"""
# Reference
Python utilities required by Keras.
    https://github.com/keras-team/keras/blob/master/keras/utils/generic_utils.py
"""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import binascii
import numpy as np

import time
import sys
import six
import marshal
import types as python_types
import inspect
import codecs
import collections

_GLOBAL_CUSTOM_OBJECTS = {}


class CustomObjectScope(object):
    """Provides a scope that changes to `_GLOBAL_CUSTOM_OBJECTS` cannot escape.

    Code within a `with` statement will be able to access custom objects
    by name. Changes to global custom objects persist
    within the enclosing `with` statement. At end of the `with` statement,
    global custom objects are reverted to state
    at beginning of the `with` statement.

    # Example

    Consider a custom object `MyObject` (e.g. a class):

    ```python
        with CustomObjectScope({'MyObject':MyObject}):
            layer = Dense(..., kernel_regularizer='MyObject')
            # save, load, etc. will recognize custom object by name
    ```
    """

    def __init__(self, *args):
        self.custom_objects = args
        self.backup = None

    def __enter__(self):
        self.backup = _GLOBAL_CUSTOM_OBJECTS.copy()
        for objects in self.custom_objects:
            _GLOBAL_CUSTOM_OBJECTS.update(objects)
        return self

    def __exit__(self, *args, **kwargs):
        _GLOBAL_CUSTOM_OBJECTS.clear()
        _GLOBAL_CUSTOM_OBJECTS.update(self.backup)


def custom_object_scope(*args):
    """Provides a scope that changes to `_GLOBAL_CUSTOM_OBJECTS` cannot escape.

    Convenience wrapper for `CustomObjectScope`.
    Code within a `with` statement will be able to access custom objects
    by name. Changes to global custom objects persist
    within the enclosing `with` statement. At end of the `with` statement,
    global custom objects are reverted to state
    at beginning of the `with` statement.

    # Example

    Consider a custom object `MyObject`

    ```python
        with custom_object_scope({'MyObject':MyObject}):
            layer = Dense(..., kernel_regularizer='MyObject')
            # save, load, etc. will recognize custom object by name
    ```

    # Arguments
        *args: Variable length list of dictionaries of name,
            class pairs to add to custom objects.

    # Returns
        Object of type `CustomObjectScope`.
    """
    return CustomObjectScope(*args)


def get_custom_objects():
    """Retrieves a live reference to the global dictionary of custom objects.

    Updating and clearing custom objects using `custom_object_scope`
    is preferred, but `get_custom_objects` can
    be used to directly access `_GLOBAL_CUSTOM_OBJECTS`.

    # Example

    ```python
        get_custom_objects().clear()
        get_custom_objects()['MyObject'] = MyObject
    ```

    # Returns
        Global dictionary of names to classes (`_GLOBAL_CUSTOM_OBJECTS`).
    """
    return _GLOBAL_CUSTOM_OBJECTS


def serialize_keras_object(instance):
    if instance is None:
        return None
    if hasattr(instance, 'get_config'):
        return {
            'class_name': instance.__class__.__name__,
            'config': instance.get_config()
        }
    if hasattr(instance, '__name__'):
        return instance.__name__
    else:
        raise ValueError('Cannot serialize', instance)


def deserialize_keras_object(identifier, module_objects=None,
                             custom_objects=None,
                             printable_module_name='object'):
    if isinstance(identifier, dict):
        # In this case we are dealing with a Keras config dictionary.
        config = identifier
        if 'class_name' not in config or 'config' not in config:
            raise ValueError('Improper config format: ' + str(config))
        class_name = config['class_name']
        if custom_objects and class_name in custom_objects:
            cls = custom_objects[class_name]
        elif class_name in _GLOBAL_CUSTOM_OBJECTS:
            cls = _GLOBAL_CUSTOM_OBJECTS[class_name]
        else:
            module_objects = module_objects or {}
            cls = module_objects.get(class_name)
            if cls is None:
                raise ValueError('Unknown ' + printable_module_name +
                                 ': ' + class_name)
        if hasattr(cls, 'from_config'):
            custom_objects = custom_objects or {}
            if has_arg(cls.from_config, 'custom_objects'):
                return cls.from_config(config['config'],
                                       custom_objects=dict(list(_GLOBAL_CUSTOM_OBJECTS.items()) +
                                                           list(custom_objects.items())))
            with CustomObjectScope(custom_objects):
                return cls.from_config(config['config'])
        else:
            # Then `cls` may be a function returning a class.
            # in this case by convention `config` holds
            # the kwargs of the function.
            custom_objects = custom_objects or {}
            with CustomObjectScope(custom_objects):
                return cls(**config['config'])
    elif isinstance(identifier, six.string_types):
        function_name = identifier
        if custom_objects and function_name in custom_objects:
            fn = custom_objects.get(function_name)
        elif function_name in _GLOBAL_CUSTOM_OBJECTS:
            fn = _GLOBAL_CUSTOM_OBJECTS[function_name]
        else:
            fn = module_objects.get(function_name)
            if fn is None:
                raise ValueError('Unknown ' + printable_module_name +
                                 ':' + function_name)
        return fn
    else:
        raise ValueError('Could not interpret serialized ' +
                         printable_module_name + ': ' + identifier)


