# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:

# Copyright 2014-2016 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
#
# This file is part of qutebrowser.
#
# qutebrowser is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# qutebrowser is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.

"""Utilities used for debugging."""

import re
import inspect
import logging
import functools
import datetime

from PyQt5.QtCore import Qt, QEvent, QMetaMethod, QObject
from PyQt5.QtWidgets import QApplication

from qutebrowser.utils import log, utils, qtutils, objreg


def log_events(klass):
    """Class decorator to log Qt events."""
    old_event = klass.event

    @functools.wraps(old_event)
    def new_event(self, e, *args, **kwargs):
        """Wrapper for event() which logs events."""
        log.misc.debug("Event in {}: {}".format(utils.qualname(klass),
                                                qenum_key(QEvent, e.type())))
        return old_event(self, e, *args, **kwargs)

    klass.event = new_event
    return klass


def log_signals(obj):
    """Log all signals of an object or class.

    Can be used as class decorator.
    """
    def log_slot(obj, signal, *args):
        """Slot connected to a signal to log it."""
        dbg = dbg_signal(signal, args)
        try:
            r = repr(obj)
        except RuntimeError:  # pragma: no cover
            r = '<deleted>'
        log.signals.debug("Signal in {}: {}".format(r, dbg))

    def connect_log_slot(obj):
        """Helper function to connect all signals to a logging slot."""
        metaobj = obj.metaObject()
        for i in range(metaobj.methodCount()):
            meta_method = metaobj.method(i)
            qtutils.ensure_valid(meta_method)
            if meta_method.methodType() == QMetaMethod.Signal:
                name = bytes(meta_method.name()).decode('ascii')
                if name != 'destroyed':
                    signal = getattr(obj, name)
                    signal.connect(functools.partial(log_slot, obj, signal))

    if inspect.isclass(obj):
        old_init = obj.__init__

        @functools.wraps(old_init)
        def new_init(self, *args, **kwargs):
            """Wrapper for __init__() which logs signals."""
            ret = old_init(self, *args, **kwargs)
            connect_log_slot(self)
            return ret

        obj.__init__ = new_init
        return obj
    else:
        connect_log_slot(obj)


def qenum_key(base, value, add_base=False, klass=None):
    """Convert a Qt Enum value to its key as a string.

    Args:
        base: The object the enum is in, e.g. QFrame.
        value: The value to get.
        add_base: Whether the base should be added to the printed name.
        klass: The enum class the value belongs to.
               If None, the class will be auto-guessed.

    Return:
        The key associated with the value as a string if it could be found.
        The original value as a string if not.
    """
    if klass is None:
        klass = value.__class__
        if klass == int:
            raise TypeError("Can't guess enum class of an int!")

    try:
        idx = base.staticMetaObject.indexOfEnumerator(klass.__name__)
        ret = base.staticMetaObject.enumerator(idx).valueToKey(value)
    except AttributeError:
        ret = None

    if ret is None:
        for name, obj in vars(base).items():
            if isinstance(obj, klass) and obj == value:
                ret = name
                break
        else:
            ret = '0x{:04x}'.format(int(value))

    if add_base and hasattr(base, '__name__'):
        return '.'.join([base.__name__, ret])
    else:
        return ret


def qflags_key(base, value, add_base=False, klass=None):
    """Convert a Qt QFlags value to its keys as string.

    Note: Passing a combined value (such as Qt.AlignCenter) will get the names
    for the individual bits (e.g. Qt.AlignVCenter | Qt.AlignHCenter). FIXME

    https://github.com/The-Compiler/qutebrowser/issues/42

    Args:
        base: The object the flags are in, e.g. QtCore.Qt
        value: The value to get.
        add_base: Whether the base should be added to the printed names.
        klass: The flags class the value belongs to.
               If None, the class will be auto-guessed.

