1 files changed, 159 insertions, 0 deletions
diff --git a/examples/tools/agenda.py b/examples/tools/agenda.py
new file mode 100755
index 0000000..44bc34b
--- /dev/null
+++ b/examples/tools/agenda.py
@@ -0,0 +1,159 @@
+#!/usr/bin/env python3
+# desktop-assistant tool: events from a vdir (vdirsyncer's .ics folders).
+# Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License version 2 as published
+# by the Free Software Foundation.
+#
+# 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, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+"""agenda.py [START] [DAYS]: events from START (YYYY-MM-DD, empty = today)
+for DAYS days (empty = 1), one line each. Reads every .ics under
+CALENDAR_DIR (default ~/.local/share/calendars). --test runs the self-check.
+
+Not named calendar.py: that would shadow the stdlib module dateutil imports.
+"""
+
+import datetime as dt
+import glob
+import os
+import re
+import sys
+import time
+
+from dateutil import rrule, tz
+
+
+def unfold(text):
+    return re.sub(r"\r?\n[ \t]", "", text).splitlines()
+
+
+def events(text):
+    # The lines we need from each VEVENT; VTIMEZONE and VALARM are skipped,
+    # their RRULE and SUMMARY lines are not the event's.
+    ev, alarm = None, False
+    for line in unfold(text):
+        if line == "BEGIN:VEVENT":
+            ev = {"EXDATE": []}
+        elif line == "END:VEVENT":
+            yield ev
+            ev = None
+        elif line == "BEGIN:VALARM":
+            alarm = True
+        elif line == "END:VALARM":
+            alarm = False
+        elif ev is not None and not alarm:
+            name = re.split("[;:]", line, maxsplit=1)[0]
+            if name == "EXDATE":
+                ev["EXDATE"].append(line)
+            elif name in ("UID", "DTSTART", "RRULE", "RECURRENCE-ID", "SUMMARY"):
+                ev.setdefault(name, line)
+
+
+def local(params, value):
+    # ICS date or date-time to naive local time, and whether it is all-day.
+    if len(value) == 8:
+        return dt.datetime.strptime(value, "%Y%m%d"), True
+    t = dt.datetime.strptime(value.rstrip("Z"), "%Y%m%dT%H%M%S")
+    m = re.search(r"TZID=([^;:]+)", params)
+    zone = tz.UTC if value.endswith("Z") else tz.gettz(m.group(1)) if m else None
+    if zone:
+        t = t.replace(tzinfo=zone).astimezone(tz.tzlocal()).replace(tzinfo=None)
+    return t, False
+
+
+def when(line):
+    params, value = line.split(":", 1)
+    return local(params, value)
+
+
+def agenda(d, start, days):
+    # ponytail: naive local times, so a recurring event in a zone other than
+    # ours drifts by an hour across DST; multi-day events show on day one only.
+    lo = dt.datetime.fromisoformat(start)
+    hi = lo + dt.timedelta(days=days)
+    evs = []
+    for path in glob.glob(os.path.join(d, "**", "*.ics"), recursive=True):
+        with open(path, encoding="utf-8", errors="replace") as f:
+            evs += [e for e in events(f.read()) if "DTSTART" in e]
+    moved = {(e.get("UID"), when(e["RECURRENCE-ID"])[0]) for e in evs if "RECURRENCE-ID" in e}
+    out = []
+    for e in evs:
+        first, allday = when(e["DTSTART"])
+        if "RRULE" in e and "RECURRENCE-ID" not in e:
+            # dateutil rejects a UTC UNTIL next to a naive start: make it local.
