using System.Collections.Generic;
using JetBrains.Annotations;
using UnityEditor;
using UnityEditor.Experimental.SceneManagement;
using UnityEditorInternal;
using UnityEngine;
using UTools = UnityEditor.Tools;

namespace Module.NavigationTool.Editor.Tools
{
    [UsedImplicitly]
    internal sealed class ToolUICanvasPicker : AbstractToolbarDrawer
    {
        public override bool Enabled => (UTools.visibleLayers & (1 << LayerMask.NameToLayer("UI"))) != 0;
        public override EToolbarPlacement Placement => EToolbarPlacement.Left;

        private static bool IS_DIRTY = true;
        private static string[] OPTIONS = new string[0];
        private static int[] INSTANCE_IDS = new int[0];
        
        private static void Initialize()
        {
            if (!IS_DIRTY)
                return;

            PrefabStage prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
            Canvas[] canvases = prefabStage != null ? prefabStage.prefabContentsRoot.GetComponentsInParent<Canvas>() : Object.FindObjectsOfType<Canvas>();

            var list = new List<Canvas>(canvases.Length);
            var listNames = new List<string>(canvases.Length);
            var listIds = new List<int>(canvases.Length);
            
            listNames.Add("Select");
            listIds.Add(-1);

            for (var i = 0; i < canvases.Length; i++)
            {
                Canvas root = canvases[i].rootCanvas;
                
                if (list.Contains(root))
                    continue;
                
                list.Add(root);
                listNames.Add(root.name);
                listIds.Add(root.GetInstanceID());
            }

            OPTIONS = listNames.ToArray();
            INSTANCE_IDS = listIds.ToArray();
            IS_DIRTY = false;
        }
        
        public override void Update()
        {
            Initialize();
        }

        protected override void Draw(Rect rect)
        {
            // Note: To fix an issue, where instantiated canvases wouldn't be detected, due to no events for canvas additions/removals exist in Unity API (at the moment)
            if (Event.current.type == EventType.MouseDown)
            {
                IS_DIRTY = true;
                Initialize();
            }

            int temp = EditorGUI.Popup(rect, 0, OPTIONS, styles.popup);

            if (temp != 0 && OPTIONS.Length != 1)
                Focus(INSTANCE_IDS[temp]);
        }
        
        public override float CalculateWidth()
        {
            return 100.0f;
        }
        
        private static void Focus(int instanceId)
        {
            Object obj = EditorUtility.InstanceIDToObject(instanceId);
            var canvas = obj as Canvas;
            
            if (canvas == null)
            {
                if (obj != null)
                    Debug.LogWarning("Failed to find Canvas component on object", obj);
                
                return;
            }

            Selection.activeObject = canvas;
            Bounds bounds = InternalEditorUtility.CalculateSelectionBounds(false, true, true);
            Vector3 point = bounds.center;
            Quaternion direction = canvas.transform.rotation;
            float size = Mathf.Max(bounds.extents.x, bounds.extents.y);
            bool ortho = canvas.renderMode == RenderMode.ScreenSpaceOverlay;

            for (var i = 0; i < SceneView.sceneViews.Count; i++)
            {
                var view = (SceneView)SceneView.sceneViews[i];
                view.in2DMode = false;
                view.LookAt(point, direction, size, ortho, false);
            }
        }

        public static void SetAsDirty()
        {
            IS_DIRTY = true;
        }
    }
}