app/config.py

"""
Application configuration using Pydantic Settings.

Loads configuration from environment variables and .env file.
"""

from functools import lru_cache
from typing import Literal

import torch
from pydantic import Field
from pydantic import field_validator
from pydantic_settings import BaseSettings
from pydantic_settings import SettingsConfigDict


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

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

    # -------------------------------------------------------------------------
    # Application Settings
    # -------------------------------------------------------------------------
    APP_NAME: str = "VoiceAuth API"
    APP_VERSION: str = "1.0.0"
    DEBUG: bool = False
    HOST: str = "0.0.0.0"
    PORT: int = 8000

    # -------------------------------------------------------------------------
    # Security Settings
    # -------------------------------------------------------------------------
    API_KEYS: str = Field(
        default="",
        description="Comma-separated list of valid API keys",
    )
    CORS_ORIGINS: str = Field(
        default="http://localhost:3000,http://localhost:8000",
        description="Comma-separated list of allowed CORS origins",
    )
    RATE_LIMIT_REQUESTS: int = Field(default=100, ge=1)
    RATE_LIMIT_PERIOD: int = Field(default=60, ge=1, description="Period in seconds")

    # -------------------------------------------------------------------------
    # ML Model Settings
    # -------------------------------------------------------------------------
    MODEL_NAME: str = "facebook/wav2vec2-base"
    MODEL_PATH: str = ""
    DEVICE: str = "auto"
    MAX_AUDIO_DURATION: float = Field(default=30.0, ge=1.0)
    MIN_AUDIO_DURATION: float = Field(default=0.5, ge=0.1)
    SAMPLE_RATE: int = Field(default=16000, ge=8000, le=48000)

    # -------------------------------------------------------------------------
    # Redis Settings
    # -------------------------------------------------------------------------
    REDIS_URL: str = "redis://localhost:6379"
    REDIS_DB: int = 0

    # -------------------------------------------------------------------------
    # Logging Settings
    # -------------------------------------------------------------------------
    LOG_LEVEL: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"] = "INFO"
    LOG_FORMAT: Literal["json", "console"] = "json"

    # -------------------------------------------------------------------------
    # Computed Properties
    # -------------------------------------------------------------------------
    @property
    def api_keys_list(self) -> list[str]:
        """Parse comma-separated API keys into a list."""
        if not self.API_KEYS:
            return []
        return [key.strip() for key in self.API_KEYS.split(",") if key.strip()]

    @property
    def cors_origins_list(self) -> list[str]:
        """Parse comma-separated CORS origins into a list."""
        if not self.CORS_ORIGINS:
            return []
        return [origin.strip() for origin in self.CORS_ORIGINS.split(",") if origin.strip()]

    @property
    def torch_device(self) -> str:
        """Determine the appropriate torch device."""
        if self.DEVICE == "auto":
            return "cuda" if torch.cuda.is_available() else "cpu"
        return self.DEVICE

    @property
    def model_identifier(self) -> str:
        """Get the model path or name to load."""
        return self.MODEL_PATH if self.MODEL_PATH else self.MODEL_NAME

    # -------------------------------------------------------------------------
    # Validators
    # -------------------------------------------------------------------------
    @field_validator("DEVICE")
    @classmethod
    def validate_device(cls, v: str) -> str:
        """Validate device configuration."""
        valid_devices = {"auto", "cpu", "cuda", "mps"}
        # Allow cuda:N format
        if v.startswith("cuda:"):
            return v
        if v not in valid_devices:
            raise ValueError(f"Device must be one of {valid_devices} or 'cuda:N' format")
        return v


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

    Uses lru_cache to ensure settings are only loaded once.
    """
    return Settings()