"""
Model configuration and loading for time series forecasting.
Supports multiple Chronos model variants with different architectures.
"""

import torch
from chronos import Chronos2Pipeline, ChronosPipeline


class ModelConfig:
    """Configuration for available forecasting models"""
    
    CHRONOS_2_MODELS = {
        "Chronos-2 (Latest, 120M params)": {
            "model_id": "amazon/chronos-2",
            "pipeline_class": Chronos2Pipeline,
            "description": "Latest Chronos-2 model with 120M parameters"
        }
    }
    
    CHRONOS_T5_MODELS = {
        "Chronos-T5 Tiny (8M params)": {
            "model_id": "amazon/chronos-t5-tiny",
            "pipeline_class": ChronosPipeline,
            "description": "Smallest Chronos-T5 model, fastest inference"
        },
        "Chronos-T5 Mini (20M params)": {
            "model_id": "amazon/chronos-t5-mini",
            "pipeline_class": ChronosPipeline,
            "description": "Mini Chronos-T5 model"
        },
        "Chronos-T5 Small (46M params)": {
            "model_id": "amazon/chronos-t5-small",
            "pipeline_class": ChronosPipeline,
            "description": "Small Chronos-T5 model"
        },
        "Chronos-T5 Base (200M params)": {
            "model_id": "amazon/chronos-t5-base",
            "pipeline_class": ChronosPipeline,
            "description": "Base Chronos-T5 model"
        },
        "Chronos-T5 Large (710M params)": {
            "model_id": "amazon/chronos-t5-large",
            "pipeline_class": ChronosPipeline,
            "description": "Largest Chronos-T5 model, best accuracy"
        }
    }
    
    @classmethod
    def get_all_models(cls):
        """Get all available models"""
        all_models = {}
        all_models.update(cls.CHRONOS_2_MODELS)
        all_models.update(cls.CHRONOS_T5_MODELS)
        return all_models
    
    @classmethod
    def get_model_names(cls):
        """Get list of model names for dropdown"""
        return list(cls.get_all_models().keys())
    
    @classmethod
    def get_model_config(cls, model_name):
        """Get configuration for a specific model"""
        return cls.get_all_models().get(model_name)


def load_model_pipeline(model_name, device_map="cpu", dtype=torch.float32):
    """
    Load a forecasting model pipeline.
    
    Args:
        model_name: Display name of the model
        device_map: Device to load model on (default: "cpu")
        dtype: Data type for model weights (default: torch.float32)
    
    Returns:
        Loaded pipeline instance
    """
    config = ModelConfig.get_model_config(model_name)
    
    if config is None:
        raise ValueError(f"Unknown model: {model_name}")
    
    pipeline_class = config["pipeline_class"]
    model_id = config["model_id"]
    
    # Load the appropriate pipeline
    pipeline = pipeline_class.from_pretrained(
        model_id,
        device_map=device_map,
        dtype=dtype,
    )
    
    return pipeline


def get_model_info(model_name):
    """
    Get information about a model.
    
    Args:
        model_name: Display name of the model
    
    Returns:
        Dictionary with model information
    """
    config = ModelConfig.get_model_config(model_name)
    
    if config is None:
        return None
    
    return {
        "name": model_name,
        "model_id": config["model_id"],
        "description": config["description"],
        "pipeline": config["pipeline_class"].__name__
    }