// This code is part of the Fungus library (http://fungusgames.com) maintained by Chris Gregan (http://twitter.com/gofungus).
// It is released for free under the MIT open source license (https://github.com/snozbot/fungus/blob/master/LICENSE)

using UnityEditor;
using UnityEngine;
using System.Collections.Generic;
using Rotorz.ReorderableList;

namespace Fungus.EditorUtils
{

    [CustomEditor (typeof(Command), true)]
    public class CommandEditor : Editor 
    {
        public static Command selectedCommand;

        public static CommandInfoAttribute GetCommandInfo(System.Type commandType)
        {
            object[] attributes = commandType.GetCustomAttributes(typeof(CommandInfoAttribute), false);
            foreach (object obj in attributes)
            {
                CommandInfoAttribute commandInfoAttr = obj as CommandInfoAttribute;
                if (commandInfoAttr != null)
                {
                    return commandInfoAttr;
                }
            }
            
            return null;
        }

        public virtual void DrawCommandInspectorGUI()
        {
            Command t = target as Command;
            if (t == null)
            {
                return;
            }

            var flowchart = (Flowchart)t.GetFlowchart();
            if (flowchart == null)
            {
                return;
            }

            CommandInfoAttribute commandInfoAttr = CommandEditor.GetCommandInfo(t.GetType());
            if (commandInfoAttr == null)
            {
                return;
            }

            GUILayout.BeginVertical(GUI.skin.box);

            if (t.enabled)
            {
                if (flowchart.ColorCommands)
                {
                    GUI.backgroundColor = t.GetButtonColor();
                }
                else
                {
                    GUI.backgroundColor = Color.white;
                }
            }
            else
            {
                GUI.backgroundColor = Color.grey;
            }
            GUILayout.BeginHorizontal(GUI.skin.button);

            string commandName = commandInfoAttr.CommandName;
            GUILayout.Label(commandName, GUILayout.MinWidth(80), GUILayout.ExpandWidth(true));

            GUILayout.FlexibleSpace();

            GUILayout.Label(new GUIContent("(" + t.ItemId + ")"));

            GUILayout.Space(10);

            GUI.backgroundColor = Color.white;
            bool enabled = t.enabled;
            enabled = GUILayout.Toggle(enabled, new GUIContent());

            if (t.enabled != enabled)
            {
                Undo.RecordObject(t, "Set Enabled");
                t.enabled = enabled;
            }

            GUILayout.EndHorizontal();
            GUI.backgroundColor = Color.white;

            EditorGUILayout.Separator();
            
            DrawCommandGUI();

            EditorGUILayout.Separator();

            if (t.ErrorMessage.Length > 0)
            {
                GUIStyle style = new GUIStyle(GUI.skin.label);
                style.normal.textColor = new Color(1,0,0);
                EditorGUILayout.LabelField(new GUIContent("Error: " + t.ErrorMessage), style);
            }

            GUILayout.EndVertical();

            // Display help text
            CommandInfoAttribute infoAttr = CommandEditor.GetCommandInfo(t.GetType());
            if (infoAttr != null)
            {
                EditorGUILayout.HelpBox(infoAttr.HelpText, MessageType.Info, true);
            }
        }

        public virtual void DrawCommandGUI()
        {
            Command t = target as Command;
            
            // Code below was copied from here
            // http://answers.unity3d.com/questions/550829/how-to-add-a-script-field-in-custom-inspector.html

            // Users should not be able to change the MonoScript for the command using the usual Script field.
            // Doing so could cause block.commandList to contain null entries.
            // To avoid this we manually display all properties, except for m_Script.
            serializedObject.Update();
            SerializedProperty iterator = serializedObject.GetIterator();
            bool enterChildren = true;
            while (iterator.NextVisible(enterChildren))
            {
                enterChildren = false;

                if (iterator.name == "m_Script")
                {
                    continue;
                }

                if (!t.IsPropertyVisible(iterator.name))
                {
                    continue;
                }

                if (iterator.isArray &&
                    t.IsReorderableArray(iterator.name))
                {
                    ReorderableListGUI.Title(new GUIContent(iterator.displayName, iterator.tooltip));
                    ReorderableListGUI.ListField(iterator);
                }
                else
                {
                    EditorGUILayout.PropertyField(iterator, true, new GUILayoutOption[0]);
                }
            }

            serializedObject.ApplyModifiedProperties();
        }

        
        static public void ObjectField<T>(SerializedProperty property, GUIContent label, GUIContent nullLabel, List<T> objectList) where T : Object 
        {
            if (property == null)
            {
                return;
            }

            List<GUIContent> objectNames = new List<GUIContent>();

            T selectedObject = property.objectReferenceValue as T;

            int selectedIndex = -1; // Invalid index

            // First option in list is <None>
            objectNames.Add(nullLabel);
            if (selectedObject == null)
            {
                selectedIndex = 0;
            }

            for (int i = 0; i < objectList.Count; ++i)
            {
                if (objectList[i] == null) continue;
                objectNames.Add(new GUIContent(objectList[i].name));

                if (selectedObject == objectList[i])
                {
                    selectedIndex = i + 1;
                }
            }

            T result;
            
            selectedIndex = EditorGUILayout.Popup(label, selectedIndex, objectNames.ToArray());

            if (selectedIndex == -1)
            {
                // Currently selected object is not in list, but nothing else was selected so no change.
                return;
            }
            else if (selectedIndex == 0)
            {
                result = null; // Null option
            }
            else
            {
                result = objectList[selectedIndex - 1];
            }

            property.objectReferenceValue = result;
        }

        // When modifying custom editor code you can occasionally end up with orphaned editor instances.
        // When this happens, you'll get a null exception error every time the scene serializes / deserialized.
        // Once this situation occurs, the only way to fix it is to restart the Unity editor.
        // 
        // As a workaround, this function detects if this command editor is an orphan and deletes it. 
        // To use it, just call this function at the top of the OnEnable() method in your custom editor.
        protected virtual bool NullTargetCheck()
        {
            try
            {
                // The serializedObject accessor create a new SerializedObject if needed.
                // However, this will fail with a null exception if the target object no longer exists.
                #pragma warning disable 0219
                SerializedObject so = serializedObject;
            }
            catch (System.NullReferenceException)
            {
                DestroyImmediate(this);
                return true;
            }

            return false;
        }
    }
}