Add Apple iCloud adapter

README.md

@@ -106,6 +106,7 @@ documentation [here](./docs/adapters.md).
 - Google
 - Outlook
 - [ZEP](https://www.zep.de/en/)
+- Apple
 
 ## Sink
 
@@ -128,6 +129,7 @@ documentation [here](./docs/adapters.md).
 
 - Google
 - Outlook
+- Apple
 
 ## Transformers
 
@@ -228,7 +230,7 @@ events which weren't synced with CalendarSync alone! :) )
 # Trademarks
 
 GOOGLE is a trademark of GOOGLE INC. OUTLOOK is a trademark of Microsoft
-Corporation
+Corporation. APPLE is a trademark of Apple Inc.
 
 # Relevant RFCs and Links
 

docs/adapters.md

@@ -88,3 +88,53 @@ sink:
 ```
 
 If you want to use the created OAuth Application also with accounts outside of your Google Workspace, make sure to set the Usertype to `external` in the `OAuth Consent Screen` Menu.
+
+## Apple CalDAV Adapter Setup
+
+The Apple CalDAV adapter allows synchronization with iCloud calendars using the industry-standard CalDAV protocol. This adapter works with any Apple ID that has iCloud calendar access enabled.
+
+### Prerequisites
+
+Before setting up the adapter, you need:
+- An Apple ID with iCloud enabled
+- Access to Apple ID account settings (appleid.apple.com)
+- The calendar identifier from your Calendar.app
+
+### Setting up App-Specific Password
+
+Since Apple requires two-factor authentication for iCloud access, you cannot use your regular Apple ID password. Instead, you must generate an app-specific password:
+
+1. Sign in to [appleid.apple.com](https://appleid.apple.com)
+2. Navigate to "Sign-In and Security"
+3. Select "App-Specific Passwords"
+4. Click "Generate an app-specific password"
+5. Enter a label like "CalendarSync"
+6. Copy the generated password (format: `xxxx-xxxx-xxxx-xxxx`)
+
+**Important**: Save this password immediately — Apple will only show it once.
+
+### Finding Your Calendar ID
+
+The calendar ID is needed to specify which iCloud calendar to sync:
+
+1. Open Calendar.app on macOS
+2. Right-click on the desired calendar in the sidebar
+3. Select "Get Info"
+4. The calendar ID is typically the calendar name in lowercase with special characters removed
+5. Common examples: `home`, `work`, `personal`
+
+Alternatively, you can use CalDAV discovery tools or inspect the CalDAV URLs in Calendar.app's account settings.
+
+### Configuration
+
+```yaml
+source:
+  adapter:
+    type: "apple"
+    calendar: "personal"  # Your calendar identifier
+    config: {}
+    oAuth:
+      clientId: "your-apple-id@icloud.com"    # Your Apple ID email
+      clientKey: "xxxx-xxxx-xxxx-xxxx"        # App-specific password
+      tenantId: ""                            # Leave empty for Apple CalDAV
+```

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/aquilax/truncate v1.0.1
 	github.com/cenkalti/backoff/v4 v4.3.0
 	github.com/charmbracelet/log v0.4.2
-	github.com/emersion/go-ical v0.0.0-20240127095438-fc1c9d8fb2b6
+	github.com/emersion/go-ical v0.0.0-20250609112844-439c63cef608
 	github.com/emersion/go-webdav v0.6.0
 	github.com/microcosm-cc/bluemonday v1.0.27
 	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8

go.sum

@@ -36,6 +36,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/emersion/go-ical v0.0.0-20240127095438-fc1c9d8fb2b6 h1:kHoSgklT8weIDl6R6xFpBJ5IioRdBU1v2X2aCZRVCcM=
