package com.baiyue.lastleg.appointmentplanning;

import java.util.Objects;

/** Source-local observations can prove a change, not a cross-time-zone delivery violation. */
public final class AppointmentImpactPolicy {
    private AppointmentImpactPolicy() { }
    public record Decision(boolean reviewRequired,String reason) { }
    public static Decision compare(AppointmentForecastClient.Fact baseline,AppointmentForecastClient.Fact latest) {
        if(latest==null || latest.estimatedAt()==null && latest.actualAt()==null) return new Decision(true,"FORECAST_MISSING");
        if(latest.actualAt()!=null) {
            return baseline==null || !Objects.equals(baseline.actualAt(),latest.actualAt())
                ? new Decision(true,"ACTUAL_ARRIVAL_REVIEW") : new Decision(false,"UNCHANGED");
        }
        if(baseline==null) return new Decision(false,"BASELINE_ESTABLISHED");
        if(!Objects.equals(baseline.estimatedAt(),latest.estimatedAt()) || !Objects.equals(baseline.actualAt(),latest.actualAt()))
            return new Decision(true,"FORECAST_CHANGED");
        if(!Objects.equals(baseline.providerCode(),latest.providerCode()) || !Objects.equals(baseline.sourceReference(),latest.sourceReference()))
            return new Decision(true,"SOURCE_CHANGED");
        return new Decision(false,"UNCHANGED");
    }
}