Basic Permissions Class

/**
 * User permission class.
 */
export class Permission {
    private permissions: bigint;

    public static readonly PERMISSIONS = {
        NONE: 0n,
        READ: 1n << 0n,
        WRITE: 1n << 1n,
        ADMIN: 1n << 2n,
        OWNER: 1n << 3n
        // Add more permissions here by increasing the last number
    } as const;

    constructor(permission: bigint = 0n) {
        this.permissions = permission;
    }

    private toBitMask(keys: PermissionKey[]): bigint {
        return keys.reduce((acc, key) => acc | Permission.PERMISSIONS[key], 0n);
    }

    getPermissions(): { string: string; array: PermissionKey[] } {
        const array = Object.entries(Permission.PERMISSIONS)
            .filter(([, value]) => (this.permissions & value) !== 0n)
            .map(([key]) => key as PermissionKey);

        return { string: this.permissions.toString(), array };
    }

    setPermissions(keys: PermissionKey[]) {
        this.permissions = this.toBitMask(keys);
        return this.getPermissions();
    }

    removePermissions(keys: PermissionKey[]) {
        this.permissions &= ~this.toBitMask(keys);
        return this.getPermissions();
    }

    addPermissions(keys: PermissionKey[]) {
        this.permissions |= this.toBitMask(keys);
        return this.getPermissions();
    }

    hasAnyPermission(keys: PermissionKey[]): boolean {
        return (this.permissions & this.toBitMask(keys)) !== 0n;
    }

    hasAllPermissions(keys: PermissionKey[]): boolean {
        const required = this.toBitMask(keys);
        return (this.permissions & required) === required;
    }

    static getPermissionKeys(): PermissionKey[] {
        return Object.keys(Permission.PERMISSIONS) as PermissionKey[];
    }

    // Helper method to create Permission from database string
    static fromString(permissionString: string): Permission {
        return new Permission(BigInt(permissionString));
    }
}

export type PermissionKey = keyof typeof Permission.PERMISSIONS;

const userPerms = new Permission()
console.log(userPerms.getPermissions()) // { string: "0", array: [] }

// Set permissions (replaces all existing permissions)
userPerms.setPermissions(['ADMIN', 'OWNER'])

// Add more permissions (keeps existing ones)
userPerms.addPermissions(['READ'])

// Remove specific permissions
userPerms.removePermissions(['ADMIN']);

// Check if user has ANY of the specified permissions
userPerms.hasAnyPermission(['READ', 'WRITE', 'ADMIN']) // true (has READ)

// Check if user has ALL specified permissions
userPerms.hasAllPermissions(['READ', 'ADMIN']) // false (missing ADMIN)

// Get all available permission keys
Permission.getPermissionKeys() // ["NONE", "READ", "WRITE", "ADMIN", "OWNER"]

// Create instance with initial permissions using bigint
const readOnlyUser = new Permission(1n) // READ permission

// Create instance with multiple initial permissions
const editor = new Permission(3n) // READ (1) + WRITE (2) = 3

const user = new Permission();
user.setPermissions(['READ', 'WRITE']);

// Store in database
user.getPermissions().string // "3"

// Restore from database
const userPerms = Permission.fromString(stringFromDatabase);