# Copyright (c) 2011-2020 Eric Froemling
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
# -----------------------------------------------------------------------------
"""Utility snippets applying to generic Python code."""
from __future__ import annotations

import gc
import types
import weakref
import random
import inspect
from typing import TYPE_CHECKING, TypeVar
from typing_extensions import Protocol

from efro.terminal import Clr
from ba._error import print_error, print_exception
from ba._enums import TimeType
import _ba

if TYPE_CHECKING:
    from typing import Any, Type, Optional
    from efro.call import Call as Call  # 'as Call' so we re-export.
    from weakref import ReferenceType


class Existable(Protocol):
    """A Protocol for objects supporting an exists() method.

    Category: Protocols
    """

    def exists(self) -> bool:
        """Whether this object exists."""
        ...


ExistableType = TypeVar('ExistableType', bound=Existable)
T = TypeVar('T')


def existing(obj: Optional[ExistableType]) -> Optional[ExistableType]:
    """Convert invalid references to None for any ba.Existable type.

    Category: Gameplay Functions

    To best support type checking, it is important that invalid references
    not be passed around and instead get converted to values of None.
    That way the type checker can properly flag attempts to pass dead
    objects into functions expecting only live ones, etc.
    This call can be used on any 'existable' object (one with an exists()
    method) and will convert it to a None value if it does not exist.
    For more info, see notes on 'existables' here:
    https://ballistica.net/wiki/Coding-Style-Guide
    """
    assert obj is None or hasattr(obj, 'exists'), f'No "exists" on {obj}'
    return obj if obj is not None and obj.exists() else None


def getclass(name: str, subclassof: Type[T]) -> Type[T]:
    """Given a full class name such as foo.bar.MyClass, return the class.

    Category: General Utility Functions

    The class will be checked to make sure it is a subclass of the provided
    'subclassof' class, and a TypeError will be raised if not.
    """
    import importlib
    splits = name.split('.')
    modulename = '.'.join(splits[:-1])
    classname = splits[-1]
    module = importlib.import_module(modulename)
    cls: Type = getattr(module, classname)

    if not issubclass(cls, subclassof):
        raise TypeError(f'{name} is not a subclass of {subclassof}.')
    return cls


def json_prep(data: Any) -> Any:
    """Return a json-friendly version of the provided data.

    This converts any tuples to lists and any bytes to strings
    (interpreted as utf-8, ignoring errors). Logs errors (just once)
    if any data is modified/discarded/unsupported.
    """

    if isinstance(data, dict):
        return dict((json_prep(key), json_prep(value))
                    for key, value in list(data.items()))
    if isinstance(data, list):
        return [json_prep(element) for element in data]
    if isinstance(data, tuple):
        print_error('json_prep encountered tuple', once=True)
        return [json_prep(element) for element in data]
    if isinstance(data, bytes):
        try:
            return data.decode(errors='ignore')
        except Exception:
            from ba import _error
            print_error('json_prep encountered utf-8 decode error', once=True)
            return data.decode(errors='ignore')
    if not isinstance(data, (str, float, bool, type(None), int)):
        print_error('got unsupported type in json_prep:' + str(type(data)),
                    once=True)
    return data


def utf8_all(data: Any) -> Any:
    """Convert any unicode data in provided sequence(s) to utf8 bytes."""
    if isinstance(data, dict):
        return dict((utf8_all(key), utf8_all(value))
                    for key, value in list(data.items()))
    if isinstance(data, list):
        return [utf8_all(element) for element in data]
    if isinstance(data, tuple):
        return tuple(utf8_all(element) for element in data)
    if isinstance(data, str):
        return data.encode('utf-8', errors='ignore')
    return data


def print_refs(obj: Any) -> None:
    """Print a list of known live references to an object."""

    # Hmmm; I just noticed that calling this on an object
    # seems to keep it alive. Should figure out why.
    print('REFERENCES FOR', obj, ':')
    refs = list(gc.get_referrers(obj))
    i = 1
    for ref in refs:
        print('     ref', i, ':', ref)
        i += 1


def get_type_name(cls: Type) -> str:
    """Return a full type name including module for a class."""
    return cls.__module__ + '.' + cls.__name__


class _WeakCall:
    """Wrap a callable and arguments into a single callable object.

    Category: General Utility Classes

    When passed a bound method as the callable, the instance portion
    of it is weak-referenced, meaning the underlying instance is
    free to die if all other references to it go away. Should this
    occur, calling the WeakCall is simply a no-op.

    Think of this as a handy way to tell an object to do something
    at some point in the future if it happens to still exist.

    # EXAMPLE A: this code will create a FooClass instance and call its
    # bar() method 5 seconds later; it will be kept alive even though
    # we overwrite its variable with None because the bound method
    # we pass as a timer callback (foo.bar) strong-references it
    foo = FooClass()
    ba.timer(5.0, foo.bar)
    foo = None

    # EXAMPLE B: this code will *not* keep our object alive; it will die
    # when we overwrite it with None and the timer will be a no-op when it
    # fires
    foo = FooClass()
    ba.timer(5.0, ba.WeakCall(foo.bar))
    foo = None

    Note: additional args and keywords you provide to the WeakCall()
    constructor are stored as regular strong-references; you'll need
    to wrap them in weakrefs manually if desired.
    """

    def __init__(self, *args: Any, **keywds: Any) -> None:
        """
        Instantiate a WeakCall; pass a callable as the first
        arg, followed by any number of arguments or keywords.

