Add Google Calendar integration

- Add GoogleCalendarClient for fetching upcoming events
- Add GoogleCalendarAPI interface and CalendarEvent model
- Add config for GOOGLE_CREDENTIALS_FILE and GOOGLE_CALENDAR_ID
- Display events in Planning tab with date/time formatting
- Update handlers and tests to support optional calendar client

Config env vars:
- GOOGLE_CREDENTIALS_FILE: Path to service account JSON
- GOOGLE_CALENDAR_ID: Calendar ID (defaults to "primary")

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

1 files changed, 21 insertions, 5 deletions

diff --git a/internal/handlers/tabs.go b/internal/handlers/tabs.go
index 2f22c44..b651dac 100644
--- a/internal/handlers/tabs.go
+++ b/internal/handlers/tabs.go
@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"task-dashboard/internal/api"
 	"task-dashboard/internal/models"
 	"task-dashboard/internal/store"
 )
@@ -46,12 +47,13 @@ func atomUrgencyTier(a models.Atom) int {
 
 // TabsHandler handles tab-specific rendering with Atom model
 type TabsHandler struct {
-	store     *store.Store
-	templates *template.Template
+	store                *store.Store
+	googleCalendarClient api.GoogleCalendarAPI
+	templates            *template.Template
 }
 
 // NewTabsHandler creates a new TabsHandler instance
-func NewTabsHandler(store *store.Store, templateDir string) *TabsHandler {
+func NewTabsHandler(store *store.Store, googleCalendarClient api.GoogleCalendarAPI, templateDir string) *TabsHandler {
 	// Parse templates including partials
 	tmpl, err := template.ParseGlob(filepath.Join(templateDir, "*.html"))
 	if err != nil {
@@ -65,8 +67,9 @@ func NewTabsHandler(store *store.Store, templateDir string) *TabsHandler {
 	}
 
 	return &TabsHandler{
-		store:     store,
-		templates: tmpl,
+		store:                store,
+		googleCalendarClient: googleCalendarClient,
+		templates:            tmpl,
 	}
 }
 
@@ -178,12 +181,25 @@ func (h *TabsHandler) HandlePlanning(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Fetch Google Calendar events
+	var events []models.CalendarEvent
+	if h.googleCalendarClient != nil {
+		var err error
+		events, err = h.googleCalendarClient.GetUpcomingEvents(r.Context(), 10)
+		if err != nil {
+			log.Printf("Error fetching calendar events: %v", err)
+			// Don't fail the whole request, just show empty events
+		}
+	}
+
 	data := struct {
 		Boards   []models.Board
 		Projects []models.Project
+		Events   []models.CalendarEvent
 	}{
 		Boards:   boards,
 		Projects: []models.Project{}, // Empty for now
+		Events:   events,
 	}
 
 	if err := h.templates.ExecuteTemplate(w, "planning-tab", data); err != nil {