import torch
import logging
import os
from pathlib import Path
from dust3r.model import AsymmetricCroCo3DStereo, inf

logger = logging.getLogger(__name__)


def download_weights(model_path: str):
    """Download model weights if they don't exist"""
    if os.path.exists(model_path):
        logger.info(f"Weights already exist at {model_path}")
        return
    
    logger.info("Weights not found. Downloading...")
    Path(model_path).parent.mkdir(parents=True, exist_ok=True)
    
    import urllib.request
    url = "https://huggingface.co/camenduru/dust3r/resolve/main/DUSt3R_ViTLarge_BaseDecoder_512_dpt.pth"
    
    logger.info(f"Downloading from {url}")
    urllib.request.urlretrieve(url, model_path)
    logger.info("Download complete!")


def initialize(model_path: str, device: str) -> torch.nn.Module:
    download_weights(model_path)
    logger.info(f"Loading model from: {model_path}")
    
    logger.info("Loading checkpoint...")
    ckpt = torch.load(model_path, map_location='cpu', weights_only=False)
    
    logger.info("Parsing model arguments...")
    args = ckpt['args'].model.replace("ManyAR_PatchEmbed", "PatchEmbedDust3R")

    if isinstance(args, str) and 'landscape_only' not in args:
        args = args[:-1] + ', landscape_only=False)'
    elif isinstance(args, str):
        args = args.replace(" ", "").replace('landscape_only=True', 'landscape_only=False')

    logger.info("Instantiating model...")
    net = eval(args)
    
    logger.info("Loading model weights...")
    net.load_state_dict(ckpt['model'], strict=False)
    
    logger.info(f"Moving model to {device}...")
    model = net.to(device)
    
    logger.info("Model initialization complete!")
    return model