def func_dump(func):
    """Serializes a user defined function.

    # Arguments
        func: the function to serialize.

    # Returns
        A tuple `(code, defaults, closure)`.
    """
    raw_code = marshal.dumps(func.__code__)
    code = codecs.encode(raw_code, 'base64').decode('ascii')
    defaults = func.__defaults__
    if func.__closure__:
        closure = tuple(c.cell_contents for c in func.__closure__)
    else:
        closure = None
    return code, defaults, closure


def func_load(code, defaults=None, closure=None, globs=None):
    """Deserializes a user defined function.

    # Arguments
        code: bytecode of the function.
        defaults: defaults of the function.
        closure: closure of the function.
        globs: dictionary of global objects.

    # Returns
        A function object.
    """
    if isinstance(code, (tuple, list)):  # unpack previous dump
        code, defaults, closure = code
        if isinstance(defaults, list):
            defaults = tuple(defaults)

    def ensure_value_to_cell(value):
        """Ensures that a value is converted to a python cell object.

        # Arguments
            value: Any value that needs to be casted to the cell type

        # Returns
            A value wrapped as a cell object (see function "func_load")

        """
        def dummy_fn():
            value  # just access it so it gets captured in .__closure__

        cell_value = dummy_fn.__closure__[0]
        if not isinstance(value, type(cell_value)):
            return cell_value
        else:
            return value

    if closure is not None:
        closure = tuple(ensure_value_to_cell(_) for _ in closure)
    try:
        raw_code = codecs.decode(code.encode('ascii'), 'base64')
        code = marshal.loads(raw_code)
    except (UnicodeEncodeError, binascii.Error, ValueError):
        # backwards compatibility for models serialized prior to 2.1.2
        raw_code = code.encode('raw_unicode_escape')
        code = marshal.loads(raw_code)
    if globs is None:
        globs = globals()
    return python_types.FunctionType(code, globs,
                                     name=code.co_name,
                                     argdefs=defaults,
                                     closure=closure)


def has_arg(fn, name, accept_all=False):
    """Checks if a callable accepts a given keyword argument.

    For Python 2, checks if there is an argument with the given name.

    For Python 3, checks if there is an argument with the given name, and
    also whether this argument can be called with a keyword (i.e. if it is
    not a positional-only argument).

    # Arguments
        fn: Callable to inspect.
        name: Check if `fn` can be called with `name` as a keyword argument.
        accept_all: What to return if there is no parameter called `name`
                    but the function accepts a `**kwargs` argument.

    # Returns
        bool, whether `fn` accepts a `name` keyword argument.
    """
    if sys.version_info < (3,):
        arg_spec = inspect.getargspec(fn)
        if accept_all and arg_spec.keywords is not None:
            return True
        return (name in arg_spec.args)
    elif sys.version_info < (3, 3):
        arg_spec = inspect.getfullargspec(fn)
        if accept_all and arg_spec.varkw is not None:
            return True
        return (name in arg_spec.args or
                name in arg_spec.kwonlyargs)
    else:
        signature = inspect.signature(fn)
        parameter = signature.parameters.get(name)
        if parameter is None:
            if accept_all:
                for param in signature.parameters.values():
                    if param.kind == inspect.Parameter.VAR_KEYWORD:
                        return True
            return False
        return (parameter.kind in (inspect.Parameter.POSITIONAL_OR_KEYWORD,
                                   inspect.Parameter.KEYWORD_ONLY))


class Progbar(object):
    """Displays a progress bar.

