"""
Configuration management for voice-server.

Loads configuration from environment variables with sensible defaults.
Uses pydantic-settings for type-safe configuration loading and validation.
"""

from functools import lru_cache
from typing import Annotated, Literal

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


# Valid log levels
LogLevel = Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]


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

    All settings have sensible defaults and can be overridden via environment
    variables or a .env file.
    """

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

    # Server settings
    host: Annotated[str, Field(default="0.0.0.0", description="Host to bind to")]
    port: Annotated[
        int,
        Field(default=8888, ge=1, le=65535, description="Port to listen on"),
    ]

    # TTS settings
    model_dir: Annotated[
        str,
        Field(default="./models", description="Directory containing voice models"),
    ]
    default_voice: Annotated[
        str,
        Field(default="en_US-ryan-high", description="Default voice model"),
    ]
    default_rate: Annotated[
        int,
        Field(default=170, ge=50, le=400, description="Default speech rate (WPM)"),
    ]

    # Queue settings
    queue_max_size: Annotated[
        int,
        Field(default=50, gt=0, description="Maximum TTS queue size"),
    ]
    request_timeout_seconds: Annotated[
        int,
        Field(default=60, gt=0, description="Request processing timeout"),
    ]

    # Logging
    log_level: Annotated[
        LogLevel,
        Field(default="INFO", description="Logging level"),
    ]
    log_file: Annotated[
        str | None,
        Field(default=None, description="Log file path (None for stdout only)"),
    ]

    # Debug
    voice_enabled: Annotated[
        bool,
        Field(default=True, description="Enable/disable TTS playback"),
    ]

    @field_validator("log_level", mode="before")
    @classmethod
    def uppercase_log_level(cls, v: str) -> str:
        """Ensure log level is uppercase."""
        if isinstance(v, str):
            return v.upper()
        return v


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

    Returns the same Settings instance on subsequent calls for efficiency.
    The cache can be cleared by calling get_settings.cache_clear().
    """
    return Settings()