# -*- coding: utf-8 -*-
#
# Project:     weechat-notify-send
# Homepage:    https://github.com/s3rvac/weechat-notify-send
# Description: Sends highlight and message notifications through notify-send.
#              Requires libnotify.
# License:     MIT (see below)
#
# Copyright (c) 2015-2016 by Petr Zemek <s3rvac@gmail.com> and contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# 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
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# 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.
#

import os
import subprocess
import sys
import time


# Ensure that we are running under WeeChat.
try:
    import weechat
except ImportError:
    print('This script has to run under WeeChat (https://weechat.org/).')
    sys.exit(1)


# Name of the script.
SCRIPT_NAME = 'notify_send'

# Author of the script.
SCRIPT_AUTHOR = 's3rvac'

# Version of the script.
SCRIPT_VERSION = '0.7 (dev)'

# License under which the script is distributed.
SCRIPT_LICENSE = 'MIT'

# Description of the script.
SCRIPT_DESC = 'Sends highlight and message notifications through notify-send.'

# Name of a function to be called when the script is unloaded.
SCRIPT_SHUTDOWN_FUNC = ''

# Used character set (utf-8 by default).
SCRIPT_CHARSET = ''

# Script options.
OPTIONS = {
    'notify_on_highlights': (
        'on',
        'Send notifications on highlights.'
    ),
    'notify_on_privmsgs': (
        'on',
        'Send notifications on private messages.'
    ),
    'notify_on_filtered_messages': (
        'off',
        'Send notifications also on filtered (hidden) messages.'
    ),
    'notify_when_away': (
        'on',
        'Send also notifications when away.'
    ),
    'notify_for_current_buffer': (
        'on',
        'Send also notifications for the currently active buffer.'
    ),
    'notify_on_all_messages_in_buffers': (
        '',
        'A comma-separated list of buffers for which you want to receive '
        'notifications on all messages that appear in them.'
    ),
    'min_notification_delay': (
        '500',
        'A minimal delay between successive notifications from the same '
        'buffer (in milliseconds; set to 0 to show all notifications).'
    ),
    'ignore_messages_tagged_with': (
        # irc_join:      Joined IRC
        # irc_quit:      Quit IRC
        # irc_part:      Parted a channel
        # irc_status:    Status messages
        # irc_nick_back: A nick is back on server
        # irc_401:       No such nick/channel
        # irc_402:       No such server
        'irc_join,irc_quit,irc_part,irc_status,irc_nick_back,irc_401,irc_402',
        'A comma-separated list of message tags for which no notifications '
        'should be shown.'
    ),
    'ignore_buffers': (
        '',
        'A comma-separated list of buffers from which no notifications should '
        'be shown.'
    ),
    'ignore_buffers_starting_with': (
        '',
        'A comma-separated list of buffer prefixes from which no '
        'notifications should be shown.'
    ),
    'ignore_nicks': (
        '',
        'A comma-separated list of nicks from which no notifications should '
        'be shown.'
    ),
    'ignore_nicks_starting_with': (
        '',
        'A comma-separated list of nick prefixes from which no '
        'notifications should be shown.'
    ),
    'nick_separator': (
        ': ',
        'A separator between a nick and a message.'
    ),
    'escape_html': (
        'on',
        "Escapes the '<', '>', and '&' characters in notification messages."
    ),
    'max_length': (
        '72',
        'Maximal length of a notification (0 means no limit).'
    ),
    'ellipsis': (
        '[..]',
        'Ellipsis to be used for notifications that are too long.'
    ),
    'icon': (
        '/usr/share/icons/hicolor/32x32/apps/weechat.png',
        'Path to an icon to be shown in notifications.'
    ),
    'timeout': (
        '5000',
        'Time after which the notification disappears (in milliseconds; '
        'set to 0 to disable).'
    ),
    'urgency': (
        'normal',
        'Urgency (low, normal, critical).'
    )
}


class Notification(object):
    """A representation of a notification."""

    def __init__(self, source, message, icon, timeout, urgency):
        self.source = source
        self.message = message
        self.icon = icon
        self.timeout = timeout
        self.urgency = urgency


def default_value_of(option):
    """Returns the default value of the given option."""
    return OPTIONS[option][0]


def add_default_value_to(description, default_value):
    """Adds the given default value to the given option description."""
    # All descriptions end with a period, so do not add another period.
    return '{} Default: {}.'.format(
        description,
        default_value if default_value else '""'
    )


def nick_that_sent_message(tags, prefix):
    """Returns a nick that sent the message based on the given data passed to
    the callback.
    """
    # 'tags' is a comma-separated list of tags that WeeChat passed to the
    # callback. It should contain a tag of the following form: nick_XYZ, where
    # XYZ is the nick that sent the message.
    for tag in tags:
        if tag.startswith('nick_'):
            return tag[5:]

