README.md

@@ -3,7 +3,8 @@
 Small tools needed to solve immediate tasks independently or as part of a project
 
 * [`build-python`.sh](https://git.hmp.today/pavel.muhortov/utils#build-python-sh)
-* [`cert-info`.sh](https://git.hmp.today/pavel.muhortov/utils#cert-info-sh)
+* [`cronutil`](https://git.hmp.today/pavel.muhortov/utils#cronutil)
+* [`confutil`.py](https://git.hmp.today/pavel.muhortov/utils#confutil-py)
 * [`sendmail`.py](https://git.hmp.today/pavel.muhortov/utils#sendmail-py)
 * [`simplewc`.py](https://git.hmp.today/pavel.muhortov/utils#simplewc-py)
 
@@ -40,32 +41,87 @@ sudo su - -c "bash <(curl -s https://git.hmp.today/pavel.muhortov/utils/raw/bran
 
 ____
 
-## `cert-info`.sh
+## `cronutil`
 
 **Description:**  
-> Get certificate info.  
+> Control wrapper for the [schedule](https://github.com/dbader/schedule) package.  
 
 **Dependencies:**  
 >
-> * [bash](https://www.gnu.org/software/bash/) (tested versions: 4.2.46 on [CentOS 7](https://wiki.centos.org/Manuals/ReleaseNotes/CentOS7.2009))
-> * [openssl](https://www.openssl.org/) (tested version 1.0.2k on [CentOS 7](https://wiki.centos.org/Manuals/ReleaseNotes/CentOS7.2009))
+> * [Python 3](https://www.python.org/downloads/) (tested version 3.9.5 on [Debian GNU/Linux 11](http://ftp.debian.org/debian/dists/bullseye/))
 
-|  POSITION | PARAMETERS   |       DESCRIPTION      |    DEFAULT    |
-|-----------|--------------|------------------------|---------------|
-|     1     |**[hostname:port \| /path/to/cert]**|certificate location||
-|     2     |**[-e]**|print of the expired date timestamp||
-|     2     |**[-f]**|print of the fingerprint||
-|     2     |**[-r]**|print of the remaining days||
+Scheduler works only on a weekly scale. This is due to the use of the [schedule](https://github.com/dbader/schedule) package.  
+Target format: wD:HH:MM:SS, where:
+>
+> wD - day of week unit: `'1'`, `'2'`, ... , `'6'`, `'7'`, `'*'`  
+> HH - hour unit in 24-hours format: `'00'`, `'01'`, ... , `'22'`, `'23'`, `'**'`  
+> MM - minute unit: `'00'`, `'01'`, ... , `'58'`, `'59'`, `'**'`  
+> SS - second unit: `'00'`, `'01'`, ... , `'58'`, `'59'`, `'**'`  
 
-Example usage in terminal with make the script executable:  
+Units can be listed separated by commas. Examples:  
+> `'*:**:**:**'` - every second of every minute of every hour of every day  
+> `'*:**:**:*5'` - every 05,15,25,35,45,55 seconds of every minute of every hour of every day  
+> `'*:2*:**:**'` - every second of every minute of every 20,21,22,23 hours of every day  
+> `'*:2*:**:*5'` - every 05,15,25,35,45,55 seconds of every minute of every 20,21,22,23 hours of every day  
+> `'3,5:2*:**:*5'` - every 05,15,25,35,45,55 seconds every minute every 20,21,22,23 hours of Wednesday, Friday  
+> `'1,7:12:00:**'` - every second 00 minutes 12 hours of Monday, Sunday  
+> `'1:07:00:00'` - every 00 seconds 00 minutes 07 hours Monday  
 
-```bash
-# download
-sudo wget https://git.hmp.today/pavel.muhortov/utils/raw/branch/master/cert-info.sh -O /usr/local/bin/cert-info.sh
-sudo chmod +x /usr/local/bin/cert-info.sh
-# check cert
-cert-info.sh www.hmp.today
-cert-info.sh /etc/ssl/certs/ca-certificates.crt
+Example usage in Python:
+
+```Python
+from time import strftime
+from cronutil import Scheduler
+
+
+def now():
+    print(strftime('%Y.%m.%d %H:%M:%S'))
+
+
+cron = Scheduler()
+cron.add('2,4:**:*0:00,15,30,45', now)
+cron.start()
+cron.add('2,4:**:59:59', cron.stop)
+```
+
+____
+
+## `confutil`.py
+
+**Description:**  
+> Parser of configs, arguments, parameters.  
+
+**Dependencies:**  
+>
+> * [Python 3](https://www.python.org/downloads/) (tested version 3.9.5 on [Debian GNU/Linux 11](http://ftp.debian.org/debian/dists/bullseye/))
+
+Example config to parse:
+
+```text
+[main]
+#   This block contains basic parameters
+
+
+[httpd]
+#   This block contains parameters for the http server
+
+# Address to which to bind listening
+#address=0.0.0.0;
+# Port to which to bind listening. Port below 1024 requires root privileges.
