//------------------------------------------------------------
// Game Framework
// Copyright © 2013-2021 Jiang Yin. All rights reserved.
// Homepage: https://gameframework.cn/
// Feedback: mailto:ellan@gameframework.cn
//------------------------------------------------------------

using UnityEngine;
using UnityEngine.UI;
using UnityGameFramework.Runtime;
using GeometryTD.CustomComponent;

namespace UI
{
    /// <summary>
    /// uGUI 界面组辅助器。
    /// </summary>
    [DefaultExecutionOrder(200)]
    public class UGuiGroupHelper : UIGroupHelperBase
    {
        public const int DepthFactor = 10000;

        private int m_Depth = 0;
        private Canvas m_CachedCanvas = null;
        private RectTransform m_RectTransform = null;
        private int m_LastScreenWidth = -1;
        private int m_LastScreenHeight = -1;
        private Rect m_LastViewport = new Rect(float.MinValue, float.MinValue, float.MinValue, float.MinValue);

        /// <summary>
        /// 设置界面组深度。
        /// </summary>
        /// <param name="depth">界面组深度。</param>
        public override void SetDepth(int depth)
        {
            m_Depth = depth;
            m_CachedCanvas.overrideSorting = true;
            m_CachedCanvas.sortingOrder = DepthFactor * depth;
        }

        private void Awake()
        {
            m_CachedCanvas = gameObject.GetOrAddComponent<Canvas>();
            gameObject.GetOrAddComponent<GraphicRaycaster>();
            m_RectTransform = GetComponent<RectTransform>();
        }

        private void Start()
        {
            m_CachedCanvas.overrideSorting = true;
            m_CachedCanvas.sortingOrder = DepthFactor * m_Depth;

            if (m_RectTransform == null)
            {
                return;
            }

            m_RectTransform.anchorMin = Vector2.zero;
            m_RectTransform.anchorMax = Vector2.one;
            m_RectTransform.pivot = new Vector2(0.5f, 0.5f);
            m_RectTransform.anchoredPosition = Vector2.zero;
            m_RectTransform.sizeDelta = Vector2.zero;
            ApplyViewportClip(true);
        }

        private void LateUpdate()
        {
            ApplyViewportClip(false);
        }

        private void ApplyViewportClip(bool force)
        {
            if (m_RectTransform == null)
            {
                return;
            }

            int screenWidth = Screen.width;
            int screenHeight = Screen.height;
            Rect viewport = ResolveViewportRect();
            if (!force
                && screenWidth == m_LastScreenWidth
                && screenHeight == m_LastScreenHeight
                && Mathf.Approximately(viewport.x, m_LastViewport.x)
                && Mathf.Approximately(viewport.y, m_LastViewport.y)
                && Mathf.Approximately(viewport.width, m_LastViewport.width)
                && Mathf.Approximately(viewport.height, m_LastViewport.height))
            {
                return;
            }

            m_LastScreenWidth = screenWidth;
            m_LastScreenHeight = screenHeight;
            m_LastViewport = viewport;

            if (screenWidth <= 0 || screenHeight <= 0)
            {
                return;
            }

            float horizontalPadding = Mathf.Max(0f, (1f - viewport.width) * 0.5f * screenWidth);
            float verticalPadding = Mathf.Max(0f, (1f - viewport.height) * 0.5f * screenHeight);
            float canvasScale = ResolveCanvasScaleFactor();
            float horizontalPaddingInCanvasUnit = horizontalPadding / canvasScale;
            float verticalPaddingInCanvasUnit = verticalPadding / canvasScale;
            m_RectTransform.offsetMin = new Vector2(horizontalPaddingInCanvasUnit, verticalPaddingInCanvasUnit);
            m_RectTransform.offsetMax = new Vector2(-horizontalPaddingInCanvasUnit, -verticalPaddingInCanvasUnit);
        }

        private Rect ResolveViewportRect()
        {
            if (ResolutionAdapterComponent.TryGetTargetViewport(out Rect adapterViewport))
            {
                return adapterViewport;
            }

            Camera camera = m_CachedCanvas != null ? m_CachedCanvas.worldCamera : null;
            if (camera == null && m_CachedCanvas != null && m_CachedCanvas.rootCanvas != null)
            {
                camera = m_CachedCanvas.rootCanvas.worldCamera;
            }

            if (camera == null && GameEntry.Scene != null)
            {
                camera = GameEntry.Scene.MainCamera;
            }

            if (camera == null)
            {
                camera = Camera.main;
            }

            return camera != null ? camera.rect : new Rect(0f, 0f, 1f, 1f);
        }

        private float ResolveCanvasScaleFactor()
        {
            Canvas rootCanvas = m_CachedCanvas != null ? m_CachedCanvas.rootCanvas : null;
            float scale = rootCanvas != null ? rootCanvas.scaleFactor : (m_CachedCanvas != null ? m_CachedCanvas.scaleFactor : 1f);
            return scale > 0.0001f ? scale : 1f;
        }
    }
}