com.vtence.molecule.middlewares.Flash Maven / Gradle / Ivy

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package com.vtence.molecule.middlewares;

import com.vtence.molecule.Application;
import com.vtence.molecule.Middleware;
import com.vtence.molecule.Request;
import com.vtence.molecule.Response;
import com.vtence.molecule.lib.FlashHash;
import com.vtence.molecule.session.Session;

import java.util.HashMap;
import java.util.Map;
import java.util.function.BiConsumer;
import java.util.function.Consumer;

public class Flash implements Middleware {

    public Application then(Application next) {
        return request -> {
            FlashHash flash = loadFlash(request);
            flash.bind(request);

            try {
                return next.handle(request)
                           .whenSuccessful(commitFlash(request))
                           .whenComplete(unbindFlashFrom(request));
            } catch (Throwable error) {
                FlashHash.unbind(request);
                throw error;
            }
        };
    }

    private BiConsumer unbindFlashFrom(final Request request) {
        return (response, throwable) -> FlashHash.unbind(request);
    }

    private FlashHash loadFlash(Request request) {
        Session session = fetchSession(request);
        Map flashes = session.contains(FlashHash.class) ?
                session.remove(FlashHash.class) : new HashMap<>();
        return new FlashHash(flashes);
    }

    private Consumer commitFlash(Request request) {
        return response -> {
            Session session = fetchSession(request);
            FlashHash flash = FlashHash.get(request);
            flash.sweep();
            if (!session.invalid() && !flash.empty()) {
                session.put(FlashHash.class, flash.toMap());
            }
        };
    }

    private Session fetchSession(Request request) {
        Session session = Session.get(request);
        if (session == null) throw new IllegalStateException("No session bound to request");
        return session;
    }
}