#!/usr/bin/env python3
# -*- coding: utf-8  -*-
#
#  jogobot.py
#
#  Copyright 2017 Jonathan Golder <jonathan@golderweb.de>
#
#  This program 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 2 of the License, or
#  (at your option) any later version.
#
#  This program 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 this program; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#  MA 02110-1301, USA.
#
#

import os
import shlex
from datetime import datetime
from email.mime.text import MIMEText
from subprocess import Popen, PIPE, TimeoutExpired

import pywikibot

# Location of logging related stuff in pywikibot was changed with
# commit d7d7a14 on Mon Sep 7 14:41:43 2015
# This is to be compatible with recent versions as well as 2.0-branch
try:
    from pywikibot.logging import(
        DEBUG, INFO, WARNING, ERROR, CRITICAL, STDOUT, VERBOSE, logoutput )
except( ImportError ):
    # Legacy support (pywikibot 2.0 branch)
    from pywikibot.bot import(
        DEBUG, INFO, WARNING, ERROR, CRITICAL, STDOUT, VERBOSE, logoutput )

from jogobot.config import config


def output( text, level="INFO", decoder=None, newline=True,
            layer=None, **kwargs ):
    """
    Wrapper for pywikibot output functions
    """

    text = datetime.utcnow().strftime( config["log_timestamp"] ) + " " + text

    if ( level.upper() == "STDOUT" ):
        _level = STDOUT
    elif( level.upper() == "INFO" ):
        _level = INFO
    elif( level.upper() == "WARNING" ):
        _level = WARNING
    elif( level.upper() == "ERROR" ):
        _level = ERROR
    elif( level.upper() == "LOG" or level.upper() == "VERBOSE" ):
        _level = VERBOSE
    elif( level.upper() == "CRITICAL" ):
        _level = CRITICAL
    elif( level.upper() == "DEBUG" ):
        _level = DEBUG
    else:
        pass

    if ( level == DEBUG ):
        logoutput(text, decoder, newline, _level, layer, **kwargs)
    else:
        logoutput(text, decoder, newline, _level, **kwargs)


# Since we like to have timestamps in Output for logging, we replace
# pywikibot.output with jogobot.output via monkey patching
def pywikibot_output( text, decoder=None, newline=True,
                      toStdout=False, **kwargs ):
    r"""Output a message to the user via the userinterface.

    Works like print, but uses the encoding used by the user's console
    (console_encoding in the configuration file) instead of ASCII.

    If decoder is None, text should be a unicode string. Otherwise it
    should be encoded in the given encoding.

    If newline is True, a line feed will be added after printing the text.

    If toStdout is True, the text will be sent to standard output,
    so that it can be piped to another process. All other text will
    be sent to stderr. See: https://en.wikipedia.org/wiki/Pipeline_%28Unix%29

    text can contain special sequences to create colored output. These
    consist of the escape character \03 and the color name in curly braces,
    e. g. \03{lightpurple}. \03{default} resets the color.

    Other keyword arguments are passed unchanged to the logger; so far, the
    only argument that is useful is "exc_info=True", which causes the
    log message to include an exception traceback.

    """
    if toStdout:  # maintained for backwards-compatibity only
        output(text, "STDOUT", decoder, newline, **kwargs)
    else:
        output(text, "INFO", decoder, newline, **kwargs)

pywikibot.output = pywikibot_output


def sendmail( Subject, Body, To=None, CC=None, BCC=None,
              From=config["mail_from"] ):
    """
    Provides a simple wrapper for exim (MTA) on tool labs
    Params should be formated according related fields in RFC 5322

    @param subject  Mail subject
    @type subject str
    @param body    Mail body as (formated) string
    @type body  unicode-str
    @param to   Mail-Recipiends (comma-separeded)
    @type str
    @param from Mail-Sender
    @type str
    """

    # Create mail body as MIME-Object
    msg = MIMEText(Body)

    # Set up mail header
    msg['Subject'] = Subject

    msg['From'] = From

    if To:
        msg['To'] = To

    if CC:
        msg['CC'] = CC

    if BCC:
        msg['BCC'] = BCC

    msg['Content-Type'] = 'text/plain; charset="utf-8"'

    # Make sure we have a recipient
    if not( To or CC or BCC):
        raise MailError( "No recipient was provided!" )

    # We have no local MTA so we need to catch errors and write to file instead
    try:
        # Send the message via exim
        with Popen( shlex.split(config['mail_cmd']), stdin=PIPE,
                    universal_newlines=True ) as MTA:

            MTA.communicate(msg.as_string())

            # Try to get returncode of MTA
            # Process is not terminated until timeout, set returncode to None
            try:
                returncode = MTA.wait(timeout=30)
            except TimeoutExpired:
                returncode = None

        # Catch MTA errors
        if returncode:
            raise MailError( "/usr/sbin/exim terminated with " +
                             "returncode != 0. Returncode was " +
                             str( returncode ) )

    except FileNotFoundError:

        # Local fallback
        with open( config["dir"] + "/Mail.txt", "a" ) as mail:
            mail.write( "\n\n" )
            mail.write( datetime.utcnow().strftime( config["log_timestamp"]))
            mail.write( "\n" + msg.as_string() )


def is_active( task_slug, write=True ):
    """
    Simple wrapper function for our ActiveAPI to use in Tasks
    """

    status = StatusAPI()

