fix calendar export

hosts/www/caldav-export.py

@@ -1,5 +1,4 @@
 import argparse
-import os
 import re
 from pathlib import Path
 
@@ -12,7 +11,12 @@ def safe_filename(name: str) -> str:
     return re.sub(r"[^a-zA-Z0-9._-]+", "_", name)
 
 
-def export_calendar(url: str, username: str, password: str, calendar: str) -> Calendar:
+def export_calendar(
+    url: str,
+    username: str,
+    password: str,
+    calendar: str,
+) -> Calendar:
     client = DAVClient(
         url=url,
         username=username,
@@ -58,13 +62,45 @@ def export_calendar(url: str, username: str, password: str, calendar: str) -> Ca
 
         cal = Calendar.from_ical(data)
 
-        for component in cal.walk():
-            if component.name != "VCALENDAR":
-                result.add_component(component)
+        # Only copy top-level components.
+        #
+        # Do NOT use cal.walk() here. walk() also returns the
+        # STANDARD/DAYLIGHT components inside VTIMEZONE.
+        for component in cal.subcomponents:
+            result.add_component(component)
 
     return result
 
 
+def add_normalized_components(
+    target: Calendar,
+    source: Calendar,
+    timezones: dict[str, object],
+) -> None:
+    """
+    Add components from source to target while collecting VTIMEZONE
+    components separately.
+
+    Exactly one VTIMEZONE is retained for each TZID.
+    """
+
+    for component in source.subcomponents:
+        if component.name == "VTIMEZONE":
+            tzid = component.get("TZID")
+
+            if tzid is None:
+                print("  warning: ignoring VTIMEZONE without TZID")
+                continue
+
+            tzid = str(tzid)
+
+            if tzid not in timezones:
+                timezones[tzid] = component
+
+        else:
+            target.add_component(component)
+
+
 def main():
     parser = argparse.ArgumentParser()
     parser.add_argument("config")
@@ -81,12 +117,16 @@ def main():
     output_dir = Path(args.output)
     output_dir.mkdir(parents=True, exist_ok=True)
 
+    username = config["username"]
+    password = config["password"]
+
     combined = Calendar()
     combined.add("prodid", "-//Combined calendar//")
     combined.add("version", "2.0")
 
-    username = config["username"]
-    password = config["password"]
+    # TZID -> VTIMEZONE component
+    timezones = {}
+
     for entry in config["calendars"]:
         cal = export_calendar(
             entry["url"],
@@ -97,19 +137,37 @@ def main():
 
         filename = output_dir / f"{safe_filename(entry['calendar'])}.ics"
 
+        # Individual calendar export stays as-is.
         with open(filename, "wb") as f:
             f.write(cal.to_ical())
 
         print(f"  -> {filename}")
 
-        for component in cal.walk():
-            if component.name != "VCALENDAR":
-                combined.add_component(component)
+        # Normalize components for the combined calendar.
+        add_normalized_components(
+            combined,
+            cal,
+            timezones,
+        )
+
+    # Add each VTIMEZONE exactly once.
+    #
+    # Put them before events/components in the resulting VCALENDAR.
+    normalized = Calendar()
+    normalized.add("prodid", "-//Combined calendar//")
+    normalized.add("version", "2.0")
+
+    for tzid, timezone in timezones.items():
+        print(f"  timezone: {tzid}")
+        normalized.add_component(timezone)
+
+    for component in combined.subcomponents:
+        normalized.add_component(component)
 
     combined_file = output_dir / "all.ics"
 
     with open(combined_file, "wb") as f:
-        f.write(combined.to_ical())
+        f.write(normalized.to_ical())
 
     print()
     print(f"Combined export: {combined_file}")