import os
import sys
from pathlib import Path
import numpy as np
import torch

def intersperse(lst, item):
    # Adds blank symbol
    result = [item] * (len(lst) * 2 + 1)
    result[1::2] = lst
    return result

def to_numpy(tensor):
    if isinstance(tensor, np.ndarray):
        return tensor
    elif isinstance(tensor, torch.Tensor):
        return tensor.detach().cpu().numpy()
    elif isinstance(tensor, list):
        return np.array(tensor)
    else:
        raise TypeError("Unsupported type for conversion to numpy array")

def get_user_data_dir(appname="matcha_tts"):
    MATCHA_HOME = os.environ.get("MATCHA_HOME")
    if MATCHA_HOME is not None:
        ans = Path(MATCHA_HOME).expanduser().resolve(strict=False)
    elif sys.platform == "win32":
        import winreg  # pylint: disable=import-outside-toplevel
        key = winreg.OpenKey(
            winreg.HKEY_CURRENT_USER,
            r"Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders",
        )
        dir_, _ = winreg.QueryValueEx(key, "Local AppData")
        ans = Path(dir_).resolve(strict=False)
    elif sys.platform == "darwin":
        ans = Path("~/Library/Application Support/").expanduser()
    else:
        ans = Path.home().joinpath(".local/share")

    final_path = ans.joinpath(appname)
    final_path.mkdir(parents=True, exist_ok=True)
    return final_path

def assert_model_downloaded(checkpoint_path, url, use_wget=True):
    if Path(checkpoint_path).exists():
        return
    raise FileNotFoundError(f"Model not found at {checkpoint_path}! Standalone mode requires models to be pre-downloaded.")