relational/relational/maintenance.py

# Relational
# Copyright (C) 2008-2020  Salvo "LtWorf" Tomaselli
#
# Relation 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 Salvo "LtWorf" Tomaselli <tiposchi@tiscali.it>
#
# Stuff non-related to relational algebra, but used for maintenance.

import os.path
import pickle
import base64
from typing import Optional, Tuple
from gettext import gettext as _

from relational.relation import Relation
from relational import parser
from relational.rtypes import is_valid_relation_name


def send_survey(data) -> int:
    '''Sends the survey. Data must be a dictionary.
    returns the http response.

    returns 0 in case of error
    returns -1 in case of swearwords'''
    import urllib.parse
    from http.client import HTTPConnection

    SWEARWORDS = {'fuck', 'shit', 'suck', 'merda', 'mierda', 'merde'}

    post = ''
    for i in data.keys():
        post += '%s: %s\n' % (i, data[i].strip())

    lowpost = post.lower()
    for i in SWEARWORDS:
        if i in lowpost:
            return -1

    # sends the string
    params = urllib.parse.urlencode({'survey': post})
    headers = {"Content-type":
               "application/x-www-form-urlencoded", "Accept": "text/plain"}
    connection = HTTPConnection('feedback-ltworf.appspot.com')
    try:
        connection.request("POST", "/feedback/relational", params, headers)
        return connection.getresponse().status
    except:
        return 0


def check_latest_version() -> Optional[str]:
    '''Returns the latest version available.
    Heavely dependent on server and server configurations
    not granted to work forever.'''
    import json
    import urllib.request

    try:
        req = urllib.request.Request('https://api.github.com/repos/ltworf/relational/releases')
        with urllib.request.urlopen(req) as f:
            data = json.load(f)
        return data[0]['name']
    except:
        return None


class UserInterface:

    '''It is used to provide services to the user interfaces, in order to
    reduce the amount of duplicated code present in different user interfaces.
    '''

    def __init__(self) -> None:
        self.session_reset()

    def load(self, filename: str, name: str) -> None:
        '''Loads a relation from file, and gives it a name to
        be used in subsequent queries.

        Files ending with .csv are loaded as csv, the others are
        loaded as json.
        '''
        if filename.endswith('.csv'):
            rel = Relation.load_csv(filename)
        else:
            rel = Relation.load(filename)
        self.set_relation(name, rel)

    def unload(self, name: str) -> None:
        '''Unloads an existing relation.'''
        del self.relations[name]

    def store(self, filename: str, name: str) -> None:
        '''Stores a relation to file.'''
        if filename.endswith('.csv'):
            self.relations[name].save_csv(filename)
        else:
            self.relations[name].save(filename)

    def session_dump(self, filename: Optional[str] = None) -> Optional[str]:
        '''
        Dumps the session.

        If a filename is specified, the session is dumped
        inside the file, and None is returned.

        If no filename is specified, the session is returned
        as string.
        '''
        if filename:
            with open(filename, 'wb') as f:
                pickle.dump(self.relations, f)
                return None
        return base64.b64encode(pickle.dumps(self.relations)).decode()

    def session_restore(self, session: Optional[bytes] = None, filename: Optional[str] = None) -> None:
        '''
        Restores a session.

        Either from bytes or from a file.
        '''
        if session:
            try:
                self.relations = pickle.loads(base64.b64decode(session))
            except:
                pass
        elif filename:
            with open(filename, 'rb') as f:
                self.relations = pickle.load(f)

    def session_reset(self) -> None:
        '''
        Resets the session to a clean one
        '''
        self.relations = {}

    def get_relation(self, name: str) -> Relation:
        '''Returns the relation corresponding to name.'''
        return self.relations[name]

    def set_relation(self, name: str, rel: Relation) -> None:
        '''Sets the relation corresponding to name.'''
        if not is_valid_relation_name(name):
            raise Exception(_('Invalid name for destination relation'))
        self.relations[name] = rel

    def suggest_name(self, filename: str) -> Optional[str]:
        '''
        Returns a possible name for a relation, given
        a filename.

        If it is impossible to extract a possible name,
        returns None
        '''
        name = os.path.basename(filename).lower()
        if len(name) == 0:
            return None

        # Removing the extension
        try:
            pos = name.rindex('.')
        except ValueError:
            return None
        name = name[:pos]

        if not is_valid_relation_name(name):
            return None
        return name

    def execute(self, query: str, relname: str = 'last_') -> Relation:
        '''Executes a query, returns the result and if
        relname is not None, adds the result to the
        dictionary, with the name given in relname.'''
        if not is_valid_relation_name(relname):
            raise Exception(_('Invalid name for destination relation'))

        expr = parser.parse(query)
        result = expr(self.relations)
        self.relations[relname] = result
        return result

    @staticmethod
    def split_query(query: str, default_name='last_') -> Tuple[str, str]:
        '''
        Accepts a query which might have an initial value
        assignment
        a = query

        Returns a tuple with

        result_name, query
        '''
        sq = query.split('=', 1)
        if len(sq) == 2 and is_valid_relation_name(sq[0].strip()):
            default_name = sq[0].strip()
            query = sq[1].strip()
        return default_name, query

    def multi_execute(self, query: str) -> Relation:
        '''Executes multiple queries, separated by \n

        They can have a syntax of
        [varname =] query
        to assign the result to a new relation
        '''
        r = None
        queries = query.split('\n')
        for query in queries:
            if query.strip() == '':
                continue

            relname, query = self.split_query(query)

            try:
                r = self.execute(query, relname)
            except Exception as e:
                raise Exception(_('Error in query: %s\n%s') % (
                    query,
                    str(e)
                ))
        if r is None:
            raise Exception(_('No query executed'))
        return r