# ---------------------------------------------------------------------

# Section 3: Recurrence rules - schedules, holidays, and exceptions.

# ---------------------------------------------------------------------

# Package imports for the example.

from datetime import datetime

from dateutil.parser import parse

from dateutil.rrule import (

rrule, rruleset, rrulestr,

YEARLY, MONTHLY, WEEKLY, DAILY,

MO, TU, WE, TH, FR, SA, SU,

)

heading("3. rrule: generate schedules from recurrence rules")

note(

"rrule implements the iCalendar RECUR specification. You can "

"describe a schedule declaratively and iterate over its "

"occurrences, just like a calendar app does behind the scenes."

)

# A standing meeting: every other Tuesday and Thursday at 10:00,

# for the next eight occurrences.

standup = rrule(

WEEKLY,

interval=2,

byweekday=(TU, TH),

count=8,

dtstart=datetime(2024, 4, 2, 10, 0),

)

note("Bi-weekly stand-up on Tuesdays and Thursdays:")

display(HTML(

"<ul>"

+ "".join(f"<li>{when:%a %Y-%m-%d %H:%M}</li>" for when in standup)

+ "</ul>"

), append=True)

# Every Friday the 13th in the 21st century (first six).

unlucky = rrule(

YEARLY,

byweekday=FR,

bymonthday=13,

count=6,

dtstart=datetime(2024, 1, 1),

)

note("The next six Friday the 13ths:")

display(HTML(

"<ul>"

+ "".join(f"<li>{when:%A, %B %d, %Y}</li>" for when in unlucky)

+ "</ul>"

), append=True)

# US Presidential Election Day: first Tuesday after a Monday in

# November, every 4 years. The bymonthday=(2..8) clause forces the

# Tuesday to fall after the first Monday of the month.

elections = rrule(

YEARLY,

interval=4,

bymonth=11,

byweekday=TU,

bymonthday=(2, 3, 4, 5, 6, 7, 8),

count=4,

dtstart=datetime(2024, 1, 1),

)

note("Upcoming US Presidential Election Days:")

display(HTML(

"<ul>"

+ "".join(f"<li>{when:%A, %B %d, %Y}</li>" for when in elections)

+ "</ul>"

), append=True)

# ---------------------------------------------------------------------

# rruleset: combine rules and add or remove specific dates.

# ---------------------------------------------------------------------

heading("4. rruleset: combining rules with exceptions")

note(

"Real-world calendars are rarely a single clean rule. rruleset "

"lets you union multiple rules, add one-off dates with rdate, "

"and exclude dates with exdate."

)

# Daily for two weeks, but skip weekends and one specific holiday.

schedule = rruleset()

schedule.rrule(rrule(

DAILY,

count=14,

dtstart=datetime(2024, 7, 1, 9, 0),

))

# Exclude all Saturdays and Sundays in this range.

schedule.exrule(rrule(

DAILY,

byweekday=(SA, SU),

dtstart=datetime(2024, 7, 1, 9, 0),

until=datetime(2024, 7, 15, 9, 0),

))

# Exclude US Independence Day, which falls inside the window.

schedule.exdate(datetime(2024, 7, 4, 9, 0))

note("Working days in the first half of July 2024:")

display(HTML(

"<ul>"

+ "".join(f"<li>{when:%a %Y-%m-%d}</li>" for when in schedule)

+ "</ul>"

), append=True)

# ---------------------------------------------------------------------

# rrulestr: parse an iCalendar RRULE string directly.

# ---------------------------------------------------------------------

heading("5. rrulestr: parse iCalendar RRULE strings")

note(

"If you already have an RFC 5545 RRULE string (for example, from "

"an .ics file), rrulestr parses it directly."

)

ical_rule = """

DTSTART:20240115T080000

RRULE:FREQ=MONTHLY;BYDAY=3MO;COUNT=6

"""

note("Parsing: <code>FREQ=MONTHLY;BYDAY=3MO;COUNT=6</code> "

"(third Monday of the month, six times):")

occurrences = list(rrulestr(ical_rule))

display(HTML(

"<ul>"

+ "".join(f"<li>{when:%A, %B %d, %Y at %H:%M}</li>"

for when in occurrences)

+ "</ul>"

), append=True)