    # First check if Bot is blocked
    if write and status.is_blocked():

        status.blocked()

    task_slugs = ( None, task_slug )

    for _task_slug in task_slugs:
        # Then check if whole Bot is disabled by file
        if status.is_disabled_by_file(_task_slug):

            # Disabling by file normaly results out of Disabling on wiki
            if status.is_disabled_on_wiki(_task_slug):

                status.disabled_on_wiki(_task_slug, True)

            else:

                status.disabled_by_file(_task_slug)

        # Status disabled is set on wiki but not yet by file
        elif status.is_disabled_on_wiki(_task_slug):

                status.disabled_on_wiki(_task_slug)


class StatusAPI:
    """
    Provide an API for checking if Jogobot or specific task is blocked,
    disabled on wiki or by file
    """

    def __init__( self ):
        """
        Initialise our class
        """

        # We need a pywikibot site object
        self.site = pywikibot.Site()

        # We need the shell working directory
        self.cwd = config["dir"]

    def is_disabled_on_wiki( self, task_slug=None ):
        """
        Checks if whole bot or task specified by task_slug is disabled
        on wiki

        @param task_slug    Slug of task to check, None for whole Bot
        @type str
        """

        # Define page for look up
        if task_slug:
            page_title = "Benutzer:JogoBot/" + task_slug + "/active"
        else:
            page_title = "Benutzer:JogoBot/active"

        # Get pywikibot page object
        page = pywikibot.Page( self.site, page_title )

        # Make sure page exists
        if not page.exists():
            raise DisablingPageError

        # Get page text
        page_text = page.get()

        if "true" not in page_text.lower():
            return True

        return False

    def is_blocked( self ):
        """
        Checks if bot user is blocked on wiki
        """
        if self.site.is_blocked():
            return True

        return False

    def is_disabled_by_file(self, task_slug=None):
        """
        Checks if whole bot or task specified by task_slug is disabled
        by file

        @param task_slug    Slug of task to check, None for whole Bot
        @type str
        """

        # Define filepath
        if task_slug:
            disable_file = self.cwd + "/" + task_slug + "/disabled"
        else:
            disable_file = self.cwd + "/disabled"

        if os.path.isfile( disable_file ):
            return True

        return False

    def create_disable_file( self, task_slug=None ):
        """
        Creates disable file for whole bot or task specified by task_slug

        @param task_slug    Slug of task to check, None for whole Bot
        @type str
        """

        # Define filepath
        if task_slug:
            disable_file = self.cwd + "/" + task_slug + "/disabled"
        else:
            disable_file = self.cwd + "/disabled"

        # Try to create file
        with open(disable_file, 'a'):
            pass

    def blocked( self ):
        """
        Handles process if Bot user is blocked
        """

        # Mail-Fields
        subject = "JogoBot: Bot-Account is blocked"
        body = """Your Bot-Account is blocked on Wiki"""
        mailto = "jogobot-status@golderweb.de"

        sendmail( subject, body, mailto )

        raise Blocked( body )

    def disabled_by_file( self, task_slug=None ):
        """
        Handles process if Bot/Task is disabled by file
        """

        if task_slug:
            subject = "JogoBot: Task " + task_slug + " is disabled by file!"
            body = """
The Bot-Task with slug %s is disabled by file!
""" % task_slug
            mailto = "jogobot-" + task_slug + "-status@golderweb.de"

        else:
            subject = "JogoBot: Bot is disabled by file!"
            body = """The Bot is disabled by file!"""
            mailto = "jogobot-status@golderweb.de"

        sendmail( subject, body, mailto )

        raise DisabledByFile( body )

    def disabled_on_wiki( self, task_slug=None, file=False ):
        """
        Handles process if Bot/Task is disabled on wiki
        """

        if file:
            suffix = " and also by file!"
        else:
            suffix = "!\nA disabled file is going to be created."

        if task_slug:
            subject = "JogoBot: Task " + task_slug + " is disabled on wiki!"
            body = """
The Bot-Task with slug %s is disabled on wiki%s
""" % (task_slug, suffix)
            mailto = "jogobot-" + task_slug + "-status@golderweb.de"
        else:
            subject = "JogoBot: Bot is disabled on wiki!"
            body = """
The Bot is disabled by on wiki%s
""" % suffix
            mailto = "jogobot-status@golderweb.de"

        sendmail( subject, body, mailto )

        self.create_disable_file( task_slug )

        raise DisabledOnWiki( body )


class Disabled( Exception ):
    """
    Handles disabled Bot/Task
    """
    pass


class DisablingPageError( Disabled ):
    """
    Handles errors with missing disabling pages
    """
    pass


class Blocked( Disabled ):
    """
    Raised if Bot-Account is blocked
    """
    pass


class DisabledByFile( Disabled ):
    """
    Raised if Bot/Task is disabled by File
    """
    pass


class DisabledOnWiki( Disabled ):
    """
    Raised if Bot/Task is disabled on Wiki
    """
    pass


class MailError( Exception ):
    """
    Handles errors occuring in class JogoBot related to mail actions
    """
    pass