"""Typed application configuration.

Values come from ``PHOTO_PIPELINE_*`` environment variables. Secrets use
``SecretStr`` so they are masked in logs, reprs, and model dumps, and are never
returned by the API. Only ``.get_secret_value()`` exposes them, and only where a
real external call needs them.

pydantic-settings would do this too, but a prefix-scan over the declared fields
is a few lines and one fewer dependency.
"""

from __future__ import annotations

import os
from pathlib import Path
from typing import Mapping

from pydantic import BaseModel, ConfigDict, SecretStr

ENV_PREFIX = "PHOTO_PIPELINE_"


class Config(BaseModel):
    model_config = ConfigDict(frozen=True)

    data_dir: Path = Path("data")
    db_path: Path | None = None  # defaults to data_dir/photo_pipeline.db
    host: str = "127.0.0.1"
    port: int = 8000
    log_level: str = "INFO"
    log_format: str = "json"  # "json" or "text"

    # Library boundary for path validation (os.pathsep-separated in the env var).
    library_roots: tuple[Path, ...] = ()
    thumbnail_cache_quota_bytes: int = 500_000_000
    thumbnail_max_pixels: int = 100_000_000

    vision_api_key: SecretStr | None = None
    immich_api_key: SecretStr | None = None
    immich_server_url: str = ""
    immich_go_binary: str = "immich-go"

    @property
    def database_path(self) -> Path:
        return self.db_path or (self.data_dir / "photo_pipeline.db")

    @property
    def database_url(self) -> str:
        return f"sqlite:///{self.database_path}"

    @property
    def thumbnail_cache_dir(self) -> Path:
        return self.data_dir / "cache" / "thumbs"

    @classmethod
    def from_env(cls, environ: Mapping[str, str] | None = None) -> "Config":
        env = os.environ if environ is None else environ
        data: dict = {}
        for name in cls.model_fields:
            raw = env.get(ENV_PREFIX + name.upper())
            if not raw:
                continue
            data[name] = raw.split(os.pathsep) if name == "library_roots" else raw
        return cls(**data)