#!/usr/bin/env python3
# vim: ai ts=4 sts=4 sw=4
"""PostgreSQL Planet Aggregator

This file contains the functions to generate short
URLs and tweets from what's currently in the database.

Copyright (C) 2009-2019 PostgreSQL Global Development Group
"""

# Post links to articles on twitter

import psycopg2
import psycopg2.extensions
import configparser
import html
import requests_oauthlib


# Simple map used to shorten id values to URLs
_urlvalmap = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '-', '_']


class PostToTwitter(object):
    def __init__(self, cfg):
        self.tw = requests_oauthlib.OAuth1Session(cfg.get('twitter', 'consumer'),
                                                  cfg.get('twitter', 'consumersecret'),
                                                  cfg.get('twitter', 'token'),
                                                  cfg.get('twitter', 'secret'))

        psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
        self.db = psycopg2.connect(c.get('planet', 'db'))

    def do_post(self, msg):
        """
        Actually make a post to twitter!
        """
        r = self.tw.post('https://api.twitter.com/2/tweets', json={
            'text': html.unescape(msg),
        })
        if r.status_code != 201:
            raise Exception("Could not post to twitter, status code {0}, error {1}".format(r.status_code, r.text))

        # Return the id of the tweet
        return r.json()['data']['id']

    def Run(self):
        c = self.db.cursor()
        c.execute("""SELECT posts.id, posts.title, posts.link, posts.shortlink, feeds.name, feeds.twitteruser
                 FROM posts INNER JOIN feeds ON posts.feed=feeds.id
                 WHERE approved AND age(dat) < '7 days' AND NOT (twittered OR hidden) ORDER BY dat""")
        for post in c.fetchall():
            if post[3] and len(post[3]) > 1:
                short = post[3]
            else:
                # No short-link exists, so create one. We need the short-link
                # to twitter, and we store it separately in the database
                # in case it's needed.
                try:
                    short = self.shortid(post[0])
                except Exception as e:
                    print("Failed to shorten URL %s: %s" % (post[2], e))
                    continue

                c.execute("UPDATE posts SET shortlink=%(short)s WHERE id=%(id)s", {
                    'short': short,
                    'id': post[0],
                })
                self.db.commit()

            # Set up the string to twitter
            if post[5] and len(post[5]) > 1:
                # Twitter username registered
                msg = "%s (@%s): %s %s" % (
                    post[4],
                    post[5],
                    self.trimpost(post[1], len(post[4]) + len(post[5]) + len(short) + 7),
                    short,
                )
            else:
                msg = "%s: %s %s" % (
                    post[4],
                    self.trimpost(post[1], len(post[4]) + len(short) + 3),
                    short,
                )

            # Now post it to twitter
            try:
                tweetid = self.do_post(msg)
            except Exception as e:
                print("Error posting to twitter (post %s): %s" % (post[0], e))
                # We'll just try again with the next one
                continue

            # Flag this item as posted
            c.execute("UPDATE posts SET twittered='t', tweetid=%(tweetid)s WHERE id=%(id)s", {
                'id': post[0],
                'tweetid': tweetid,
            })
            self.db.commit()

            print("Twittered: %s" % msg)

    # Trim a post to the length required by twitter, so we don't fail to post
    # if a title is really long. Assume other parts of the string to be
    # posted are <otherlen> characters.
    def trimpost(self, txt, otherlen):
        if len(txt) + otherlen < 140:
            return txt
        return "%s..." % (txt[:(140 - otherlen - 3)])

    # Trim an URL using https://postgr.es
    def shortid(self, id):
        s = ""
        while id > 0:
            s = _urlvalmap[id % 64] + s
            id /= 64
        return "https://postgr.es/p/%s" % s


if __name__ == "__main__":
    c = configparser.ConfigParser()
    c.read('planet.ini')
    PostToTwitter(c).Run()