import inspect
import pathlib
import sys
import textwrap
from collections import UserList


def is_cyfunction(obj):
    return type(obj).__name__ == "cython_function_or_method"


def is_function(obj):
    return (
        inspect.isbuiltin(obj)
        or is_cyfunction(obj)
        or type(obj) is type(ord)
    )  # fmt: skip


def is_method(obj):
    return (
        inspect.ismethoddescriptor(obj)
        or inspect.ismethod(obj)
        or is_cyfunction(obj)
        or type(obj) in (
            type(str.index),
            type(str.__add__),
            type(str.__new__),
        )
    )  # fmt: skip


def is_classmethod(obj):
    return (
        inspect.isbuiltin(obj)
        or type(obj).__name__ in (
            "classmethod",
            "classmethod_descriptor",
        )
    )  # fmt: skip


def is_staticmethod(obj):
    return type(obj).__name__ == "staticmethod"


def is_datadescr(obj):
    return inspect.isdatadescriptor(obj) and not hasattr(obj, "fget")


def is_property(obj):
    return inspect.isdatadescriptor(obj) and hasattr(obj, "fget")


def is_class(obj):
    return inspect.isclass(obj) or type(obj) is type(int)


class Lines(UserList):
    INDENT = " " * 4
    level = 0

    @property
    def add(self):
        return self

    @add.setter
    def add(self, lines):
        if lines is None:
            return
        if isinstance(lines, str):
            lines = textwrap.dedent(lines).strip().split("\n")
        indent = self.INDENT * self.level
        for line in lines:
            self.append(indent + line)


def signature(obj):
    doc = obj.__doc__
    sig = doc.partition("\n")[0]
    return sig or None


def docstring(obj):
    doc = obj.__doc__
    doc = doc.partition("\n")[2]
    doc = textwrap.dedent(doc).strip()
    doc = f'"""{doc}\n"""'
    doc = textwrap.indent(doc, Lines.INDENT)
    return doc


def visit_constant(constant):
    name, value = constant
    typename = type(value).__name__
    kind = "Constant" if isinstance(value, (str, int, float)) else "Object"
    init = f"_def({typename}, '{name}')"
    doc = f"#: {kind} ``{name}`` of type :class:`{typename}`"
    return f"{name}: {typename} = {init}  {doc}\n"


def visit_function(function):
    sig = signature(function)
    doc = docstring(function)
    body = Lines.INDENT + "..."
    return f"def {sig}:\n{doc}\n{body}\n"


def visit_method(method):
    sig = signature(method)
    doc = docstring(method)
    body = Lines.INDENT + "..."
    return f"def {sig}:\n{doc}\n{body}\n"


def visit_datadescr(datadescr, name=None):
    sig = signature(datadescr)
    doc = docstring(datadescr)
    name = sig.split(":")[0].strip()
    type = sig.split(":")[1].strip()  # noqa: A001
    sig = f"{name}(self) -> {type}"
    body = Lines.INDENT + "..."
    return f"@property\ndef {sig}:\n{doc}\n{body}\n"


def visit_property(prop, name=None):
    gname = prop.fget.__name__
    pname = name or gname
    if pname == gname:
        meth = visit_method(prop.fget)
    else:
        sig = signature(prop.fget)
        name = name or prop.fget.__name__
        type = sig.rsplit("->", 1)[-1].strip()  # noqa: A001
        sig = f"{name}(self) -> {type}"
        doc = docstring(prop)
        body = Lines.INDENT + "..."
        meth = f"def {sig}:\n{doc}\n{body}\n"
    return f"@property\n{meth}"


def visit_constructor(cls, name="__init__", args=None):
    init = name == "__init__"
    argname = cls.__mro__[-2].__name__.lower()
    argtype = cls.__name__
    initarg = args or f"{argname}: {argtype} | None = None"
    selfarg = "self" if init else "cls"
    rettype = "None" if init else "Self"
    arglist = f"{selfarg}, {initarg}"
    sig = f"{name}({arglist}) -> {rettype}"
    ret = "..." if init else "return super().__new__(cls)"
    body = Lines.INDENT + ret
    return f"def {sig}:\n{body}"


def visit_class(cls, done=None):
    skip = {
        "__doc__",
        "__dict__",
        "__module__",
        "__weakref__",
        "__pyx_vtable__",
        "__lt__",
        "__le__",
        "__ge__",
        "__gt__",
        "__str__",
        "__repr__",
    }
    special = {
        "__len__": ("self", "int", None),
        "__bool__": ("self", "bool", None),
        "__hash__": ("self", "int", None),
        "__int__": ("self", "int", None),
        "__index__": ("self", "int", None),
        "__eq__": ("self", "other: object", "/", "bool", None),
        "__ne__": ("self", "other: object", "/", "bool", None),
        "__buffer__": ("self", "flags: int", "/", "memoryview", (3, 12)),
    }
    constructor = (
        "__new__",
        "__init__",
    )

    override = OVERRIDE.get(cls.__name__, {})
    done = set() if done is None else done
    lines = Lines()

