using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.SceneManagement;


public enum LevelState
{
    Loading,
    Loaded,
}

public struct LevelLayer
{
    public AsyncOperation loadOperation;
}

public class Level
{
    public LevelState state;
    public string name;
    public List<LevelLayer> layers = new List<LevelLayer>(10);
}

public class LevelManager
{
    public static readonly string[] layerNames = new string[]
    {
        "background",
        "gameplay",
    };

    public Level currentLevel { get; private set; }

    public void Init()
    {
    }

    public bool IsCurrentLevelLoaded()
    {
        return currentLevel != null && currentLevel.state == LevelState.Loaded;
    }

    public bool IsLoadingLevel()
    {
        return currentLevel != null && currentLevel.state == LevelState.Loading;
    }

    public bool CanLoadLevel(string name)
    {
        // TODO (petera). We can't really promise you can load a level before trying.
        // Refactor to handle errors during load.
        var bundle = SimpleBundleManager.LoadLevelAssetBundle(name);
        return bundle != null;
    }

    public bool LoadLevel(string name)
    {
        if (currentLevel != null)
            UnloadLevel();

        // This is a pretty ugly hack to handle problems with loading camera and post processing volumes
        // and those not being initalized at the same time. We simply disable the old camera and the 
        Game.game.TopCamera().enabled = false;
        Game.game.BlackFade(true);

        var newLevel = new Level();
        newLevel.name = name;

        // TODO (petera) Use async? Seem to be not needed here.
        var bundle = SimpleBundleManager.LoadLevelAssetBundle(name);
        if (bundle == null)
        {
            GameDebug.Log("Could not load asset bundle for scene " + name);
            return false;
        }

        // Load using the name found in GetAllScenePaths because SceneManager.LoadSceneAsync is case sensitive
        // yet name may not have correct casing as file system may be case insensitive 

        var scenePaths = new List<string>(bundle.GetAllScenePaths());
        if (scenePaths.Count < 1)
        {
            GameDebug.Log("No scenes in asset bundle " + name);
            return false;
        }

        // If there is a main scene, load that first
        // TODO (petera) switch to LevelInfo based layers
        var mainScenePath = scenePaths.Find(x => x.ToLower().EndsWith("_main.unity"));
        var useLayers = true;
        if (mainScenePath == null)
        {
            useLayers = false;
            mainScenePath = scenePaths[0];
        }

        GameDebug.Log("Loading " + mainScenePath);
        var mainLoadOperation = SceneManager.LoadSceneAsync(mainScenePath, LoadSceneMode.Single);
        if (mainLoadOperation == null)
        {
            GameDebug.Log("Failed to load level : " + name);
            return false;
        }

        currentLevel = newLevel;
        currentLevel.layers.Add(new LevelLayer { loadOperation = mainLoadOperation });

        if (!useLayers)
            return true;

        // Now load all additional layers that may be here
        foreach (var l in layerNames)
        {
            var layerScenePath = scenePaths.Find(x => x.ToLower().EndsWith(l + ".unity"));
            if (layerScenePath == null)
                continue;

            // TODO : Are we guaranteed that the scenes are initialized in order without setting allowactivation = false?
            GameDebug.Log("+Loading " + layerScenePath);
            var layerLoadOperation = SceneManager.LoadSceneAsync(layerScenePath, LoadSceneMode.Additive);
            if (layerLoadOperation != null)
            {
                currentLevel.layers.Add(new LevelLayer { loadOperation = layerLoadOperation });
            }
            else
            {
                GameDebug.Log("Warning : Unable to load level layer : " + layerScenePath);
            }
        }

        return true;
    }

    public void UnloadLevel()
    {
        if (currentLevel == null)
            return;

        if (currentLevel.state == LevelState.Loading)
            throw new NotImplementedException("TODO : Implement unload during load");

        // TODO (ulfj) : Load empty scene for now
        SceneManager.LoadScene(1);

        SimpleBundleManager.ReleaseLevelAssetBundle(currentLevel.name);
        currentLevel = null;
    }

    public void Update()
    {
        if (currentLevel != null && currentLevel.state == LevelState.Loading)
        {
            var done = currentLevel.layers.All(l => l.loadOperation.isDone);
            if (done)
            {
                // Do activation here?
                currentLevel.state = LevelState.Loaded;

                if (Game.GameLoopCount == 1)
                {
                    if (Game.GetGameLoop<ServerGameLoop>() != null)
                        StripCode(BuildType.Server, true);
                    else if (Game.GetGameLoop<ClientGameLoop>() != null)
                        StripCode(BuildType.Client, true);  
                    else
                        StripCode(BuildType.Default, true);
                }
                else
                    StripCode(BuildType.Default, true);
                
                GameDebug.Log("Scene " + currentLevel.name + " loaded");
            }
        }
    }


    // TODO (petera) this code was moved here to make it available outside of editor - until we start cooking for client/server
    public enum BuildType
    {
        Default,
        Client,
        Server,
    }

    public static void StripCode(BuildType buildType, bool isDevelopmentBuild)
    {
        GameDebug.Log("Stripping code for " + buildType.ToString() + " (" + (isDevelopmentBuild ? "DevBuild" : "NonDevBuild") + ")");
        var deleteBehaviors = new List<MonoBehaviour>();
        var deleteGameObjects = new List<GameObject>();

        foreach (var behavior in UnityEngine.Object.FindObjectsOfType<MonoBehaviour>())
        {
            if (behavior.GetType().GetCustomAttributes(typeof(EditorOnlyComponentAttribute), false).Length > 0)
                deleteBehaviors.Add(behavior);
            else if (behavior.GetType().GetCustomAttributes(typeof(EditorOnlyGameObjectAttribute), false).Length > 0)
                deleteGameObjects.Add(behavior.gameObject);
            else if (buildType == BuildType.Server && behavior.GetType().GetCustomAttributes(typeof(ClientOnlyComponentAttribute), false).Length > 0)
                deleteBehaviors.Add(behavior);
            else if (buildType == BuildType.Client && behavior.GetType().GetCustomAttributes(typeof(ServerOnlyComponentAttribute), false).Length > 0)
                deleteBehaviors.Add(behavior);
            else if (!isDevelopmentBuild && behavior.GetType().GetCustomAttributes(typeof(DevelopmentOnlyComponentAttribute), false).Length > 0)
                deleteBehaviors.Add(behavior);
        }

        GameDebug.Log(string.Format("Stripping {0} game object(s) and {1} behavior(s)", deleteGameObjects.Count, deleteBehaviors.Count));

        foreach (var gameObject in deleteGameObjects)
            UnityEngine.Object.DestroyImmediate(gameObject);

        foreach (var behavior in deleteBehaviors)
            UnityEngine.Object.DestroyImmediate(behavior);
    }
}