# Copyright (C) 2017 Damon Lynch <damonlynch@gmail.com>

# This file is part of Rapid Photo Downloader.
#
# Rapid Photo Downloader 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.
#
# Rapid Photo Downloader 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 Rapid Photo Downloader.  If not,
# see <http://www.gnu.org/licenses/>.

"""
Widgets and program logic to check for new program versions and
to download them.
"""

__author__ = 'Damon Lynch'
__copyright__ = "Copyright 2017, Damon Lynch"

import logging
import pkg_resources
from collections import namedtuple
import shlex
import hashlib
import os
import traceback
import shutil
import sys
import subprocess
from typing import Optional

from gettext import gettext as _
import requests

import arrow
from PyQt5.QtCore import (QObject, pyqtSignal, pyqtSlot, Qt)
from PyQt5.QtWidgets import (QDialog, QLabel, QStackedWidget, QDialogButtonBox, QGridLayout,
                             QPushButton, QProgressBar)
import zmq

from raphodo.constants import (remote_versions_file, CheckNewVersionDialogState,
                               CheckNewVersionDialogResult, standardProgressBarWidth)
from raphodo.utilities import (create_temp_dir, format_size_for_user)
from raphodo.interprocess import ThreadNames

version_details = namedtuple('version_details', 'version release_date url md5 changelog_url')

class NewVersion(QObject):
    """
    Check for and download a new version of the program.

    Runs in its own thread.
    """

    checkMade = pyqtSignal(bool, version_details, version_details, str, bool, bool)
    # See http://pyqt.sourceforge.net/Docs/PyQt5/signals_slots.html#the-pyqt-pyobject-
    # signal-argument-type
    bytesDownloaded = pyqtSignal('PyQt_PyObject')  # don't convert python int to C++ int
    downloadSize = pyqtSignal('PyQt_PyObject')  # don't convert python int to C++ int
    # if not empty, file downloaded okay and saved to this temp directory
    # if empty, file failed to download and verify
    fileDownloaded = pyqtSignal(str, bool)
    # signal True if downloaded tar passed md5sum check, else signal False
    # also include path to tar
    reverified = pyqtSignal(bool, str)

    def __init__(self, rapidApp):
        super().__init__()
        self.rapidApp = rapidApp
        self.rapidApp.checkForNewVersionRequest.connect(self.check)
        self.rapidApp.downloadNewVersionRequest.connect(self.download)
        self.installed_via_pip_check_made = False
        self.installed_via_pip = None  # type: bool

    @pyqtSlot()
    def start(self) -> None:
        context = zmq.Context.instance()
        self.thread_controller = context.socket(zmq.PAIR)
        self.thread_controller.connect('inproc://{}'.format(ThreadNames.new_version))

    def installedUsingPip(self, package='rapid-photo-downloader') -> bool:
        """
        Determine if python package was installed using pip.

        Exceptions are not caught.

        Calling pip directly as python code and redirecting stdout
        totally messes up debugging output, even when using a context
        manager. So don't do that!

        :param package: package name to search for
        :return: True if installed via pip, else False
        """

        command_line = '{} -m pip show --verbose {}'.format(sys.executable, package)
        args = shlex.split(command_line)
        try:
            pip_output = subprocess.check_output(args)
        except subprocess.SubprocessError:
            return False
        return pip_output.decode().find('Installer: pip') >= 0

    @pyqtSlot()
    def check(self) -> None:
        success = False
        dev_version = version_details('', '', '', '', '')
        stable_version = version_details('', '', '', '', '')
        download_page = ''
        no_upgrade = True
        try:
            r = requests.get(remote_versions_file)
        except:
            logging.debug("Failed to download versions file %s", remote_versions_file)
        else:
            status_code = r.status_code
            success = status_code == 200
            if not success:
                logging.debug("Got error code %d while accessing versions file", self.status_code)
                self._reset_values()
                self.status_code = r.status_code
            else:
                try:
                    self.version = r.json()
                except:
                    logging.error("Error accessing versions JSON file", self.status_code)
                    success = False
                    self._reset_values()
                    self.status_code = r.status_code
                else:
                    stable = self.version['stable']
                    dev = self.version['dev']
                    dev_version = version_details(
                        version=pkg_resources.parse_version(dev['version']),
                        release_date=arrow.get(dev['date']).to('local'),
                        url=dev['url'],
                        md5=dev['md5'],
                        changelog_url=dev['changelog']
                    )
                    stable_version = version_details(
                        version=pkg_resources.parse_version(stable['version']),
                        release_date=arrow.get(stable['date']).to('local'),
                        url=stable['url'],
                        md5 =stable['md5'],
                        changelog_url=stable['changelog']
                    )
                    download_page = self.version['download_page']
                    no_upgrade = self.version['no_upgrade']

        if not self.installed_via_pip_check_made:
            try:
                self.installed_via_pip = self.installedUsingPip()
            except Exception:
                logging.warning("Exception encountered when checking if pip was used to "
                                "install")
                self.installed_via_pip = False

        self.checkMade.emit(success, stable_version, dev_version, download_page, no_upgrade,
                            self.installed_via_pip)

    def verifyDownload(self, downloaded_tar: str, md5_url: str) -> bool:
        """
        Verifies downloaded tarball against the launchpad generated md5sum file.

