gistfile1.txt

import jakarta.persistence.*;
import lombok.AccessLevel;
import lombok.Getter;
import lombok.NoArgsConstructor;
import org.hibernate.annotations.JdbcTypeCode;
import org.hibernate.type.SqlTypes;
import org.springframework.data.domain.AbstractAggregateRoot;
import org.springframework.data.jpa.domain.support.AuditingEntityListener;

import java.util.UUID;

@Entity
@Table(name = "transactions")
@EntityListeners(AuditingEntityListener.class)
@Getter
@NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Transaction extends AbstractAggregateRoot<Transaction> {

    @Id
    @GeneratedValue(strategy = GenerationType.UUID)
    private UUID id;

    @Version
    private Long version;

    @Embedded
    private TransactionStatus status;

    @Embedded
    private AuditData audit = new AuditData();

    @Embedded
    private Brief brief;

    @JdbcTypeCode(SqlTypes.JSON)
    @Column(name = "json_data")
    private Details details;

    public Transaction(Brief brief, Details details) {
        this.status = new TransactionStatus(TransactionStatus.MainStatus.NEW, TransactionStatus.SubStatus.IN_PROGRESS);
        this.brief = brief;
        this.details = details;
    }

    // --- WZORZEC STATE ---

    public <T extends TransactionState> T state(Class<T> type) {
        var state = switch (this.status.getMain()) {
            case NEW -> new ReceivedState(this);
            case ON_HOLD, AWAITING_VERIFICATION -> new ValidatedState(this);
            case COMPLETED, FAILED -> throw new IllegalStateException("Transakcja w stanie końcowym: " + status.getMain());
            default -> throw new IllegalStateException("Nieobsługiwany status: " + status.getMain());
        };
        
        // check czy jest to tej klasy
        return (T) state;
    }

    void updateStatus(TransactionStatus.MainStatus newMain, TransactionStatus.SubStatus newSub) {
        this.status = new TransactionStatus(newMain, newSub);
        // Opcjonalnie: registerEvent(new TransactionStatusChangedEvent(this.id, newMain));
    }
}

gistfile2.txt

import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;

// 1. Polimorficzny JSON
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "type")
@JsonSubTypes({
    @JsonSubTypes.Type(value = TransactionDetails.class, name = "PAYMENT"),
    @JsonSubTypes.Type(value = ReturnDetails.class, name = "RETURN")
})
public interface Details {}
public record TransactionDetails(String type, String extraField) implements Details {}
public record ReturnDetails(String type, String reasonCode) implements Details {}

// 2. Interfejs stanu
public interface TransactionState {

}