+port=8800;
+# Working directory (available to everyone)
+directory=www;
+```
+
+Example usage in Python:
+
+```Python
+from os import path
+from confutil import Parse
+
+conf = path.splitext(__file__)[0] + '.conf'
+if path.exists(conf):
+    print(Parse(parameters=conf, block='httpd'))
 ```
 
 ____

cert-info.sh

@@ -1,105 +0,0 @@
-#!/usr/bin/env bash
-
-# DESCRIPTION:
-#   get certificate info
-#
-# DEPENDENCIES:
-#   - openssl
-#
-# PARAMETERS:
-#   1: "hostname:port | /path/to/cert" - certificate location
-#   -e - print of the expired date timestamp
-#   -f - print of the fingerprint
-#   -r - print of the remaining days
-#
-# FUNCTIONS:
-#
-#
-# VARIABLES:
-#
-
-if ! command -v openssl &> /dev/null; then
-  printf "%s\n" "Not found dependencies"
-
-  exit 1
-fi
-
-datetime=$(date +%s)
-certdest=$1
-
-#
-# MAIN:
-#
-
-if [ -n "${certdest}" ]; then
-  certpath="$(printf "%s" "${certdest}" | cut -d':' -f1)"
-
-  if [ -f "${certpath}" ]; then
-    certdata=$(cat "${certpath}")
-
-  else
-    certport="$(printf "%s" "${certdest}" | cut -d':' -f2 -s)"
-    if [ -z "${certport}" ]; then
-        certport=443
-    fi
-    certdata=$( \
-      openssl s_client "${certpath}:${certport}" < /dev/null 2>/dev/null \
-      )
-
-  fi
-
-  if [ -n "${certdata}" ]; then
-    expired=$(date -d \
-      "$(printf "%s" "${certdata}" | \
-        openssl x509 -noout -enddate | \
-        cut -d'=' -f2- \
-        )" \
-      +%s
-      )
-    subject=$(printf "%s" "${certdata}" | \
-      openssl x509 -noout -subject | \
-      cut -d'=' -f3- | cut -d' ' -f2- \
-      )
-    release=$(printf "%s" "${certdata}" | \
-      openssl x509 -noout -startdate | \
-      cut -d'=' -f2- \
-      )
-    fingerp=$(printf "%s" "${certdata}" | \
-      openssl x509 -noout -fingerprint | \
-      cut -d'=' -f2- \
-      )
-    remains=0; remains=$(( expired-datetime )); remains=$(( remains/60/60/24 ))
-
-    if [ -z "${2}" ]; then
-      printf '%s\n' "certpath: ${certpath}"
-      printf '%s\n' "certport: ${certport}"
-      printf '%s\n' "fingerprint: ${fingerp}"
-      printf '%s\n' "subject name: ${subject}"
-      printf '%s\n' "release date: ${release}"
-      printf '%s\n' "expired date: ${expired}"
-      printf '%s\n' "remains days: ${remains}"
-    elif [ "${2}" == "-e" ];then
-      printf '%s\n' "${expired}"
-    elif [ "${2}" == "-f" ];then
-      printf '%s\n' "${fingerp}"
-    elif [ "${2}" == "-r" ];then
-      printf '%s\n' "${remains}"
-    else
-      printf '%s\n' "certdata: ${certdata}"
-    fi
-
-  else
-    printf "%s\n" "Certificate was not loaded"
-
-    exit 1
-  fi
-
-else
-  printf "%s\n" "Usage example: ${0} 'name.domain.zone'"
-  printf "%s\n" "Usage example: ${0} 'name.domain.zone:port' -r"
-  printf "%s\n" "Usage example: ${0} '/path/to/cert' -f"
-
-  exit 1
-fi
-
-exit 0

confutil.py

@@ -0,0 +1,135 @@
+from argparse import ArgumentParser
+from os import path, sep
+
+
+class Parse:
+    """
+    Parser of configs, arguments, parameters
+    """
+    def __init__(self, parameters, block: str = None):
+        """
+        Object constructor
+        :param parameters: dictionary as "key":"value" or
+                            ArgumentParser class object or
+                            string path to the file or
+                            string as "var1=val1;var2=val2"
+        :param block: string name of target block from text
+        """
+        self.data = {}
+        if type(parameters) is dict:
+            self._dict2dict(parameters)
+        if type(parameters) is ArgumentParser:
+            self._dict2dict(self.argv2dict(parameters))
+        if type(parameters) is str:
+            if path.exists(parameters):
+                self._dict2dict(self.strs2dict(self.conf2strs(parameters), block))
+            else:
+                self._dict2dict(self.strs2dict(parameters, block))
+
+    def __str__(self):
+        """
+        Overrides method for print(object)
+        :return: string with contents of the object's dictionary
+        """
+        string = ''
+        for key, val in self.data.items():
+            string += str(type(val)) + ' ' + str(key) + ' = ' + str(val) + '\n'
+        return string
+
+    def _dict2dict(self, dictionary: dict):
+        """
+        Updates or adds dictionary data
+        :param dictionary: dictionary as "key":"value"
+        :return: None
+        """
+        self.data.update(dictionary)
+
+    def expand(self, store: str = None):
+        """
+        Expand dictionary "key":"name.conf" to dictionary "key":{subkey: subval}
+        :param store: string path to directory with name.conf
+        :return: expanded dictionary as "key":{subkey: subval}
+        """
+        for key in self.data:
+            if store:
+                config = store + sep + self.data[key]
+            else:
+                config = self.data[key]
+            with open(config) as file:
+                self.data[key] = Parse(file.read()).data
+        return self.data
+
+    @classmethod
+    def argv2dict(cls, parser: ArgumentParser):
+        """
+        Converts startup arguments to a dictionary
+        :param parser: argparse.ArgumentParser class object
+        :return: dictionary as "key":"value"
+        """
+        parser = ArgumentParser(add_help=False, parents=[parser])
+        return vars(parser.parse_args())
+
+    @classmethod
+    def conf2strs(cls, config: str):
+        """
+        Builds a dictionary from a file containing parameters
+        :param config: string path to the file
+        :return: string as "var1=val1;\nvar2=val2;"
+        """
+        with open(config) as file:
+            raw = file.read()
+            strs = ''
+            for line in raw.splitlines():
+                if not line.lstrip().startswith('#'):
+                    strs += line + '\n'
+            return strs
+
+    @classmethod
+    def strs2dict(cls, strings: str, blockname: str):
+        """
+        Builds a dictionary from a strings containing parameters
+        :param strings: string as "var1=val1;var2=val2;"
+        :param blockname: string name of target block from text
+        :return: dictionary as "key":"value"
+        """
+        dictionary = {}
+        if blockname:
+            strings = cls.block(blockname, strings)
+        for line in strings.replace('\n', ';').split(';'):
+            if not line.lstrip().startswith('#') and "=" in line:
+                dictionary[line.split('=')[0].strip()] = line.split('=')[1].strip().split(';')[0].strip()
+        return dictionary
+
+    @classmethod
+    def str2bool(cls, value: str):
+        """
+        Converts a string value to boolean
+        :param value: string containing "true" or "false", "yes" or "no", "1" or "0"
+        :return: bool True or False
+        """
+        return str(value).lower() in ("true", "yes", "1")
+
+    @classmethod
+    def block(cls, blockname: str, text: str):
+        """
+        Cuts a block of text between line [blockname] and line [next block] or EOF
+        :param blockname: string in [] after which the block starts
+        :param text: string of text from which the block is needed
+        :return: string of text between line [block name] and line [next block]
+        """
+        level = 1
+        save = False
+        result = ''
+        for line in text.splitlines():
+            if line.startswith('[') and blockname in line:
+                level = line.count('[')
+                save = True
+            elif line.startswith('[') and '['*level in line:
+                save = False
+            elif save:
+                result += line + '\n'
+        return result
+
+
+if __name__ == "__main__":
+    pass

cronutil/__init__.py

@@ -0,0 +1,169 @@
+"""
+Scheduler works only on a weekly scale. This is due to the use of the schedule package.
