Project 5 — Design Hotel Management System

classDiagram
    class Hotel {
        -rooms: Room[]
        -reservations: Reservation[]
        +searchRooms(type: RoomType, checkIn: Date, checkOut: Date): Room[]
        +bookRoom(guest: Guest, room: Room, checkIn: Date, checkOut: Date): Reservation
        +checkIn(reservation: Reservation): void
        +checkOut(reservation: Reservation): Bill
    }
    class Room {
        +id: string
        +number: string
        +type: RoomType
        -isAvailable: boolean
    }
    class Reservation {
        +id: string
        +guest: Guest
        +room: Room
        +checkInDate: Date
        +checkOutDate: Date
        +status: ReservationStatus
        +confirm(): void
        +cancel(): void
    }
    class Guest {
        +id: string
        +name: string
        +email: string
        +phone: string
    }
    class Bill {
        +reservation: Reservation
        -charges: Charge[]
        +addCharge(description: string, amount: number): void
        +getTotal(): number
    }
    class RoomType {
        <<enumeration>>
        SINGLE DOUBLE SUITE DELUXE
    }
    class ReservationStatus {
        <<enumeration>>
        PENDING CONFIRMED CHECKED_IN CHECKED_OUT CANCELLED
    }

    Hotel *-- Room
    Hotel *-- Reservation
    Reservation --> Guest
    Reservation --> Room
    Bill --> Reservation

enum RoomType { SINGLE, DOUBLE, SUITE, DELUXE }
enum ReservationStatus { PENDING, CONFIRMED, CHECKED_IN, CHECKED_OUT, CANCELLED }

const ROOM_RATES: Record<RoomType, number> = {
  [RoomType.SINGLE]: 100,
  [RoomType.DOUBLE]: 150,
  [RoomType.SUITE]: 300,
  [RoomType.DELUXE]: 500,
};

class Reservation {
  public id: string = Math.random().toString(36).substr(2, 9);
  public status: ReservationStatus = ReservationStatus.PENDING;

  constructor(
    public guest: Guest,
    public room: Room,
    public checkInDate: Date,
    public checkOutDate: Date
  ) {}

  getNights(): number {
    return Math.ceil((this.checkOutDate.getTime() - this.checkInDate.getTime()) / (1000 * 60 * 60 * 24));
  }

  getEstimatedTotal(): number {
    return this.getNights() * ROOM_RATES[this.room.type];
  }
}

class Hotel {
  private rooms: Room[] = [];
  private reservations: Reservation[] = [];

  searchRooms(type: RoomType, checkIn: Date, checkOut: Date): Room[] {
    // Find rooms of this type that aren't reserved for the date range
    return this.rooms.filter(room => {
      if (room.type !== type) return false;
      return !this.reservations.some(res =>
        res.room.id === room.id &&
        res.status !== ReservationStatus.CANCELLED &&
        res.checkInDate < checkOut && res.checkOutDate > checkIn
      );
    });
  }

  bookRoom(guest: Guest, room: Room, checkIn: Date, checkOut: Date): Reservation {
    const reservation = new Reservation(guest, room, checkIn, checkOut);
    reservation.confirm();
    this.reservations.push(reservation);
    return reservation;
  }
}