from functools import lru_cache
from typing import Literal, Optional

from pydantic import Field, SecretStr, validator
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """
    Application settings loaded from environment variables.
    """
    # API Configuration
    API_HOST: str = "0.0.0.0"
    API_PORT: int = 8000
    DEBUG: bool = False

    # Vectorization Configuration
    EMBEDDING_MODEL: str = "text-embedding-3-small"
    VECTOR_DIMENSION: int = 1536
    CHUNK_SIZE: int = 1000
    CHUNK_OVERLAP: int = 200
    TOP_K_MATCHES: int = 5
    
    # MongoDB Configuration
    MONGODB_URI: Optional[SecretStr] = None # TODO: Remove optionality
    MONGODB_DB_NAME: str = "ctp_slack_bot"
    
    # Slack Configuration
    SLACK_BOT_TOKEN: Optional[SecretStr] = None # TODO: Remove optionality
    SLACK_SIGNING_SECRET: Optional[SecretStr] = None # TODO: Remove optionality
    SLACK_APP_TOKEN: Optional[SecretStr] = None
    
    # Hugging Face Configuration
    HF_API_TOKEN: Optional[SecretStr] = None

    
    
    # Logging Configuration
    LOG_LEVEL: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"] = "INFO"
    LOG_FORMAT: Literal["text", "json"] = "json"
    
    # APScheduler Configuration
    SCHEDULER_TIMEZONE: str = "UTC"
    
    @validator("MONGODB_URI")
    def validate_mongodb_uri(cls, v):
        """Validate MongoDB URI format"""
        #if not v.get_secret_value().startswith("mongodb"):
        #    raise ValueError("MONGODB_URI must be a valid MongoDB connection string")
        return v
    
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=True,
    )


@lru_cache
def get_settings() -> Settings:
    """
    Get cached settings instance.
    """
    return Settings()


settings = get_settings()