"""Configuration management using Pydantic settings."""

from typing import List, Optional
from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict
import json


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"
    )

    # Server Configuration
    host: str = Field(default="0.0.0.0", description="Server host address")
    port: int = Field(default=8000, description="Server port")
    external_ip: Optional[str] = Field(default=None, description="External IP for NAT traversal")

    # Audio Configuration
    sample_rate: int = Field(default=16000, description="Audio sample rate in Hz")
    chunk_size_ms: int = Field(default=20, description="Audio chunk duration in milliseconds")
    default_codec: str = Field(default="pcm", description="Default audio codec")

    # VAD Configuration
    vad_type: str = Field(default="silero", description="VAD algorithm type")
    vad_model_path: str = Field(default="data/vad/silero_vad.onnx", description="Path to VAD model")
    vad_threshold: float = Field(default=0.5, description="VAD detection threshold")
    vad_min_speech_duration_ms: int = Field(default=250, description="Minimum speech duration in milliseconds")
    vad_eou_threshold_ms: int = Field(default=400, description="End of utterance (silence) threshold in milliseconds")

    # Logging
    log_level: str = Field(default="INFO", description="Logging level")
    log_format: str = Field(default="json", description="Log format (json or text)")

    # CORS
    cors_origins: str = Field(
        default='["http://localhost:3000", "http://localhost:8080"]',
        description="CORS allowed origins"
    )

    # ICE Servers (WebRTC)
    ice_servers: str = Field(
        default='[{"urls": "stun:stun.l.google.com:19302"}]',
        description="ICE servers configuration"
    )

    @property
    def chunk_size_bytes(self) -> int:
        """Calculate chunk size in bytes based on sample rate and duration."""
        # 16-bit (2 bytes) per sample, mono channel
        return int(self.sample_rate * 2 * (self.chunk_size_ms / 1000.0))

    @property
    def cors_origins_list(self) -> List[str]:
        """Parse CORS origins from JSON string."""
        try:
            return json.loads(self.cors_origins)
        except json.JSONDecodeError:
            return ["http://localhost:3000", "http://localhost:8080"]

    @property
    def ice_servers_list(self) -> List[dict]:
        """Parse ICE servers from JSON string."""
        try:
            return json.loads(self.ice_servers)
        except json.JSONDecodeError:
            return [{"urls": "stun:stun.l.google.com:19302"}]


# Global settings instance
settings = Settings()


def get_settings() -> Settings:
    """Get application settings instance."""
    return settings