    Return:
        The keys associated with the flags as a '|' separated string if they
        could be found. Hex values as a string if not.
    """
    if klass is None:
        # We have to store klass here because it will be lost when iterating
        # over the bits.
        klass = value.__class__
        if klass == int:
            raise TypeError("Can't guess enum class of an int!")
    bits = []
    names = []
    mask = 0x01
    value = int(value)
    while mask <= value:
        if value & mask:
            bits.append(mask)
        mask <<= 1
    for bit in bits:
        # We have to re-convert to an enum type here or we'll sometimes get an
        # empty string back.
        names.append(qenum_key(base, klass(bit), add_base))
    return '|'.join(names)


def signal_name(sig):
    """Get a cleaned up name of a signal.

    Args:
        sig: The pyqtSignal

    Return:
        The cleaned up signal name.
    """
    m = re.match(r'[0-9]+(.*)\(.*\)', sig.signal)
    return m.group(1)


def format_args(args=None, kwargs=None):
    """Format a list of arguments/kwargs to a function-call like string."""
    if args is not None:
        arglist = [utils.compact_text(repr(arg), 200) for arg in args]
    else:
        arglist = []
    if kwargs is not None:
        for k, v in kwargs.items():
            arglist.append('{}={}'.format(k, utils.compact_text(repr(v), 200)))
    return ', '.join(arglist)


def dbg_signal(sig, args):
    """Get a string representation of a signal for debugging.

    Args:
        sig: A pyqtSignal.
        args: The arguments as list of strings.

    Return:
        A human-readable string representation of signal/args.
    """
    return '{}({})'.format(signal_name(sig), format_args(args))


def format_call(func, args=None, kwargs=None, full=True):
    """Get a string representation of a function calls with the given args.

    Args:
        func: The callable to print.
        args: A list of positional arguments.
        kwargs: A dict of named arguments.
        full: Whether to print the full name

    Return:
        A string with the function call.
    """
    if full:
        name = utils.qualname(func)
    else:
        name = func.__name__
    return '{}({})'.format(name, format_args(args, kwargs))


class log_time:  # pylint: disable=invalid-name

    """Log the time an operation takes.

    Usable as context manager or as decorator.
    """

    def __init__(self, logger, action='operation'):
        """Constructor.

        Args:
            logger: The logging.Logger to use for logging, or a logger name.
            action: A description of what's being done.
        """
        if isinstance(logger, str):
            self._logger = logging.getLogger(logger)
        else:
            self._logger = logger
        self._started = None
        self._action = action

    def __enter__(self):
        self._started = datetime.datetime.now()

    def __exit__(self, _exc_type, _exc_val, _exc_tb):
        assert self._started is not None
        finished = datetime.datetime.now()
        delta = (finished - self._started).total_seconds()
        self._logger.debug("{} took {} seconds.".format(
            self._action.capitalize(), delta))

    def __call__(self, func):
        @functools.wraps(func)
        def wrapped(*args, **kwargs):
            with self:
                func(*args, **kwargs)

        return wrapped


def _get_widgets():
    """Get a string list of all widgets."""
    widgets = QApplication.instance().allWidgets()
    widgets.sort(key=repr)
    return [repr(w) for w in widgets]


def _get_pyqt_objects(lines, obj, depth=0):
    """Recursive method for get_all_objects to get Qt objects."""
    for kid in obj.findChildren(QObject, '', Qt.FindDirectChildrenOnly):
        lines.append('    ' * depth + repr(kid))
        _get_pyqt_objects(lines, kid, depth + 1)


def get_all_objects(start_obj=None):
    """Get all children of an object recursively as a string."""
    output = ['']
    widget_lines = _get_widgets()
    widget_lines = ['    ' + e for e in widget_lines]
    widget_lines.insert(0, "Qt widgets - {} objects:".format(
        len(widget_lines)))
    output += widget_lines

    if start_obj is None:
        start_obj = QApplication.instance()

    pyqt_lines = []
    _get_pyqt_objects(pyqt_lines, start_obj)
    pyqt_lines = ['    ' + e for e in pyqt_lines]
    pyqt_lines.insert(0, 'Qt objects - {} objects:'.format(len(pyqt_lines)))

    output += ['']
    output += pyqt_lines
    output += objreg.dump_objects()
    return '\n'.join(output)
