Command interpreter

type AccessContext = {
  role: string;
  region: string;
};

interface Expression {
  interpret(context: AccessContext): boolean;
}

class RoleExpression implements Expression {
  constructor(private readonly expectedRole: string) {}

  interpret(context: AccessContext) {
    return context.role === this.expectedRole;
  }
}

class RegionExpression implements Expression {
  constructor(private readonly expectedRegion: string) {}

  interpret(context: AccessContext) {
    return context.region === this.expectedRegion;
  }
}

class AndExpression implements Expression {
  constructor(
    private readonly left: Expression,
    private readonly right: Expression,
  ) {}

  interpret(context: AccessContext) {
    return this.left.interpret(context) && this.right.interpret(context);
  }
}

class OrExpression implements Expression {
  constructor(
    private readonly left: Expression,
    private readonly right: Expression,
  ) {}

  interpret(context: AccessContext) {
    return this.left.interpret(context) || this.right.interpret(context);
  }
}

const canManageBilling = new AndExpression(
  new RoleExpression("admin"),
  new RegionExpression("us"),
);

const canViewDashboard = new OrExpression(
  canManageBilling,
  new RoleExpression("analyst"),
);

console.log(
  canViewDashboard.interpret({
    role: "analyst",
    region: "eu",
  }),
);