+            rule = re.sub(r"UNTIL=(\d{8}T\d{6})Z",
+                          lambda m: "UNTIL=" + local("", m.group(1) + "Z")[0].strftime("%Y%m%dT%H%M%S"),
+                          e["RRULE"].split(":", 1)[1])
+            rs = rrule.rruleset()
+            rs.rrule(rrule.rrulestr(rule, dtstart=first))
+            for line in e["EXDATE"]:
+                params, values = line.split(":", 1)
+                for v in values.split(","):
+                    rs.exdate(local(params, v)[0])
+            for uid, t in moved:
+                if uid == e.get("UID"):
+                    rs.exdate(t)
+            occ = [t for t in rs.between(lo, hi, inc=True) if t < hi]
+        else:
+            occ = [first] if lo <= first < hi else []
+        summary = e.get("SUMMARY", "SUMMARY:(no title)").split(":", 1)[1]
+        summary = summary.replace("\\,", ",").replace("\\;", ";").replace("\\n", " ")
+        out += [(t, f"{t:%Y-%m-%d} {'all day' if allday else f'{t:%H:%M}'} {summary}")
+                for t in occ]
+    return [line for _, line in sorted(out)]
+
+
+def test():
+    import tempfile
+    os.environ["TZ"] = "Europe/Rome"
+    time.tzset()
+    cal = lambda body: f"BEGIN:VCALENDAR\r\nVERSION:2.0\r\n{body}END:VCALENDAR\r\n"
+    files = {
+        "once.ics": cal("BEGIN:VEVENT\r\nUID:a\r\nDTSTART:20261001T100000\r\n"
+                        "SUMMARY:Dentist\\, checkup\r\nEND:VEVENT\r\n"),
+        "yearly.ics": cal("BEGIN:VEVENT\r\nUID:b\r\nDTSTART;VALUE=DATE:19900312\r\n"
+                          "RRULE:FREQ=YEARLY\r\nSUMMARY:Birthday\r\n"
+                          "BEGIN:VALARM\r\nACTION:EMAIL\r\nSUMMARY:not the event\r\n"
+                          "END:VALARM\r\nEND:VEVENT\r\n"),
+        "weekly.ics": cal(
+            "BEGIN:VTIMEZONE\r\nTZID:Europe/Rome\r\nBEGIN:DAYLIGHT\r\nDTSTART:19700329T020000\r\n"
+            "RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU\r\nEND:DAYLIGHT\r\nEND:VTIMEZONE\r\n"
+            "BEGIN:VEVENT\r\nUID:c\r\nDTSTART;TZID=Europe/Rome:20260901T180000\r\n"
+            "RRULE:FREQ=WEEKLY;UNTIL=20261231T170000Z\r\n"
+            "EXDATE;TZID=Europe/Rome:20260908T180000\r\nSUMMARY:Gym\r\nEND:VEVENT\r\n"
+            "BEGIN:VEVENT\r\nUID:c\r\nRECURRENCE-ID;TZID=Europe/Rome:20260915T180000\r\n"
+            "DTSTART;TZID=Europe/Rome:20260916T190000\r\nSUMMARY:Gym moved\r\nEND:VEVENT\r\n"),
+        "utc.ics": cal("BEGIN:VEVENT\r\nUID:d\r\nDTSTART:20261001T160000Z\r\n"
+                       "SUMMARY:Call\r\nEND:VEVENT\r\n"),
+    }
+    with tempfile.TemporaryDirectory() as d:
+        os.mkdir(os.path.join(d, "cal"))
+        for name, text in files.items():
+            with open(os.path.join(d, "cal", name), "w", newline="") as f:
+                f.write(text)
+        assert agenda(d, "2026-09-01", 30) == [
+            "2026-09-01 18:00 Gym", "2026-09-16 19:00 Gym moved",
+            "2026-09-22 18:00 Gym", "2026-09-29 18:00 Gym"], agenda(d, "2026-09-01", 30)
+        assert agenda(d, "2026-03-10", 5) == ["2026-03-12 all day Birthday"]
+        assert agenda(d, "2026-10-01", 1) == [
+            "2026-10-01 10:00 Dentist, checkup", "2026-10-01 18:00 Call"]    # 16Z = 18 local
+        assert agenda(d, "2026-10-02", 1) == []
+    print("ok")
+
+
+if __name__ == "__main__":
+    if sys.argv[1:] == ["--test"]:
+        test()
+    else:
+        a = sys.argv[1:] + ["", ""]
+        d = os.environ.get("CALENDAR_DIR") or os.path.expanduser("~/.local/share/calendars")
+        print("\n".join(agenda(d, a[0] or dt.date.today().isoformat(), int(a[1] or 1)))
+              or "no events")