        Exceptions not caught.

        :param downloaded_tar: local file
        :param md5_url: remote md5sum file for the download
        :return: True if md5sum matches, False otherwise,
        """

        if not md5_url:
            return True

        r = requests.get(md5_url)
        assert r.status_code == 200
        self.remote_md5 = r.text.split()[0]
        with open(downloaded_tar, 'rb') as tar:
            m = hashlib.md5()
            m.update(tar.read())
        return m.hexdigest() == self.remote_md5

    @pyqtSlot(str)
    def reVerifyDownload(self, downloaded_tar: str) -> None:
        """
        Reverify a tar that has been downloaded.

        Emits signal reverified.

        All exceptions caught and logged.

        :param downloaded_tar: file to verify
        """
        try:
            with open(downloaded_tar, 'rb') as tar:
                m = hashlib.md5()
                m.update(tar.read())
            self.reverified.emit(m.hexdigest() == self.remote_md5, downloaded_tar)
        except (FileNotFoundError, OSError):
            logging.exception("Could not open tarfile %s for hash reverification", downloaded_tar)
            self.reverified.emit(False, '')
        except Exception:
            logging.exception("Unknown exception when doing hash reverification of tarfile %s",
                          downloaded_tar)
            self.reverified.emit(False, '')

    def checkForCmd(self) -> Optional[bytes]:
        try:
            return self.thread_controller.recv(zmq.DONTWAIT)
        except zmq.Again:
            return None

    def handleDownloadNotCompleted(self, temp_dir: str, cancelled: bool=False) -> None:
        """
        Cleanup download file and signal we're done
        :param temp_dir: the directory into which the file was downloaded
        :param cancelled: if True, the user cancelled the download
        """

        # Delete the temporary directory and any file in it
        shutil.rmtree(temp_dir, ignore_errors=True)
        self.fileDownloaded.emit('', cancelled)

    @pyqtSlot(str, str)
    def download(self, tarball_url: str, md5_url: str):
        """
        Downloads tarball from website e.g. Launchpad

        Deletes temp dir if download failed.

        Emits:
         - download size
         - bytes downloaded
         - filename if successful, blank filename if not

        :param tarball_url: tarball to download
        :param md5_url: md5sum of the download. If empty or None,
         will not do md5sum check for the download.
        """

        temp_dir = create_temp_dir()
        if temp_dir is not None:
            try:
                r = requests.get(tarball_url, stream=True)
                assert r.status_code == 200
                local_file = os.path.join(temp_dir, tarball_url.split('/')[-1])
                chunk_size = 1024
                bytes_downloaded = 0
                total_size = int(r.headers['content-length'])
                self.downloadSize.emit(total_size)
                terminated = False
                with open(local_file, 'wb') as f:
                    for chunk in r.iter_content(chunk_size=chunk_size):
                        cmd = self.checkForCmd()
                        if cmd is None:
                            if chunk: # filter out keep-alive new chunks
                                f.write(chunk)
                                bytes_downloaded += chunk_size
                                self.bytesDownloaded.emit(min(total_size, bytes_downloaded))
                        else:
                            assert cmd == b'STOP'
                            terminated = True
                            break
                if terminated:
                    self.handleDownloadNotCompleted(temp_dir=temp_dir, cancelled=True)
                else:
                    try:
                        if self.verifyDownload(local_file, md5_url):
                            self.fileDownloaded.emit(local_file, False)
                        else:
                            self.handleDownloadNotCompleted(temp_dir=temp_dir)
                    except Exception:
                        self.handleDownloadNotCompleted(temp_dir=temp_dir)

            except Exception as e:
                logging.exception("Failed to download %s", tarball_url)
                self.handleDownloadNotCompleted(temp_dir=temp_dir)


class NewVersionCheckDialog(QDialog):
    """
    Dialog that shows to the user that the program is either checking for a new version
    or the results of such a check. The idea is to not create a temporary dialog to show
    it is checking and then another to show the results.

