feat: permissions, middleware authentication, migrations

projects/greenlight/internal/data/models.go

@@ -12,21 +12,18 @@ var (
 	ErrEditConflict   = errors.New("edit conflict")
 )
 
-// Models struct which wraps the MovieModel. We'll add other models to this,
-// like a UserModel and PermissionModel, as our build progresses.
 type Models struct {
-	Movies MovieModel
-	Tokens TokenModel // Add a new Tokens field.
-	Users  UserModel
+	Movies      MovieModel
+	Permissions PermissionModel // Add a new Permissions field.
+	Tokens      TokenModel
+	Users       UserModel
 }
 
-// NewModels For ease of use, we also add a New()
-// method which returns a Models struct containing
-// the initialized MovieModel.
 func NewModels(db *sql.DB) Models {
 	return Models{
-		Movies: MovieModel{DB: db},
-		Tokens: TokenModel{DB: db}, // Initialize a new TokenModel instance.
-		Users:  UserModel{DB: db},
+		Movies:      MovieModel{DB: db},
+		Permissions: PermissionModel{DB: db}, // Initialize a new PermissionModel instance.
+		Tokens:      TokenModel{DB: db},
+		Users:       UserModel{DB: db},
 	}
 }

projects/greenlight/internal/data/permissions.go

@@ -0,0 +1,66 @@
+package data
+
+import (
+	"context"
+	"database/sql"
+	"time"
+)
+
+// Define a Permissions slice, which we will use to will hold the permission codes (like
+// "movies:read" and "movies:write") for a single user.
+type Permissions []string
+
+// Add a helper method to check whether the Permissions slice contains a specific
+// permission code.
+func (p Permissions) Include(code string) bool {
+	for i := range p {
+		if code == p[i] {
+			return true
+		}
+	}
+	return false
+}
+
+// PermissionModel type.
+type PermissionModel struct {
+	DB *sql.DB
+}
+
+// GetAllForUser method returns all permission codes for a specific user in a
+// Permissions slice. The code in this method should feel very familiar --- it uses the
+// standard pattern that we've already seen before for retrieving multiple data rows in
+// an SQL query.
+func (m PermissionModel) GetAllForUser(userID int64) (Permissions, error) {
+	query := `
+        SELECT permissions.code
+        FROM permissions
+        INNER JOIN users_permissions ON users_permissions.permission_id = permissions.id
+        INNER JOIN users ON users_permissions.user_id = users.id
+        WHERE users.id = $1`
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	rows, err := m.DB.QueryContext(ctx, query, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var permissions Permissions
+
+	for rows.Next() {
+		var permission string
+
+		err := rows.Scan(&permission)
+		if err != nil {
+			return nil, err
+		}
+
+		permissions = append(permissions, permission)
+	}
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return permissions, nil
+}