package org.apidesign.stateful.api;

/** API for notifying progress that cannot call

 * {@link #start(int)} and {@link InProgress#progress(int)} in wrong

 * order. In contract to {@link ProgressStateful} class which allows that.

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

public abstract class ProgressStateless {

// BEGIN: progress.phases

    public static ProgressStateless create(String name) {

        return createImpl(name);

    }

    public abstract InProgress start(int totalAmount);

    public abstract class InProgress {

        public abstract void progress(int howMuch);

        public abstract void finish();

        // FINISH: progress.phases

        InProgress() {

        }

    }

    ProgressStateless() {

    }

    private static ProgressStateless createImpl(String name) {

        return new Impl(name);

    }

    private static final class Impl extends ProgressStateless {

        private final String name;

        public Impl(String name) {

            this.name = name;

        }

        @Override

        public InProgress start(int totalAmount) {

            return new InImpl(totalAmount);

        }

        private class InImpl extends InProgress {

            private final int total;

            private int current;

            public InImpl(int total) {

                this.total = total;

            }

            @Override

            public void progress(int howMuch) {

                current = howMuch;

            }

            @Override

            public void finish() {

                current = total;

            }

        }

    }

}