# Copyright (c) MONAI Consortium
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#     http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

import enum
import functools
import os
import pdb
import re
import sys
import warnings
from collections.abc import Callable, Collection, Hashable, Mapping
from functools import partial, wraps
from importlib import import_module
from pkgutil import walk_packages
from pydoc import locate
from re import match
from types import FunctionType, ModuleType
from typing import Any, cast

import torch

# bundle config system flags
# set MONAI_EVAL_EXPR=1 to use 'eval', default value: run_eval=True
run_eval = os.environ.get("MONAI_EVAL_EXPR", "1") != "0"
# set MONAI_DEBUG_CONFIG=1 to run in debug mode, default value: run_debug=False
run_debug = os.environ.get("MONAI_DEBUG_CONFIG", "0") != "0"
# set MONAI_ALLOW_MISSING_REFERENCE=1 to allow missing references, default value: allow_missing_reference=False
allow_missing_reference = os.environ.get("MONAI_ALLOW_MISSING_REFERENCE", "0") != "0"

OPTIONAL_IMPORT_MSG_FMT = "{}"

__all__ = [
    "InvalidPyTorchVersionError",
    "OptionalImportError",
    "exact_version",
    "export",
    "damerau_levenshtein_distance",
    "look_up_option",
    "min_version",
    "optional_import",
    "require_pkg",
    "load_submodules",
    "instantiate",
    "get_full_type_name",
    "get_package_version",
    "get_torch_version_tuple",
    "version_leq",
    "pytorch_after",
]


def look_up_option(
    opt_str: Hashable,
    supported: Collection | enum.EnumMeta,
    default: Any = "no_default",
    print_all_options: bool = True,
) -> Any:
    """
    Look up the option in the supported collection and return the matched item.
    Raise a value error possibly with a guess of the closest match.

    Args:
        opt_str: The option string or Enum to look up.
        supported: The collection of supported options, it can be list, tuple, set, dict, or Enum.
        default: If it is given, this method will return `default` when `opt_str` is not found,
            instead of raising a `ValueError`. Otherwise, it defaults to `"no_default"`,
            so that the method may raise a `ValueError`.
        print_all_options: whether to print all available options when `opt_str` is not found. Defaults to True

    Examples:

    .. code-block:: python

        from enum import Enum
        from monai.utils import look_up_option
        class Color(Enum):
            RED = "red"
            BLUE = "blue"
        look_up_option("red", Color)  # <Color.RED: 'red'>
        look_up_option(Color.RED, Color)  # <Color.RED: 'red'>
        look_up_option("read", Color)
        # ValueError: By 'read', did you mean 'red'?
        # 'read' is not a valid option.
        # Available options are {'blue', 'red'}.
        look_up_option("red", {"red", "blue"})  # "red"

    Adapted from https://github.com/NifTK/NiftyNet/blob/v0.6.0/niftynet/utilities/util_common.py#L249
    """
    if not isinstance(opt_str, Hashable):
        raise ValueError(f"Unrecognized option type: {type(opt_str)}:{opt_str}.")
    if isinstance(opt_str, str):
        opt_str = opt_str.strip()
    if isinstance(supported, enum.EnumMeta):
        if isinstance(opt_str, str) and opt_str in {item.value for item in supported}:  # type: ignore
            # such as: "example" in MyEnum
            return supported(opt_str)
        if isinstance(opt_str, enum.Enum) and opt_str in supported:
            # such as: MyEnum.EXAMPLE in MyEnum
            return opt_str
    elif isinstance(supported, Mapping) and opt_str in supported:
        # such as: MyDict[key]
        return supported[opt_str]
    elif isinstance(supported, Collection) and opt_str in supported:
        return opt_str

    if default != "no_default":
        return default

    # find a close match
    set_to_check: set
    if isinstance(supported, enum.EnumMeta):
        set_to_check = {item.value for item in supported}  # type: ignore
    else:
        set_to_check = set(supported) if supported is not None else set()
    if not set_to_check:
        raise ValueError(f"No options available: {supported}.")
    edit_dists = {}
    opt_str = f"{opt_str}"
    for key in set_to_check:
        edit_dist = damerau_levenshtein_distance(f"{key}", opt_str)
        if edit_dist <= 3:
            edit_dists[key] = edit_dist

