#! /usr/bin/env python
#-*- coding: utf-8 -*-

# pyAggr3g470r - A Web based news aggregator.
# Copyright (C) 2010-2013  Cédric Bonhomme - http://cedricbonhomme.org/
#
# For more information : http://bitbucket.org/cedricbonhomme/pyaggr3g470r/
#
# 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 3 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, see <http://www.gnu.org/licenses/>

__author__ = "Cedric Bonhomme"
__version__ = "$Revision: 1.5 $"
__date__ = "$Date: 2010/12/07 $"
__revision__ = "$Date: 2013/07/24 $"
__copyright__ = "Copyright (c) Cedric Bonhomme"
__license__ = "GPLv3"

#
# This file provides functions used for:
# - the database management;
# - generation of tags cloud;
# - HTML processing;
# - e-mail notifications.
#

import os
import re
import glob
import operator
import calendar
import html.entities

try:
    from qrcode.pyqrnative.PyQRNative import QRCode, QRErrorCorrectLevel, CodeOverflowException
    from qrcode import qr
except:
    pass

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

import urllib.request, urllib.error, urllib.parse
import http.server
from bs4 import BeautifulSoup

from collections import Counter
from contextlib import contextmanager

import conf

# regular expression to check URL
url_finders = [ \
    re.compile("([0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}|(((news|telnet|nttp|file|http|ftp|https)://)|(www|ftp)[-A-Za-z0-9]*\\.)[-A-Za-z0-9\\.]+)(:[0-9]*)?/[-A-Za-z0-9_\\$\\.\\+\\!\\*\\(\\),;:@&=\\?/~\\#\\%]*[^]'\\.}>\\),\\\"]"), \
    re.compile("([0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}|(((news|telnet|nttp|file|http|ftp|https)://)|(www|ftp)[-A-Za-z0-9]*\\.)[-A-Za-z0-9\\.]+)(:[0-9]*)?"), \
    re.compile("(~/|/|\\./)([-A-Za-z0-9_\\$\\.\\+\\!\\*\\(\\),;:@&=\\?/~\\#\\%]|\\\\)+"), \
    re.compile("'\\<((mailto:)|)[-A-Za-z0-9\\.]+@[-A-Za-z0-9\\.]+") \
]

import log
pyaggr3g470r_log = log.Log()

@contextmanager
def opened_w_error(filename, mode="r"):
    try:
        f = open(filename, mode)
    except IOError as err:
        yield None, err
    else:
        try:
            yield f, None
        finally:
            f.close()

def open_url(url):
    """
    Open an URL with the proxy and the user-agent
    specified in the configuration file.
    """
    if conf.HTTP_PROXY == "":
        proxy = {}
    else:
        proxy = {"http" : conf.HTTP_PROXY}
    opener = urllib.request.FancyURLopener(proxy)
    try:
        opener = urllib.request.build_opener()
        opener.addheaders = [('User-agent', conf.USER_AGENT)]
        return (True, opener.open(url))
    except urllib.error.HTTPError as e:
        # server couldn't fulfill the request
        error = (url, e.code, \
                        http.server.BaseHTTPRequestHandler.responses[e.code][1])
        pyaggr3g470r_log.error(url + " " + str(e.code) + " " + \
                                http.server.BaseHTTPRequestHandler.responses[e.code][1])
        return (False, error)
    except urllib.error.URLError as e:
        # failed to reach the server
        if type(e.reason) == str:
            error = (url, e.reason, e.reason)
            pyaggr3g470r_log.error(url + " " + e.reason)
        else:
            error = (url, e.reason.errno, e.reason.strerror)
            pyaggr3g470r_log.error(url + " " + str(e.reason.errno) + " " + \
                                    e.reason.strerror)
        return (False, error)

def generate_qr_code(article):
    """
    Generated a QR Code for the article given in parameter.
    """
    try:
        os.makedirs("./var/qrcode/")
    except OSError:
        pass
    if not os.path.isfile("./var/qrcode/" + article["article_id"] + ".png"):
        # QR Code generation
        try:
            f = qr.QRUrl(url = article["article_link"])
            f.make()
            f.save("./var/qrcode/" + article["article_id"] + ".png")
        except:
            pass

def clear_string(data):
    """
    Clear a string by removing HTML tags, HTML special caracters
    and consecutive white spaces (more that one).
    """
    p = re.compile(b'<[^>]+>') # HTML tags
    q = re.compile(b'\s') # consecutive white spaces
    return p.sub(b'', q.sub(b' ', bytes(data, "utf-8"))).decode("utf-8", "strict")

def normalize_filename(name):
    """
    Normalize a file name.
    """
    file_name = re.sub("[,'!?|&]", "", name)
    file_name = re.sub("[\s.]", "_", file_name)
    file_name = file_name.strip('_')
    file_name = file_name.strip('.')
    return os.path.normpath(file_name)

def load_stop_words():
    """
    Load the stop words and return them in a list.
    """
    stop_words_lists = glob.glob('./var/stop_words/*.txt')
    stop_words = []

