Support multiple Google Calendars

GOOGLE_CALENDAR_ID now accepts comma-separated calendar IDs:
  GOOGLE_CALENDAR_ID=cal1@group.calendar.google.com,cal2@gmail.com

Events from all calendars are merged and sorted by start time.
If one calendar fails to fetch, others still load.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 57 insertions, 29 deletions

diff --git a/internal/api/google_calendar.go b/internal/api/google_calendar.go
index 836d98c..8dd48f0 100644
--- a/internal/api/google_calendar.go
+++ b/internal/api/google_calendar.go
@@ -3,6 +3,9 @@ package api
 import (
 	"context"
 	"fmt"
+	"log"
+	"sort"
+	"strings"
 	"time"
 
 	"task-dashboard/internal/models"
@@ -12,51 +15,76 @@ import (
 )
 
 type GoogleCalendarClient struct {
-	srv        *calendar.Service
-	calendarID string
+	srv         *calendar.Service
+	calendarIDs []string
 }
 
-func NewGoogleCalendarClient(ctx context.Context, credentialsFile, calendarID string) (*GoogleCalendarClient, error) {
+// NewGoogleCalendarClient creates a client that fetches from multiple calendars.
+// calendarIDs can be comma-separated (e.g., "cal1@group.calendar.google.com,cal2@group.calendar.google.com")
+func NewGoogleCalendarClient(ctx context.Context, credentialsFile, calendarIDs string) (*GoogleCalendarClient, error) {
 	srv, err := calendar.NewService(ctx, option.WithCredentialsFile(credentialsFile))
 	if err != nil {
 		return nil, fmt.Errorf("unable to retrieve Calendar client: %v", err)
 	}
 
+	// Parse comma-separated calendar IDs
+	ids := strings.Split(calendarIDs, ",")
+	var trimmedIDs []string
+	for _, id := range ids {
+		if trimmed := strings.TrimSpace(id); trimmed != "" {
+			trimmedIDs = append(trimmedIDs, trimmed)
+		}
+	}
+
 	return &GoogleCalendarClient{
-		srv:        srv,
-		calendarID: calendarID,
+		srv:         srv,
+		calendarIDs: trimmedIDs,
 	}, nil
 }
 
 func (c *GoogleCalendarClient) GetUpcomingEvents(ctx context.Context, maxResults int) ([]models.CalendarEvent, error) {
 	t := time.Now().Format(time.RFC3339)
-	events, err := c.srv.Events.List(c.calendarID).ShowDeleted(false).
-		SingleEvents(true).TimeMin(t).MaxResults(int64(maxResults)).OrderBy("startTime").Do()
-	if err != nil {
-		return nil, fmt.Errorf("unable to retrieve events: %v", err)
-	}
+	var allEvents []models.CalendarEvent
 
-	var calendarEvents []models.CalendarEvent
-	for _, item := range events.Items {
-		var start, end time.Time
-		if item.Start.DateTime == "" {
-			// All-day event
-			start, _ = time.Parse("2006-01-02", item.Start.Date)
-			end, _ = time.Parse("2006-01-02", item.End.Date)
-		} else {
-			start, _ = time.Parse(time.RFC3339, item.Start.DateTime)
-			end, _ = time.Parse(time.RFC3339, item.End.DateTime)
+	for _, calendarID := range c.calendarIDs {
+		events, err := c.srv.Events.List(calendarID).ShowDeleted(false).
+			SingleEvents(true).TimeMin(t).MaxResults(int64(maxResults)).OrderBy("startTime").Do()
+		if err != nil {
+			log.Printf("Warning: failed to fetch events from calendar %s: %v", calendarID, err)
+			continue // Don't fail entirely, just skip this calendar
 		}
 
-		calendarEvents = append(calendarEvents, models.CalendarEvent{
-			ID:          item.Id,
-			Summary:     item.Summary,
-			Description: item.Description,
-			Start:       start,
-			End:         end,
-			HTMLLink:    item.HtmlLink,
-		})
+		for _, item := range events.Items {
+			var start, end time.Time
+			if item.Start.DateTime == "" {
+				// All-day event
+				start, _ = time.Parse("2006-01-02", item.Start.Date)
+				end, _ = time.Parse("2006-01-02", item.End.Date)
+			} else {
+				start, _ = time.Parse(time.RFC3339, item.Start.DateTime)
+				end, _ = time.Parse(time.RFC3339, item.End.DateTime)
+			}
+
+			allEvents = append(allEvents, models.CalendarEvent{
+				ID:          item.Id,
+				Summary:     item.Summary,
+				Description: item.Description,
+				Start:       start,
+				End:         end,
+				HTMLLink:    item.HtmlLink,
+			})
+		}
+	}
+
+	// Sort all events by start time
+	sort.Slice(allEvents, func(i, j int) bool {
+		return allEvents[i].Start.Before(allEvents[j].Start)
+	})
+
+	// Limit to maxResults
+	if len(allEvents) > maxResults {
+		allEvents = allEvents[:maxResults]
 	}
 
-	return calendarEvents, nil
+	return allEvents, nil
 }