Design optaplanner constraints of booking system - optaplanner

Question

I would like to design a booking system using optaplanner, bellow my business model:
Customers (id, name) //Customer table
Services(id, name, description, duration) //services that a customer can book, duration can be 15min, 30min, ..., N x 15min
Employees(id, name) //Employee tables
Appointment(id, customerId, employeeId, serviceId, startTime, endTime)
To book an appointment, the customer will select:
The day of the appointment (mandatory)
A list of services (mandatory)
A list of employees (optional)
I would like to know I can design the model to return the list of availability for a given day, given list of services.
Bellow a basic pseudo-code model :
#Entity
public class Service extends PanacheEntityBase {
#Id
#GeneratedValue
#NotNull
private Long id;
#NotBlank
private String name;
private int durationInGrains;
}
public class TimeGrain {
public static final int GRAIN_LENGTH_IN_MINUTES = 15;
private int grainIndex; // unique
private int startingMinuteOfDay;
}
#Entity
public class Employee extends PanacheEntityBase {
#PlanningId
#Id
#GeneratedValue
#NotNull
private Long id;
#NotBlank
private String name;
}
#Entity
public class Appointment extends PanacheEntityBase {
#Id
#GeneratedValue
#NotNull
private Long id;
private Employee employee;
private Service service;
private LocalDateTime startTime;
private LocalDateTime endTime;
}
#PlanningEntity
public class Availability {
#PlanningVariable(valueRangeProviderRefs = { "timeGrainRange" })
private TimeGrain startingTimeGrain;
#PlanningVariable(valueRangeProviderRefs = "providerRange")
private Provider provider;
private Service service;
}
#PlanningSolution
public class AppointmentAvailability {
#ValueRangeProvider(id = "timeGrainRange")
#ProblemFactCollectionProperty
private List<TimeGrain> timeGrainList;
#ProblemFactCollectionProperty
#ValueRangeProvider(id = "providerRange")
private List<Provider> providerList;
#ProblemFactCollectionProperty
#ValueRangeProvider(id = "appointmentsRange")
private List<Appointment> appointmentList;
#PlanningEntityCollectionProperty
private List<Availability> availabilityList;
#PlanningScore
private HardMediumSoftScore score;
}
As I am new to optaplanner, could you please advise if this is the way to go?
UPDATE 1: I have simplified the problem to the minimum for design purposes.

Answer 1

Take a look at the meeting scheduling example in optaplanner-examples, to get inspired on how to model it. Also see the Time Grain pattern in the docs in the section Design Patterns. The school timetabling quickstart follows the Timeslot pattern instead.