add brief for functions in db, implemet full group manipulation (except owner,color), some fixes

database.go

@@ -63,6 +63,8 @@ func DbInit(ctx context.Context) {
 	}
 }
 
+// DbSaveClientWithoutGroups saves client in db without groups and sets its id
+// return: error if not successful
 func DbSaveClientWithoutGroups(ctx context.Context, client *Client) error {
 	err := dbConn.QueryRow(ctx, `
         INSERT INTO clients (name, pass_hash, pronouns, color_red, color_green, color_blue, created_at)
@@ -73,6 +75,8 @@ func DbSaveClientWithoutGroups(ctx context.Context, client *Client) error {
 	return err
 }
 
+// DbSetClientByName sets all fields of given struct with database's data using name
+// return: error if not successful
 func DbSetClientByName(ctx context.Context, client *Client) error {
 	err := dbConn.QueryRow(ctx, `
 		SELECT id, name, pass_hash, pronouns, color_red, color_green, color_blue, created_at FROM clients WHERE name = $1
@@ -83,6 +87,8 @@ func DbSetClientByName(ctx context.Context, client *Client) error {
 	return DbSetClientGroups(ctx, client)
 }
 
+// DbSetClientByIdWithoutGroups sets all fields of given struct with database's data using id, excluding groups
+// return: error if not successful
 func DbSetClientByIdWithoutGroups(ctx context.Context, client *Client) error {
 	err := dbConn.QueryRow(ctx, `
 		SELECT name, pass_hash, pronouns, color_red, color_green, color_blue, created_at FROM clients WHERE id = $1
@@ -90,6 +96,8 @@ func DbSetClientByIdWithoutGroups(ctx context.Context, client *Client) error {
 	return err
 }
 
+// DbSetClientById sets all fields of given struct with database's data using id, including groups
+// return: error if not successful
 func DbSetClientById(ctx context.Context, client *Client) error {
 	err := DbSetClientByIdWithoutGroups(ctx, client)
 	if err != nil {
@@ -98,6 +106,8 @@ func DbSetClientById(ctx context.Context, client *Client) error {
 	return DbSetClientGroups(ctx, client)
 }
 
+// DbSaveGroupWithoutClients saves group in db and sets its id, also adds the owner as first member
+// return: error if not successful
 func DbSaveGroupWithoutClients(ctx context.Context, group *Group) error {
 	err := dbConn.QueryRow(ctx, `
 		INSERT INTO chat_groups (name, creator_id, owner_id, enable_client_colors, color_red, color_green, color_blue, created_at)
@@ -115,6 +125,8 @@ func DbSaveGroupWithoutClients(ctx context.Context, group *Group) error {
 	return err
 }
 
+// DbSetGroupByIdWithoutClients sets all fields of given struct with database's data using id, populates Clients map with member ids but not their data
+// return: error if not successful
 func DbSetGroupByIdWithoutClients(ctx context.Context, group *Group) error {
 	err := dbConn.QueryRow(ctx, `
 		SELECT name, creator_id, owner_id, enable_client_colors, color_red, color_green, color_blue, created_at FROM chat_groups WHERE id = $1
@@ -142,6 +154,8 @@ func DbSetGroupByIdWithoutClients(ctx context.Context, group *Group) error {
 	return rows.Err()
 }
 
+// DbSetGroupById sets all fields of given struct with database's data using id, including full member client data
+// return: error if not successful
 func DbSetGroupById(ctx context.Context, group *Group) error {
 	err := DbSetGroupByIdWithoutClients(ctx, group)
 	if err != nil {
@@ -150,6 +164,8 @@ func DbSetGroupById(ctx context.Context, group *Group) error {
 	return DbSetGroupMemberClients(ctx, group)
 }
 
+// DbSetGroupMemberClients populates group's Clients map with ids of all members from database
+// return: error if not successful
 func DbSetGroupMemberClients(ctx context.Context, group *Group) error {
 	rows, err := dbConn.Query(ctx, `
 		SELECT user_id FROM chat_group_members WHERE group_id = $1
@@ -170,19 +186,26 @@ func DbSetGroupMemberClients(ctx context.Context, group *Group) error {
 	return rows.Err()
 }
 
-func DbAddClientsToGroup(ctx context.Context, groupId uint32, clientIds []uint32) error {
+// DbAddClientsToGroup adds given clients to group in db, silently ignores already existing members
+// return: error if not successful
+func DbAddClientsToGroup(ctx context.Context, groupId uint32, clientIds *[MaxClientsInGroup]uint32) error {
 	batch := &pgx.Batch{}
 	now := time.Now()
+	var count int
 	for _, cid := range clientIds {
+		if cid == 0 {
+			continue
+		}
 		batch.Queue(`
 			INSERT INTO chat_group_members (group_id, user_id, joined_at)
 			VALUES ($1, $2, $3)
 			ON CONFLICT DO NOTHING
 		`, groupId, cid, now)
+		count++
 	}
 	br := dbConn.SendBatch(ctx, batch)
 	defer br.Close()
-	for range clientIds {
+	for range count {
 		if _, err := br.Exec(); err != nil {
 			return err
 		}
@@ -190,6 +213,35 @@ func DbAddClientsToGroup(ctx context.Context, groupId uint32, clientIds []uint32
 	return nil
 }
 
+// DbRemoveClientsFromGroup removes given clients from group in db, silently ignores not existing members
+// return: deleted clients count, error if not successful
+func DbRemoveClientsFromGroup(ctx context.Context, groupId uint32, clientIds *[MaxClientsInGroup]uint32) (int, error) {
+	batch := &pgx.Batch{}
+	var count int
+	for _, cid := range clientIds {
+		if cid == 0 {
+			continue
+		}
+		batch.Queue(`
+			DELETE FROM chat_group_members WHERE group_id = $1 AND user_id = $2
+		`, groupId, cid)
+		count++
+	}
+	br := dbConn.SendBatch(ctx, batch)
+	defer br.Close()
+	var deleted int
+	for range count {
+		tag, err := br.Exec()
+		if err != nil {
+			return deleted, err
+		}
+		deleted += int(tag.RowsAffected())
+	}
+	return deleted, nil
+}
+
+// DbSetClientGroups populates client's Groups map with ids of all groups the client belongs to from database
+// return: error if not successful
 func DbSetClientGroups(ctx context.Context, client *Client) error {
 	rows, err := dbConn.Query(ctx, `
 		SELECT group_id FROM chat_group_members WHERE user_id = $1