using System;
using GamecraftModdingAPI.Utility;
using Svelto.DataStructures;
using UnityEngine;

namespace GamecraftModdingAPI.Interface.IMGUI
{
    /// <summary>
    /// A group of elements.
    /// This wraps Unity's GUILayout Area and GUI Group system.
    /// </summary>
    public class Group : UIElement
    {
        private bool automaticLayout;
        
        private FasterList<UIElement> elements = new FasterList<UIElement>();

        /// <summary>
        /// The rectangular area in the window that the UI group can use
        /// </summary>
        public Rect Box { get; set; }

        public void OnGUI()
        {
            /*if (Constants.Default == null) return;
            if (Constants.Default.box == null) return;*/
            GUIStyle guiStyle = Constants.Default.box;
            UIElement[] elems = elements.ToArrayFast(out uint count);
            if (automaticLayout)
            {
                GUILayout.BeginArea(Box, guiStyle);
                for (uint i = 0; i < count; i++)
                {
                    /*try
                    {
                        if (elems[i].Enabled)
                            elems[i].OnGUI();
                    }
                    catch (ArgumentException)
                    {
                        // ignore these, since this is (hopefully) just Unity being dumb
                    }
                    catch (Exception e)
                    {
                        Logging.MetaDebugLog($"Element '{elems[i].Name}' threw exception:\n{e.ToString()}");
                    }*/
                    if (elems[i].Enabled)
                        elems[i].OnGUI();
                }
                GUILayout.EndArea();
            }
            else
            {
                GUI.BeginGroup(Box, guiStyle);
                for (uint i = 0; i < count; i++)
                {
                    if (elems[i].Enabled)
                        elems[i].OnGUI();
                }
                GUI.EndGroup();
            }
        }

        /// <summary>
        /// The group's unique name.
        /// </summary>
        public string Name { get; }
        
        /// <summary>
        /// Whether to display the group and everything in it.
        /// </summary>
        public bool Enabled { set; get; } = true;
        
        /// <summary>
        /// The amount of elements in the group.
        /// </summary>
        public int Length
        {
            get => elements.count;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="T:GamecraftModdingAPI.Interface.IMGUI.Group"/> class.
        /// </summary>
        /// <param name="box">The rectangular area to use in the window.</param>
        /// <param name="name">Name of the group.</param>
        /// <param name="automaticLayout">Whether to use automatic UI layout.</param>
        public Group(Rect box, string name = null, bool automaticLayout = false)
        {
            Box = box;
            if (name == null)
            {
                this.Name = typeof(Group).FullName + "::" + box.ToString().Replace(" ", "");
            }
            else
            {
                this.Name = name;
            }
            this.automaticLayout = automaticLayout;
            IMGUIManager.AddElement(this);
        }

        /// <summary>
        /// Add an element to the group.
        /// </summary>
        /// <param name="element">The element to add.</param>
        /// <returns>Index of the new element.</returns>
        public int AddElement(UIElement element)
        {
            IMGUIManager.RemoveElement(element); // groups manage internal elements themselves
            elements.Add(element);
            return elements.count - 1;
        }

        /// <summary>
        /// Remove an element from the group.
        /// </summary>
        /// <param name="element">The element to remove.</param>
        /// <returns>Whether removal was successful.</returns>
        public bool RemoveElement(UIElement element)
        {
            int index = IndexOf(element);
            return RemoveAt(index);
        }

        /// <summary>
        /// Remove the element in a specific location.
        /// </summary>
        /// <param name="index">Index of the element.</param>
        /// <returns>Whether removal was successful.</returns>
        public bool RemoveAt(int index)
        {
            if (index < 0 || index >= elements.count) return false;
            IMGUIManager.AddElement(elements[index]); // re-add to global manager
            elements.RemoveAt(index);
            return true;
        }

        /// <summary>
        /// Get the index of an element.
        /// </summary>
        /// <param name="element">The element to search for.</param>
        /// <returns>The element's index, or -1 if not found.</returns>
        public int IndexOf(UIElement element)
        {
            UIElement[] elems = elements.ToArrayFast(out uint count);
            for (int i = 0; i < count; i++)
            {
                if (elems[i].Name == element.Name)
                {
                    return i;
                }
            }
            return -1;
        }
    }
}