From d28c20686263de15db8fac68ab830b306e586c1c Mon Sep 17 00:00:00 2001
From: sstent <stuart.stent@gmail.com>
Date: Tue, 17 Feb 2026 08:35:56 -0800
Subject: [PATCH] Bump version to 0.2.16 and add detailed offset logging

---
 icalendar.ts | 58 ++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 47 insertions(+), 11 deletions(-)

diff --git a/icalendar.ts b/icalendar.ts
index 1315410..9c089fb 100644
--- a/icalendar.ts
+++ b/icalendar.ts
@@ -1,10 +1,25 @@
 import { clientStore, config, datastore, editor, index } from "@silverbulletmd/silverbullet/syscalls";
 import { convertIcsCalendar, type IcsCalendar, type IcsEvent, type IcsDateObjects } from "ts-ics";
 
-const VERSION = "0.2.14";
+const VERSION = "0.2.15";
 const CACHE_KEY = "icalendar:lastSync";
 const DEFAULT_CACHE_DURATION_SECONDS = 21600; // 6 hours
 
+// Mapping of common Windows/Outlook timezones to their standard offsets (in hours)
+const TIMEZONE_OFFSETS: Record<string, number> = {
+  "GMT Standard Time": 0,
+  "W. Europe Standard Time": 1,
+  "Central Europe Standard Time": 1,
+  "Romance Standard Time": 1,
+  "Central European Standard Time": 1,
+  "Eastern Standard Time": -5,
+  "Central Standard Time": -6,
+  "Mountain Standard Time": -7,
+  "Pacific Standard Time": -8,
+  "UTC": 0,
+  "None": 0
+};
+
 console.log(`[iCalendar] Plug loading (Version ${VERSION})...`);
 
 // ============================================================================
@@ -53,21 +68,42 @@ function toLocalISO(d: Date): string {
 }
 
 /**
- * Simplified date processor that trusts the parsed Date object
+ * Robustly converts an ICS date object to a localized PST string
  */
 function processIcsDate(obj: any, manualShift = 0): string {
   if (!obj) return "";
 
-  // The 'date' property from ts-ics is already a native JS Date object
-  // which has been parsed with the correct TZID context if available.
-  const d = obj.date instanceof Date ? obj.date : (obj instanceof Date ? obj : null);
-  
-  if (!d) return "";
+  // 1. Get the "Wall Time" (the hour shown in the organizer's calendar)
+  // ts-ics often puts this in obj.local.date but marks it with 'Z'
+  let wallTimeStr = (obj.local && typeof obj.local.date === "string") 
+    ? obj.local.date 
+    : (typeof obj.date === "string" ? obj.date : "");
+    
+  if (!wallTimeStr) return "";
 
-  // Apply ONLY the user requested shift
-  const shiftedDate = new Date(d.getTime() + (manualShift * 3600000));
+  // Remove any 'Z' to treat it as a raw floating time initially
+  wallTimeStr = wallTimeStr.replace("Z", "");
   
-  return toLocalISO(shiftedDate);
+  // Parse as UTC so we have a stable starting point
+  const baseDate = new Date(wallTimeStr + "Z");
+  
+  // 2. Identify the Source Timezone
+  const tzName = obj.local?.timezone || obj.timezone || "UTC";
+  const sourceOffset = TIMEZONE_OFFSETS[tzName] ?? 0;
+  
+  // 3. Calculate True UTC
+  // UTC = WallTime - SourceOffset
+  // Example: 16:00 WallTime in GMT+1 (+1) -> 15:00 UTC
+  const utcMillis = baseDate.getTime() - (sourceOffset * 3600000);
+  
+  const envOffset = new Date().getTimezoneOffset();
+  console.log(`[iCalendar] Date Calc: Wall=${wallTimeStr}, TZ=${tzName}, SourceOffset=${sourceOffset}, EnvOffset=${envOffset}, UTC=${new Date(utcMillis).toISOString()}`);
+
+  // 4. Apply User's Manual Shift (if any)
+  const finalMillis = utcMillis + (manualShift * 3600000);
+
+  // 5. Localize to environment
+  return toLocalISO(new Date(finalMillis));
 }
 
 function isIcsDateObjects(obj: any): obj is IcsDateObjects {
@@ -196,4 +232,4 @@ export async function clearCache() {
 
 export async function showVersion() {
   await editor.flashNotification(`iCalendar Plug ${VERSION}`, "info");
-}
+}
\ No newline at end of file