+
+Target format: wD:HH:MM:SS, where:
+wD - day of week unit: '1', '2', ... , '6', '7', '*'
+HH - hour unit in 24-hours format: '00', '01', ... , '22', '23', '**'
+MM - minute unit: '00', '01', ... , '58', '59', '**'
+SS - second unit: '00', '01', ... , '58', '59', '**'
+Units can be listed separated by commas.
+
+Examples:
+'*:**:**:**' - every second of every minute of every hour of every day
+'*:**:**:*5' - every 05,15,25,35,45,55 seconds of every minute of every hour of every day
+'*:2*:**:**' - every second of every minute of every 20,21,22,23 hours of every day
+'*:2*:**:*5' - every 05,15,25,35,45,55 seconds of every minute of every 20,21,22,23 hours of every day
+'3,5:2*:**:*5' - every 05,15,25,35,45,55 seconds every minute every 20,21,22,23 hours of Wednesday, Friday
+'1,7:12:00:**' - every second 00 minutes 12 hours of Monday, Sunday
+'1:07:00:00' - every 00 seconds 00 minutes 07 hours Monday
+"""
+
+from itertools import cycle
+from time import sleep
+from threading import Event, Thread
+from . import schedule
+
+
+class Scheduler:
+    """
+    Control wrapper for the schedule package
+    """
+    def __init__(self):
+        """
+        Object constructor
+        """
+        self.scheduler_entity = schedule.Scheduler()
+        self.scheduler_signal = None
+
+    def _start_thread(self, interval: int = 1):
+        """
+        Running the scheduler with a thread in the background
+        :param interval: an integer specifying the period in seconds to start pending jobs
+        """
+        signal = Event()
+
+        class ScheduleThread(Thread):
+            @classmethod
+            def run(cls):
+                while not signal.is_set():
+                    self.scheduler_entity.run_pending()
+                    sleep(interval)
+
+        ScheduleThread().start()
+        return signal
+
+    def start(self):
+        """
+        Scheduler launch
+        """
+        self.scheduler_signal = self._start_thread()
+
+    def stop(self):
+        """
+        Stopping the Scheduler
+        """
+        self.scheduler_signal.set()
+
+    def add(self, target: str, action):
+        """
+        Adding a job to the execution queue
+        :param target: a string in the format wD:HH:MM:SS specifying the target of the launch time
+        :param action: a string with the name of the function to run
+        """
+        target_undefined = target.split(':')
+        if len(target_undefined) == 4:
+            wd, hh, mm, ss = target_undefined[0], target_undefined[1], target_undefined[2], target_undefined[3]
+            if '*' in wd and '**' in hh and '**' in mm and '**' in ss:
+                self.scheduler_entity.every().seconds.do(action)
+            elif '*' in wd and '**' in hh and '**' in mm:
+                for element in self._expand_target(wd.split(','),
+                                                   hh.split(','),
+                                                   mm.split(','),
+                                                   self._expand_time(ss, 'ss')):
+                    ss = element[3]
+                    self.scheduler_entity.every().minute.at(':' + ss).do(action)
+            elif '*' in wd and '**' in hh:
+                for element in self._expand_target(wd.split(','),
+                                                   hh.split(','),
+                                                   self._expand_time(mm, 'mm'),
+                                                   self._expand_time(ss, 'ss')):
+                    mm, ss = element[2], element[3]
+                    self.scheduler_entity.every().hour.at(mm + ':' + ss).do(action)
+                pass
+            elif '*' in wd:
+                for element in self._expand_target(wd.split(','),
+                                                   self._expand_time(hh, 'hh'),
+                                                   self._expand_time(mm, 'mm'),
+                                                   self._expand_time(ss, 'ss')):
+                    hh, mm, ss = element[1], element[2], element[3]
+                    self.scheduler_entity.every().day.at(hh + ':' + mm + ':' + ss).do(action)
+            else:
+                for element in self._expand_target(self._expand_time(wd, 'wd'),
+                                                   self._expand_time(hh, 'hh'),
+                                                   self._expand_time(mm, 'mm'),
+                                                   self._expand_time(ss, 'ss')):
+                    wd, hh, mm, ss = element[0], element[1], element[2], element[3]
+                    if wd == '1':
+                        self.scheduler_entity.every().monday.at(hh + ':' + mm + ':' + ss).do(action)
+                    elif wd == '2':
+                        self.scheduler_entity.every().tuesday.at(hh + ':' + mm + ':' + ss).do(action)
+                    elif wd == '3':
+                        self.scheduler_entity.every().wednesday.at(hh + ':' + mm + ':' + ss).do(action)
+                    elif wd == '4':
+                        self.scheduler_entity.every().thursday.at(hh + ':' + mm + ':' + ss).do(action)
+                    elif wd == '5':
+                        self.scheduler_entity.every().friday.at(hh + ':' + mm + ':' + ss).do(action)
+                    elif wd == '6':
+                        self.scheduler_entity.every().saturday.at(hh + ':' + mm + ':' + ss).do(action)
+                    elif wd == '7':
+                        self.scheduler_entity.every().sunday.at(hh + ':' + mm + ':' + ss).do(action)
