using System;

using UnityEngine;

using System.Linq;

using System.IO;

#if UNITY_EDITOR

using UnityEditor;

using UnityEditor.SceneManagement;

#endif

namespace DevLocker.Utils

{

/// <summary>

/// Keeps reference to a scene asset and tracks it's path, so it can be used in the game runtime.

///

/// It's a well known fact that scenes can't be referenced like prefabs etc.

/// The <see cref="UnityEngine.SceneManagement.SceneManager"/> API works with relative scene paths or names.

/// Use this class to avoid manually typing and updating scene path strings - it will try to do it for you as best as it can,

/// including when <b>building the player</b>.

///

/// Using <see cref="ISerializationCallbackReceiver" /> was inspired by the <see cref="https://github.com/JohannesMP/unity-scene-reference">unity-scene-reference</see> implementation.

/// </summary>

[Serializable]

public class SceneReference : ISerializationCallbackReceiver

{

#if UNITY_EDITOR

// Reference to the asset used in the editor. Player builds don't know about SceneAsset.

// Will be used to update the scene path.

[SerializeField] private SceneAsset m_SceneAsset;

#pragma warning disable 0414 // Never used warning - will be used by SerializedProperty.

// Used to dirtify the data when needed upon displaying in the inspector.

// Otherwise the user will never get the changes to save (unless he changes any other field of the object / scene).

[SerializeField] private bool m_IsDirty;

#pragma warning restore 0414

#endif

// Player builds will use the path stored here. Should be updated in the editor or during build.

// If scene is deleted, path will remain.

[SerializeField]

private string m_ScenePath = string.Empty;

/// <summary>

/// Returns the scene path to be used in the <see cref="UnityEngine.SceneManagement.SceneManager"/> API.

/// While in the editor, this path will always be up to date (if asset was moved or renamed).

/// If the referred scene asset was deleted, the path will remain as is.

/// </summary>

public string ScenePath

{

get {

#if UNITY_EDITOR

AutoUpdateReference();

#endif

return m_ScenePath;

}

set {

m_ScenePath = value;

#if UNITY_EDITOR

m_SceneAsset = AssetDatabase.LoadAssetAtPath<SceneAsset>(m_ScenePath);

if (m_SceneAsset == null) {

Debug.LogError($"Setting {nameof(SceneReference)} to {value}, but no scene could be located there.");

}

#endif

}

}

/// <summary>

/// Returns the name of the scene without the extension.

/// </summary>

public string SceneName => Path.GetFileNameWithoutExtension(ScenePath);

public override string ToString()

{

return m_ScenePath;

}

[Obsolete("Needed for the editor, don't use it in runtime code!", true)]

public void OnBeforeSerialize()

{

#if UNITY_EDITOR

AutoUpdateReference();

#endif

}

[Obsolete("Needed for the editor, don't use it in runtime code!", true)]

public void OnAfterDeserialize()

{

#if UNITY_EDITOR

// OnAfterDeserialize is called in the deserialization thread so we can't touch Unity API.

// Wait for the next update frame to do it.

EditorApplication.update += OnAfterDeserializeHandler;

#endif

}

#if UNITY_EDITOR

private void OnAfterDeserializeHandler()

{

EditorApplication.update -= OnAfterDeserializeHandler;

AutoUpdateReference();

}

private void AutoUpdateReference()

{

if (m_SceneAsset == null) {

if (string.IsNullOrEmpty(m_ScenePath))

return;

SceneAsset foundAsset = AssetDatabase.LoadAssetAtPath<SceneAsset>(m_ScenePath);

if (foundAsset) {

m_SceneAsset = foundAsset;

m_IsDirty = true;

if (!Application.isPlaying) {

// NOTE: This doesn't work for scriptable objects, hence the m_IsDirty.

EditorSceneManager.MarkAllScenesDirty();

}

}

} else {

string foundPath = AssetDatabase.GetAssetPath(m_SceneAsset);

if (string.IsNullOrEmpty(foundPath))

return;

if (foundPath != m_ScenePath) {

m_ScenePath = foundPath;

m_IsDirty = true;

if (!Application.isPlaying) {

// NOTE: This doesn't work for scriptable objects, hence the m_IsDirty.

EditorSceneManager.MarkAllScenesDirty();

}

}

}

}

#endif

}

#if UNITY_EDITOR

[CustomPropertyDrawer(typeof(SceneReference))]

[CanEditMultipleObjects]

internal class SceneReferencePropertyDrawer : PropertyDrawer

{

public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)

{

var isDirtyProperty = property.FindPropertyRelative("m_IsDirty");

if (isDirtyProperty.boolValue) {

isDirtyProperty.boolValue = false;

// This will force change in the property and make it dirty.

// After the user saves, he'll actually see the changed changes and commit them.

}

EditorGUI.BeginProperty(position, label, property);

position = EditorGUI.PrefixLabel(position, GUIUtility.GetControlID(FocusType.Passive), label);

const float buildSettingsWidth = 20f;

const float padding = 2f;

Rect assetPos = position;

assetPos.width -= buildSettingsWidth + padding;

Rect buildSettingsPos = position;

buildSettingsPos.x += position.width - buildSettingsWidth + padding;

buildSettingsPos.width = buildSettingsWidth;

var sceneAssetProperty = property.FindPropertyRelative("m_SceneAsset");

EditorGUI.PropertyField(assetPos, sceneAssetProperty, new GUIContent());

string guid = string.Empty;

int indexInSettings = -1;

if (sceneAssetProperty.objectReferenceValue) {

long localId;

if (AssetDatabase.TryGetGUIDAndLocalFileIdentifier(sceneAssetProperty.objectReferenceValue, out guid, out localId)) {

indexInSettings = Array.FindIndex(EditorBuildSettings.scenes, s => s.guid.ToString() == guid);

}

}

GUIContent settingsContent = indexInSettings != -1

? new GUIContent("-", "Scene is already in the Editor Build Settings. Click here to remove it.")

: new GUIContent("+", "Scene is missing in the Editor Build Settings. Click here to add it.")

;

Color prevBackgroundColor = GUI.backgroundColor;

GUI.backgroundColor = indexInSettings != -1 ? Color.red : Color.green;

if (GUI.Button(buildSettingsPos, settingsContent, EditorStyles.miniButtonRight) && sceneAssetProperty.objectReferenceValue) {

if (indexInSettings != -1) {

var scenes = EditorBuildSettings.scenes.ToList();

scenes.RemoveAt(indexInSettings);

EditorBuildSettings.scenes = scenes.ToArray();

} else {

var newScenes = new EditorBuildSettingsScene[] {

new EditorBuildSettingsScene(AssetDatabase.GetAssetPath(sceneAssetProperty.objectReferenceValue), true)

};

EditorBuildSettings.scenes = EditorBuildSettings.scenes.Concat(newScenes).ToArray();

}

}

GUI.backgroundColor = prevBackgroundColor;

EditorGUI.EndProperty();

}

}

#endif

}