    # Arguments
        target: Total number of steps expected, None if unknown.
        width: Progress bar width on screen.
        verbose: Verbosity mode, 0 (silent), 1 (verbose), 2 (semi-verbose)
        stateful_metrics: Iterable of string names of metrics that
            should *not* be averaged over time. Metrics in this list
            will be displayed as-is. All others will be averaged
            by the progbar before display.
        interval: Minimum visual progress update interval (in seconds).
    """

    def __init__(self, target, width=30, verbose=1, interval=0.05,
                 stateful_metrics=None):
        self.target = target
        self.width = width
        self.verbose = verbose
        self.interval = interval
        if stateful_metrics:
            self.stateful_metrics = set(stateful_metrics)
        else:
            self.stateful_metrics = set()

        self._dynamic_display = ((hasattr(sys.stdout, 'isatty') and
                                  sys.stdout.isatty()) or
                                 'ipykernel' in sys.modules)
        self._total_width = 0
        self._seen_so_far = 0
        self._values = collections.OrderedDict()
        self._start = time.time()
        self._last_update = 0

    def update(self, current, values=None):
        """Updates the progress bar.

        # Arguments
            current: Index of current step.
            values: List of tuples:
                `(name, value_for_last_step)`.
                If `name` is in `stateful_metrics`,
                `value_for_last_step` will be displayed as-is.
                Else, an average of the metric over time will be displayed.
        """
        values = values or []
        for k, v in values:
            if k not in self.stateful_metrics:
                if k not in self._values:
                    self._values[k] = [v * (current - self._seen_so_far),
                                       current - self._seen_so_far]
                else:
                    self._values[k][0] += v * (current - self._seen_so_far)
                    self._values[k][1] += (current - self._seen_so_far)
            else:
                self._values[k] = v
        self._seen_so_far = current

        now = time.time()
        info = ' - %.0fs' % (now - self._start)
        if self.verbose == 1:
            if (now - self._last_update < self.interval and
                    self.target is not None and current < self.target):
                return

            prev_total_width = self._total_width
            if self._dynamic_display:
                sys.stdout.write('\b' * prev_total_width)
                sys.stdout.write('\r')
            else:
                sys.stdout.write('\n')

            if self.target is not None:
                numdigits = int(np.floor(np.log10(self.target))) + 1
                barstr = '%%%dd/%d [' % (numdigits, self.target)
                bar = barstr % current
                prog = float(current) / self.target
                prog_width = int(self.width * prog)
                if prog_width > 0:
                    bar += ('=' * (prog_width - 1))
                    if current < self.target:
                        bar += '>'
                    else:
                        bar += '='
                bar += ('.' * (self.width - prog_width))
                bar += ']'
            else:
                bar = '%7d/Unknown' % current

            self._total_width = len(bar)
            sys.stdout.write(bar)

            if current:
                time_per_unit = (now - self._start) / current
            else:
                time_per_unit = 0
            if self.target is not None and current < self.target:
                eta = time_per_unit * (self.target - current)
                if eta > 3600:
                    eta_format = '%d:%02d:%02d' % (eta // 3600, (eta % 3600) // 60, eta % 60)
                elif eta > 60:
                    eta_format = '%d:%02d' % (eta // 60, eta % 60)
                else:
                    eta_format = '%ds' % eta

                info = ' - ETA: %s' % eta_format
            else:
                if time_per_unit >= 1:
                    info += ' %.0fs/step' % time_per_unit
                elif time_per_unit >= 1e-3:
                    info += ' %.0fms/step' % (time_per_unit * 1e3)
                else:
                    info += ' %.0fus/step' % (time_per_unit * 1e6)

            for k in self._values:
                info += ' - %s:' % k
                if isinstance(self._values[k], list):
                    avg = np.mean(
                        self._values[k][0] / max(1, self._values[k][1]))
                    if abs(avg) > 1e-3:
                        info += ' %.4f' % avg
                    else:
                        info += ' %.4e' % avg
                else:
                    info += ' %s' % self._values[k]

            self._total_width += len(info)
            if prev_total_width > self._total_width:
                info += (' ' * (prev_total_width - self._total_width))

            if self.target is not None and current >= self.target:
                info += '\n'

            sys.stdout.write(info)
            sys.stdout.flush()

        elif self.verbose == 2:
            if self.target is None or current >= self.target:
                for k in self._values:
                    info += ' - %s:' % k
                    avg = np.mean(
                        self._values[k][0] / max(1, self._values[k][1]))
                    if avg > 1e-3:
                        info += ' %.4f' % avg
                    else:
                        info += ' %.4e' % avg
                info += '\n'

                sys.stdout.write(info)
                sys.stdout.flush()

        self._last_update = now

    def add(self, n, values=None):
        self.update(self._seen_so_far + n, values)