+
+    @classmethod
+    def _expand_time(cls, time_raw: str, unit: str):
+        """
+        Converts an undefined time units to a list of specific time units
+        :param time_raw: a string with time unit
+        :param unit: string description of the time unit
+        :return: list of specific time units
+        """
+        if ',' in time_raw:
+            pass
+        elif '*' in time_raw and (unit == 'wd' or unit == 'hh' or unit == 'mm' or unit == 'ss'):
+            time_out, time_min, time_max = [], 0, 60
+            if unit == 'hh':
+                time_max = 24
+            if unit == 'wd':
+                time_min, time_max = 1, 8
+            for i in range(time_max):
+                out = time_raw.replace('**', format(i, '02d')).replace('*', str(i))
+                if 0 <= int(out) < time_max:
+                    time_out.append(out)
+            return time_out
+        return time_raw.split(',')
+
+    @classmethod
+    def _expand_target(cls, wd: list, hh: list, mm: list, ss: list):
+        """
+        Converts an undefined target to a list of specific target
+        :param wd: list with day of week time units
+        :param hh: list with hour time units
+        :param mm: list with minute time units
+        :param ss: list with second time units
+        :return: list of specific time targets
+        """
+        cwd, chh, cmm, css = cycle(wd), cycle(hh), cycle(mm), cycle(ss)
+        target_defined = []
+        for a in range(len(wd)):
+            a_wd = next(cwd)
+            for b in range(len(hh)):
+                b_hh = next(chh)
+                for c in range(len(mm)):
+                    c_mm = next(cmm)
+                    for d in range(len(ss)):
+                        d_ss = next(css)
+                        target_defined.append([a_wd, b_hh, c_mm, d_ss])
+        return target_defined
+
+
+if __name__ == "__main__":
+    pass

cronutil/schedule/__init__.py

@@ -0,0 +1,839 @@
+"""
+Python job scheduling for humans.
+
+github.com/dbader/schedule
+
+An in-process scheduler for periodic jobs that uses the builder pattern
+for configuration. Schedule lets you run Python functions (or any other
+callable) periodically at pre-determined intervals using a simple,
+human-friendly syntax.
+
+Inspired by Addam Wiggins' article "Rethinking Cron" [1] and the
+"clockwork" Ruby module [2][3].
+
+Features:
+    - A simple to use API for scheduling jobs.
+    - Very lightweight and no external dependencies.
+    - Excellent test coverage.
+    - Tested on Python 3.6, 3.7, 3.8, 3.9
+
+Usage:
+    >>> import schedule
+    >>> import time
+
+    >>> def job(message='stuff'):
+    >>>     print("I'm working on:", message)
+
+    >>> schedule.every(10).minutes.do(job)
+    >>> schedule.every(5).to(10).days.do(job)
+    >>> schedule.every().hour.do(job, message='things')
+    >>> schedule.every().day.at("10:30").do(job)
+
+    >>> while True:
+    >>>     schedule.run_pending()
+    >>>     time.sleep(1)
+
+[1] https://adam.herokuapp.com/past/2010/4/13/rethinking_cron/
+[2] https://github.com/Rykian/clockwork
+[3] https://adam.herokuapp.com/past/2010/6/30/replace_cron_with_clockwork/
+"""
+from collections.abc import Hashable
+import datetime
+import functools
+import logging
+import random
+import re
+import time
+from typing import Set, List, Optional, Callable, Union
+
+logger = logging.getLogger("schedule")
+
+
+class ScheduleError(Exception):
+    """Base schedule exception"""
+
+    pass
+
+
+class ScheduleValueError(ScheduleError):
+    """Base schedule value error"""
+
+    pass
+
+
+class IntervalError(ScheduleValueError):
+    """An improper interval was used"""
+
+    pass
+
+
+class CancelJob(object):
+    """
+    Can be returned from a job to unschedule itself.
+    """
+
+    pass
+
+
+class Scheduler(object):
+    """
+    Objects instantiated by the :class:`Scheduler <Scheduler>` are
+    factories to create jobs, keep record of scheduled jobs and
+    handle their execution.
+    """
+
+    def __init__(self) -> None:
+        self.jobs: List[Job] = []
+
+    def run_pending(self) -> None:
+        """
+        Run all jobs that are scheduled to run.
+
+        Please note that it is *intended behavior that run_pending()
+        does not run missed jobs*. For example, if you've registered a job
+        that should run every minute and you only call run_pending()
+        in one hour increments then your job won't be run 60 times in
+        between but only once.
+        """
+        runnable_jobs = (job for job in self.jobs if job.should_run)
+        for job in sorted(runnable_jobs):
+            self._run_job(job)
+
+    def run_all(self, delay_seconds: int = 0) -> None:
+        """
+        Run all jobs regardless if they are scheduled to run or not.
+
+        A delay of `delay` seconds is added between each job. This helps
+        distribute system load generated by the jobs more evenly
+        over time.
+
+        :param delay_seconds: A delay added between every executed job
+        """
+        logger.debug(
+            "Running *all* %i jobs with %is delay in between",
+            len(self.jobs),
+            delay_seconds,
+        )
+        for job in self.jobs[:]:
+            self._run_job(job)
+            time.sleep(delay_seconds)
+
+    def get_jobs(self, tag: Optional[Hashable] = None) -> List["Job"]:
+        """
+        Gets scheduled jobs marked with the given tag, or all jobs
+        if tag is omitted.
