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

# Copyright 2014-2017 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/>.

"""Things which need to be done really early (e.g. before importing Qt).

At this point we can be sure we have all python 3.5 features available.
"""

try:
    # Importing hunter to register its atexit handler early so it gets called
    # late.
    import hunter  # pylint: disable=unused-import
except ImportError:
    hunter = None

import sys
import faulthandler
import traceback
import signal
import importlib
import datetime
try:
    import tkinter
except ImportError:
    tkinter = None

# NOTE: No qutebrowser or PyQt import should be done here, as some early
# initialization needs to take place before that!


START_TIME = datetime.datetime.now()


def _missing_str(name, *, webengine=False):
    """Get an error string for missing packages.

    Args:
        name: The name of the package.
        webengine: Whether this is checking the QtWebEngine package
    """
    blocks = ["Fatal error: <b>{}</b> is required to run qutebrowser but "
              "could not be imported! Maybe it's not installed?".format(name),
              "<b>The error encountered was:</b><br />%ERROR%"]
    lines = ['Please search for the python3 version of {} in your '
             'distributions packages, or see '
             'https://github.com/qutebrowser/qutebrowser/blob/master/doc/install.asciidoc'
             .format(name)]
    blocks.append('<br />'.join(lines))
    if not webengine:
        lines = ['<b>If you installed a qutebrowser package for your '
                 'distribution, please report this as a bug.</b>']
        blocks.append('<br />'.join(lines))
    return '<br /><br />'.join(blocks)


def _die(message, exception=None):
    """Display an error message using Qt and quit.

    We import the imports here as we want to do other stuff before the imports.

    Args:
        message: The message to display.
        exception: The exception object if we're handling an exception.
    """
    from PyQt5.QtWidgets import QApplication, QMessageBox
    from PyQt5.QtCore import Qt
    if (('--debug' in sys.argv or '--no-err-windows' in sys.argv) and
            exception is not None):
        print(file=sys.stderr)
        traceback.print_exc()
    app = QApplication(sys.argv)
    if '--no-err-windows' in sys.argv:
        print(message, file=sys.stderr)
        print("Exiting because of --no-err-windows.", file=sys.stderr)
    else:
        if exception is not None:
            message = message.replace('%ERROR%', str(exception))
        msgbox = QMessageBox(QMessageBox.Critical, "qutebrowser: Fatal error!",
                             message)
        msgbox.setTextFormat(Qt.RichText)
        msgbox.resize(msgbox.sizeHint())
        msgbox.exec_()
    app.quit()
    sys.exit(1)


def init_faulthandler(fileobj=sys.__stderr__):
    """Enable faulthandler module if available.

    This print a nice traceback on segfaults.

    We use sys.__stderr__ instead of sys.stderr here so this will still work
    when sys.stderr got replaced, e.g. by "Python Tools for Visual Studio".

    Args:
        fobj: An opened file object to write the traceback to.
    """
    if fileobj is None:
        # When run with pythonw.exe, sys.__stderr__ can be None:
        # https://docs.python.org/3/library/sys.html#sys.__stderr__
        # If we'd enable faulthandler in that case, we just get a weird
        # exception, so we don't enable faulthandler if we have no stdout.
        #
        # Later when we have our data dir available we re-enable faulthandler
        # to write to a file so we can display a crash to the user at the next
        # start.
        return
    faulthandler.enable(fileobj)
    if (hasattr(faulthandler, 'register') and hasattr(signal, 'SIGUSR1') and
            sys.stderr is not None):
        # If available, we also want a traceback on SIGUSR1.
        # pylint: disable=no-member,useless-suppression
        faulthandler.register(signal.SIGUSR1)


def check_pyqt_core():
    """Check if PyQt core is installed."""
    try:
        import PyQt5.QtCore  # pylint: disable=unused-variable
    except ImportError as e:
        text = _missing_str('PyQt5')
        text = text.replace('<b>', '')
        text = text.replace('</b>', '')
        text = text.replace('<br />', '\n')
        text = text.replace('%ERROR%', str(e))
        if tkinter and '--no-err-windows' not in sys.argv:
            root = tkinter.Tk()
            root.withdraw()
            tkinter.messagebox.showerror("qutebrowser: Fatal error!", text)
        else:
            print(text, file=sys.stderr)
        if '--debug' in sys.argv or '--no-err-windows' in sys.argv:
            print(file=sys.stderr)
            traceback.print_exc()
        sys.exit(1)