    # There is no nick in the tags, so check the prefix as a fallback.
    # 'prefix' (str) is the prefix of the printed line with the message.
    # Usually (but not always), it is a nick with an optional mode (e.g. on
    # IRC, @ denotes an operator and + denotes a user with voice). We have to
    # remove the mode (if any) before returning the nick.
    # Strip also a space as some protocols (e.g. Matrix) may start prefixes
    # with a space. It probably means that the nick has no mode set.
    if prefix.startswith(('~', '&', '@', '%', '+', '-', ' ')):
        return prefix[1:]

    return prefix


def parse_tags(tags):
    """Parses the given "list" of tags (str) from WeeChat into a list.
    """
    return tags.split(',')


def message_printed_callback(data, buffer, date, tags, is_displayed,
                             is_highlight, prefix, message):
    """A callback when a message is printed."""
    is_displayed = int(is_displayed)
    is_highlight = int(is_highlight)
    tags = parse_tags(tags)
    nick = nick_that_sent_message(tags, prefix)

    if notification_should_be_sent(buffer, tags, nick, is_displayed, is_highlight):
        notification = prepare_notification(
            buffer, is_highlight, nick, message
        )
        send_notification(notification)

    return weechat.WEECHAT_RC_OK


def notification_should_be_sent(buffer, tags, nick, is_displayed, is_highlight):
    """Should a notification be sent?"""
    if notification_should_be_sent_disregarding_time(buffer, tags, nick,
                                                     is_displayed, is_highlight):
        # The following function should be called only when the notification
        # should be sent (it updates the last notification time).
        if not is_below_min_notification_delay(buffer):
            return True
    return False


def notification_should_be_sent_disregarding_time(buffer, tags, nick,
                                                  is_displayed, is_highlight):
    """Should a notification be sent when not considering time?"""
    if i_am_author_of_message(buffer, nick):
        return False

    if not is_displayed:
        if not notify_on_filtered_messages():
            return False

    if buffer == weechat.current_buffer():
        if not notify_for_current_buffer():
            return False

    if is_away(buffer):
        if not notify_when_away():
            return False

    if ignore_notifications_from_messages_tagged_with(tags):
        return False

    if ignore_notifications_from_nick(nick):
        return False

    if ignore_notifications_from_buffer(buffer):
        return False

    if is_private_message(buffer):
        return notify_on_private_messages()

    if is_highlight:
        return notify_on_highlights()

    if notify_on_all_messages_in_buffer(buffer):
        return True

    return False


def is_below_min_notification_delay(buffer):
    """Is a notification in the given buffer below the minimal delay between
    successive notifications from the same buffer?

    When called, this function updates the time of the last notification.
    """
    # We store the time of the last notification in a buffer-local variable to
    # make it persistent over the lifetime of this plugin.
    LAST_NOTIFICATION_TIME_VAR = 'notify_send_last_notification_time'
    last_notification_time = buffer_get_float(
        buffer,
        'localvar_' + LAST_NOTIFICATION_TIME_VAR
    )

    min_notification_delay = weechat.config_get_plugin('min_notification_delay')
    # min_notification_delay is in milliseconds (str). To compare it with
    # last_notification_time (float in seconds), we have to convert it to
    # seconds (float).
    min_notification_delay = float(min_notification_delay) / 1000

    current_time = time.time()

    # We have to update the last notification time before returning the result.
    buffer_set_float(
        buffer,
        'localvar_set_' + LAST_NOTIFICATION_TIME_VAR,
        current_time
    )

    return (min_notification_delay > 0 and
            current_time - last_notification_time < min_notification_delay)


def buffer_get_float(buffer, property):
    """A variant of weechat.buffer_get_x() for floats.

    This variant is needed because WeeChat supports only buffer_get_string()
    and buffer_get_int().
    """
    value = weechat.buffer_get_string(buffer, property)
    return float(value) if value else 0.0


def buffer_set_float(buffer, property, value):
    """A variant of weechat.buffer_set() for floats.