+
+        :param tag: An identifier used to identify a subset of
+                    jobs to retrieve
+        """
+        if tag is None:
+            return self.jobs[:]
+        else:
+            return [job for job in self.jobs if tag in job.tags]
+
+    def clear(self, tag: Optional[Hashable] = None) -> None:
+        """
+        Deletes scheduled jobs marked with the given tag, or all jobs
+        if tag is omitted.
+
+        :param tag: An identifier used to identify a subset of
+                    jobs to delete
+        """
+        if tag is None:
+            logger.debug("Deleting *all* jobs")
+            del self.jobs[:]
+        else:
+            logger.debug('Deleting all jobs tagged "%s"', tag)
+            self.jobs[:] = (job for job in self.jobs if tag not in job.tags)
+
+    def cancel_job(self, job: "Job") -> None:
+        """
+        Delete a scheduled job.
+
+        :param job: The job to be unscheduled
+        """
+        try:
+            logger.debug('Cancelling job "%s"', str(job))
+            self.jobs.remove(job)
+        except ValueError:
+            logger.debug('Cancelling not-scheduled job "%s"', str(job))
+
+    def every(self, interval: int = 1) -> "Job":
+        """
+        Schedule a new periodic job.
+
+        :param interval: A quantity of a certain time unit
+        :return: An unconfigured :class:`Job <Job>`
+        """
+        job = Job(interval, self)
+        return job
+
+    def _run_job(self, job: "Job") -> None:
+        ret = job.run()
+        if isinstance(ret, CancelJob) or ret is CancelJob:
+            self.cancel_job(job)
+
+    @property
+    def next_run(self) -> Optional[datetime.datetime]:
+        """
+        Datetime when the next job should run.
+
+        :return: A :class:`~datetime.datetime` object
+                 or None if no jobs scheduled
+        """
+        if not self.jobs:
+            return None
+        return min(self.jobs).next_run
+
+    @property
+    def idle_seconds(self) -> Optional[float]:
+        """
+        :return: Number of seconds until
+                 :meth:`next_run <Scheduler.next_run>`
+                 or None if no jobs are scheduled
+        """
+        if not self.next_run:
+            return None
+        return (self.next_run - datetime.datetime.now()).total_seconds()
+
+
+class Job(object):
+    """
+    A periodic job as used by :class:`Scheduler`.
+
+    :param interval: A quantity of a certain time unit
+    :param scheduler: The :class:`Scheduler <Scheduler>` instance that
+                      this job will register itself with once it has
+                      been fully configured in :meth:`Job.do()`.
+
+    Every job runs at a given fixed time interval that is defined by:
+
+    * a :meth:`time unit <Job.second>`
+    * a quantity of `time units` defined by `interval`
+
+    A job is usually created and returned by :meth:`Scheduler.every`
+    method, which also defines its `interval`.
+    """
+
+    def __init__(self, interval: int, scheduler: Scheduler = None):
+        self.interval: int = interval  # pause interval * unit between runs
+        self.latest: Optional[int] = None  # upper limit to the interval
+        self.job_func: Optional[functools.partial] = None  # the job job_func to run
+
+        # time units, e.g. 'minutes', 'hours', ...
+        self.unit: Optional[str] = None
+
+        # optional time at which this job runs
+        self.at_time: Optional[datetime.time] = None
+
+        # datetime of the last run
+        self.last_run: Optional[datetime.datetime] = None
+
+        # datetime of the next run
+        self.next_run: Optional[datetime.datetime] = None
+
+        # timedelta between runs, only valid for
+        self.period: Optional[datetime.timedelta] = None
+
+        # Specific day of the week to start on
+        self.start_day: Optional[str] = None
+
+        # optional time of final run
+        self.cancel_after: Optional[datetime.datetime] = None
+
+        self.tags: Set[Hashable] = set()  # unique set of tags for the job
+        self.scheduler: Optional[Scheduler] = scheduler  # scheduler to register with
+
+    def __lt__(self, other) -> bool:
+        """
+        PeriodicJobs are sortable based on the scheduled time they
+        run next.
