// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

using System.Collections.Generic;
using System.Linq;
using NUnit.Framework;
using osu.Framework.Allocation;
using osu.Framework.Screens;
using osu.Framework.Testing;
using osu.Framework.Utils;
using osu.Game.Beatmaps;
using osu.Game.Online.Spectator;
using osu.Game.Replays.Legacy;
using osu.Game.Rulesets.Osu;
using osu.Game.Rulesets.Osu.Replays;
using osu.Game.Rulesets.UI;
using osu.Game.Screens.Play;
using osu.Game.Tests.Beatmaps.IO;
using osu.Game.Users;

namespace osu.Game.Tests.Visual.Gameplay
{
    public class TestSceneSpectator : ScreenTestScene
    {
        [Cached(typeof(SpectatorStreamingClient))]
        private TestSpectatorStreamingClient testSpectatorStreamingClient = new TestSpectatorStreamingClient();

        private Spectator spectatorScreen;

        [Resolved]
        private OsuGameBase game { get; set; }

        public override void SetUpSteps()
        {
            base.SetUpSteps();

            AddStep("import beatmap", () => ImportBeatmapTest.LoadOszIntoOsu(game, virtualTrack: true).Wait());

            AddStep("add streaming client", () =>
            {
                Remove(testSpectatorStreamingClient);
                Add(testSpectatorStreamingClient);
            });
        }

        private OsuFramedReplayInputHandler replayHandler =>
            (OsuFramedReplayInputHandler)Stack.ChildrenOfType<OsuInputManager>().First().ReplayInputHandler;

        private Player player => Stack.CurrentScreen as Player;

        [Test]
        public void TestBasicSpectatingFlow()
        {
            beginSpectating();
            AddStep("start play", () => testSpectatorStreamingClient.StartPlay());
            sendFrames();
            AddUntilStep("wait for player", () => Stack.CurrentScreen is Player);

            AddAssert("ensure frames arrived", () => replayHandler.HasFrames);

            AddUntilStep("wait for frame starvation", () => replayHandler.NextFrame == null);
            AddAssert("game is paused", () => player.ChildrenOfType<DrawableRuleset>().First().IsPaused.Value);
        }

        private void sendFrames(int count = 10)
        {
            AddStep("send frames", () => testSpectatorStreamingClient.SendFrames(count));
        }

        [Test]
        public void TestSpectatingDuringGameplay()
        {
            AddStep("start play", () => testSpectatorStreamingClient.StartPlay());
            sendFrames();
            // should seek immediately to available frames
            beginSpectating();
        }

        [Test]
        public void TestHostStartsPlayingWhileAlreadyWatching()
        {
            beginSpectating();

            AddStep("start play", () => testSpectatorStreamingClient.StartPlay());
            sendFrames();
            AddStep("start play", () => testSpectatorStreamingClient.StartPlay());
            sendFrames();
        }

        [Test]
        public void TestHostFails()
        {
            beginSpectating();

            AddStep("start play", () => testSpectatorStreamingClient.StartPlay());
            sendFrames();

            // should replay until running out of frames then fail
        }

        [Test]
        public void TestStopWatchingDuringPlay()
        {
            beginSpectating();

            AddStep("start play", () => testSpectatorStreamingClient.StartPlay());
            sendFrames();
            AddUntilStep("wait for player", () => Stack.CurrentScreen is Player);

            // should immediately exit and unbind from streaming client
            AddStep("stop spectating", () => (Stack.CurrentScreen as Player)?.Exit());

            AddUntilStep("spectating stopped", () => spectatorScreen.GetParentScreen() == null);
        }

        [Test]
        public void TestWatchingBeatmapThatDoesntExistLocally()
        {
            beginSpectating();

            AddStep("start play", () => testSpectatorStreamingClient.StartPlay());
            sendFrames();
            // player should never arrive.
        }

        private void beginSpectating() =>
            AddStep("load screen", () => LoadScreen(spectatorScreen = new Spectator(testSpectatorStreamingClient.StreamingUser)));

        internal class TestSpectatorStreamingClient : SpectatorStreamingClient
        {
            [Resolved]
            private BeatmapManager beatmaps { get; set; }

            public readonly User StreamingUser = new User { Id = 1234, Username = "Test user" };

            public void StartPlay() => sendState();

            public void EndPlay()
            {
                ((ISpectatorClient)this).UserFinishedPlaying((int)StreamingUser.Id, new SpectatorState
                {
                    BeatmapID = beatmaps.GetAllUsableBeatmapSets().First().Beatmaps.First(b => b.RulesetID == 0).OnlineBeatmapID,
                    RulesetID = 0,
                });
            }

            public void SendFrames(int count)
            {
                var frames = new List<LegacyReplayFrame>();

                for (int i = 0; i < count; i++)
                {
                    frames.Add(new LegacyReplayFrame(i * 100, RNG.Next(0, 512), RNG.Next(0, 512), ReplayButtonState.Left1));
                }

                frames.Add(new LegacyReplayFrame(count * 100, 0, 0, ReplayButtonState.None));

                var bundle = new FrameDataBundle(frames);
                ((ISpectatorClient)this).UserSentFrames((int)StreamingUser.Id, bundle);
            }

            public override void WatchUser(int userId)
            {
                // usually the server would do this.
                sendState();

                base.WatchUser(userId);
            }

            private void sendState()
            {
                ((ISpectatorClient)this).UserBeganPlaying((int)StreamingUser.Id, new SpectatorState
                {
                    BeatmapID = beatmaps.GetAllUsableBeatmapSets().First().Beatmaps.First(b => b.RulesetID == 0).OnlineBeatmapID,
                    RulesetID = 0,
                });
            }
        }
    }
}