    supported_msg = f"Available options are {set_to_check}.\n" if print_all_options else ""
    if edit_dists:
        guess_at_spelling = min(edit_dists, key=edit_dists.get)  # type: ignore
        raise ValueError(
            f"By '{opt_str}', did you mean '{guess_at_spelling}'?\n"
            + f"'{opt_str}' is not a valid value.\n"
            + supported_msg
        )
    raise ValueError(f"Unsupported option '{opt_str}', " + supported_msg)


def damerau_levenshtein_distance(s1: str, s2: str) -> int:
    """
    Calculates the Damerau–Levenshtein distance between two strings for spelling correction.
    https://en.wikipedia.org/wiki/Damerau–Levenshtein_distance
    """
    if s1 == s2:
        return 0
    string_1_length = len(s1)
    string_2_length = len(s2)
    if not s1:
        return string_2_length
    if not s2:
        return string_1_length
    d = {(i, -1): i + 1 for i in range(-1, string_1_length + 1)}
    for j in range(-1, string_2_length + 1):
        d[(-1, j)] = j + 1

    for i, s1i in enumerate(s1):
        for j, s2j in enumerate(s2):
            cost = 0 if s1i == s2j else 1
            d[(i, j)] = min(
                d[(i - 1, j)] + 1, d[(i, j - 1)] + 1, d[(i - 1, j - 1)] + cost  # deletion  # insertion  # substitution
            )
            if i and j and s1i == s2[j - 1] and s1[i - 1] == s2j:
                d[(i, j)] = min(d[(i, j)], d[i - 2, j - 2] + cost)  # transposition

    return d[string_1_length - 1, string_2_length - 1]


def export(modname):
    """
    Make the decorated object a member of the named module. This will also add the object under its aliases if it has
    a `__aliases__` member, thus this decorator should be before the `alias` decorator to pick up those names. Alias
    names which conflict with package names or existing members will be ignored.
    """

    def _inner(obj):
        mod = import_module(modname)
        if not hasattr(mod, obj.__name__):
            setattr(mod, obj.__name__, obj)

            # add the aliases for `obj` to the target module
            for alias in getattr(obj, "__aliases__", ()):
                if not hasattr(mod, alias):
                    setattr(mod, alias, obj)

        return obj

    return _inner


def load_submodules(
    basemod: ModuleType, load_all: bool = True, exclude_pattern: str = "(.*[tT]est.*)|(_.*)"
) -> tuple[list[ModuleType], list[str]]:
    """
    Traverse the source of the module structure starting with module `basemod`, loading all packages plus all files if
    `load_all` is True, excluding anything whose name matches `exclude_pattern`.
    """
    submodules = []
    err_mod: list[str] = []
    for importer, name, is_pkg in walk_packages(
        basemod.__path__, prefix=basemod.__name__ + ".", onerror=err_mod.append
    ):
        if (is_pkg or load_all) and name not in sys.modules and match(exclude_pattern, name) is None:
            try:
                mod = import_module(name)
                importer.find_module(name).load_module(name)  # type: ignore
                submodules.append(mod)
            except OptionalImportError:
                pass  # could not import the optional deps., they are ignored
            except ImportError as e:
                msg = (
                    "\nMultiple versions of MONAI may have been installed?\n"
                    "Please see the installation guide: https://docs.monai.io/en/stable/installation.html\n"
                )  # issue project-monai/monai#5193
                raise type(e)(f"{e}\n{msg}").with_traceback(e.__traceback__) from e  # raise with modified message

    return submodules, err_mod


def instantiate(__path: str, __mode: str, **kwargs: Any) -> Any:
    """
    Create an object instance or call a callable object from a class or function represented by ``_path``.
    `kwargs` will be part of the input arguments to the class constructor or function.
    The target component must be a class or a function, if not, return the component directly.

    Args:
        __path: if a string is provided, it's interpreted as the full path of the target class or function component.
            If a callable is provided, ``__path(**kwargs)`` or ``functools.partial(__path, **kwargs)`` will be returned.
        __mode: the operating mode for invoking the (callable) ``component`` represented by ``__path``:

            - ``"default"``: returns ``component(**kwargs)``
            - ``"partial"``: returns ``functools.partial(component, **kwargs)``
            - ``"debug"``: returns ``pdb.runcall(component, **kwargs)``

        kwargs: keyword arguments to the callable represented by ``__path``.

