feat: now simple users can only occupy one seat at a time

server/db/database.go

@@ -6,6 +6,9 @@ package db
 import (
 	"errors"
 	"fmt"
+	"sync"
+
+	"git.phc.dm.unipi.it/aziis98/posti-dm/server/util"
 )
 
 // ErrAlreadyExists is the error thrown from Store functions when an entity already exists.
@@ -14,6 +17,11 @@ var ErrAlreadyExists = errors.New(`object already exists in database`)
 // ErrDoesntExist is the error thrown from Store functions when an entity doesn't exist.
 var ErrDoesntExist = errors.New(`object doesn't exist in database`)
 
+const (
+	PermissionAdmin     = "admin"
+	PermissionModerator = "moderator"
+)
+
 // Entities
 
 // type FrontendUser struct {
@@ -24,23 +32,12 @@ var ErrDoesntExist = errors.New(`object doesn't exist in database`)
 
 // User represents a user in the database.
 type User struct {
-	ID          string   `json:"id"`
-	Permissions []string `json:"permissions"`
+	ID          string         `json:"id"`
+	Permissions util.StringSet `json:"permissions"`
 
 	// passwordSaltHash string
 }
 
-// HasPermission checks if the user has a specific permission.
-func (user User) HasPermission(neededPerm string) bool {
-	for _, perm := range user.Permissions {
-		if perm == neededPerm {
-			return true
-		}
-	}
-
-	return false
-}
-
 // Room represents a room in the database, a room has an id, a name and a collection of seatIDs of this room.
 type Room struct {
 	ID      string   `json:"id"`
@@ -49,6 +46,26 @@ type Room struct {
 	// gridRows, gridCols int
 }
 
+// Version 1:
+//
+// type SeatState struct {
+// 	Occupied  bool
+// 	Anonymous bool
+// 	UserID    string
+// }
+
+// Version 2:
+//
+// type SeatState interface{ isSeatState() }
+//
+// type SeatNotOccupied struct{}
+// type SeatOccupiedByUser struct{ UserID string }
+// type SeatOccupiedByAnonymous struct{}
+//
+// func (s SeatNotOccupied) isSeatState()
+// func (s SeatOccupiedByUser) isSeatState()
+// func (s SeatOccupiedByAnonymous) isSeatState()
+
 // Seat represents a seat in the database, it belongs to a single room and can be free or occupied by some user (referenced by userID).
 type Seat struct {
 	ID     string `json:"id"`
@@ -81,6 +98,9 @@ type Seat struct {
 
 // Store is the main interface for interacting with database implementations, for now the only implementation is "memDB".
 type Store interface {
+	BeginTransaction()
+	EndTransaction()
+
 	CreateUser(user *User) error
 	CreateRoom(room *Room) error
 	CreateSeat(seat *Seat) error
@@ -98,7 +118,7 @@ type Store interface {
 	GetRoomOccupiedSeats(roomID string) ([]string, error)
 	GetRoomFreeSeats(roomID string) ([]string, error)
 
-	GetUserSeat(userID string) ([]string, error)
+	GetUserSeats(userID string) (util.StringSet, error)
 
 	OccupySeat(seatID, userID string) error
 	FreeSeat(seatID string) error
@@ -109,6 +129,8 @@ type Store interface {
 // NewInMemoryStore creates an instance of memDB hidden behind the Store interface.
 func NewInMemoryStore() Store {
 	db := &memDB{
+		&sync.Mutex{},
+
 		make(map[string]*User),
 		make(map[string]*Room),
 		make(map[string]*Seat),
@@ -135,12 +157,12 @@ func NewInMemoryStore() Store {
 
 	db.users["aziis98"] = &User{
 		ID:          "aziis98",
-		Permissions: []string{"admin"},
+		Permissions: util.NewStringSet(PermissionAdmin),
 	}
 
 	db.users["bachoseven"] = &User{
 		ID:          "bachoseven",
-		Permissions: []string{"admin"},
+		Permissions: util.NewStringSet(PermissionAdmin),
 	}
 
 	return db

server/db/inmemory.go

@@ -1,17 +1,29 @@
 package db
 
-import "fmt"
+import (
+	"fmt"
+	"sync"
+
+	"git.phc.dm.unipi.it/aziis98/posti-dm/server/util"
+)
 
 // memDB is the first Store implementation used for testing.
 type memDB struct {
-	// FIXME: Giusto per la cronaca fare le modifiche in questo modo alle mappe non è per niente thread safe, servirebbe come minimo usare un mutex per quando si scrive su una di queste variabili
-	// mutex *sync.Mutex
+	mutex *sync.Mutex
 
 	users map[string]*User
 	rooms map[string]*Room
 	seats map[string]*Seat
 }
 
+func (db *memDB) BeginTransaction() {
+	db.mutex.Lock()
+}
+
+func (db *memDB) EndTransaction() {
+	db.mutex.Unlock()
+}
+
 func (db *memDB) CreateUser(user *User) error {
 	if _, present := db.users[user.ID]; present {
 		return ErrAlreadyExists
@@ -134,14 +146,14 @@ func (db *memDB) GetRoomFreeSeats(roomID string) ([]string, error) {
 	return seats, nil
 }
 
-func (db *memDB) GetUserSeat(userID string) ([]string, error) {
+func (db *memDB) GetUserSeats(userID string) (util.StringSet, error) {
 	for _, seat := range db.seats {
 		if len(seat.OccupiedBy) > 0 && seat.OccupiedBy[0] == userID {
-			return []string{userID}, nil
+			return util.NewStringSet(seat.ID), nil
 		}
 	}
 
-	return []string{}, nil
+	return util.NewStringSet(), nil
 }
 
 func (db *memDB) OccupySeat(seatID, userID string) error {