"""Application configuration.

SPEC §14: the complete env list is read exactly once here (pydantic-settings).
No ``os.environ`` access is permitted anywhere else in the codebase.
"""

from __future__ import annotations

from functools import lru_cache

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """All runtime configuration, sourced from the environment (SPEC §14)."""

    model_config = SettingsConfigDict(env_file=None, extra="ignore")

    app_domain: str = Field(alias="APP_DOMAIN")
    database_url: str = Field(alias="DATABASE_URL")
    redis_url: str = Field(alias="REDIS_URL")
    master_key: str = Field(alias="MASTER_KEY")  # 32 bytes, base64

    blob_root: str = Field(default="./var/blobs", alias="BLOB_ROOT")

    search_backend: str = Field(default="pg", alias="SEARCH_BACKEND")
    meili_url: str = Field(default="http://127.0.0.1:7700", alias="MEILI_URL")
    meili_key: str = Field(default="", alias="MEILI_KEY")

    undo_seconds: int = Field(default=10, alias="UNDO_SECONDS")
    poll_interval: int = Field(default=120, alias="POLL_INTERVAL")
    session_ttl_days: int = Field(default=30, alias="SESSION_TTL_DAYS")
    max_attachment_mb: int = Field(default=25, alias="MAX_ATTACHMENT_MB")
    log_level: str = Field(default="INFO", alias="LOG_LEVEL")

    oauth_google_client_id: str = Field(default="", alias="OAUTH_GOOGLE_CLIENT_ID")
    oauth_google_client_secret: str = Field(default="", alias="OAUTH_GOOGLE_CLIENT_SECRET")
    oauth_ms_client_id: str = Field(default="", alias="OAUTH_MS_CLIENT_ID")
    oauth_ms_client_secret: str = Field(default="", alias="OAUTH_MS_CLIENT_SECRET")


@lru_cache(maxsize=1)
def get_settings() -> Settings:
    """Return the process-wide settings singleton."""
    return Settings()  # values are sourced from the environment