tsk-8: Create Message endpoint (#15)

Closes #8

Reviewed-on: phoenix/textsender-api#15
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

internal/handler/mock_store_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/google/uuid"
 
 	"git.kundeng.us/phoenix/textsender-models/pkg/contact"
+	"git.kundeng.us/phoenix/textsender-models/pkg/message"
 )
 
 type Key struct {
@@ -115,3 +116,57 @@ func (m *MockContactStore) ContactExists(ctx context.Context, phoneNumber string
 
 	return exists, nil
 }
+
+type MessageKey struct {
+	Content string
+	UserId  uuid.UUID
+}
+
+type MockMessageStore struct {
+	Messages      map[uuid.UUID]*message.Message
+	MessagesByKey map[MessageKey]*message.Message
+	mu            sync.RWMutex
+	Error         error // Optional: simulate errors
+}
+
+func NewMockMessageStore() *MockMessageStore {
+	return &MockMessageStore{
+		Messages:      make(map[uuid.UUID]*message.Message),
+		MessagesByKey: make(map[MessageKey]*message.Message),
+	}
+}
+
+func (m *MockMessageStore) CreateMessage(ctx context.Context, msg *message.Message) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if m.Error != nil {
+		return m.Error
+	}
+
+	if msg.Id == uuid.Nil {
+		msg.Id = uuid.New()
+	}
+
+	key := MessageKey{Content: msg.Content, UserId: msg.UserId}
+	if _, exists := m.MessagesByKey[key]; exists {
+		return errors.New("Message already exists")
+	}
+
+	m.Messages[msg.Id] = msg
+	m.MessagesByKey[key] = msg
+	return nil
+}
+
+func (m *MockMessageStore) MessageExists(ctx context.Context, msg *message.Message) (bool, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if m.Error != nil {
+		return false, m.Error
+	}
+
+	_, exists := m.MessagesByKey[MessageKey{Content: msg.Content, UserId: msg.UserId}]
+
+	return exists, nil
+}