"""Core configuration for NotebookLM Agent API."""

from functools import lru_cache
from typing import Any

from pydantic import Field, field_validator
from pydantic_settings import BaseSettings, 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",
    )

    # API Configuration
    api_key: str = Field(default="", alias="NOTEBOOKLM_AGENT_API_KEY")
    webhook_secret: str = Field(default="", alias="NOTEBOOKLM_AGENT_WEBHOOK_SECRET")
    port: int = Field(default=8000, alias="NOTEBOOKLM_AGENT_PORT")
    host: str = Field(default="0.0.0.0", alias="NOTEBOOKLM_AGENT_HOST")
    reload: bool = Field(default=False, alias="NOTEBOOKLM_AGENT_RELOAD")

    # NotebookLM Configuration
    notebooklm_home: str = Field(default="~/.notebooklm", alias="NOTEBOOKLM_HOME")
    notebooklm_profile: str = Field(default="default", alias="NOTEBOOKLM_PROFILE")

    # Redis Configuration
    redis_url: str = Field(default="redis://localhost:6379/0", alias="REDIS_URL")

    # Logging
    log_level: str = Field(default="INFO", alias="LOG_LEVEL")
    log_format: str = Field(default="json", alias="LOG_FORMAT")

    # Development
    debug: bool = Field(default=False, alias="DEBUG")
    testing: bool = Field(default=False, alias="TESTING")

    # Security
    cors_origins: list[str] = Field(default_factory=list, alias="CORS_ORIGINS")

    @field_validator("cors_origins", mode="before")
    @classmethod
    def parse_cors_origins(cls, v: Any) -> list[str]:
        """Parse CORS origins from string or list."""
        if isinstance(v, str):
            return [origin.strip() for origin in v.split(",") if origin.strip()]
        return v if v else []

    @field_validator("log_level")
    @classmethod
    def validate_log_level(cls, v: str) -> str:
        """Validate log level is one of the allowed values."""
        allowed = {"DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"}
        v_upper = v.upper()
        if v_upper not in allowed:
            raise ValueError(f"log_level must be one of {allowed}")
        return v_upper

    @property
    def is_production(self) -> bool:
        """Check if running in production mode."""
        return not self.debug and not self.testing


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

    Returns:
        Settings instance loaded from environment.
    """
    return Settings()