+        """
+        return self.next_run < other.next_run
+
+    def __str__(self) -> str:
+        if hasattr(self.job_func, "__name__"):
+            job_func_name = self.job_func.__name__  # type: ignore
+        else:
+            job_func_name = repr(self.job_func)
+
+        return ("Job(interval={}, unit={}, do={}, args={}, kwargs={})").format(
+            self.interval,
+            self.unit,
+            job_func_name,
+            "()" if self.job_func is None else self.job_func.args,
+            "{}" if self.job_func is None else self.job_func.keywords,
+        )
+
+    def __repr__(self):
+        def format_time(t):
+            return t.strftime("%Y-%m-%d %H:%M:%S") if t else "[never]"
+
+        def is_repr(j):
+            return not isinstance(j, Job)
+
+        timestats = "(last run: %s, next run: %s)" % (
+            format_time(self.last_run),
+            format_time(self.next_run),
+        )
+
+        if hasattr(self.job_func, "__name__"):
+            job_func_name = self.job_func.__name__
+        else:
+            job_func_name = repr(self.job_func)
+        args = [repr(x) if is_repr(x) else str(x) for x in self.job_func.args]
+        kwargs = ["%s=%s" % (k, repr(v)) for k, v in self.job_func.keywords.items()]
+        call_repr = job_func_name + "(" + ", ".join(args + kwargs) + ")"
+
+        if self.at_time is not None:
+            return "Every %s %s at %s do %s %s" % (
+                self.interval,
+                self.unit[:-1] if self.interval == 1 else self.unit,
+                self.at_time,
+                call_repr,
+                timestats,
+            )
+        else:
+            fmt = (
+                "Every %(interval)s "
+                + ("to %(latest)s " if self.latest is not None else "")
+                + "%(unit)s do %(call_repr)s %(timestats)s"
+            )
+
+            return fmt % dict(
+                interval=self.interval,
+                latest=self.latest,
+                unit=(self.unit[:-1] if self.interval == 1 else self.unit),
+                call_repr=call_repr,
+                timestats=timestats,
+            )
+
+    @property
+    def second(self):
+        if self.interval != 1:
+            raise IntervalError("Use seconds instead of second")
+        return self.seconds
+
+    @property
+    def seconds(self):
+        self.unit = "seconds"
+        return self
+
+    @property
+    def minute(self):
+        if self.interval != 1:
+            raise IntervalError("Use minutes instead of minute")
+        return self.minutes
+
+    @property
+    def minutes(self):
+        self.unit = "minutes"
+        return self
+
+    @property
+    def hour(self):
+        if self.interval != 1:
+            raise IntervalError("Use hours instead of hour")
+        return self.hours
+
+    @property
+    def hours(self):
+        self.unit = "hours"
+        return self
+
+    @property
+    def day(self):
+        if self.interval != 1:
+            raise IntervalError("Use days instead of day")
+        return self.days
+
+    @property
+    def days(self):
+        self.unit = "days"
+        return self
+
+    @property
+    def week(self):
+        if self.interval != 1:
+            raise IntervalError("Use weeks instead of week")
+        return self.weeks
+
+    @property
+    def weeks(self):
+        self.unit = "weeks"
+        return self
+
+    @property
+    def monday(self):
+        if self.interval != 1:
+            raise IntervalError(
+                "Scheduling .monday() jobs is only allowed for weekly jobs. "
+                "Using .monday() on a job scheduled to run every 2 or more weeks "
+                "is not supported."
+            )
+        self.start_day = "monday"
+        return self.weeks
+
+    @property
+    def tuesday(self):
+        if self.interval != 1:
+            raise IntervalError(
+                "Scheduling .tuesday() jobs is only allowed for weekly jobs. "
+                "Using .tuesday() on a job scheduled to run every 2 or more weeks "
+                "is not supported."
+            )
+        self.start_day = "tuesday"
+        return self.weeks
+
+    @property
+    def wednesday(self):
+        if self.interval != 1:
+            raise IntervalError(
+                "Scheduling .wednesday() jobs is only allowed for weekly jobs. "
+                "Using .wednesday() on a job scheduled to run every 2 or more weeks "
+                "is not supported."
+            )
+        self.start_day = "wednesday"
+        return self.weeks
+
+    @property
+    def thursday(self):
+        if self.interval != 1:
+            raise IntervalError(
+                "Scheduling .thursday() jobs is only allowed for weekly jobs. "
+                "Using .thursday() on a job scheduled to run every 2 or more weeks "
+                "is not supported."
+            )
+        self.start_day = "thursday"
+        return self.weeks
+
+    @property
+    def friday(self):
+        if self.interval != 1:
+            raise IntervalError(
+                "Scheduling .friday() jobs is only allowed for weekly jobs. "
+                "Using .friday() on a job scheduled to run every 2 or more weeks "
+                "is not supported."
+            )
+        self.start_day = "friday"
+        return self.weeks
+
+    @property
+    def saturday(self):
+        if self.interval != 1:
+            raise IntervalError(
+                "Scheduling .saturday() jobs is only allowed for weekly jobs. "
+                "Using .saturday() on a job scheduled to run every 2 or more weeks "
+                "is not supported."
+            )
+        self.start_day = "saturday"
+        return self.weeks
+
+    @property
+    def sunday(self):
+        if self.interval != 1:
+            raise IntervalError(
+                "Scheduling .sunday() jobs is only allowed for weekly jobs. "
+                "Using .sunday() on a job scheduled to run every 2 or more weeks "
+                "is not supported."
+            )
+        self.start_day = "sunday"
+        return self.weeks
+
+    def tag(self, *tags: Hashable):
+        """
+        Tags the job with one or more unique identifiers.
+
+        Tags must be hashable. Duplicate tags are discarded.
+
+        :param tags: A unique list of ``Hashable`` tags.
+        :return: The invoked job instance
+        """
+        if not all(isinstance(tag, Hashable) for tag in tags):
+            raise TypeError("Tags must be hashable")
+        self.tags.update(tags)
+        return self
+
+    def at(self, time_str):
+
+        """
+        Specify a particular time that the job should be run at.
+
+        :param time_str: A string in one of the following formats:
+
+            - For daily jobs -> `HH:MM:SS` or `HH:MM`
+            - For hourly jobs -> `MM:SS` or `:MM`
+            - For minute jobs -> `:SS`
+
+            The format must make sense given how often the job is
+            repeating; for example, a job that repeats every minute
+            should not be given a string in the form `HH:MM:SS`. The
+            difference between `:MM` and :SS` is inferred from the
+            selected time-unit (e.g. `every().hour.at(':30')` vs.
+            `every().minute.at(':30')`).
+
+        :return: The invoked job instance
+        """
+        if self.unit not in ("days", "hours", "minutes") and not self.start_day:
+            raise ScheduleValueError(
+                "Invalid unit (valid units are `days`, `hours`, and `minutes`)"
+            )
+        if not isinstance(time_str, str):
+            raise TypeError("at() should be passed a string")
+        if self.unit == "days" or self.start_day:
+            if not re.match(r"^([0-2]\d:)?[0-5]\d:[0-5]\d$", time_str):
+                raise ScheduleValueError(
+                    "Invalid time format for a daily job (valid format is HH:MM(:SS)?)"
