using System;
#if UNITY_EDITOR
using System.Collections.Generic;
using System.Reflection;
using UnityEditor;
using UnityEngine;
#endif

namespace Golems.Attributes
{
    /// <summary>
    /// Show the EditorInspectableLevel property on the field.
    /// </summary>
    [AttributeUsage(AttributeTargets.Field)]
    public class ShowLevelAttribute : Attribute
    {
        public bool ShowWhenNotPlaying
        {
            get;
            private set;
        }

        public ShowLevelAttribute()
        {
            ShowWhenNotPlaying = false;
        }

        public ShowLevelAttribute(bool showWhenNotPlaying)
        {
            ShowWhenNotPlaying = showWhenNotPlaying;
        }

#if UNITY_EDITOR
        private const BindingFlags k_ShowLevelBindingFlags = BindingFlags.Public | BindingFlags.NonPublic |
                                                             BindingFlags.Instance | BindingFlags.DeclaredOnly;

        private static readonly List<FieldInfo> s_Fields = new List<FieldInfo>();

        private static GUIStyle s_LabelStyle = null;

        private const string k_EditorLevelProperty = "EditorInspectableLevel";

        public static void EditorShowLevelInfo(UnityEngine.Object target, string label)
        {
            s_Fields.Clear();

            GetShowLevelAttributeFields(target, s_Fields, EditorApplication.isPlaying);

            if (s_Fields.Count <= 0)
            {
                return;
            }
            if (!string.IsNullOrEmpty(label))
            {
                if (s_LabelStyle == null)
                {
                    s_LabelStyle = EditorStyles.boldLabel;
                    s_LabelStyle.richText = true;
                }
                EditorGUILayout.LabelField(label, s_LabelStyle);
            }

            var origIndent = EditorGUI.indentLevel;
            EditorGUI.indentLevel += 1;
            for (int i = 0; i < s_Fields.Count; i++)
            {
                var field = s_Fields[i];

                var niceName = ObjectNames.NicifyVariableName(field.Name);
                var fieldValue = field.GetValue(target);
                if (fieldValue != null)
                {
                    var levelProperty = GetLevelNoSideEffectsProperty(fieldValue);

                    if (levelProperty != null)
                    {
                        var levelValue = levelProperty.GetValue(fieldValue);
                        var level = levelValue;
                        EditorGUI.BeginDisabledGroup(true);
                        EditorGUI.EndDisabledGroup();
                    }
                    else
                    {
                        EditorGUILayout.LabelField($"{niceName} does not implement LevelNoSideEffects");
                    }
                }
                else
                {
                    EditorGUILayout.LabelField($"{niceName} is null");
                }
            }
            EditorGUI.indentLevel = origIndent;
        }

        private static void GetShowLevelAttributeFields(object target, List<FieldInfo> resList, bool appPlaying)
        {
            int count = 0;
            for (var currentType = target.GetType(); currentType != null; currentType = currentType.BaseType)
            {
                if (count == 100)
                {
                    return;
                }
                
                var fields = currentType.GetFields(k_ShowLevelBindingFlags);
            
                //
                // Search for ShowLevelAttribute within each field on this Object
                //
                for (int i = 0, counti = fields.Length; i < counti; ++i)
                {
                    var field = fields[i];
                    var showLevelAttribute = field.GetCustomAttribute<ShowLevelAttribute>(true);
                    if (showLevelAttribute == null)
                        continue;

                    if (!appPlaying && !showLevelAttribute.ShowWhenNotPlaying)
                    {
                        continue;
                    }
                    resList.Add(field);
                }

                count += 1;
            }
        }

        private static PropertyInfo GetLevelNoSideEffectsProperty(object fieldValue)
        {
            var properties = fieldValue.GetType().GetProperties(BindingFlags.GetProperty |
                                                        BindingFlags.Public | BindingFlags.Instance);

            for (int i = 0; i < properties.Length; i++)
            {
                var property = properties[i];

                if (k_EditorLevelProperty.CompareTo(property.Name) == 0)
                {
                    return property;
                }
            }

            return null;
        }
#endif
    }
}