def qt_version(qversion=None, qt_version_str=None):
    """Get a Qt version string based on the runtime/compiled versions."""
    if qversion is None:
        from PyQt5.QtCore import qVersion
        qversion = qVersion()
    if qt_version_str is None:
        from PyQt5.QtCore import QT_VERSION_STR
        qt_version_str = QT_VERSION_STR

    if qversion != qt_version_str:
        return '{} (compiled {})'.format(qversion, qt_version_str)
    else:
        return qversion


def check_qt_version():
    """Check if the Qt version is recent enough."""
    from PyQt5.QtCore import (qVersion, QT_VERSION, PYQT_VERSION,
                              PYQT_VERSION_STR)
    from pkg_resources import parse_version
    if (QT_VERSION < 0x050701 or PYQT_VERSION < 0x050700 or
            parse_version(qVersion()) < parse_version('5.7.1')):
        text = ("Fatal error: Qt >= 5.7.1 and PyQt >= 5.7 are required, "
                "but Qt {} / PyQt {} is installed.".format(qt_version(),
                                                           PYQT_VERSION_STR))
        _die(text)


def check_ssl_support():
    """Check if SSL support is available."""
    # pylint: disable=unused-variable
    try:
        from PyQt5.QtNetwork import QSslSocket
    except ImportError:
        _die("Fatal error: Your Qt is built without SSL support.")


def _check_modules(modules):
    """Make sure the given modules are available."""
    from qutebrowser.utils import log

    for name, text in modules.items():
        try:
            # https://github.com/pallets/jinja/pull/628
            # https://bitbucket.org/birkenfeld/pygments-main/issues/1314/
            # https://github.com/pallets/jinja/issues/646
            # https://bitbucket.org/fdik/pypeg/commits/dd15ca462b532019c0a3be1d39b8ee2f3fa32f4e
            messages = ['invalid escape sequence',
                        'Flags not at the start of the expression']
            with log.ignore_py_warnings(
                    category=DeprecationWarning,
                    message=r'({})'.format('|'.join(messages))
            ), log.ignore_py_warnings(
                    category=PendingDeprecationWarning,
                    module='imp'
            ), log.ignore_py_warnings(
                    category=ImportWarning,
                    message=r'Not importing directory .*: missing __init__'
            ):
                importlib.import_module(name)
        except ImportError as e:
            _die(text, e)


def check_libraries():
    """Check if all needed Python libraries are installed."""
    modules = {
        'pkg_resources': _missing_str("pkg_resources/setuptools"),
        'pypeg2': _missing_str("pypeg2"),
        'jinja2': _missing_str("jinja2"),
        'pygments': _missing_str("pygments"),
        'yaml': _missing_str("PyYAML"),
        'attr': _missing_str("attrs"),
        'PyQt5.QtQml': _missing_str("PyQt5.QtQml"),
        'PyQt5.QtSql': _missing_str("PyQt5.QtSql"),
        'PyQt5.QtOpenGL': _missing_str("PyQt5.QtOpenGL"),
    }
    _check_modules(modules)


def configure_pyqt():
    """Remove the PyQt input hook and enable overflow checking.

    Doing this means we can't use the interactive shell anymore (which we don't
    anyways), but we can use pdb instead.
    """
    from PyQt5.QtCore import pyqtRemoveInputHook
    pyqtRemoveInputHook()

    import sip
    try:
        # Added in sip 4.19.4
        sip.enableoverflowchecking(True)
    except AttributeError:
        pass


def init_log(args):
    """Initialize logging.

    Args:
        args: The argparse namespace.
    """
    from qutebrowser.utils import log
    log.init_log(args)
    log.init.debug("Log initialized.")


def check_optimize_flag():
    from qutebrowser.utils import log
    if sys.flags.optimize >= 2:
        log.init.warning("Running on optimize level higher than 1, "
                         "unexpected behavior may occur.")


def early_init(args):
    """Do all needed early initialization.

    Note that it's vital the other earlyinit functions get called in the right
    order!

    Args:
        args: The argparse namespace.
    """
    # First we initialize the faulthandler as early as possible, so we
    # theoretically could catch segfaults occurring later during earlyinit.
    init_faulthandler()
    # Here we check if QtCore is available, and if not, print a message to the
    # console or via Tk.
    check_pyqt_core()
    # Init logging as early as possible
    init_log(args)
    # Now we can be sure QtCore is available, so we can print dialogs on
    # errors, so people only using the GUI notice them as well.
    check_libraries()
    check_qt_version()
    configure_pyqt()
    check_ssl_support()
    check_optimize_flag()
