feat: add notifications inbox db (#16599)

This PR is linked [to the following
issue](https://github.com/coder/internal/issues/334).

The objective is to create the DB layer and migration for the new `Coder
Inbox`.

coderd/database/dbmem/dbmem.go

@@ -67,6 +67,7 @@ func New() database.Store {
 			gitSSHKey:                 make([]database.GitSSHKey, 0),
 			notificationMessages:      make([]database.NotificationMessage, 0),
 			notificationPreferences:   make([]database.NotificationPreference, 0),
+			InboxNotification:         make([]database.InboxNotification, 0),
 			parameterSchemas:          make([]database.ParameterSchema, 0),
 			provisionerDaemons:        make([]database.ProvisionerDaemon, 0),
 			provisionerKeys:           make([]database.ProvisionerKey, 0),
@@ -206,6 +207,7 @@ type data struct {
 	notificationMessages                 []database.NotificationMessage
 	notificationPreferences              []database.NotificationPreference
 	notificationReportGeneratorLogs      []database.NotificationReportGeneratorLog
+	InboxNotification                    []database.InboxNotification
 	oauth2ProviderApps                   []database.OAuth2ProviderApp
 	oauth2ProviderAppSecrets             []database.OAuth2ProviderAppSecret
 	oauth2ProviderAppCodes               []database.OAuth2ProviderAppCode
@@ -1606,6 +1608,26 @@ func (*FakeQuerier) CleanTailnetTunnels(context.Context) error {
 	return ErrUnimplemented
 }
 
+func (q *FakeQuerier) CountUnreadInboxNotificationsByUserID(_ context.Context, userID uuid.UUID) (int64, error) {
+	q.mutex.RLock()
+	defer q.mutex.RUnlock()
+
+	var count int64
+	for _, notification := range q.InboxNotification {
+		if notification.UserID != userID {
+			continue
+		}
+
+		if notification.ReadAt.Valid {
+			continue
+		}
+
+		count++
+	}
+
+	return count, nil
+}
+
 func (q *FakeQuerier) CustomRoles(_ context.Context, arg database.CustomRolesParams) ([]database.CustomRole, error) {
 	q.mutex.Lock()
 	defer q.mutex.Unlock()
@@ -3130,6 +3152,45 @@ func (q *FakeQuerier) GetFileTemplates(_ context.Context, id uuid.UUID) ([]datab
 	return rows, nil
 }
 
+func (q *FakeQuerier) GetFilteredInboxNotificationsByUserID(_ context.Context, arg database.GetFilteredInboxNotificationsByUserIDParams) ([]database.InboxNotification, error) {
+	q.mutex.RLock()
+	defer q.mutex.RUnlock()
+
+	notifications := make([]database.InboxNotification, 0)
+	for _, notification := range q.InboxNotification {
+		if notification.UserID == arg.UserID {
+			for _, template := range arg.Templates {
+				templateFound := false
+				if notification.TemplateID == template {
+					templateFound = true
+				}
+
+				if !templateFound {
+					continue
+				}
+			}
+
+			for _, target := range arg.Targets {
+				isFound := false
+				for _, insertedTarget := range notification.Targets {
+					if insertedTarget == target {
+						isFound = true
+						break
+					}
+				}
+
+				if !isFound {
+					continue
+				}
+
+				notifications = append(notifications, notification)
+			}
+		}
+	}
+
+	return notifications, nil
+}
+
 func (q *FakeQuerier) GetGitSSHKey(_ context.Context, userID uuid.UUID) (database.GitSSHKey, error) {
 	q.mutex.RLock()
 	defer q.mutex.RUnlock()
@@ -3328,6 +3389,33 @@ func (q *FakeQuerier) GetHungProvisionerJobs(_ context.Context, hungSince time.T
 	return hungJobs, nil
 }
 
+func (q *FakeQuerier) GetInboxNotificationByID(_ context.Context, id uuid.UUID) (database.InboxNotification, error) {
+	q.mutex.RLock()
+	defer q.mutex.RUnlock()
+
+	for _, notification := range q.InboxNotification {
+		if notification.ID == id {
+			return notification, nil
+		}
+	}
+
+	return database.InboxNotification{}, sql.ErrNoRows
+}
+
+func (q *FakeQuerier) GetInboxNotificationsByUserID(_ context.Context, params database.GetInboxNotificationsByUserIDParams) ([]database.InboxNotification, error) {
+	q.mutex.RLock()
+	defer q.mutex.RUnlock()
+
+	notifications := make([]database.InboxNotification, 0)
+	for _, notification := range q.InboxNotification {
+		if notification.UserID == params.UserID {
+			notifications = append(notifications, notification)
+		}
+	}
+
+	return notifications, nil
+}
+
 func (q *FakeQuerier) GetJFrogXrayScanByWorkspaceAndAgentID(_ context.Context, arg database.GetJFrogXrayScanByWorkspaceAndAgentIDParams) (database.JfrogXrayScan, error) {
 	err := validateDatabaseType(arg)
 	if err != nil {
@@ -7965,6 +8053,30 @@ func (q *FakeQuerier) InsertGroupMember(_ context.Context, arg database.InsertGr
 	return nil
 }
 
+func (q *FakeQuerier) InsertInboxNotification(_ context.Context, arg database.InsertInboxNotificationParams) (database.InboxNotification, error) {
+	if err := validateDatabaseType(arg); err != nil {
+		return database.InboxNotification{}, err
+	}
+
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	notification := database.InboxNotification{
+		ID:         arg.ID,
+		UserID:     arg.UserID,
+		TemplateID: arg.TemplateID,
+		Targets:    arg.Targets,
+		Title:      arg.Title,
+		Content:    arg.Content,
+		Icon:       arg.Icon,
+		Actions:    arg.Actions,
+		CreatedAt:  time.Now(),
+	}
+
+	q.InboxNotification = append(q.InboxNotification, notification)
+	return notification, nil
+}
+
 func (q *FakeQuerier) InsertLicense(
 	_ context.Context, arg database.InsertLicenseParams,
 ) (database.License, error) {
@@ -9679,6 +9791,24 @@ func (q *FakeQuerier) UpdateInactiveUsersToDormant(_ context.Context, params dat
 	return updated, nil
 }
 
+func (q *FakeQuerier) UpdateInboxNotificationReadStatus(_ context.Context, arg database.UpdateInboxNotificationReadStatusParams) error {
+	err := validateDatabaseType(arg)
+	if err != nil {
+		return err
+	}
+
+	q.mutex.Lock()
+	defer q.mutex.Unlock()
+
+	for i := range q.InboxNotification {
+		if q.InboxNotification[i].ID == arg.ID {
+			q.InboxNotification[i].ReadAt = arg.ReadAt
+		}
+	}
+
+	return nil
+}
+
 func (q *FakeQuerier) UpdateMemberRoles(_ context.Context, arg database.UpdateMemberRolesParams) (database.OrganizationMember, error) {
 	if err := validateDatabaseType(arg); err != nil {
 		return database.OrganizationMember{}, err