    This variant is needed because WeeChat supports only integers and strings.
    """
    weechat.buffer_set(buffer, property, str(value))


def names_for_buffer(buffer):
    """Returns a list of all names for the given buffer."""
    # The 'buffer' parameter passed to our callback is actually the buffer's ID
    # (e.g. '0x2719cf0'). We have to check its name (e.g. 'freenode.#weechat')
    # and short name (e.g. '#weechat') because these are what users specify in
    # their configs.
    buffer_names = []

    full_name = weechat.buffer_get_string(buffer, 'name')
    if full_name:
        buffer_names.append(full_name)

    short_name = weechat.buffer_get_string(buffer, 'short_name')
    if short_name:
        buffer_names.append(short_name)
        # Consider >channel and #channel to be equal buffer names. The reason
        # is that the https://github.com/rawdigits/wee-slack plugin replaces
        # '#' with '>' to indicate that someone in the buffer is typing. This
        # fixes the behavior of several configuration options (e.g.
        # 'notify_on_all_messages_in_buffers') when weechat_notify_send is used
        # together with the wee_slack plugin.
        #
        # Note that this is only needed to be done for the short name. Indeed,
        # the full name always stays unchanged.
        if short_name.startswith('>'):
            buffer_names.append('#' + short_name[1:])

    return buffer_names


def notify_for_current_buffer():
    """Should we also send notifications for the current buffer?"""
    return weechat.config_get_plugin('notify_for_current_buffer') == 'on'


def notify_on_highlights():
    """Should we send notifications on highlights?"""
    return weechat.config_get_plugin('notify_on_highlights') == 'on'


def notify_on_private_messages():
    """Should we send notifications on private messages?"""
    return weechat.config_get_plugin('notify_on_privmsgs') == 'on'


def notify_on_filtered_messages():
    """Should we also send notifications for filtered (hidden) messages?"""
    return weechat.config_get_plugin('notify_on_filtered_messages') == 'on'


def notify_when_away():
    """Should we also send notifications when away?"""
    return weechat.config_get_plugin('notify_when_away') == 'on'


def is_away(buffer):
    """Is the user away?"""
    return weechat.buffer_get_string(buffer, 'localvar_away') != ''


def is_private_message(buffer):
    """Has a private message been sent?"""
    return weechat.buffer_get_string(buffer, 'localvar_type') == 'private'


def i_am_author_of_message(buffer, nick):
    """Am I (the current WeeChat user) the author of the message?"""
    return weechat.buffer_get_string(buffer, 'localvar_nick') == nick


def split_option_value(option, separator=','):
    """Splits the value of the given plugin option by the given separator and
    returns the result in a list.
    """
    values = weechat.config_get_plugin(option)
    return [value.strip() for value in values.split(separator)]


def ignore_notifications_from_messages_tagged_with(tags):
    """Should notifications be ignored for a message tagged with the given
    tags?
    """
    ignored_tags = split_option_value('ignore_messages_tagged_with')
    for ignored_tag in ignored_tags:
        for tag in tags:
            if tag == ignored_tag:
                return True
    return False


def ignore_notifications_from_buffer(buffer):
    """Should notifications from the given buffer be ignored?"""
    buffer_names = names_for_buffer(buffer)

    for buffer_name in buffer_names:
        if buffer_name and buffer_name in ignored_buffers():
            return True

    for buffer_name in buffer_names:
        for prefix in ignored_buffer_prefixes():
            if prefix and buffer_name and buffer_name.startswith(prefix):
                return True

    return False


def ignored_buffers():
    """A generator of buffers from which notifications should be ignored."""
    for buffer in split_option_value('ignore_buffers'):
        yield buffer


def ignored_buffer_prefixes():
    """A generator of buffer prefixes from which notifications should be
    ignored.
    """
    for prefix in split_option_value('ignore_buffers_starting_with'):
        yield prefix


def ignore_notifications_from_nick(nick):
    """Should notifications from the given nick be ignored?"""
    if nick in ignored_nicks():
        return True

    for prefix in ignored_nick_prefixes():
        if prefix and nick.startswith(prefix):
            return True

    return False


def ignored_nicks():
    """A generator of nicks from which notifications should be ignored."""
    for nick in split_option_value('ignore_nicks'):
        yield nick


def ignored_nick_prefixes():
    """A generator of nick prefixes from which notifications should be
    ignored.
    """
    for prefix in split_option_value('ignore_nicks_starting_with'):
        yield prefix


def buffers_to_notify_on_all_messages():
    """A generator of buffer names in which the user wants to be notified for
    all messages.
    """
    for buffer in split_option_value('notify_on_all_messages_in_buffers'):
        yield buffer


def notify_on_all_messages_in_buffer(buffer):
    """Does the user want to be notified for all messages in the given buffer?
    """
    buffer_names = names_for_buffer(buffer)
    for buf in buffers_to_notify_on_all_messages():
        if buf in buffer_names:
            return True
    return False


def prepare_notification(buffer, is_highlight, nick, message):
    """Prepares a notification from the given data."""
    if is_highlight:
        source = (weechat.buffer_get_string(buffer, 'short_name') or
                  weechat.buffer_get_string(buffer, 'name'))
        message = nick + nick_separator() + message
    else:
        # A private message.
        source = nick

