using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System;
using System.Linq;
using System.Reflection;
using MBT;

namespace MBTEditor
{
    [CustomEditor(typeof(Blackboard))]
    public class BlackboardEditor : Editor
    {
        const double CONSTANT_REPAINT_INTERVAL = 0.5d;

        readonly string[] varOptions = new string[]{"Delete"};
        SerializedProperty variables;
        SerializedProperty masterBlackboardProperty;
        GUIStyle popupStyle;
        string newVariableKey = "";
        string[] variableTypesNames = new string[0];
        Type[] variableTypes = new Type[0];
        int selectedVariableType = 0;
        Blackboard blackboard;
        GameObject blackboardGameObject;
        bool showVariables = true;
        private double lastRepaint;

        void OnEnable()
        {
            // Set hide flags in case object was duplicated or turned into prefab
            if (target != null)
            {
                Blackboard bb = (Blackboard) target;
                // Sample one variable and check if its hidden. Hide all varialbes if sample is visible.
                if (bb.TryGetComponent<BlackboardVariable>(out BlackboardVariable bv) && bv.hideFlags != HideFlags.HideInInspector)
                {
                    BlackboardVariable[] vars = bb.GetComponents<BlackboardVariable>();
                    for (int i = 0; i < vars.Length; i++)
                    {
                        vars[i].hideFlags = HideFlags.HideInInspector;
                    }
                }
            }
            // Init
            variables = serializedObject.FindProperty("variables");
            masterBlackboardProperty = serializedObject.FindProperty("masterBlackboard");
            blackboard = target as Blackboard;
            blackboardGameObject = blackboard.gameObject;
            SetupVariableTypes();
        }

        void OnDestroy()
        {
            // Remove all variables in case Blackboard was removed
            if (Application.isEditor && (Blackboard)target == null && blackboardGameObject != null)
            {
                // Additional check to avoid errors when exiting playmode
                if (Application.IsPlaying(blackboardGameObject) || blackboardGameObject.GetComponent<Blackboard>() != null)
                {
                    return;
                }
                BlackboardVariable[] blackboardVariables = blackboardGameObject.GetComponents<BlackboardVariable>();
                for (int i = 0; i < blackboardVariables.Length; i++)
                {
                    Undo.DestroyObjectImmediate(blackboardVariables[i]);
                }
            }
        }

        public override bool RequiresConstantRepaint()
        {
            return Application.isPlaying && EditorApplication.timeSinceStartup > lastRepaint + CONSTANT_REPAINT_INTERVAL;
        }

        private void SetupVariableTypes()
        {
            List<Type> types = new List<Type>();
            List<string> names = new List<string>();
            
            // Find all types
            foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
            {
                IEnumerable<Type> enumerable = assembly.GetTypes()
                .Where(myType => myType.IsClass && !myType.IsAbstract && myType.IsSubclassOf(typeof(BlackboardVariable)));
                foreach (Type type in enumerable)
                {
                    names.Add(type.Name);
                    types.Add(type);
                }
            }
            variableTypesNames = names.ToArray();
            variableTypes = types.ToArray();
        }

        public override void OnInspectorGUI()
        {
            // Update repaint timer
            lastRepaint = EditorApplication.timeSinceStartup;
            // Init styles
            if (popupStyle == null) {
                popupStyle = new GUIStyle(GUI.skin.GetStyle("PaneOptions"));
                popupStyle.imagePosition = ImagePosition.ImageOnly;
                popupStyle.margin.top += 3;
            }


            EditorGUI.BeginChangeCheck();
                EditorGUILayout.PropertyField(masterBlackboardProperty);
                EditorGUILayout.Space();
            if (EditorGUI.EndChangeCheck()) {
                serializedObject.ApplyModifiedProperties();
            }
            