 github.com/emersion/go-ical v0.0.0-20240127095438-fc1c9d8fb2b6/go.mod h1:BEksegNspIkjCQfmzWgsgbu6KdeJ/4LwUZs7DMBzjzw=
+github.com/emersion/go-ical v0.0.0-20250609112844-439c63cef608 h1:5XWaET4YAcppq3l1/Yh2ay5VmQjUdq6qhJuucdGbmOY=
+github.com/emersion/go-ical v0.0.0-20250609112844-439c63cef608/go.mod h1:BEksegNspIkjCQfmzWgsgbu6KdeJ/4LwUZs7DMBzjzw=
 github.com/emersion/go-vcard v0.0.0-20230815062825-8fda7d206ec9/go.mod h1:HMJKR5wlh/ziNp+sHEDV2ltblO4JD2+IdDOWtGcQBTM=
 github.com/emersion/go-webdav v0.6.0 h1:rbnBUEXvUM2Zk65Him13LwJOBY0ISltgqM5k6T5Lq4w=
 github.com/emersion/go-webdav v0.6.0/go.mod h1:mI8iBx3RAODwX7PJJ7qzsKAKs/vY429YfS2/9wKnDbQ=

internal/adapter/adapter.go

@@ -10,6 +10,7 @@ const (
 	GoogleCalendarType      Type = "google"
 	ZepCalendarType         Type = "zep"
 	OutlookHttpCalendarType Type = "outlook_http"
+	AppleCalendarType       Type = "apple"
 )
 
 // ConfigReader provides an interface for adapters to load their own configuration map.

internal/adapter/apple/adapter.go

@@ -0,0 +1,180 @@
+package apple
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/charmbracelet/log"
+
+	"github.com/inovex/CalendarSync/internal/adapter/port"
+	"github.com/inovex/CalendarSync/internal/auth"
+	"github.com/inovex/CalendarSync/internal/models"
+)
+
+const (
+	baseUrl    = "https://caldav.icloud.com"
+	timeFormat = "20060102T150405Z"
+)
+
+type AppleCalendarClient interface {
+	ListEvents(ctx context.Context, starttime time.Time, endtime time.Time) ([]models.Event, error)
+	CreateEvent(ctx context.Context, event models.Event) error
+	UpdateEvent(ctx context.Context, event models.Event) error
+	DeleteEvent(ctx context.Context, event models.Event) error
+	ResolveCalendarID(ctx context.Context, calendarID string) (string, string, error)
+	DiscoverCalendars(ctx context.Context) ([]string, error)
+	GetCalendarHash() string
+}
+
+type CalendarAPI struct {
+	appleClient AppleCalendarClient
+	calendarID  string
+
+	username      string
+	appPassword   string
+	authenticated bool
+
+	logger *log.Logger
+
+	storage auth.Storage
+}
+
+// Assert that the expected interfaces are implemented
+var _ port.Configurable = &CalendarAPI{}
+var _ port.LogSetter = &CalendarAPI{}
+
+func (c *CalendarAPI) SetupAuth(ctx context.Context, credentials auth.Credentials, storage auth.Storage, bindPort uint) error {
+	// Reuse OAuth fields for basic auth:
+	// clientId = Apple ID
+	// clientSecret = App-specific password
+	// tenantId = unused (empty)
+
+	switch {
+	case credentials.Client.Id == "":
+		return fmt.Errorf("%s adapter 'clientId' (Apple ID) cannot be empty", c.Name())
+	case credentials.Client.Secret == "":
+		return fmt.Errorf("%s adapter 'clientSecret' (app-specific password) cannot be empty", c.Name())
+	case credentials.CalendarId == "":
+		return fmt.Errorf("%s adapter 'calendar' cannot be empty", c.Name())
+	}
+
+	c.calendarID = credentials.CalendarId
+	c.username = credentials.Client.Id
+	c.appPassword = credentials.Client.Secret
+	c.storage = storage
+	c.authenticated = true
+	return nil
+}
+
+// Stub for interface compliance
+func (c *CalendarAPI) SetupOauth2(ctx context.Context, credentials auth.Credentials, storage auth.Storage, bindPort uint) error {
+	return c.SetupAuth(ctx, credentials, storage, bindPort)
+}
+
