src/ctp_slack_bot/core/config.py

from pydantic import Field, MongoDsn, NonNegativeFloat, NonNegativeInt, PositiveInt, SecretStr
from pydantic_settings import BaseSettings, SettingsConfigDict
from typing import Literal, Optional

class Settings(BaseSettings): # TODO: Strong guarantees of validity, because garbage in = garbage out, and settings flow into all the nooks and crannies
    """
    Application settings loaded from environment variables.
    """
    # Application Configuration
    DEBUG: bool = False

    # Logging Configuration
    LOG_LEVEL: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"] = Field(default_factory=lambda data: "DEBUG" if data.get("DEBUG", False) else "INFO")
    LOG_FORMAT: Literal["text", "json"] = "json"

    # API Configuration
    API_HOST: str = "0.0.0.0"
    API_PORT: int = 8000

    # APScheduler Configuration
    SCHEDULER_TIMEZONE: Optional[str] = "UTC"

    # Slack Configuration
    SLACK_USER_TOKEN: Optional[SecretStr] = None
    SLACK_BOT_TOKEN: SecretStr
    SLACK_SIGNING_SECRET: Optional[SecretStr] = None
    SLACK_APP_TOKEN: SecretStr

    # Vectorization Configuration
    EMBEDDING_MODEL: str
    VECTOR_DIMENSION: PositiveInt
    CHUNK_SIZE: PositiveInt
    CHUNK_OVERLAP: NonNegativeInt
    TOP_K_MATCHES: PositiveInt
    
    # MongoDB Configuration
    MONGODB_URI: SecretStr # TODO: Contemplate switching to MongoDsn type for the main URL, and separate out the credentials to SecretStr variables.
    MONGODB_NAME: str
    SCORE_THRESHOLD: NonNegativeFloat

    # Hugging Face Configuration
    HF_API_TOKEN: Optional[SecretStr] = None

    # OpenAI Configuration
    OPENAI_API_KEY: SecretStr
    CHAT_MODEL: str
    MAX_TOKENS: PositiveInt 
    TEMPERATURE: NonNegativeFloat
    SYSTEM_PROMPT: str

    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=True,
    )