"""
Global application configuration.
Following best practice of splitting config across domains.
"""
from enum import Enum
from functools import lru_cache

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


class Environment(str, Enum):
    """Application environment."""
    DEVELOPMENT = "development"
    PRODUCTION = "production"
    TESTING = "testing"


class Config(BaseSettings):
    """
    Global application configuration.
    
    Loads from environment variables and .env file.
    Domain-specific configs should be in their respective modules.
    """
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=True,
        extra="ignore",
    )
    
    # Application
    APP_NAME: str = "OpenAI-Compatible API"
    APP_VERSION: str = "0.2.5"
    ENVIRONMENT: Environment = Environment.DEVELOPMENT
    DEBUG: bool = Field(default=False, description="Debug mode")
    
    # API Configuration
    API_HOST: str = Field(default="0.0.0.0", description="API host")
    API_PORT: int = Field(default=8000, description="API port")
    API_PREFIX: str = Field(default="/v1", description="API route prefix")
    
    # Ollama Configuration
    OLLAMA_HOST: HttpUrl = Field(
        default="http://localhost:11434",
        description="Ollama server URL"
    )
    OLLAMA_DEFAULT_MODEL: str = Field(
        default="mistral-nemo:latest",
        description="Default Ollama model"
    )
    OLLAMA_TIMEOUT: int = Field(
        default=120,
        description="Ollama request timeout in seconds"
    )
    STREAM_TIMEOUT: int = Field(
        default=20,
        description="Timeout for each streaming turn in seconds"
    )

    # SearXNG Configuration
    SEARXNG_HOST: HttpUrl = Field(
        default="http://localhost:8087",
        description="SearXNG server URL"
    )
    SEARXNG_TIMEOUT: int = Field(
        default=30,
        description="SearXNG request timeout in seconds"
    )

    # Redis Configuration
    REDIS_HOST: str = Field(
        default="localhost",
        description="Redis server host"
    )
    REDIS_PORT: int = Field(
        default=6379,
        description="Redis server port"
    )
    REDIS_DB: int = Field(
        default=1,
        description="Redis database number"
    )
    REDIS_TIMEOUT: int = Field(
        default=5,
        description="Redis connection timeout in seconds"
    )

    # Logging
    LOG_LEVEL: str = Field(default="INFO", description="Logging level")
    ENABLE_BENCHMARKS: bool = Field(default=True, description="Enable performance benchmarking")

    # CORS
    CORS_ORIGINS: list[str] = Field(
        default=["*"],
        description="Allowed CORS origins"
    )
    CORS_ALLOW_CREDENTIALS: bool = True
    CORS_ALLOW_METHODS: list[str] = ["*"]
    CORS_ALLOW_HEADERS: list[str] = ["*"]

    @property
    def redis_url(self) -> str:
        """Construct Redis connection URL."""
        return f"redis://{self.REDIS_HOST}:{self.REDIS_PORT}/{self.REDIS_DB}"

    @property
    def log_format(self) -> str:
        """
        Determine log format based on environment.

        - production: JSON format for machine parsing
        - development/testing: Console format for human readability
        """
        return "json" if self.ENVIRONMENT == Environment.PRODUCTION else "console"


@lru_cache
def get_config() -> Config:
    """
    Get cached configuration instance.
    
    Uses lru_cache to ensure config is loaded once and reused.
    """
    return Config()


# Global config instance
config = get_config()