import abc
import hashlib
import os
import tempfile
from pathlib import Path

from ..common.build import _build
from .cache import get_cache_manager


class DriverBase(metaclass=abc.ABCMeta):

    CUDA = 0
    HIP = 1

    @staticmethod
    def third_party_dir():
        return os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "third_party")

    def __init__(self) -> None:
        pass
# -----------------------------
# CUDA
# -----------------------------


class CudaUtils(object):

    def __new__(cls):
        if not hasattr(cls, 'instance'):
            cls.instance = super(CudaUtils, cls).__new__(cls)
        return cls.instance

    def __init__(self):
        dirname = os.path.dirname(os.path.realpath(__file__))
        src = Path(os.path.join(dirname, "backends", "cuda.c")).read_text()
        key = hashlib.md5(src.encode("utf-8")).hexdigest()
        cache = get_cache_manager(key)
        fname = "cuda_utils.so"
        cache_path = cache.get_file(fname)
        if cache_path is None:
            with tempfile.TemporaryDirectory() as tmpdir:
                src_path = os.path.join(tmpdir, "main.c")
                with open(src_path, "w") as f:
                    f.write(src)
                so = _build("cuda_utils", src_path, tmpdir)
                with open(so, "rb") as f:
                    cache_path = cache.put(f.read(), fname, binary=True)
        import importlib.util
        spec = importlib.util.spec_from_file_location("cuda_utils", cache_path)
        mod = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(mod)
        self.load_binary = mod.load_binary
        self.get_device_properties = mod.get_device_properties


class CudaDriver(DriverBase):

    def __new__(cls):
        if not hasattr(cls, 'instance'):
            cls.instance = super(CudaDriver, cls).__new__(cls)
        return cls.instance

    def __init__(self):
        self.utils = CudaUtils()
        self.backend = self.CUDA

# -----------------------------
# HIP
# -----------------------------


class HIPUtils(object):
    def __new__(cls):
        if not hasattr(cls, 'instance'):
            cls.instance = super(HIPUtils, cls).__new__(cls)
        return cls.instance

    def __init__(self):
        dirname = os.path.dirname(os.path.realpath(__file__))
        src = Path(os.path.join(dirname, "backends", "hip.c")).read_text()
        key = hashlib.md5(src.encode("utf-8")).hexdigest()
        cache = get_cache_manager(key)
        fname = "hip_utils.so"
        cache_path = cache.get_file(fname)
        if cache_path is None:
            with tempfile.TemporaryDirectory() as tmpdir:
                src_path = os.path.join(tmpdir, "main.c")
                with open(src_path, "w") as f:
                    f.write(src)
                so = _build("hip_utils", src_path, tmpdir)
                with open(so, "rb") as f:
                    cache_path = cache.put(f.read(), fname, binary=True)
        import importlib.util
        spec = importlib.util.spec_from_file_location("hip_utils", cache_path)
        mod = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(mod)
        self.load_binary = mod.load_binary
        self.get_device_properties = mod.get_device_properties


class HIPDriver(DriverBase):

    def __new__(cls):
        if not hasattr(cls, 'instance'):
            cls.instance = super(HIPDriver, cls).__new__(cls)
        return cls.instance

    def __init__(self):
        self.utils = HIPUtils()
        self.backend = self.HIP


class UnsupportedDriver(DriverBase):

    def __new__(cls):
        if not hasattr(cls, 'instance'):
            cls.instance = super(UnsupportedDriver, cls).__new__(cls)
        return cls.instance

    def __init__(self):
        self.utils = None
        self.backend = None

# -----------------------------
# Driver
# -----------------------------


class LazyProxy:
    def __init__(self, init_fn):
        self._init_fn = init_fn
        self._obj = None

    def _initialize_obj(self):
        if self._obj is None:
            self._obj = self._init_fn()

    def __getattr__(self, name):
        self._initialize_obj()
        return getattr(self._obj, name)

    def __setattr__(self, name, value):
        if name in ['_init_fn', '_obj']:
            super().__setattr__(name, value)
        else:
            self._initialize_obj()
            setattr(self._obj, name, value)

    def __delattr__(self, name):
        self._initialize_obj()
        delattr(self._obj, name)

    def __repr__(self):
        if self._obj is None:
            return f"<{self.__class__.__name__} for {self._init_fn} not yet initialized>"
        return repr(self._obj)

    def __str__(self):
        self._initialize_obj()
        return str(self._obj)


def initialize_driver():
    import torch
    if torch.version.hip is not None:
        return HIPDriver()
    elif torch.cuda.is_available():
        return CudaDriver()
    else:
        return UnsupportedDriver()


driver = LazyProxy(initialize_driver)