+                )
+        if self.unit == "hours":
+            if not re.match(r"^([0-5]\d)?:[0-5]\d$", time_str):
+                raise ScheduleValueError(
+                    "Invalid time format for an hourly job (valid format is (MM)?:SS)"
+                )
+
+        if self.unit == "minutes":
+            if not re.match(r"^:[0-5]\d$", time_str):
+                raise ScheduleValueError(
+                    "Invalid time format for a minutely job (valid format is :SS)"
+                )
+        time_values = time_str.split(":")
+        hour: Union[str, int]
+        minute: Union[str, int]
+        second: Union[str, int]
+        if len(time_values) == 3:
+            hour, minute, second = time_values
+        elif len(time_values) == 2 and self.unit == "minutes":
+            hour = 0
+            minute = 0
+            _, second = time_values
+        elif len(time_values) == 2 and self.unit == "hours" and len(time_values[0]):
+            hour = 0
+            minute, second = time_values
+        else:
+            hour, minute = time_values
+            second = 0
+        if self.unit == "days" or self.start_day:
+            hour = int(hour)
+            if not (0 <= hour <= 23):
+                raise ScheduleValueError(
+                    "Invalid number of hours ({} is not between 0 and 23)"
+                )
+        elif self.unit == "hours":
+            hour = 0
+        elif self.unit == "minutes":
+            hour = 0
+            minute = 0
+        minute = int(minute)
+        second = int(second)
+        self.at_time = datetime.time(hour, minute, second)
+        return self
+
+    def to(self, latest: int):
+        """
+        Schedule the job to run at an irregular (randomized) interval.
+
+        The job's interval will randomly vary from the value given
+        to  `every` to `latest`. The range defined is inclusive on
+        both ends. For example, `every(A).to(B).seconds` executes
+        the job function every N seconds such that A <= N <= B.
+
+        :param latest: Maximum interval between randomized job runs
+        :return: The invoked job instance
+        """
+        self.latest = latest
+        return self
+
+    def until(
+        self,
+        until_time: Union[datetime.datetime, datetime.timedelta, datetime.time, str],
+    ):
+        """
+        Schedule job to run until the specified moment.
+
+        The job is canceled whenever the next run is calculated and it turns out the
+        next run is after the until_time. The job is also canceled right before it runs,
+        if the current time is after until_time. This latter case can happen when the
+        the job was scheduled to run before until_time, but runs after until_time.
+
+        If until_time is a moment in the past, ScheduleValueError is thrown.
+
+        :param until_time: A moment in the future representing the latest time a job can
+           be run. If only a time is supplied, the date is set to today.
+           The following formats are accepted:
+
+           - datetime.datetime
+           -  datetime.timedelta
+           - datetime.time
+           - String in one of the following formats: "%Y-%m-%d %H:%M:%S",
+             "%Y-%m-%d %H:%M", "%Y-%m-%d", "%H:%M:%S", "%H:%M"
+             as defined by strptime() behaviour. If an invalid string format is passed,
+             ScheduleValueError is thrown.
+
+        :return: The invoked job instance
+        """
+
+        if isinstance(until_time, datetime.datetime):
+            self.cancel_after = until_time
+        elif isinstance(until_time, datetime.timedelta):
+            self.cancel_after = datetime.datetime.now() + until_time
+        elif isinstance(until_time, datetime.time):
+            self.cancel_after = datetime.datetime.combine(
+                datetime.datetime.now(), until_time
+            )
+        elif isinstance(until_time, str):
+            cancel_after = self._decode_datetimestr(
+                until_time,
+                [
+                    "%Y-%m-%d %H:%M:%S",
+                    "%Y-%m-%d %H:%M",
+                    "%Y-%m-%d",
+                    "%H:%M:%S",
+                    "%H:%M",
+                ],
+            )
+            if cancel_after is None:
+                raise ScheduleValueError("Invalid string format for until()")
+            if "-" not in until_time:
+                # the until_time is a time-only format. Set the date to today
+                now = datetime.datetime.now()
+                cancel_after = cancel_after.replace(
+                    year=now.year, month=now.month, day=now.day
+                )
+            self.cancel_after = cancel_after
+        else:
+            raise TypeError(
+                "until() takes a string, datetime.datetime, datetime.timedelta, "
+                "datetime.time parameter"
+            )
+        if self.cancel_after < datetime.datetime.now():
+            raise ScheduleValueError(
+                "Cannot schedule a job to run until a time in the past"
+            )
+        return self
+
+    def do(self, job_func: Callable, *args, **kwargs):
+        """
+        Specifies the job_func that should be called every time the
+        job runs.
+
+        Any additional arguments are passed on to job_func when
+        the job runs.
+
+        :param job_func: The function to be scheduled
+        :return: The invoked job instance
+        """
+        self.job_func = functools.partial(job_func, *args, **kwargs)
+        functools.update_wrapper(self.job_func, job_func)
+        self._schedule_next_run()
+        if self.scheduler is None:
+            raise ScheduleError(
+                "Unable to a add job to schedule. "
+                "Job is not associated with an scheduler"
+            )
+        self.scheduler.jobs.append(self)
+        return self
+
+    @property
+    def should_run(self) -> bool:
+        """
+        :return: ``True`` if the job should be run now.
+        """
+        assert self.next_run is not None, "must run _schedule_next_run before"
+        return datetime.datetime.now() >= self.next_run
+
+    def run(self):
+        """
+        Run the job and immediately reschedule it.
+        If the job's deadline is reached (configured using .until()), the job is not
+        run and CancelJob is returned immediately. If the next scheduled run exceeds
+        the job's deadline, CancelJob is returned after the execution. In this latter
+        case CancelJob takes priority over any other returned value.
+
+        :return: The return value returned by the `job_func`, or CancelJob if the job's
+                 deadline is reached.
+
+        """
+        if self._is_overdue(datetime.datetime.now()):
+            logger.debug("Cancelling job %s", self)
+            return CancelJob
+
+        logger.debug("Running job %s", self)
+        ret = self.job_func()
+        self.last_run = datetime.datetime.now()
+        self._schedule_next_run()
+
+        if self._is_overdue(self.next_run):
+            logger.debug("Cancelling job %s", self)
+            return CancelJob
+        return ret
+
+    def _schedule_next_run(self) -> None:
+        """
+        Compute the instant when this job should run next.