    """
    from monai.utils.enums import CompInitMode

    component = locate(__path) if isinstance(__path, str) else __path
    if component is None:
        raise ModuleNotFoundError(f"Cannot locate class or function path: '{__path}'.")
    m = look_up_option(__mode, CompInitMode)
    try:
        if kwargs.pop("_debug_", False) or run_debug:
            warnings.warn(
                f"\n\npdb: instantiating component={component}, mode={m}\n"
                f"See also Debugger commands documentation: https://docs.python.org/3/library/pdb.html\n"
            )
            breakpoint()
        if not callable(component):
            warnings.warn(f"Component {component} is not callable when mode={m}.")
            return component
        if m == CompInitMode.DEFAULT:
            return component(**kwargs)
        if m == CompInitMode.PARTIAL:
            return partial(component, **kwargs)
        if m == CompInitMode.DEBUG:
            warnings.warn(
                f"\n\npdb: instantiating component={component}, mode={m}\n"
                f"See also Debugger commands documentation: https://docs.python.org/3/library/pdb.html\n"
            )
            return pdb.runcall(component, **kwargs)
    except Exception as e:
        raise RuntimeError(
            f"Failed to instantiate component '{__path}' with kwargs: {kwargs}"
            f"\n set '_mode_={CompInitMode.DEBUG}' to enter the debugging mode."
        ) from e

    warnings.warn(f"Component to instantiate must represent a valid class or function, but got {__path}.")
    return component


def get_full_type_name(typeobj):
    """
    Utility to get the full path name of a class or object type.

    """
    module = typeobj.__module__
    if module is None or module == str.__class__.__module__:
        return typeobj.__name__  # Avoid reporting __builtin__
    return module + "." + typeobj.__name__


def min_version(the_module: Any, min_version_str: str = "", *_args: Any) -> bool:
    """
    Convert version strings into tuples of int and compare them.

    Returns True if the module's version is greater or equal to the 'min_version'.
    When min_version_str is not provided, it always returns True.
    """
    if not min_version_str or not hasattr(the_module, "__version__"):
        return True  # always valid version

    mod_version = tuple(int(x) for x in the_module.__version__.split(".")[:2])
    required = tuple(int(x) for x in min_version_str.split(".")[:2])
    return mod_version >= required


def exact_version(the_module: Any, version_str: str = "", *_args: Any) -> bool:
    """
    Returns True if the module's __version__ matches version_str
    """
    if not hasattr(the_module, "__version__"):
        warnings.warn(f"{the_module} has no attribute __version__ in exact_version check.")
        return False
    return bool(the_module.__version__ == version_str)


class InvalidPyTorchVersionError(Exception):
    """
    Raised when called function or method requires a more recent
    PyTorch version than that installed.
    """

    def __init__(self, required_version, name):
        message = f"{name} requires PyTorch version {required_version} or later"
        super().__init__(message)


class OptionalImportError(ImportError):
    """
    Could not import APIs from an optional dependency.
    """


def optional_import(
    module: str,
    version: str = "",
    version_checker: Callable[..., bool] = min_version,
    name: str = "",
    descriptor: str = OPTIONAL_IMPORT_MSG_FMT,
    version_args: Any = None,
    allow_namespace_pkg: bool = False,
    as_type: str = "default",
) -> tuple[Any, bool]:
    """
    Imports an optional module specified by `module` string.
    Any importing related exceptions will be stored, and exceptions raise lazily
    when attempting to use the failed-to-import module.

    Args:
        module: name of the module to be imported.
        version: version string used by the version_checker.
        version_checker: a callable to check the module version, Defaults to monai.utils.min_version.
        name: a non-module attribute (such as method/class) to import from the imported module.
        descriptor: a format string for the final error message when using a not imported module.
        version_args: additional parameters to the version checker.
        allow_namespace_pkg: whether importing a namespace package is allowed. Defaults to False.
        as_type: there are cases where the optionally imported object is used as
            a base class, or a decorator, the exceptions should raise accordingly. The current supported values
            are "default" (call once to raise), "decorator" (call the constructor and the second call to raise),
            and anything else will return a lazy class that can be used as a base class (call the constructor to raise).

