/*
 * Copyright 2015 Open Networking Laboratory
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.onosproject.ui.impl;

import org.onosproject.ui.UiExtension;
import org.onosproject.ui.UiExtensionService;
import org.onosproject.ui.UiView;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.SequenceInputStream;

import static com.google.common.collect.ImmutableList.of;
import static com.google.common.io.ByteStreams.toByteArray;

/**
 * Resource for serving the dynamically composed onos.js.
 */
@Path("/")
public class MainExtResource extends AbstractInjectionResource {

    private static final String MAIN_JS = "/onos-template.js";
    private static final String NAV_HTML = "/nav-template.html";

    private static final String INJECT_VIEW_IDS = "// {INJECTED-VIEW-IDS}";
    private static final String INJECT_VIEW_ITEMS = "<!-- {INJECTED-VIEW-NAV} -->";

    private static final String NAV_FORMAT =
            "    <li> <a ng-click=\"navCtrl.hideNav()\" href=\"#/%s\">%s</a></li>";

    @Path("/onos.js")
    @GET
    @Produces(MediaType.TEXT_HTML)
    public Response getMainModule() throws IOException {
        UiExtensionService service = get(UiExtensionService.class);
        InputStream jsTemplate = getClass().getClassLoader().getResourceAsStream(MAIN_JS);
        String js = new String(toByteArray(jsTemplate));

        int p1 = split(js, 0, INJECT_VIEW_IDS);
        int p2 = split(js, p1, null);

        StreamEnumeration streams =
                new StreamEnumeration(of(stream(js, 0, p1),
                                         includeViewIds(service),
                                         stream(js, p1, p2)));

        return Response.ok(new SequenceInputStream(streams)).build();
    }

    // Produces an input stream including view id injections from all extensions.
    private InputStream includeViewIds(UiExtensionService service) {
        StringBuilder sb = new StringBuilder("\n");
        for (UiExtension extension : service.getExtensions()) {
            for (UiView view : extension.views()) {
                sb.append("        '").append(view.id()).append("',");
            }
        }
        return new ByteArrayInputStream(sb.toString().getBytes());
    }

    @Path("/nav/nav.html")
    @GET
    @Produces(MediaType.TEXT_HTML)
    public Response getNavigation() throws IOException {
        UiExtensionService service = get(UiExtensionService.class);
        InputStream navTemplate = getClass().getClassLoader().getResourceAsStream(NAV_HTML);
        String js = new String(toByteArray(navTemplate));

        int p1 = split(js, 0, INJECT_VIEW_ITEMS);
        int p2 = split(js, p1, null);

        StreamEnumeration streams =
                new StreamEnumeration(of(stream(js, 0, p1),
                                         includeNavItems(service),
                                         stream(js, p1, p2)));

        return Response.ok(new SequenceInputStream(streams)).build();
    }

    // Produces an input stream including nav item injections from all extensions.
    private InputStream includeNavItems(UiExtensionService service) {
        StringBuilder sb = new StringBuilder("\n");
        for (UiExtension extension : service.getExtensions()) {
            for (UiView view : extension.views()) {
                sb.append(String.format(NAV_FORMAT, view.id(), view.label()));
            }
        }
        return new ByteArrayInputStream(sb.toString().getBytes());
    }
}