    if cls.__name__ == "Exception":
        skip = skip - {f"__{a}{b}__" for a in "lg" for b in "et"}
        constructor = ()
    if "__hash__" in cls.__dict__:
        if cls.__hash__ is None:
            done.add("__hash__")

    base = cls.__base__
    if base is object:
        lines.add = f"class {cls.__name__}:"
    else:
        lines.add = f"class {cls.__name__}({base.__name__}):"
    lines.level += 1

    lines.add = docstring(cls)

    name = "__init__"
    if name not in override:
        sig = signature(cls)
        if sig is not None:
            done.update(constructor)
            args = sig.strip().split("->", 1)[0].strip()
            pidx = args.index("(")
            args = args[pidx:][1:-1]
            lines.add = visit_constructor(cls, name, args)

    for name in constructor:
        if name in done:
            break
        if name in override:
            done.update(constructor)
            lines.add = override[name]
            break
        if name in cls.__dict__:
            done.update(constructor)
            lines.add = visit_constructor(cls, name)
            break

    if "__hash__" in cls.__dict__:
        if cls.__hash__ is None:
            done.add("__hash__")

    dct = cls.__dict__
    keys = list(dct.keys())
    for name in keys:
        if name in done:
            continue

        if name in override:
            done.add(name)
            lines.add = override[name]
            continue

        if name in skip:
            continue

        if name in special:
            done.add(name)
            *args, retv, py = special[name]
            sig = f"{name}({', '.join(args)}) -> {retv}"
            if py is not None:
                lines.add = f"if sys.version_info >= {py}:"
                lines.level += 1
            lines.add = f"def {sig}: ..."
            if py is not None:
                lines.level -= 1
            continue

        attr = getattr(cls, name)

        if is_method(attr):
            done.add(name)
            if name == attr.__name__:
                obj = dct[name]
                if is_classmethod(obj):
                    lines.add = "@classmethod"
                elif is_staticmethod(obj):
                    lines.add = "@staticmethod"
                lines.add = visit_method(attr)
            elif False:
                lines.add = f"{name} = {attr.__name__}"
            continue

        if is_datadescr(attr):
            done.add(name)
            lines.add = visit_datadescr(attr)
            continue

        if is_property(attr):
            done.add(name)
            lines.add = visit_property(attr, name)
            continue

    leftovers = [
        name for name in keys if name not in done and name not in skip
    ]
    if leftovers:
        raise RuntimeError(f"leftovers: {leftovers}")

    lines.level -= 1
    return lines


def visit_module(module, done=None):
    skip = {
        "__doc__",
        "__name__",
        "__loader__",
        "__spec__",
        "__file__",
        "__package__",
        "__builtins__",
    }

    done = set() if done is None else done
    lines = Lines()

    keys = list(module.__dict__.keys())
    keys.sort(key=lambda name: name.startswith("_"))

    constants = [
        (name, getattr(module, name))
        for name in keys
        if all((
            name not in done and name not in skip,
            isinstance(getattr(module, name), int),
        ))
    ]
    for _, value in constants:
        cls = type(value)
        name = cls.__name__
        if name in done or name in skip:
            continue
        if cls.__module__ == module.__name__:
            done.add(name)
            lines.add = visit_class(cls)
            lines.add = ""
    for name, value in constants:
        done.add(name)
        if name in OVERRIDE:
            lines.add = OVERRIDE[name]
        else:
            lines.add = visit_constant((name, value))
    if constants:
        lines.add = ""

    for name in keys:
        if name in done or name in skip:
            continue
        value = getattr(module, name)

        if is_class(value):
            done.add(name)
            lines.add = visit_class(value)
            lines.add = ""
            aliases = [
                (k, getattr(module, k))
                for k in keys
                if all((
                    k not in done and k not in skip,
                    getattr(module, k) is value,
                ))
            ]
            for aliasname, target in aliases:
                done.add(aliasname)
                lines.add = f"{aliasname} = {target.__name__}"
            if aliases:
                lines.add = ""
            instances = [
                (k, getattr(module, k))
                for k in keys
                if all((
                    k not in done and k not in skip,
                    type(getattr(module, k)) is value,
                ))
            ]
            for attrname, attrvalue in instances:
                done.add(attrname)
                lines.add = visit_constant((attrname, attrvalue))
            if instances:
                lines.add = ""
            continue

        if is_function(value):
            done.add(name)
            if name == value.__name__:
                lines.add = visit_function(value)
            else:
                lines.add = f"{name} = {value.__name__}"
            continue

    lines.add = ""
    for name in keys:
        if name in done or name in skip:
            continue
        value = getattr(module, name)
        done.add(name)
        if name in OVERRIDE:
            lines.add = OVERRIDE[name]
        else:
            lines.add = visit_constant((name, value))

    leftovers = [
        name for name in keys if name not in done and name not in skip
    ]
    if leftovers:
        raise RuntimeError(f"leftovers: {leftovers}")
    return lines


IMPORTS = """
import sys
from typing import (
    Any,
    AnyStr,
    Final,
    Literal,
    NoReturn,
)
from typing import (
    Callable,
    Hashable,
    Iterable,
    Iterator,
    Sequence,
    Mapping,
)
try:
    from typing import Self
except ImportError:
    Self = 'Self'
from os import PathLike
"""