        # Example: wrap a method call with some positional and
        # keyword args:
        myweakcall = ba.WeakCall(myobj.dostuff, argval1, namedarg=argval2)

        # Now we have a single callable to run that whole mess.
        # The same as calling myobj.dostuff(argval1, namedarg=argval2)
        # (provided my_obj still exists; this will do nothing otherwise)
        myweakcall()
        """
        if hasattr(args[0], '__func__'):
            self._call = WeakMethod(args[0])
        else:
            app = _ba.app
            if not app.did_weak_call_warning:
                print(('Warning: callable passed to ba.WeakCall() is not'
                       ' weak-referencable (' + str(args[0]) +
                       '); use ba.Call() instead to avoid this '
                       'warning. Stack-trace:'))
                import traceback
                traceback.print_stack()
                app.did_weak_call_warning = True
            self._call = args[0]
        self._args = args[1:]
        self._keywds = keywds

    def __call__(self, *args_extra: Any) -> Any:
        return self._call(*self._args + args_extra, **self._keywds)

    def __str__(self) -> str:
        return ('<ba.WeakCall object; _call=' + str(self._call) + ' _args=' +
                str(self._args) + ' _keywds=' + str(self._keywds) + '>')


class _Call:
    """Wraps a callable and arguments into a single callable object.

    Category: General Utility Classes

    The callable is strong-referenced so it won't die until this
    object does.

    Note that a bound method (ex: myobj.dosomething) contains a reference
    to 'self' (myobj in that case), so you will be keeping that object
    alive too. Use ba.WeakCall if you want to pass a method to callback
    without keeping its object alive.
    """

    def __init__(self, *args: Any, **keywds: Any):
        """
        Instantiate a Call; pass a callable as the first
        arg, followed by any number of arguments or keywords.

        # Example: wrap a method call with 1 positional and 1 keyword arg:
        mycall = ba.Call(myobj.dostuff, argval1, namedarg=argval2)

        # Now we have a single callable to run that whole mess.
        # ..the same as calling myobj.dostuff(argval1, namedarg=argval2)
        mycall()
        """
        self._call = args[0]
        self._args = args[1:]
        self._keywds = keywds

    def __call__(self, *args_extra: Any) -> Any:
        return self._call(*self._args + args_extra, **self._keywds)

    def __str__(self) -> str:
        return ('<ba.Call object; _call=' + str(self._call) + ' _args=' +
                str(self._args) + ' _keywds=' + str(self._keywds) + '>')


if TYPE_CHECKING:
    WeakCall = Call
    Call = Call
else:
    WeakCall = _WeakCall
    WeakCall.__name__ = 'WeakCall'
    Call = _Call
    Call.__name__ = 'Call'


class WeakMethod:
    """A weak-referenced bound method.

    Wraps a bound method using weak references so that the original is
    free to die. If called with a dead target, is simply a no-op.
    """

    def __init__(self, call: types.MethodType):
        assert isinstance(call, types.MethodType)
        self._func = call.__func__
        self._obj = weakref.ref(call.__self__)

    def __call__(self, *args: Any, **keywds: Any) -> Any:
        obj = self._obj()
        if obj is None:
            return None
        return self._func(*((obj, ) + args), **keywds)

    def __str__(self) -> str:
        return '<ba.WeakMethod object; call=' + str(self._func) + '>'


def verify_object_death(obj: object) -> None:
    """Warn if an object does not get freed within a short period.

    Category: General Utility Functions

    This can be handy to detect and prevent memory/resource leaks.
    """
    try:
        ref = weakref.ref(obj)
    except Exception:
        print_exception('Unable to create weak-ref in verify_object_death')

    # Use a slight range for our checks so they don't all land at once
    # if we queue a lot of them.
    delay = random.uniform(2.0, 5.5)
    with _ba.Context('ui'):
        _ba.timer(delay,
                  lambda: _verify_object_death(ref),
                  timetype=TimeType.REAL)


def _verify_object_death(wref: ReferenceType) -> None:
    obj = wref()
    if obj is None:
        return

    try:
        name = type(obj).__name__
    except Exception:
        print(f'Note: unable to get type name for {obj}')
        name = 'object'

    print(f'{Clr.RED}Error: {name} not dying'
          f' when expected to: {Clr.BLD}{obj}{Clr.RST}')
    refs = list(gc.get_referrers(obj))
    print(f'{Clr.YLW}Active References:{Clr.RST}')
    i = 1
    for ref in refs:
        print(f'{Clr.YLW}  reference {i}:{Clr.BLU} {ref}{Clr.RST}')
        i += 1


def storagename(suffix: str = None) -> str:
    """Generate a (hopefully) unique name for storing things in public places.

    Category: General Utility Functions

    This consists of a leading underscore, the module path at the
    call site with dots replaced by underscores, the class name, and
    the provided suffix. When storing data in public places such as
    'customdata' dicts, this minimizes the chance of collisions if a
    module or class is duplicated or renamed.

    # Example: generate a unique name for storage purposes:
    class MyThingie:

        # This will give something like '_mymodule_submodule_mythingie_data'.
        _STORENAME = ba.storagename('data')

        def __init__(self, activity):
            # Store some data in the Activity we were passed
            activity.customdata[self._STORENAME] = {}
    """
    frame = inspect.currentframe()
    if frame is None:
        raise RuntimeError('Cannot get current stack frame.')
    fback = frame.f_back
    if fback is None:
        raise RuntimeError('Cannot get parent stack frame.')
    modulepath = fback.f_globals.get('__name__')
    if modulepath is None:
        raise RuntimeError('Cannot get parent stack module path.')
    assert isinstance(modulepath, str)
    qualname = fback.f_locals.get('__qualname__')
    if qualname is not None:
        assert isinstance(qualname, str)
        fullpath = f'_{modulepath}_{qualname.lower()}'
    else:
        fullpath = f'_{modulepath}'
    if suffix is not None:
        fullpath = f'{fullpath}_{suffix}'
    return fullpath.replace('.', '_')
