity_definition_file_path.open("r", encoding="utf-8") as f:
        content = yaml.safe_load(f)

    kind = content.get("kind")

    if isinstance(kind, str):
        return kind.strip().lower()

    return None