HELPERS = """
class _Int(int): pass

def _repr(obj):
    try:
        return obj._name
    except AttributeError:
        return super(obj).__repr__()

def _def(cls, name):
    if cls is int:
       cls = _Int
    obj = cls()
    if cls.__name__ in ('Pickle', 'buffer'):
        return obj
    obj._name = name
    if '__repr__' not in cls.__dict__:
        cls.__repr__ = _repr
    return obj
"""

OVERRIDE = {
    "Exception": {
        "__init__": (
            "def __init__(self, ierr: int = SUCCESS, /) -> None:\n"
            "    return super().__init__(ierr)"
        ),
    },
    "Info": {
        "__iter__": "def __iter__(self) -> Iterator[str]: ...",
        "__getitem__": "def __getitem__(self, item: str, /) -> str: ...",
        "__setitem__": (
            "def __setitem__(self, item: str, value: str, /) -> None: ..."
        ),
        "__delitem__": "def __delitem__(self, item: str, /) -> None: ...",
        "__contains__": "def __contains__(self, value: str, /) -> bool: ...",
    },
    "Op": {
        "__call__": "def __call__(self, x: Any, y: Any, /) -> Any: ...",
    },
    "buffer": {
        "__new__": (
            "def __new__(cls, buf: Buffer, /) -> Self:\n"
            "    return super().__new__(cls)"
        ),
        "__getitem__": (
            "def __getitem__(self, item: int | slice, /) -> int | buffer: ..."
        ),
        "__setitem__": (
            "def __setitem__(self, "
            "item: int | slice, "
            "value:int | Buffer, /) "
            "-> None: ..."
        ),
        "__delitem__": None,
    },
    "__pyx_capi__": None,
    "_typedict": "_typedict: Dict[str, Datatype] = {}",
    "_typedict_c": "_typedict_c: Dict[str, Datatype] = {}",
    "_typedict_f": "_typedict_f: Dict[str, Datatype] = {}",
    "_keyval_registry": None,
}
OVERRIDE.update({
    subtype: {
        "__new__": (
            f"def __new__(cls) -> Self:\n"
            f"    return super().__new__({subtype})"
        ),
        "__repr__": "def __repr__(self) -> str: return self._name",
    }
    for subtype in (
        "BottomType",
        "InPlaceType",
        "BufferAutomaticType",
    )
})  # fmt: skip

TYPING = """
from .typing import *
"""


def visit_mpi4py_MPI():
    from mpi4py import MPI as module

    lines = Lines()
    lines.add = f'"""{module.__doc__}"""'
    lines.add = "# flake8: noqa"
    lines.add = IMPORTS
    lines.add = ""
    lines.add = HELPERS
    lines.add = ""
    lines.add = visit_module(module)
    lines.add = ""
    lines.add = TYPING
    return lines


def generate(filename):
    filename = pathlib.Path(filename)
    filename.parent.mkdir(parents=True, exist_ok=True)
    with filename.open("w", encoding="utf-8") as f:
        for line in visit_mpi4py_MPI():
            print(line, file=f)


def load_module(filename, name=None):
    filename = pathlib.Path(filename)
    if name is None:
        name = filename.stem
    module = type(sys)(name)
    module.__file__ = str(filename)
    module.__package__ = name.rsplit(".", 1)[0]
    preamble = "from __future__ import annotations"
    codelines = filename.read_text(encoding="utf-8").split("\n")
    for lineno, line in enumerate(codelines):
        match = line.strip().startswith
        if not any(map(match, "'\"#")):
            codelines.insert(lineno, preamble)
            break
    code = "\n".join(codelines)
    exec(code, module.__dict__)
    return module


_sys_modules = {}


def replace_module(module):
    name = module.__name__
    assert name not in _sys_modules
    _sys_modules[name] = sys.modules[name]
    sys.modules[name] = module
    pkgname, _, modname = name.rpartition(".")
    if pkgname:
        setattr(sys.modules[pkgname], modname, module)


def restore_module(module):
    name = module.__name__
    assert name in _sys_modules
    sys.modules[name] = _sys_modules[name]
    pkgname, _, modname = name.rpartition(".")
    if pkgname:
        setattr(sys.modules[pkgname], modname, sys.modules[name])


def annotate(dest, source):
    try:
        dest.__annotations__ = source.__annotations__
    except AttributeError:
        pass
    if isinstance(dest, type):
        for name in dest.__dict__.keys():
            if hasattr(source, name):
                obj = getattr(dest, name)
                annotate(obj, getattr(source, name))
    if isinstance(dest, type(sys)):
        for name in dir(dest):
            if hasattr(source, name):
                obj = getattr(dest, name)
                mod = getattr(obj, "__module__", None)
                if dest.__name__ == mod:
                    annotate(obj, getattr(source, name))
        for name in dir(source):
            if not hasattr(dest, name):
                setattr(dest, name, getattr(source, name))


OUTDIR = pathlib.Path("reference")

if __name__ == "__main__":
    generate(OUTDIR / "mpi4py.MPI.py")