import ctypes as ct
import os
from warnings import warn
from bitsandbytes.cuda_setup import evaluate_cuda_setup


class CUDALibrary_Singleton(object):
    _instance = None

    def __init__(self):
        raise RuntimeError('Call get_instance() instead')

    def initialize(self):
        self.context = {}
        binary_name = evaluate_cuda_setup()
        if not os.path.exists(os.path.dirname(__file__) + f'/{binary_name}'):
            print(f'TODO: compile library for specific version: {binary_name}')
            print('defaulting to libbitsandbytes.so')
            self.lib = ct.cdll.LoadLibrary(os.path.dirname(__file__) + '/libbitsandbytes.so')
        else:
            self.lib = ct.cdll.LoadLibrary(os.path.dirname(__file__) + f'/{binary_name}')

    @classmethod
    def get_instance(cls):
        if cls._instance is None:
            cls._instance = cls.__new__(cls)
            cls._instance.initialize()
        return cls._instance


lib = CUDALibrary_Singleton.get_instance().lib
try:
    lib.cadam32bit_g32
    lib.get_context.restype = ct.c_void_p
    lib.get_cusparse.restype = ct.c_void_p
    COMPILED_WITH_CUDA = True
except AttributeError:
    warn("The installed version of bitsandbytes was compiled without GPU support. "
         "8-bit optimizers and GPU quantization are unavailable.")
    COMPILED_WITH_CUDA = False