    Returns:
        The imported module and a boolean flag indicating whether the import is successful.

    Examples::

        >>> torch, flag = optional_import('torch', '1.1')
        >>> print(torch, flag)
        <module 'torch' from 'python/lib/python3.6/site-packages/torch/__init__.py'> True

        >>> the_module, flag = optional_import('unknown_module')
        >>> print(flag)
        False
        >>> the_module.method  # trying to access a module which is not imported
        OptionalImportError: import unknown_module (No module named 'unknown_module').

        >>> torch, flag = optional_import('torch', '42', exact_version)
        >>> torch.nn  # trying to access a module for which there isn't a proper version imported
        OptionalImportError: import torch (requires version '42' by 'exact_version').

        >>> conv, flag = optional_import('torch.nn.functional', '1.0', name='conv1d')
        >>> print(conv)
        <built-in method conv1d of type object at 0x11a49eac0>

        >>> conv, flag = optional_import('torch.nn.functional', '42', name='conv1d')
        >>> conv()  # trying to use a function from the not successfully imported module (due to unmatched version)
        OptionalImportError: from torch.nn.functional import conv1d (requires version '42' by 'min_version').
    """

    tb = None
    exception_str = ""
    if name:
        actual_cmd = f"from {module} import {name}"
    else:
        actual_cmd = f"import {module}"
    try:
        pkg = __import__(module)  # top level module
        the_module = import_module(module)
        if not allow_namespace_pkg:
            is_namespace = getattr(the_module, "__file__", None) is None and hasattr(the_module, "__path__")
            if is_namespace:
                raise AssertionError
        if name:  # user specified to load class/function/... from the module
            the_module = getattr(the_module, name)
    except Exception as import_exception:  # any exceptions during import
        tb = import_exception.__traceback__
        exception_str = f"{import_exception}"
    else:  # found the module
        if version_args and version_checker(pkg, f"{version}", version_args):
            return the_module, True
        if not version_args and version_checker(pkg, f"{version}"):
            return the_module, True

    # preparing lazy error message
    msg = descriptor.format(actual_cmd)
    if version and tb is None:  # a pure version issue
        msg += f" (requires '{module} {version}' by '{version_checker.__name__}')"
    if exception_str:
        msg += f" ({exception_str})"

    class _LazyRaise:
        def __init__(self, *_args, **_kwargs):
            _default_msg = (
                f"{msg}."
                + "\n\nFor details about installing the optional dependencies, please visit:"
                + "\n    https://docs.monai.io/en/latest/installation.html#installing-the-recommended-dependencies"
            )
            if tb is None:
                self._exception = OptionalImportError(_default_msg)
            else:
                self._exception = OptionalImportError(_default_msg).with_traceback(tb)

        def __getattr__(self, name):
            """
            Raises:
                OptionalImportError: When you call this method.
            """
            raise self._exception

        def __call__(self, *_args, **_kwargs):
            """
            Raises:
                OptionalImportError: When you call this method.
            """
            raise self._exception

        def __getitem__(self, item):
            raise self._exception

        def __iter__(self):
            raise self._exception

    if as_type == "default":
        return _LazyRaise(), False

    class _LazyCls(_LazyRaise):
        def __init__(self, *_args, **kwargs):
            super().__init__()
            if not as_type.startswith("decorator"):
                raise self._exception

    return _LazyCls, False


def require_pkg(
    pkg_name: str, version: str = "", version_checker: Callable[..., bool] = min_version, raise_error: bool = True
) -> Callable:
    """
    Decorator function to check the required package installation.

    Args:
        pkg_name: required package name, like: "itk", "nibabel", etc.
        version: required version string used by the version_checker.
        version_checker: a callable to check the module version, defaults to `monai.utils.min_version`.
        raise_error: if True, raise `OptionalImportError` error if the required package is not installed
            or the version doesn't match requirement, if False, print the error in a warning.

