"""
Centralised configuration helpers for the Python search toolkit.

Environment Variables:
    ELASTIC_URL: Base URL to the Elasticsearch node (default: http://localhost:9200).
    ELASTIC_USERNAME / ELASTIC_PASSWORD: Optional basic auth credentials.
    ELASTIC_INDEX: Target index name (default: this_little_corner_py).
    LOCAL_DATA_DIR: Root folder containing JSON metadata (default: ../data/video_metadata).
    YOUTUBE_API_KEY: Optional API key for pulling metadata directly from YouTube.
"""

from __future__ import annotations

import os
from dataclasses import dataclass
from pathlib import Path
from typing import Optional

# Load .env file if it exists
try:
    from dotenv import load_dotenv
    import logging

    _logger = logging.getLogger(__name__)
    _env_path = Path(__file__).parent / ".env"
    if _env_path.exists():
        _logger.info("Loading .env from: %s", _env_path)
        result = load_dotenv(_env_path, override=True)
        _logger.info("load_dotenv result: %s", result)
except ImportError:
    pass  # python-dotenv not installed


@dataclass(frozen=True)
class ElasticSettings:
    url: str
    username: Optional[str]
    password: Optional[str]
    index: str
    ca_cert: Optional[Path]
    verify_certs: bool
    api_key: Optional[str]
    debug: bool


@dataclass(frozen=True)
class DataSettings:
    root: Path


@dataclass(frozen=True)
class YoutubeSettings:
    api_key: Optional[str]


@dataclass(frozen=True)
class AppConfig:
    elastic: ElasticSettings
    data: DataSettings
    youtube: YoutubeSettings
    qdrant_url: str
    qdrant_collection: str
    qdrant_vector_name: Optional[str]
    qdrant_vector_size: int
    qdrant_embed_model: str


def _env(name: str, default: Optional[str] = None) -> Optional[str]:
    """Return an environment variable value with optional default."""
    value = os.environ.get(name)
    if value is None:
        return default
    stripped = value.strip()
    return stripped or default


def load_config() -> AppConfig:
    """Collect configuration from environment variables."""
    elastic = ElasticSettings(
        url=_env("ELASTIC_URL", "http://localhost:9200"),
        username=_env("ELASTIC_USERNAME"),
        password=_env("ELASTIC_PASSWORD"),
        index=_env("ELASTIC_INDEX", "this_little_corner_py"),
        ca_cert=Path(_env("ELASTIC_CA_CERT")).expanduser() if _env("ELASTIC_CA_CERT") else None,
        verify_certs=_env("ELASTIC_VERIFY_CERTS", "1") not in {"0", "false", "False"},
        api_key=_env("ELASTIC_API_KEY"),
        debug=_env("ELASTIC_DEBUG", "0") in {"1", "true", "True"},
    )
    data_root = Path(
        _env(
            "LOCAL_DATA_DIR",
            Path(__file__).resolve().parents[1] / "data" / "video_metadata",
        )
    )
    data = DataSettings(root=data_root)
    youtube = YoutubeSettings(api_key=_env("YOUTUBE_API_KEY"))
    return AppConfig(
        elastic=elastic,
        data=data,
        youtube=youtube,
        qdrant_url=_env("QDRANT_URL", "http://localhost:6333"),
        qdrant_collection=_env("QDRANT_COLLECTION", "tlc_embeddings"),
        qdrant_vector_name=_env("QDRANT_VECTOR_NAME"),
        qdrant_vector_size=int(_env("QDRANT_VECTOR_SIZE", "1024")),
        qdrant_embed_model=_env("QDRANT_EMBED_MODEL", "BAAI/bge-large-en-v1.5"),
    )


CONFIG = load_config()