import os
from dataclasses import dataclass
from typing import Mapping, Optional

REQUIRED = ["IMMICH_URL", "IMMICH_API_KEY"]


class ConfigError(Exception):
    def __init__(self, missing: list):
        self.missing = missing
        super().__init__(f"Missing required environment variables: {', '.join(missing)}")


@dataclass
class Config:
    immich_url: str
    immich_api_key: str
    anthropic_api_key: str
    data_dir: str
    # Postgres DSN for read-only access to Immich's pgvector embeddings.
    # Optional: only the pgvector spike / M1.5 visual-similarity work needs it;
    # REST creds (immich_url/api_key) stay required.
    immich_db_url: Optional[str] = None

    @property
    def db_path(self) -> str:
        return os.path.join(self.data_dir, "trip-cluster.db")

    @property
    def thumbs_dir(self) -> str:
        return os.path.join(self.data_dir, "thumbs")


def load_config(env: Optional[Mapping] = None) -> Config:
    env = env if env is not None else os.environ
    missing = [k for k in REQUIRED if not (env.get(k) or "").strip()]
    if missing:
        raise ConfigError(missing)
    data_dir = (env.get("DATA_DIR") or "").strip() or os.path.join(os.getcwd(), "data")
    immich_db_url = (env.get("IMMICH_DB_URL") or "").strip() or None
    return Config(
        immich_url=env["IMMICH_URL"].strip().rstrip("/"),
        immich_api_key=env["IMMICH_API_KEY"].strip(),
        anthropic_api_key=(env.get("ANTHROPIC_API_KEY") or "").strip(),
        data_dir=data_dir,
        immich_db_url=immich_db_url,
    )