import multiprocessing
import os
import uuid
from functools import partial
from multiprocessing import Pool
from typing import Dict, List, Optional

import pandas as pd
import requests
from loguru import logger
from tqdm import tqdm


def get_uid_from_str(string: str) -> str:
    """Generates a UUID from a string.

    Args:
        string (str): String to generate a UUID from.

    Returns:
        str: UUID generated from the string.
    """
    namespace = uuid.NAMESPACE_DNS
    return str(uuid.uuid5(namespace, string))


def load_smithsonian_metadata(
    download_dir: str = "~/.objaverse-xl",
) -> pd.DataFrame:
    """Loads the Smithsonian Object Metadata dataset as a Pandas DataFrame.

    Args:
        download_dir (str, optional): Directory to download the parquet metadata file.
            Defaults to "~/.objaverse-xl".

    Returns:
        pd.DataFrame: Smithsonian Object Metadata dataset as a Pandas DataFrame with
            columns for the object "title", "url", "quality", "file_type", "uid", and
            "license". The quality is always Medium and the file_type is always glb.
    """
    dirname = os.path.expanduser(os.path.join(download_dir, "smithsonian"))
    os.makedirs(dirname, exist_ok=True)
    filename = os.path.join(dirname, "object-metadata.parquet")

    url = "https://huggingface.co/datasets/allenai/objaverse-xl/resolve/main/smithsonian/object-metadata.parquet"
    response = requests.get(url)
    response.raise_for_status()
    with open(filename, "wb") as file:
        file.write(response.content)

    df = pd.read_parquet(filename)
    df["uid"] = df["url"].apply(get_uid_from_str)
    df["license"] = "CC0"
    return df


def download_smithsonian_object(url: str, download_dir: str = "~/.objaverse-xl") -> str:
    """Downloads a Smithsonian Object from a URL.

    Args:
        url (str): URL to download the Smithsonian Object from.
        download_dir (str, optional): Directory to download the Smithsonian Object to.
            Defaults to "~/.objaverse-xl".

    Returns:
        str: Path to the downloaded Smithsonian Object.
    """
    uid = get_uid_from_str(url)

    dirname = os.path.expanduser(os.path.join(download_dir, "smithsonian", "objects"))
    os.makedirs(dirname, exist_ok=True)
    filename = os.path.join(dirname, f"{uid}.glb")

    if os.path.exists(filename):
        return filename

    tmp_path = os.path.join(dirname, f"{uid}.glb.tmp")
    response = requests.get(url)
    if response.status_code == 404:
        logger.warning(f"404 for {url}")
        return None
    with open(tmp_path, "wb") as file:
        for chunk in response.iter_content(chunk_size=8192):
            file.write(chunk)
    os.rename(tmp_path, filename)

    return filename


def download_smithsonian_objects(
    urls: Optional[str] = None,
    processes: Optional[int] = None,
    download_dir: str = "~/.objaverse-xl",
) -> List[Dict[str, str]]:
    """Downloads all Smithsonian Objects.

    Args:
        urls (Optional[str], optional): List of URLs to download the Smithsonian Objects
            from. If None, all Smithsonian Objects will be downloaded. Defaults to None.
        processes (Optional[int], optional): Number of processes to use for downloading
            the Smithsonian Objects. If None, the number of processes will be set to the
            number of CPUs on the machine (multiprocessing.cpu_count()). Defaults to None.
        download_dir (str, optional): Directory to download the Smithsonian Objects to.
            Defaults to "~/.objaverse-xl".

    Returns:
        List[Dict[str, str]]: List of dictionaries with keys "download_path" and "url"
            for each downloaded object.
    """
    if processes is None:
        processes = multiprocessing.cpu_count()
    if urls is None:
        df = load_smithsonian_metadata(download_dir=download_dir)
        urls = df["url"].tolist()

    logger.info(f"Downloading {len(urls)} Smithsonian Objects with {processes=}")
    with Pool(processes=processes) as pool:
        results = list(
            tqdm(
                pool.imap_unordered(
                    partial(download_smithsonian_object, download_dir=download_dir),
                    urls,
                ),
                total=len(urls),
                desc="Downloading Smithsonian Objects",
            )
        )
    out = [
        {"download_path": download_path, "url": url}
        for download_path, url in zip(results, urls)
        if download_path is not None
    ]
    return out