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 *    This product includes software developed by the Egothor project.
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package zeroecho.pki.api.content;

/**
 * Explicit deployment-owned resource constraint.
 *
 * <p>
 * This type distinguishes absence of a deployment limit from a positive finite
 * limit without nullable numbers or sentinel values. It never changes PKI,
 * algorithm or X.509 binding semantics.
 * </p>
 */
public sealed interface ResourceLimit permits ResourceLimit.UnrestrictedByDeployment, ResourceLimit.LimitedTo {
    /** Smallest valid observed aggregate value. */
    long EMPTY = 0L;

    /**
     * Checks an incrementally observed non-negative value.
     *
     * @param observed observed aggregate count or byte length
     * @throws IllegalArgumentException if {@code observed} is negative
     * @throws ResourceLimitExceededException if the configured limit is exceeded
     */
    void requireAllows(long observed);

    /**
     * Explicit absence of a deployment-owned limit.
     */
    record UnrestrictedByDeployment() implements ResourceLimit {
        @Override
        public void requireAllows(long observed) {
            if (observed < EMPTY) {
                throw new IllegalArgumentException("Observed resource value must not be negative");
            }
        }
    }

    /**
     * Positive finite deployment-owned limit.
     *
     * @param maximum inclusive maximum
     */
    record LimitedTo(long maximum) implements ResourceLimit {
        /**
         * Creates a finite limit.
         *
         * @throws IllegalArgumentException if {@code maximum} is not positive
         */
        public LimitedTo {
            if (maximum <= EMPTY) {
                throw new IllegalArgumentException("Deployment resource limit must be positive");
            }
        }

        @Override
        public void requireAllows(long observed) {
            if (observed < EMPTY) {
                throw new IllegalArgumentException("Observed resource value must not be negative");
            }
            if (observed > maximum) {
                throw new ResourceLimitExceededException();
            }
        }
    }

    /**
     * Stable non-sensitive failure for deployment resource rejection.
     */
    final class ResourceLimitExceededException extends IllegalStateException {
        private static final long serialVersionUID = 5780535874172354935L;

        private ResourceLimitExceededException() {
            super("Deployment resource limit exceeded: code=DEPLOYMENT_RESOURCE_LIMIT_EXCEEDED");
        }
    }
}