+func (c *CalendarAPI) SetupBasicAuth(ctx context.Context, credentials auth.Credentials, storage auth.Storage) error {
+	switch {
+	case credentials.Client.Id == "": // Using Client.Id as username for Apple ID
+		return fmt.Errorf("%s adapter 'username' (Apple ID) cannot be empty", c.Name())
+	case credentials.Client.Secret == "": // Using Client.Secret as app-specific password
+		return fmt.Errorf("%s adapter 'appPassword' cannot be empty", c.Name())
+	case credentials.CalendarId == "":
+		return fmt.Errorf("%s adapter 'calendar' cannot be empty", c.Name())
+	}
+
+	c.calendarID = credentials.CalendarId
+	c.username = credentials.Client.Id
+	c.appPassword = credentials.Client.Secret
+	c.storage = storage
+
+	// For Apple CalDAV, we don't need OAuth2, just basic auth with app-specific password
+	c.authenticated = true
+	c.logger.Debug("Apple adapter configured with basic auth")
+
+	return nil
+}
+
+func (c *CalendarAPI) Initialize(ctx context.Context, openBrowser bool, config map[string]interface{}) error {
+	if !c.authenticated {
+		return fmt.Errorf("Apple adapter not properly authenticated")
+	}
+
+	c.appleClient = &ACalClient{
+		Username:    c.username,
+		AppPassword: c.appPassword,
+		CalendarID:  c.calendarID,
+	}
+
+	// Verify calendar resolution and discovery
+	calendars, err := c.appleClient.DiscoverCalendars(ctx)
+	if err != nil {
+		log.Errorf("Calendar discovery failed: %v", err)
+	} else {
+		log.Infof("Discovered calendars: %v", calendars)
+
+		principalID, resolvedID, err := c.appleClient.(*ACalClient).getResolvedCalendarInfo(ctx)
+		if err != nil {
+			return fmt.Errorf("failed to resolve calendar '%s': %w", c.calendarID, err)
+		}
+		log.Infof("Successfully resolved calendar '%s' to %s/%s", c.calendarID, principalID, resolvedID)
+	}
+
+	c.logger.Debug("Apple CalDAV client initialized")
+	return nil
+}
+
+func (c *CalendarAPI) EventsInTimeframe(ctx context.Context, start time.Time, end time.Time) ([]models.Event, error) {
+	events, err := c.appleClient.ListEvents(ctx, start, end)
+	if err != nil {
+		return nil, err
+	}
+
+	c.logger.Infof("loaded %d events between %s and %s.", len(events), start.Format(time.DateOnly), end.Format(time.DateOnly))
+
+	return events, nil
+}
+
+func (c *CalendarAPI) CreateEvent(ctx context.Context, e models.Event) error {
+	err := c.appleClient.CreateEvent(ctx, e)
+	if err != nil {
+		return err
+	}
+
+	c.logger.Info("Event created", "title", e.ShortTitle(), "time", e.StartTime.String())
+
+	return nil
+}
+
+func (c *CalendarAPI) UpdateEvent(ctx context.Context, e models.Event) error {
+	err := c.appleClient.UpdateEvent(ctx, e)
+	if err != nil {
+		return err
+	}
+
+	c.logger.Info("Event updated", "title", e.ShortTitle(), "time", e.StartTime.String())
+
+	return nil
+}
+
+func (c *CalendarAPI) DeleteEvent(ctx context.Context, e models.Event) error {
+	err := c.appleClient.DeleteEvent(ctx, e)
+	if err != nil {
+		return err
+	}
+
+	c.logger.Info("Event deleted", "title", e.ShortTitle(), "time", e.StartTime.String())
+
+	return nil
+}
+
+func (c *CalendarAPI) GetCalendarHash() string {
+	return c.appleClient.GetCalendarHash()
+}
+
+func (c *CalendarAPI) Name() string {
+	return "Apple CalDAV"
+}
+
+func (c *CalendarAPI) SetLogger(logger *log.Logger) {
+	c.logger = logger
+}