"""Configuration module using pydantic_settings for environment-based configuration."""
from secrets import token_urlsafe
from typing import List, Union
from pydantic import field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """Application settings loaded from environment variables."""

    # Security
    SECRET_KEY: str = "dev_secret_key_fixed_for_persistence_change_in_prod"
    ALGORITHM: str = "HS256"
    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
    REFRESH_TOKEN_EXPIRE_MINUTES: int = 43200  # 30 days

    # Database
    DATABASE_URL: str = "sqlite:///./data/habitforge.db"

    # CORS
    CORS_ORIGINS: Union[List[str], str] = ["http://localhost:8000", "http://localhost:3000"]
    CORS_ALLOW_CREDENTIALS: bool = True
    CORS_ALLOW_METHODS: Union[List[str], str] = ["*"]
    CORS_ALLOW_HEADERS: Union[List[str], str] = ["*"]

    # Google OAuth
    GOOGLE_CLIENT_ID: str = ""
    GOOGLE_CLIENT_SECRET: str = ""
    GOOGLE_REDIRECT_URI: str = "http://localhost:8000/api/google/callback"

    # Rate Limiting
    RATE_LIMIT_ENABLED: bool = True
    RATE_LIMIT_TIMES: int = 60
    RATE_LIMIT_SECONDS: int = 60

    # Application
    APP_NAME: str = "HabitForge API"
    APP_VERSION: str = "1.0.0"
    DEBUG: bool = True
    
    # Health Data Provider Selection
    # Options: "health_connect"
    HEALTH_PROVIDER: str = "health_connect"

    @field_validator("CORS_ORIGINS", "CORS_ALLOW_METHODS", "CORS_ALLOW_HEADERS", mode="before")
    @classmethod
    def assemble_cors_list(cls, v: Union[str, List[str]]) -> List[str]:
        """Convert a comma-separated string into a list of strings if necessary."""
        if isinstance(v, str) and not v.startswith("["):
            return [i.strip() for i in v.split(",") if i.strip()]
        return v

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


# Global settings instance
settings = Settings()