    """

    def _decorator(obj):
        is_func = isinstance(obj, FunctionType)
        call_obj = obj if is_func else obj.__init__

        @wraps(call_obj)
        def _wrapper(*args, **kwargs):
            _, has = optional_import(module=pkg_name, version=version, version_checker=version_checker)
            if not has:
                err_msg = f"required package `{pkg_name}` is not installed or the version doesn't match requirement."
                if raise_error:
                    raise OptionalImportError(err_msg)
                else:
                    warnings.warn(err_msg)

            return call_obj(*args, **kwargs)

        if is_func:
            return _wrapper
        obj.__init__ = _wrapper
        return obj

    return _decorator


def get_package_version(dep_name, default="NOT INSTALLED or UNKNOWN VERSION."):
    """
    Try to load package and get version. If not found, return `default`.
    """
    dep, has_dep = optional_import(dep_name)
    if has_dep and hasattr(dep, "__version__"):
        return dep.__version__
    return default


@functools.lru_cache(None)
def get_torch_version_tuple():
    """
    Returns:
        tuple of ints represents the pytorch major/minor version.
    """
    return tuple(int(x) for x in torch.__version__.split(".")[:2])


def version_leq(lhs: str, rhs: str) -> bool:
    """
    Returns True if version `lhs` is earlier or equal to `rhs`.

    Args:
        lhs: version name to compare with `rhs`, return True if earlier or equal to `rhs`.
        rhs: version name to compare with `lhs`, return True if later or equal to `lhs`.

    """

    lhs, rhs = str(lhs), str(rhs)
    pkging, has_ver = optional_import("pkg_resources", name="packaging")
    if has_ver:
        try:
            return cast(bool, pkging.version.Version(lhs) <= pkging.version.Version(rhs))
        except pkging.version.InvalidVersion:
            return True

    def _try_cast(val: str) -> int | str:
        val = val.strip()
        try:
            m = match("(\\d+)(.*)", val)
            if m is not None:
                val = m.groups()[0]
                return int(val)
            return val
        except ValueError:
            return val

    # remove git version suffixes if present
    lhs = lhs.split("+", 1)[0]
    rhs = rhs.split("+", 1)[0]

    # parse the version strings in this basic way without `packaging` package
    lhs_ = map(_try_cast, lhs.split("."))
    rhs_ = map(_try_cast, rhs.split("."))

    for l, r in zip(lhs_, rhs_):
        if l != r:
            if isinstance(l, int) and isinstance(r, int):
                return l < r
            return f"{l}" < f"{r}"

    return True


@functools.lru_cache(None)
def pytorch_after(major: int, minor: int, patch: int = 0, current_ver_string: str | None = None) -> bool:
    """
    Compute whether the current pytorch version is after or equal to the specified version.
    The current system pytorch version is determined by `torch.__version__` or
    via system environment variable `PYTORCH_VER`.

    Args:
        major: major version number to be compared with
        minor: minor version number to be compared with
        patch: patch version number to be compared with
        current_ver_string: if None, `torch.__version__` will be used.

    Returns:
        True if the current pytorch version is greater than or equal to the specified version.
    """

    try:
        if current_ver_string is None:
            _env_var = os.environ.get("PYTORCH_VER", "")
            current_ver_string = _env_var if _env_var else torch.__version__
        ver, has_ver = optional_import("pkg_resources", name="parse_version")
        if has_ver:
            return ver(".".join((f"{major}", f"{minor}", f"{patch}"))) <= ver(f"{current_ver_string}")  # type: ignore
        parts = f"{current_ver_string}".split("+", 1)[0].split(".", 3)
        while len(parts) < 3:
            parts += ["0"]
        c_major, c_minor, c_patch = parts[:3]
    except (AttributeError, ValueError, TypeError):
        c_major, c_minor = get_torch_version_tuple()
        c_patch = "0"
    c_mn = int(c_major), int(c_minor)
    mn = int(major), int(minor)
    if c_mn != mn:
        return c_mn > mn
    is_prerelease = ("a" in f"{c_patch}".lower()) or ("rc" in f"{c_patch}".lower())
    c_p = 0
    try:
        p_reg = re.search(r"\d+", f"{c_patch}")
        if p_reg:
            c_p = int(p_reg.group())
    except (AttributeError, TypeError, ValueError):
        is_prerelease = True
    patch = int(patch)
    if c_p != patch:
        return c_p > patch
    if is_prerelease:
        return False
    return True
