"""Factory for creating language model instances based on model name."""

import os
from typing import Dict, Any, Type

from langchain_core.language_models import BaseLanguageModel
from langchain_openai import ChatOpenAI
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_xai import ChatXAI
from .medgemma import ChatMedGemma


class ModelFactory:
    """Factory for creating language model instances based on model name.

    This class implements a registry of language model providers and provides
    methods to create appropriate language model instances based on the model name.
    """

    # Registry of model providers
    _model_providers = {
        "gpt": {
            "class": ChatOpenAI,
            "env_key": "OPENAI_API_KEY",
            "base_url_key": "OPENAI_BASE_URL",
        },
        "chatgpt": {
            "class": ChatOpenAI,
            "env_key": "OPENAI_API_KEY",
            "base_url_key": "OPENAI_BASE_URL",
        },
        "gemini": {
            "class": ChatGoogleGenerativeAI,
            "env_key": "GOOGLE_API_KEY",
            "base_url_key": "GOOGLE_BASE_URL",
        },
        "openrouter": {
            "class": ChatOpenAI,  # OpenRouter uses OpenAI-compatible interface
            "env_key": "OPENROUTER_API_KEY",
            "base_url_key": "OPENROUTER_BASE_URL",
            "default_base_url": "https://openrouter.ai/api/v1",
        },
        "grok": {
            "class": ChatXAI,
            "env_key": "XAI_API_KEY",
        },
        "medgemma": {
            "class": ChatMedGemma,
            "env_key": None,  # Local model, no API key needed
            "is_local": True,
        },
        # Add more providers with default configurations here
    }

    @classmethod
    def register_provider(cls, prefix: str, model_class: Type[BaseLanguageModel], env_key: str, **kwargs) -> None:
        """Register a new model provider.

        Args:
            prefix (str): The prefix used to identify this model provider (e.g., 'gpt', 'gemini')
            model_class (Type[BaseLanguageModel]): The LangChain model class to use
            env_key (str): The environment variable name for the API key
            **kwargs: Additional provider-specific configuration
        """
        cls._model_providers[prefix] = {"class": model_class, "env_key": env_key, **kwargs}

    @classmethod
    def create_model(
        cls, model_name: str, temperature: float = 0.7, top_p: float = 0.95, max_tokens: int = 5000, **kwargs
    ) -> BaseLanguageModel:
        """Create and return an instance of the appropriate language model.

        Args:
            model_name (str): Name of the model to create (e.g., 'gpt-4o', 'gemini-2.5-pro')
            temperature (float, optional): Temperature parameter. Defaults to 0.7.
            top_p (float, optional): Top-p sampling parameter. Defaults to 0.95.
            max_tokens (int, optional): Maximum tokens to generate. Defaults to 5000.
            **kwargs: Additional model-specific parameters

        Returns:
            BaseLanguageModel: An initialized language model instance

        Raises:
            ValueError: If no provider is found for the given model name
            ValueError: If the required API key is missing
        """
        # Find the matching provider based on model name prefix
        provider_prefix = next((prefix for prefix in cls._model_providers if model_name.startswith(prefix)), None)

        if not provider_prefix:
            raise ValueError(
                f"No provider found for model: {model_name}. "
                f"Registered providers are for: {list(cls._model_providers.keys())}"
            )

        provider = cls._model_providers[provider_prefix]
        model_class = provider["class"]
        env_key = provider["env_key"]
        is_local = provider.get("is_local", False)

        # Set up provider-specific kwargs
        provider_kwargs = {}

        # Handle API key (skip for local models)
        if not is_local:
            if env_key and env_key in os.environ:
                provider_kwargs["api_key"] = os.environ[env_key]
            elif env_key:
                # Log warning but don't fail - the model class might handle missing API keys differently
                print(f"Warning: Environment variable {env_key} not found. Authentication may fail.")

        # Check for base_url if applicable
        if "base_url_key" in provider:
            if provider["base_url_key"] in os.environ:
                provider_kwargs["base_url"] = os.environ[provider["base_url_key"]]
            elif "default_base_url" in provider:
                provider_kwargs["base_url"] = provider["default_base_url"]

        # Merge with any additional provider-specific settings from the registry
        for k, v in provider.items():
            if k not in ["class", "env_key", "base_url_key", "default_base_url"]:
                provider_kwargs[k] = v

        # Strip the provider prefix from the model name
        # For example, 'openrouter-anthropic/claude-sonnet-4' becomes 'anthropic/claude-sonnet-4'
        # But for OpenAI models like 'gpt-4o', we keep the full name since 'gpt-' is part of the model name
        actual_model_name = model_name
        if provider_prefix in ["openrouter"] and model_name.startswith(f"{provider_prefix}-"):
            actual_model_name = model_name[len(provider_prefix) + 1 :]

        # Handle GPT-5 model (special case for GPT-5 models)
        if model_name.startswith("gpt-5"):
            return model_class(
                model=actual_model_name,
                temperature=temperature,
                reasoning_effort="high",
                max_tokens=max_tokens,
                **provider_kwargs,
                **kwargs,
            )

        # Handle MedGemma (local model with different parameter names)
        if model_name.startswith("medgemma"):
            return model_class(
                model_name=actual_model_name,
                temperature=temperature,
                top_p=top_p,
                top_k=kwargs.get("top_k", 64),
                max_new_tokens=max_tokens,
                device=kwargs.get("device", "cuda"),
                load_in_4bit=kwargs.get("load_in_4bit", True),
                **provider_kwargs,
            )

        # Create and return the model instance
        return model_class(
            model=actual_model_name,
            temperature=temperature,
            top_p=top_p,
            max_tokens=max_tokens,
            **provider_kwargs,
            **kwargs,
        )

    @classmethod
    def list_providers(cls) -> Dict[str, Dict[str, Any]]:
        """List all registered model providers.

        Returns:
            Dict[str, Dict[str, Any]]: Dictionary of registered providers and their configurations
        """
        # Return a copy to prevent accidental modification
        return {k: {kk: vv for kk, vv in v.items() if kk != "class"} for k, v in cls._model_providers.items()}