+        """
+        if self.unit not in ("seconds", "minutes", "hours", "days", "weeks"):
+            raise ScheduleValueError(
+                "Invalid unit (valid units are `seconds`, `minutes`, `hours`, "
+                "`days`, and `weeks`)"
+            )
+
+        if self.latest is not None:
+            if not (self.latest >= self.interval):
+                raise ScheduleError("`latest` is greater than `interval`")
+            interval = random.randint(self.interval, self.latest)
+        else:
+            interval = self.interval
+
+        self.period = datetime.timedelta(**{self.unit: interval})
+        self.next_run = datetime.datetime.now() + self.period
+        if self.start_day is not None:
+            if self.unit != "weeks":
+                raise ScheduleValueError("`unit` should be 'weeks'")
+            weekdays = (
+                "monday",
+                "tuesday",
+                "wednesday",
+                "thursday",
+                "friday",
+                "saturday",
+                "sunday",
+            )
+            if self.start_day not in weekdays:
+                raise ScheduleValueError(
+                    "Invalid start day (valid start days are {})".format(weekdays)
+                )
+            weekday = weekdays.index(self.start_day)
+            days_ahead = weekday - self.next_run.weekday()
+            if days_ahead <= 0:  # Target day already happened this week
+                days_ahead += 7
+            self.next_run += datetime.timedelta(days_ahead) - self.period
+        if self.at_time is not None:
+            if self.unit not in ("days", "hours", "minutes") and self.start_day is None:
+                raise ScheduleValueError("Invalid unit without specifying start day")
+            kwargs = {"second": self.at_time.second, "microsecond": 0}
+            if self.unit == "days" or self.start_day is not None:
+                kwargs["hour"] = self.at_time.hour
+            if self.unit in ["days", "hours"] or self.start_day is not None:
+                kwargs["minute"] = self.at_time.minute
+            self.next_run = self.next_run.replace(**kwargs)  # type: ignore
+            # Make sure we run at the specified time *today* (or *this hour*)
+            # as well. This accounts for when a job takes so long it finished
+            # in the next period.
+            if not self.last_run or (self.next_run - self.last_run) > self.period:
+                now = datetime.datetime.now()
+                if (
+                    self.unit == "days"
+                    and self.at_time > now.time()
+                    and self.interval == 1
+                ):
+                    self.next_run = self.next_run - datetime.timedelta(days=1)
+                elif self.unit == "hours" and (
+                    self.at_time.minute > now.minute
+                    or (
+                        self.at_time.minute == now.minute
+                        and self.at_time.second > now.second
+                    )
+                ):
+                    self.next_run = self.next_run - datetime.timedelta(hours=1)
+                elif self.unit == "minutes" and self.at_time.second > now.second:
+                    self.next_run = self.next_run - datetime.timedelta(minutes=1)
+        if self.start_day is not None and self.at_time is not None:
+            # Let's see if we will still make that time we specified today
+            if (self.next_run - datetime.datetime.now()).days >= 7:
+                self.next_run -= self.period
+
+    def _is_overdue(self, when: datetime.datetime):
+        return self.cancel_after is not None and when > self.cancel_after
+
+    def _decode_datetimestr(
+        self, datetime_str: str, formats: List[str]
+    ) -> Optional[datetime.datetime]:
+        for f in formats:
+            try:
+                return datetime.datetime.strptime(datetime_str, f)
+            except ValueError:
+                pass
+        return None
+
+
+# The following methods are shortcuts for not having to
+# create a Scheduler instance:
+
+#: Default :class:`Scheduler <Scheduler>` object
+default_scheduler = Scheduler()
+
+#: Default :class:`Jobs <Job>` list
+jobs = default_scheduler.jobs  # todo: should this be a copy, e.g. jobs()?
+
+
+def every(interval: int = 1) -> Job:
+    """Calls :meth:`every <Scheduler.every>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    return default_scheduler.every(interval)
+
+
+def run_pending() -> None:
+    """Calls :meth:`run_pending <Scheduler.run_pending>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    default_scheduler.run_pending()
+
+
+def run_all(delay_seconds: int = 0) -> None:
+    """Calls :meth:`run_all <Scheduler.run_all>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    default_scheduler.run_all(delay_seconds=delay_seconds)
+
+
+def get_jobs(tag: Optional[Hashable] = None) -> List[Job]:
+    """Calls :meth:`get_jobs <Scheduler.get_jobs>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    return default_scheduler.get_jobs(tag)
+
+
+def clear(tag: Optional[Hashable] = None) -> None:
+    """Calls :meth:`clear <Scheduler.clear>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    default_scheduler.clear(tag)
+
+
+def cancel_job(job: Job) -> None:
+    """Calls :meth:`cancel_job <Scheduler.cancel_job>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    default_scheduler.cancel_job(job)
+
+
+def next_run() -> Optional[datetime.datetime]:
+    """Calls :meth:`next_run <Scheduler.next_run>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    return default_scheduler.next_run
+
+
+def idle_seconds() -> Optional[float]:
+    """Calls :meth:`idle_seconds <Scheduler.idle_seconds>` on the
+    :data:`default scheduler instance <default_scheduler>`.
+    """
+    return default_scheduler.idle_seconds
+
+
+def repeat(job, *args, **kwargs):
+    """
+    Decorator to schedule a new periodic job.
+
+    Any additional arguments are passed on to the decorated function
+    when the job runs.
+
+    :param job: a :class:`Jobs <Job>`
+    """
+
+    def _schedule_decorator(decorated_function):
+        job.do(decorated_function, *args, **kwargs)
+        return decorated_function
+
+    return _schedule_decorator