refactor: extract adapter interfaces into subpackage and assert them

The optional interfaces that can be implemented by an adapter are now
located in the adapter/port package. This allows the adapter
implementations to import and assert that those interfaces are
implemented.

internal/adapter/adapter.go

@@ -1,11 +1,6 @@
 package adapter
 
 import (
-	"context"
-
-	"github.com/charmbracelet/log"
-	"github.com/inovex/CalendarSync/internal/auth"
-
 	"github.com/inovex/CalendarSync/internal/config"
 )
 
@@ -17,21 +12,6 @@ const (
 	OutlookHttpCalendarType Type = "outlook_http"
 )
 
-// LogSetter can be implemented by a struct to allows injection of a logger instance
-type LogSetter interface {
-	SetLogger(logger *log.Logger)
-}
-
-// Configurable is an interface which defines how arbitrary configuration data can be passed
-// to a struct which implements this interface. Clients should be configurable.
-type Configurable interface {
-	Initialize(ctx context.Context, config map[string]interface{}) error
-}
-
-type OAuth2Adapter interface {
-	SetupOauth2(ctx context.Context, credentials auth.Credentials, storage auth.Storage, bindPort uint) error
-}
-
 // ConfigReader provides an interface for adapters to load their own configuration map.
 // It's the adapter's responsibility to validate that the map is valid.
 type ConfigReader interface {

internal/adapter/google/adapter.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/inovex/CalendarSync/internal/adapter/port"
 	"github.com/inovex/CalendarSync/internal/models"
 	"github.com/pkg/browser"
 
@@ -46,6 +47,11 @@ type CalendarAPI struct {
 	storage auth.Storage
 }
 
+// Assert that the expected interfaces are implemented
+var _ port.Configurable = &CalendarAPI{}
+var _ port.LogSetter = &CalendarAPI{}
+var _ port.OAuth2Adapter = &CalendarAPI{}
+
 func (c *CalendarAPI) SetupOauth2(ctx context.Context, credentials auth.Credentials, storage auth.Storage, bindPort uint) error {
 	// Google Adapter does not need the tenantId
 	switch {

internal/adapter/outlook_http/adapter.go

@@ -9,6 +9,7 @@ import (
 	"github.com/pkg/browser"
 	"golang.org/x/oauth2"
 
+	"github.com/inovex/CalendarSync/internal/adapter/port"
 	"github.com/inovex/CalendarSync/internal/auth"
 	"github.com/inovex/CalendarSync/internal/models"
 )
@@ -41,6 +42,11 @@ type CalendarAPI struct {
 	storage auth.Storage
 }
 
+// Assert that the expected interfaces are implemented
+var _ port.Configurable = &CalendarAPI{}
+var _ port.LogSetter = &CalendarAPI{}
+var _ port.OAuth2Adapter = &CalendarAPI{}
+
 func (c *CalendarAPI) SetupOauth2(ctx context.Context, credentials auth.Credentials, storage auth.Storage, bindPort uint) error {
 	// Outlook Adapter does not need the clientKey
 	switch {

internal/adapter/port/interface.go

@@ -0,0 +1,24 @@
+package port
+
+import (
+	"context"
+
+	"github.com/charmbracelet/log"
+
+	"github.com/inovex/CalendarSync/internal/auth"
+)
+
+// LogSetter can be implemented by a struct to allows injection of a logger instance
+type LogSetter interface {
+	SetLogger(logger *log.Logger)
+}
+
+// Configurable is an interface which defines how arbitrary configuration data can be passed
+// to a struct which implements this interface. Clients should be configurable.
+type Configurable interface {
+	Initialize(ctx context.Context, config map[string]interface{}) error
+}
+
+type OAuth2Adapter interface {
+	SetupOauth2(ctx context.Context, credentials auth.Credentials, storage auth.Storage, bindPort uint) error
+}

internal/adapter/sink_adapter.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/inovex/CalendarSync/internal/adapter/google"
 	outlook "github.com/inovex/CalendarSync/internal/adapter/outlook_http"
+	"github.com/inovex/CalendarSync/internal/adapter/port"
 	"github.com/inovex/CalendarSync/internal/sync"
 )
 
@@ -40,11 +41,11 @@ func NewSinkAdapterFromConfig(ctx context.Context, bindPort uint, config ConfigR
 		return nil, err
 	}
 
-	if c, ok := client.(LogSetter); ok {
+	if c, ok := client.(port.LogSetter); ok {
 		c.SetLogger(logger)
 	}
 
-	if c, ok := client.(OAuth2Adapter); ok {
+	if c, ok := client.(port.OAuth2Adapter); ok {
 		if err := c.SetupOauth2(ctx,
 			auth.Credentials{
 				Client: auth.Client{
@@ -64,7 +65,7 @@ func NewSinkAdapterFromConfig(ctx context.Context, bindPort uint, config ConfigR
 	}
 
 	// configure adapter client if possible
-	if c, ok := client.(Configurable); ok {
+	if c, ok := client.(port.Configurable); ok {
 		if err := c.Initialize(ctx, config.Adapter().Config); err != nil {
 			return nil, fmt.Errorf("unable to Initialize adapter %s: %w", config.Adapter().Type, err)
 		}

internal/adapter/source_adapter.go

@@ -10,6 +10,7 @@ import (
 	"github.com/inovex/CalendarSync/internal/models"
 
 	outlook "github.com/inovex/CalendarSync/internal/adapter/outlook_http"
+	"github.com/inovex/CalendarSync/internal/adapter/port"
 
 	"github.com/inovex/CalendarSync/internal/adapter/google"
 	"github.com/inovex/CalendarSync/internal/adapter/zep"
@@ -44,11 +45,11 @@ func NewSourceAdapterFromConfig(ctx context.Context, bindPort uint, config Confi
 		return nil, err
 	}
 
-	if c, ok := client.(LogSetter); ok {
+	if c, ok := client.(port.LogSetter); ok {
 		c.SetLogger(logger)
 	}
 
-	if c, ok := client.(OAuth2Adapter); ok {
+	if c, ok := client.(port.OAuth2Adapter); ok {
 		if err := c.SetupOauth2(ctx,
 			auth.Credentials{
 				Client: auth.Client{
@@ -68,7 +69,7 @@ func NewSourceAdapterFromConfig(ctx context.Context, bindPort uint, config Confi
 	}
 
 	// configure adapter client if possible
-	if c, ok := client.(Configurable); ok {
+	if c, ok := client.(port.Configurable); ok {
 		if err := c.Initialize(ctx, config.Adapter().Config); err != nil {
 			return nil, fmt.Errorf("unable to initialize adapter %s: %w", config.Adapter().Type, err)
 		}

internal/adapter/zep/client.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/inovex/CalendarSync/internal/adapter/port"
 	"github.com/inovex/CalendarSync/internal/models"
 
 	"github.com/charmbracelet/log"
@@ -36,6 +37,9 @@ type CalendarAPI struct {
 	homeSet   string
 }
 
+// Assert that the expected interfaces are implemented
+var _ port.Configurable = &CalendarAPI{}
+
 func (zep *CalendarAPI) GetCalendarID() string {
 	return zep.generateCalendarID()
 }