    As such, it has different states.  Each state is associated with different buttons and
    a different message.
    """

    def __init__(self, parent) -> None:
        super().__init__(parent)
        self.rapidApp = parent # type: 'RapidWindow'

        self.setModal(True)
        self.setSizeGripEnabled(False)

        self.dialog_detailed_result = None
        self.current_state = CheckNewVersionDialogState.check

        self.checkingLabel = QLabel(_('Checking for new version...'))
        self.noNewVersion = QLabel(_('You are running the latest version.'))
        self.failedToCheck = QLabel(_('Failed to contact the update server.'))
        self.url = "http://www.damonlynch.net/rapid/download.html"
        self.new_version_message = _('A new version of Rapid Photo Downloader (%s) is available.')
        self.new_version_message = '<b>{}</b>'.format(self.new_version_message)
        self.download_it = _('Do you want to download the new version?') + '<br>'
        self.changelog_msg = _('Changes in the new release can be viewed <a href="%s">here</a>.')

        for label in (self.checkingLabel, self.noNewVersion, self.failedToCheck):
            label.setAlignment(Qt.AlignLeft|Qt.AlignTop)

        self.newVersion = QLabel(
            self._makeDownloadMsg(
                '1.2.3a10', offer_download=True, changelog_url=''
            )
        )
        self.newVersion.setOpenExternalLinks(True)

        self.changelog = QLabel(self.changelog_msg)
        self.changelog.setOpenExternalLinks(True)

        self.messages = QStackedWidget()
        self.messages.addWidget(self.checkingLabel)
        self.messages.addWidget(self.noNewVersion)
        self.messages.addWidget(self.newVersion)
        self.messages.addWidget(self.failedToCheck)

        cancelBox = QDialogButtonBox(QDialogButtonBox.Cancel)
        cancelBox.rejected.connect(self.reject)

        self.downloadItBox = QDialogButtonBox(QDialogButtonBox.Yes | QDialogButtonBox.No)
        # Translators: this text appears in a button - the & sets the s key in combination with
        # the alt key to act as the keyboard shortcut
        self.dlItSkipButton = QPushButton(_('&Skip this release'))
        self.dlItSkipButton.setDefault(False)
        self.downloadItBox.addButton(self.dlItSkipButton, QDialogButtonBox.RejectRole)
        self.dlItYesButton = self.downloadItBox.button(QDialogButtonBox.Yes)  # type: QPushButton
        self.dlItNoButton = self.downloadItBox.button(QDialogButtonBox.No)  # type: QPushButton
        self.downloadItBox.clicked.connect(self.downloadItClicked)

        closeBox = QDialogButtonBox(QDialogButtonBox.Close)
        closeBox.rejected.connect(self.reject)

        openDownloadPageBox = QDialogButtonBox(QDialogButtonBox.Close)
        # Translators: this text appears in a button - the & sets the s key in combination with
        # the alt key to act as the keyboard shortcut
        self.openDlPageSkipButton = QPushButton(_('&Skip this release'))
        # Translators: this text appears in a button - the & sets the o key in combination with
        # the alt key to act as the keyboard shortcut
        self.openDlPageButton = QPushButton(_('&Open Download Page'))
        self.openDlPageButton.setDefault(True)
        openDownloadPageBox.addButton(self.openDlPageSkipButton, QDialogButtonBox.RejectRole)
        openDownloadPageBox.addButton(self.openDlPageButton, QDialogButtonBox.ActionRole)
        self.openDlCloseButton = openDownloadPageBox.button(QDialogButtonBox.Close)
        openDownloadPageBox.clicked.connect(self.openWebsiteClicked)

        self.buttons = QStackedWidget()
        self.buttons.addWidget(cancelBox)
        self.buttons.addWidget(closeBox)
        self.buttons.addWidget(self.downloadItBox)
        self.buttons.addWidget(openDownloadPageBox)

        self.messages.setCurrentIndex(0)
        self.buttons.setCurrentIndex(0)

        grid = QGridLayout()
        grid.addWidget(self.messages, 0, 0, 1, 2, Qt.AlignTop)
        grid.addWidget(self.buttons, 1, 0, 1, 2)
        self.setLayout(grid)
        self.setWindowTitle(_('Rapid Photo Downloader updates'))

    def _makeDownloadMsg(self, new_version_number: str,
                         offer_download: bool,
                         changelog_url: str) -> str:
        s1 = self.new_version_message % new_version_number
        s2 = self.changelog_msg % changelog_url
        s = '{}<br><br>{}'.format(s1, s2)
        if offer_download:
            return '<br><br>'.join((s, self.download_it))
        else:
            return s

    def displayUserMessage(self, new_state: CheckNewVersionDialogState,
                           version: Optional[str]=None,
                           download_page: Optional[str]=None,
                           changelog_url: Optional[str]=None) -> None:

        self.current_state = new_state

        if new_state == CheckNewVersionDialogState.check:
            self.messages.setCurrentIndex(0)
            self.buttons.setCurrentIndex(0)
        elif new_state == CheckNewVersionDialogState.failed_to_contact:
            self.messages.setCurrentIndex(3)
            self.buttons.setCurrentIndex(1)
        elif new_state == CheckNewVersionDialogState.have_latest_version:
            self.messages.setCurrentIndex(1)
            self.buttons.setCurrentIndex(1)
        else:
            assert new_state in (CheckNewVersionDialogState.open_website,
                                 CheckNewVersionDialogState.prompt_for_download)
            assert version is not None
            assert changelog_url is not None
            self.new_version_number = version
            self.url = download_page
            offer_download = new_state == CheckNewVersionDialogState.prompt_for_download
            self.newVersion.setText(
                self._makeDownloadMsg(
                    version, offer_download=offer_download, changelog_url=changelog_url
                )
            )
            self.messages.setCurrentIndex(2)
            if offer_download:
                self.buttons.setCurrentIndex(2)
                yesButton = self.downloadItBox.button(QDialogButtonBox.Yes)  # type: QPushButton
                yesButton.setDefault(True)

            else:
                self.buttons.setCurrentIndex(3)

    def reset(self) -> None:
        """
        Reset appearance to default checking...
        """
        self.current_state = CheckNewVersionDialogState.check
        self.messages.setCurrentIndex(0)
        self.buttons.setCurrentIndex(0)

    def downloadItClicked(self, button) -> None:
        if button == self.dlItYesButton:
            self.setResult(QDialog.Accepted)
            self.dialog_detailed_result = CheckNewVersionDialogResult.download
            super().accept()
        elif button == self.dlItNoButton:
            self.setResult(QDialog.Rejected)
            self.dialog_detailed_result = CheckNewVersionDialogResult.do_not_download
            super().reject()
        else:
            assert button == self.dlItSkipButton
            self.setResult(QDialog.Rejected)
            self.dialog_detailed_result = CheckNewVersionDialogResult.skip
            super().reject()

    def openWebsiteClicked(self, button) -> None:
        if button == self.openDlPageButton:
            self.setResult(QDialog.Accepted)
            self.dialog_detailed_result = CheckNewVersionDialogResult.open_website
            super().accept()
        elif button == self.openDlCloseButton:
            self.setResult(QDialog.Rejected)
            self.dialog_detailed_result = CheckNewVersionDialogResult.do_not_download
            super().reject()
        else:
            assert button == self.openDlPageSkipButton
            self.setResult(QDialog.Rejected)
            self.dialog_detailed_result = CheckNewVersionDialogResult.skip
            super().reject()


class DownloadNewVersionDialog(QDialog):
    def __init__(self, parent=None, bytes_downloaded: int=0, download_size: int=0) -> None:
        super().__init__(parent)
        self.rapidApp = parent # type: 'RapidWindow'

        self.setModal(True)
        self.setSizeGripEnabled(False)

        self.download_size_display = format_size_for_user(download_size, zero_string='0 KB')
        bytes_downloaded_display = format_size_for_user(bytes_downloaded, zero_string='0 KB')

        # Translators: shows how much of a file has been downloaded e.g  123 KB of 1.3 MB
        self.text = _('%(downloaded)s of %(total)s')
        self.message = QLabel(self.text % dict(downloaded=bytes_downloaded_display,
                                               total=self.download_size_display))

        self.progressBar = QProgressBar()
        self.progressBar.setMinimumWidth(standardProgressBarWidth())
        self.progressBar.setMaximum(download_size)
        self.progressBar.setValue(bytes_downloaded)

        buttonBox = QDialogButtonBox(QDialogButtonBox.Cancel)
        buttonBox.rejected.connect(self.reject)

        grid = QGridLayout()
        grid.addWidget(self.message, 0, 0, 1, 2)
        grid.addWidget(self.progressBar, 1, 0, 1, 2)
        grid.addWidget(buttonBox, 2, 0, 1, 2)
        self.setLayout(grid)
        self.setWindowTitle(_('Downloading...'))

    def updateProgress(self, bytes_downloaded: int) -> None:
        bytes_downloaded_display = format_size_for_user(bytes_downloaded, zero_string='0 KB')
        self.message.setText(self.text % dict(downloaded=bytes_downloaded_display,
                                               total=self.download_size_display))
        self.progressBar.setValue(bytes_downloaded)

    def setDownloadSize(self, download_size: int) -> None:
        self.download_size_display = format_size_for_user(download_size, zero_string='0 KB')
        self.progressBar.setMaximum(download_size)