    for stop_wods_list in stop_words_lists:
        with opened_w_error(stop_wods_list, "r") as (stop_wods_file, err):
            if err:
                stop_words = []
            else:
                stop_words += stop_wods_file.read().split(";")
    return stop_words

def top_words(articles, n=10, size=5):
    """
    Return the n most frequent words in a list.
    """
    stop_words = load_stop_words()
    words = Counter()
    wordre = re.compile(r'\b\w{%s,}\b' % size, re.I)
    for article in articles:
        for word in [elem.lower() for elem in
                wordre.findall(clear_string(article["article_content"])) \
                if elem.lower() not in stop_words]:
            words[word] += 1
    return words.most_common(n)

def tag_cloud(tags, query="word_count"):
    """
    Generates a tags cloud.
    """
    tags.sort(key=operator.itemgetter(0))
    if query == "word_count":
        # tags cloud from the management page
        return ' '.join([('<font size=%d><a href="/search/?query=%s" title="Count: %s">%s</a></font>\n' % \
                    (min(1 + count * 7 / max([tag[1] for tag in tags]), 7), word, format(count, ',d'), word)) \
                        for (word, count) in tags])
    if query == "year":
        # tags cloud for the history
        return ' '.join([('<font size=%d><a href="/history/?query=%s:%s" title="Count: %s">%s</a></font>\n' % \
                        (min(1 + count * 7 / max([tag[1] for tag in tags]), 7), query, word, format(count, ',d'), word)) \
                            for (word, count) in tags])
    return ' '.join([('<font size=%d><a href="/history/?query=%s:%s" title="Count: %s">%s</a></font>\n' % \
                        (min(1 + count * 7 / max([tag[1] for tag in tags]), 7), query, word, format(count, ',d'), calendar.month_name[int(word)])) \
                            for (word, count) in tags])

def send_mail(mfrom, mto, feed_title, article_title, description):
    """
    Send the article via mail.
    """
    # Create the body of the message (a plain-text and an HTML version).
    html = """<html>\n<head>\n<title>%s</title>\n</head>\n<body>\n%s\n</body>\n</html>""" % \
                (feed_title + ": " + article_title, description)
    text = clear_string(description)

    # Create message container - the correct MIME type is multipart/alternative.
    msg = MIMEMultipart('alternative')
    msg['Subject'] = '[pyAggr3g470r] ' + feed_title + ": " + article_title
    msg['From'] = mfrom
    msg['To'] = mto

    # Record the MIME types of both parts - text/plain and text/html.
    part1 = MIMEText(text, 'plain', 'utf-8')
    part2 = MIMEText(html, 'html', 'utf-8')

    # Attach parts into message container.
    # According to RFC 2046, the last part of a multipart message, in this case
    # the HTML message, is best and preferred.
    msg.attach(part1)
    msg.attach(part2)

    # Send the message via local SMTP server.
    try:
        s = smtplib.SMTP(conf.smtp_server)
        s.login(conf.username, conf.password)
    except Exception as e:
        print(e)
    else:
        s.send_message(msg)
        s.quit()

def add_feed(feed_url):
    """
    Add the URL feed_url in the file feed.lst.
    """
    with opened_w_error(conf.FEED_LIST, "r") as (f, err):
        if err:
            return False
        else:
            lines = f.readlines()
    lines = list(map(str.strip, lines))
    if feed_url in lines:
        return False
    lines.append(feed_url)
    with open(conf.FEED_LIST, "w") as f:
        f.write("\n".join(lines))
    return True

def change_feed_url(old_feed_url, new_feed_url):
    """
    Change the URL of a feed given in parameter.
    """
    # Replace the URL in the text file
    with opened_w_error(conf.FEED_LIST, "r") as (f, err):
        if err:
            return False
        else:
            lines = f.readlines()
    lines = list(map(str.strip, lines))
    try:
        lines[lines.index(old_feed_url)] = new_feed_url
    except:
        return False
    with opened_w_error(conf.FEED_LIST, "w") as (f, err):
        if err:
            return False
        else:
            f.write("\n".join(lines))
    return True

def remove_feed(feed_url):
    """
    Remove a feed from the file feed.lst and from the SQLite base.
    """
    with opened_w_error(conf.FEED_LIST, "r") as (f, err):
        if err:
            return False
        else:
            lines = f.readlines()
    lines = list(map(str.strip, lines))
    try:
        del lines[lines.index(feed_url)]
    except:
        return False
    with opened_w_error(conf.FEED_LIST, "w") as (f, err):
        if err:
            return False
        else:
            f.write("\n".join(lines))
    return True

def search_feed(url):
    """
    Search a feed in a HTML page.
    """
    soup, page = None, None
    try:
        result = open_url(url)
        if result[0] == True:
            page = open_url(url)[1]
        else:
            return None
        soup = BeautifulSoup(page)
    except:
        return None
    feed_links = soup('link', type='application/atom+xml')
    feed_links.extend(soup('link', type='application/rss+xml'))
    for feed_link in feed_links:
        if url not in feed_link['href']:
            return urllib.parse.urljoin(url, feed_link['href'])
        return feed_link['href']
    return None