            // Fields used to add variables
            EditorGUILayout.LabelField("Create Variable", EditorStyles.boldLabel);
            EditorGUILayout.Space();
            EditorGUILayout.BeginHorizontal();
                GUILayout.Label("Key", GUILayout.MaxWidth(80));
                newVariableKey = EditorGUILayout.TextField(newVariableKey);
            EditorGUILayout.EndHorizontal();
            EditorGUILayout.BeginHorizontal();
                GUILayout.Label("Type", GUILayout.MaxWidth(80));
                selectedVariableType = EditorGUILayout.Popup(selectedVariableType, variableTypesNames);
                GUI.SetNextControlName("AddButton");
                if (GUILayout.Button("Add", EditorStyles.miniButton)) {
                    CreateVariableAndResetInput();
                }
            EditorGUILayout.EndHorizontal();
            EditorGUILayout.Space();

            // DrawDefaultInspector();
            // EditorGUILayout.Space();

            // serializedObject.Update();
            // EditorGUI.BeginChangeCheck();
            showVariables = EditorGUILayout.BeginFoldoutHeaderGroup(showVariables, "Variables");
            if(showVariables){
                SerializedProperty vars = variables.Copy();
                if (vars.isArray) {
                // xxx: Why this line existed? Why EventType.DragPerform is not allowed here? (maybe BeginChangeCheck)
                // if (vars.isArray && Event.current.type != EventType.DragPerform) {
                    for (int i = 0; i < vars.arraySize; i++)
                    {
                        EditorGUI.BeginChangeCheck();
                        int popupOption = -1;
                        SerializedProperty serializedV = vars.GetArrayElementAtIndex(i);
                        SerializedObject serializedVariable = new SerializedObject(serializedV.objectReferenceValue);
                        EditorGUILayout.BeginHorizontal();
                            EditorGUILayout.PrefixLabel(
                                new GUIContent(serializedVariable.FindProperty("key").stringValue, 
                                serializedVariable.targetObject.GetType().Name)
                            );
                            int v = EditorGUILayout.Popup(popupOption, varOptions, popupStyle, GUILayout.MaxWidth(20));
                            EditorGUILayout.PropertyField(serializedVariable.FindProperty("val"), GUIContent.none);
                        EditorGUILayout.EndHorizontal();

                        if (EditorGUI.EndChangeCheck()) {
                            serializedVariable.ApplyModifiedProperties();
                        }
                        // Delete on change
                        if (v != popupOption) {
                            DeleteVariabe(serializedV.objectReferenceValue as BlackboardVariable);
                        }
                    }
                }
            }
            EditorGUILayout.EndFoldoutHeaderGroup();
            EditorGUILayout.Space();

            // if (EditorGUI.EndChangeCheck()) {
            //     serializedObject.ApplyModifiedProperties();
            // }
        }

        private void DeleteVariabe(BlackboardVariable blackboardVariable)
        {
            Undo.RecordObject(blackboard, "Delete Blackboard Variable");
            blackboard.variables.Remove(blackboardVariable);
            Undo.DestroyObjectImmediate(blackboardVariable);
        }

        private void CreateVariableAndResetInput()
        {
            // Validate field. Key "None" is not allowed.
            if (string.IsNullOrEmpty(newVariableKey) || newVariableKey.Equals("None")) {
                return;
            }
            string k = new string( newVariableKey.ToCharArray().Where(c => !Char.IsWhiteSpace(c)).ToArray() );
            // Check for key duplicates
            for (int i = 0; i < blackboard.variables.Count; i++)
            {
                if (blackboard.variables[i].key == k) {
                    Debug.LogWarning("Variable '"+k+"' already exists.");
                    return;
                }
            }
            // Add variable
            Undo.RecordObject(blackboard, "Create Blackboard Variable");
            BlackboardVariable var = Undo.AddComponent(blackboard.gameObject, variableTypes[selectedVariableType]) as BlackboardVariable;
            var.hideFlags = HideFlags.HideInInspector;
            var.key = k;
            blackboard.variables.Add(var);
            // Reset field
            newVariableKey = "";
            GUI.FocusControl("Clear");
        }
    }
}