    max_length = int(weechat.config_get_plugin('max_length'))
    if max_length > 0:
        ellipsis = weechat.config_get_plugin('ellipsis')
        message = shorten_message(message, max_length, ellipsis)

    if weechat.config_get_plugin('escape_html') == 'on':
        message = escape_html(message)

    message = escape_slashes(message)

    icon = weechat.config_get_plugin('icon')
    timeout = weechat.config_get_plugin('timeout')
    urgency = weechat.config_get_plugin('urgency')

    return Notification(source, message, icon, timeout, urgency)


def nick_separator():
    """Returns a nick separator to be used."""
    separator = weechat.config_get_plugin('nick_separator')
    return separator if separator else default_value_of('nick_separator')


def shorten_message(message, max_length, ellipsis):
    """Shortens the message to at most max_length characters by using the given
    ellipsis.
    """
    # In Python 2, we need to decode the message and ellipsis into Unicode to
    # correctly (1) detect their length and (2) shorten the message. Failing to
    # do that could make the shortened message invalid and cause notify-send to
    # fail. For example, when we have bytes, we cannot guarantee that we do not
    # split the message inside of a multibyte character.
    if sys.version_info.major == 2:
        try:
            message = message.decode('utf-8')
            ellipsis = ellipsis.decode('utf-8')
        except UnicodeDecodeError:
            # Either (or both) of the two cannot be decoded. Continue in a
            # best-effort manner.
            pass

    message = shorten_unicode_message(message, max_length, ellipsis)

    if sys.version_info.major == 2:
        if not isinstance(message, str):
            message = message.encode('utf-8')

    return message


def shorten_unicode_message(message, max_length, ellipsis):
    """An internal specialized version of shorten_message() when the both the
    message and ellipsis are str (in Python 3) or unicode (in Python 2).
    """
    if max_length <= 0 or len(message) <= max_length:
        # Nothing to shorten.
        return message

    if len(ellipsis) >= max_length:
        # We cannot include any part of the message.
        return ellipsis[:max_length]

    return message[:max_length - len(ellipsis)] + ellipsis


def escape_html(message):
    """Escapes HTML characters in the given message."""
    # Only the following characters need to be escaped
    # (https://wiki.ubuntu.com/NotificationDevelopmentGuidelines).
    message = message.replace('&', '&amp;')
    message = message.replace('<', '&lt;')
    message = message.replace('>', '&gt;')
    return message


def escape_slashes(message):
    """Escapes slashes in the given message."""
    # We need to escape backslashes to prevent notify-send from interpreting
    # them, e.g. we do not want to print a newline when the message contains
    # '\n'.
    return message.replace('\\', r'\\')


def send_notification(notification):
    """Sends the given notification to the user."""
    notify_cmd = ['notify-send', '--app-name', 'weechat']
    if notification.icon:
        notify_cmd += ['--icon', notification.icon]
    if notification.timeout:
        notify_cmd += ['--expire-time', str(notification.timeout)]
    if notification.urgency:
        notify_cmd += ['--urgency', notification.urgency]
    # We need to add '--' before the source and message to ensure that
    # notify-send considers the remaining parameters as the source and the
    # message. This prevents errors when a source or message starts with '--'.
    notify_cmd += ['--', notification.source, notification.message]

    # Prevent notify-send from messing up the WeeChat screen when occasionally
    # emitting assertion messages by redirecting the output to /dev/null (you
    # would need to run /redraw to fix the screen).
    # In Python < 3.3, there is no subprocess.DEVNULL, so we have to use a
    # workaround.
    with open(os.devnull, 'wb') as devnull:
        subprocess.check_call(
            notify_cmd,
            stderr=subprocess.STDOUT,
            stdout=devnull,
        )


if __name__ == '__main__':
    # Registration.
    weechat.register(
        SCRIPT_NAME,
        SCRIPT_AUTHOR,
        SCRIPT_VERSION,
        SCRIPT_LICENSE,
        SCRIPT_DESC,
        SCRIPT_SHUTDOWN_FUNC,
        SCRIPT_CHARSET
    )

    # Initialization.
    for option, (default_value, description) in OPTIONS.items():
        description = add_default_value_to(description, default_value)
        weechat.config_set_desc_plugin(option, description)
        if not weechat.config_is_set_plugin(option):
            weechat.config_set_plugin(option, default_value)

    # Catch all messages on all buffers and strip colors from them before
    # passing them into the callback.
    weechat.hook_print('', '', '', 1, 'message_printed_callback', '')