// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package org.chromium.chrome.browser.media.router.caf;

import android.os.Handler;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v7.media.MediaRouteSelector;
import android.support.v7.media.MediaRouter;
import android.support.v7.media.MediaRouter.RouteInfo;

import org.chromium.base.Log;
import org.chromium.chrome.browser.media.router.ChromeMediaRouter;
import org.chromium.chrome.browser.media.router.DiscoveryCallback;
import org.chromium.chrome.browser.media.router.DiscoveryDelegate;
import org.chromium.chrome.browser.media.router.MediaController;
import org.chromium.chrome.browser.media.router.MediaRouteManager;
import org.chromium.chrome.browser.media.router.MediaRouteProvider;
import org.chromium.chrome.browser.media.router.MediaSink;
import org.chromium.chrome.browser.media.router.MediaSource;
import org.chromium.chrome.browser.media.router.cast.CastMediaSource;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * A {@link MediaRouteProvider} implementation for Cast devices and applications, using Cast v3 API.
 */
public class CafMediaRouteProvider implements MediaRouteProvider, DiscoveryDelegate {
    private static final String TAG = "cr_CafMRP";

    protected static final List<MediaSink> NO_SINKS = Collections.emptyList();

    protected final MediaRouter mAndroidMediaRouter;
    protected final MediaRouteManager mManager;
    protected final Map<String, DiscoveryCallback> mDiscoveryCallbacks =
            new HashMap<String, DiscoveryCallback>();
    protected Handler mHandler = new Handler();

    private CafMediaRouteProvider(MediaRouter androidMediaRouter, MediaRouteManager manager) {
        mAndroidMediaRouter = androidMediaRouter;
        mManager = manager;
    }

    public static CafMediaRouteProvider create(MediaRouteManager manager) {
        return new CafMediaRouteProvider(ChromeMediaRouter.getAndroidMediaRouter(), manager);
    }

    @Override
    public boolean supportsSource(String sourceId) {
        return getSourceFromId(sourceId) != null;
    }

    @Override
    public void startObservingMediaSinks(String sourceId) {
        Log.d(TAG, "startObservingMediaSinks: " + sourceId);

        if (mAndroidMediaRouter == null) {
            // If the MediaRouter API is not available, report no devices so the page doesn't even
            // try to cast.
            onSinksReceived(sourceId, NO_SINKS);
            return;
        }

        MediaSource source = getSourceFromId(sourceId);
        if (source == null) {
            // If the source is invalid or not supported by this provider, report no devices
            // available.
            onSinksReceived(sourceId, NO_SINKS);
            return;
        }

        MediaRouteSelector routeSelector = source.buildRouteSelector();
        if (routeSelector == null) {
            // If the application invalid, report no devices available.
            onSinksReceived(sourceId, NO_SINKS);
            return;
        }

        // No-op, if already monitoring the application for this source.
        String applicationId = source.getApplicationId();
        DiscoveryCallback callback = mDiscoveryCallbacks.get(applicationId);
        if (callback != null) {
            callback.addSourceUrn(sourceId);
            return;
        }

        List<MediaSink> knownSinks = new ArrayList<MediaSink>();
        for (RouteInfo route : mAndroidMediaRouter.getRoutes()) {
            if (route.matchesSelector(routeSelector)) {
                knownSinks.add(MediaSink.fromRoute(route));
            }
        }

        callback = new DiscoveryCallback(sourceId, knownSinks, this, routeSelector);
        mAndroidMediaRouter.addCallback(
                routeSelector, callback, MediaRouter.CALLBACK_FLAG_REQUEST_DISCOVERY);
        mDiscoveryCallbacks.put(applicationId, callback);
    }

    @Override
    public void stopObservingMediaSinks(String sourceId) {
        Log.d(TAG, "startObservingMediaSinks: " + sourceId);

        if (mAndroidMediaRouter == null) {
            // If the MediaRouter API is not available, report no devices so the page doesn't even
            // try to cast.
            onSinksReceived(sourceId, NO_SINKS);
            return;
        }

        MediaSource source = getSourceFromId(sourceId);
        if (source == null) {
            // If the source is invalid or not supported by this provider, report no devices
            // available.
            onSinksReceived(sourceId, NO_SINKS);
            return;
        }

        MediaRouteSelector routeSelector = source.buildRouteSelector();
        if (routeSelector == null) {
            // If the application invalid, report no devices available.
            onSinksReceived(sourceId, NO_SINKS);
            return;
        }

        // No-op, if already monitoring the application for this source.
        String applicationId = source.getApplicationId();
        DiscoveryCallback callback = mDiscoveryCallbacks.get(applicationId);
        if (callback != null) {
            callback.addSourceUrn(sourceId);
            return;
        }

        List<MediaSink> knownSinks = new ArrayList<MediaSink>();
        for (RouteInfo route : mAndroidMediaRouter.getRoutes()) {
            if (route.matchesSelector(routeSelector)) {
                knownSinks.add(MediaSink.fromRoute(route));
            }
        }

        callback = new DiscoveryCallback(sourceId, knownSinks, this, routeSelector);
        mAndroidMediaRouter.addCallback(
                routeSelector, callback, MediaRouter.CALLBACK_FLAG_REQUEST_DISCOVERY);
        mDiscoveryCallbacks.put(applicationId, callback);
    }

    /**
     * Forward the sinks back to the native counterpart.
     */
    protected void onSinksReceivedInternal(String sourceId, @NonNull List<MediaSink> sinks) {
        Log.d(TAG, "Reporting %d sinks for source: %s", sinks.size(), sourceId);
        mManager.onSinksReceived(sourceId, this, sinks);
    }

    /**
     * {@link DiscoveryDelegate} implementation.
     */
    @Override
    public void onSinksReceived(String sourceId, @NonNull List<MediaSink> sinks) {
        Log.d(TAG, "Received %d sinks for sourceId: %s", sinks.size(), sourceId);
        mHandler.post(() -> { onSinksReceivedInternal(sourceId, sinks); });
    }

    @Override
    public void createRoute(String sourceId, String sinkId, String presentationId, String origin,
            int tabId, boolean isIncognito, int nativeRequestId) {
        // Not implemented.
    }

    @Override
    public void joinRoute(
            String sourceId, String presentationId, String origin, int tabId, int nativeRequestId) {
        // Not implemented.
    }

    @Override
    public void closeRoute(String routeId) {
        // Not implemented.
    }

    @Override
    public void detachRoute(String routeId) {
        // Not implemented.
    }

    @Override
    public void sendStringMessage(String routeId, String message, int nativeCallbackId) {
        // Not implemented.
    }

    @Override
    @Nullable
    public MediaController getMediaController(String routeId) {
        // Not implemented.
        return null;
    }

    private MediaSource getSourceFromId(String sourceId) {
        return CastMediaSource.from(sourceId);
    }
}