using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using TMPro;
using UnityEditor;
using UnityEngine.EventSystems;

public class TMPExtensions : UnityEditor.UI.ButtonEditor
{
    private const string kUILayerName = "UI";
    private const float kWidth = 160f;
    private const float kThickHeight = 30f;
    private const string kStandardSpritePath = "UI/Skin/UISprite.psd";

    private static Vector2 s_ThickGUIElementSize = new Vector2(kWidth, kThickHeight);
    private static Color s_DefaultSelectableColor = new Color(1f, 1f, 1f, 1f);
    private static Color s_TextColor = new Color(50f / 255f, 50f / 255f, 50f / 255f, 1f);
    private static float s_TextFontSize = 14;

    private static void SetPositionVisibleinSceneView(RectTransform canvasRTransform, RectTransform itemTransform)
    {
        // Find the best scene view
        SceneView sceneView = SceneView.lastActiveSceneView;
        if (sceneView == null && SceneView.sceneViews.Count > 0)
            sceneView = SceneView.sceneViews[0] as SceneView;

        // Couldn't find a SceneView. Don't set position.
        if (sceneView == null || sceneView.camera == null)
            return;

        // Create world space Plane from canvas position.
        Vector2 localPlanePosition;
        Camera camera = sceneView.camera;
        Vector3 position = Vector3.zero;
        if (RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRTransform, new Vector2(camera.pixelWidth / 2, camera.pixelHeight / 2), camera, out localPlanePosition))
        {
            // Adjust for canvas pivot
            localPlanePosition.x = localPlanePosition.x + canvasRTransform.sizeDelta.x * canvasRTransform.pivot.x;
            localPlanePosition.y = localPlanePosition.y + canvasRTransform.sizeDelta.y * canvasRTransform.pivot.y;

            localPlanePosition.x = Mathf.Clamp(localPlanePosition.x, 0, canvasRTransform.sizeDelta.x);
            localPlanePosition.y = Mathf.Clamp(localPlanePosition.y, 0, canvasRTransform.sizeDelta.y);

            // Adjust for anchoring
            position.x = localPlanePosition.x - canvasRTransform.sizeDelta.x * itemTransform.anchorMin.x;
            position.y = localPlanePosition.y - canvasRTransform.sizeDelta.y * itemTransform.anchorMin.y;

            Vector3 minLocalPosition;
            minLocalPosition.x = canvasRTransform.sizeDelta.x * (0 - canvasRTransform.pivot.x) + itemTransform.sizeDelta.x * itemTransform.pivot.x;
            minLocalPosition.y = canvasRTransform.sizeDelta.y * (0 - canvasRTransform.pivot.y) + itemTransform.sizeDelta.y * itemTransform.pivot.y;

            Vector3 maxLocalPosition;
            maxLocalPosition.x = canvasRTransform.sizeDelta.x * (1 - canvasRTransform.pivot.x) - itemTransform.sizeDelta.x * itemTransform.pivot.x;
            maxLocalPosition.y = canvasRTransform.sizeDelta.y * (1 - canvasRTransform.pivot.y) - itemTransform.sizeDelta.y * itemTransform.pivot.y;

            position.x = Mathf.Clamp(position.x, minLocalPosition.x, maxLocalPosition.x);
            position.y = Mathf.Clamp(position.y, minLocalPosition.y, maxLocalPosition.y);
        }

        itemTransform.anchoredPosition = position;
        itemTransform.localRotation = Quaternion.identity;
        itemTransform.localScale = Vector3.one;
    }

    private static GameObject CreateUIElementRoot(string name, MenuCommand menuCommand, Vector2 size)
    {
        GameObject parent = menuCommand.context as GameObject;
        if (parent == null || parent.GetComponentInParent<Canvas>() == null)
        {
            parent = GetOrCreateCanvasGameObject();
        }
        GameObject child = new GameObject(name);

        Undo.RegisterCreatedObjectUndo(child, "Create " + name);
        Undo.SetTransformParent(child.transform, parent.transform, "Parent " + child.name);
        GameObjectUtility.SetParentAndAlign(child, parent);

        RectTransform rectTransform = child.AddComponent<RectTransform>();
        rectTransform.sizeDelta = size;
        if (parent != menuCommand.context) // not a context click, so center in sceneview
        {
            SetPositionVisibleinSceneView(parent.GetComponent<RectTransform>(), rectTransform);
        }
        Selection.activeGameObject = child;
        return child;
    }

    [MenuItem("GameObject/UI/TextMeshPro - Button", false, 2012)]
    static public void AddButton(MenuCommand menuCommand)
    {
        GameObject buttonRoot = CreateUIElementRoot("TextMeshPro - Button", menuCommand, s_ThickGUIElementSize);

        GameObject childText = new GameObject("TextMeshPro - Text");
        GameObjectUtility.SetParentAndAlign(childText, buttonRoot);

        Image image = buttonRoot.AddComponent<Image>();
        image.sprite = AssetDatabase.GetBuiltinExtraResource<Sprite>(kStandardSpritePath);
        image.type = Image.Type.Sliced;
        image.color = s_DefaultSelectableColor;

        Button bt = buttonRoot.AddComponent<Button>();
        SetDefaultColorTransitionValues(bt);

        TextMeshProUGUI text = childText.AddComponent<TextMeshProUGUI>();
        text.text = "Button";
        text.alignment = TextAlignmentOptions.Center;
        SetDefaultTextValues(text);

        RectTransform textRectTransform = childText.GetComponent<RectTransform>();
        textRectTransform.anchorMin = Vector2.zero;
        textRectTransform.anchorMax = Vector2.one;
        textRectTransform.sizeDelta = Vector2.zero;
    }

    private static void SetDefaultTextValues(TextMeshProUGUI lbl)
    {
        // Set text values we want across UI elements in default controls.
        // Don't set values which are the same as the default values for the Text component,
        // since there's no point in that, and it's good to keep them as consistent as possible.
        lbl.color = s_TextColor;
        lbl.fontSize = s_TextFontSize;
    }

    static GameObject CreateUIObject(string name, GameObject parent)
    {
        GameObject go = new GameObject(name);
        go.AddComponent<RectTransform>();
        GameObjectUtility.SetParentAndAlign(go, parent);
        return go;
    }

    private static void SetDefaultColorTransitionValues(Selectable slider)
    {
        ColorBlock colors = slider.colors;
        colors.highlightedColor = new Color(0.882f, 0.882f, 0.882f);
        colors.pressedColor = new Color(0.698f, 0.698f, 0.698f);
        colors.disabledColor = new Color(0.521f, 0.521f, 0.521f);
    }

    static public GameObject CreateNewUI()
    {
        // Root for the UI
        var root = new GameObject("Canvas");
        root.layer = LayerMask.NameToLayer(kUILayerName);
        Canvas canvas = root.AddComponent<Canvas>();
        canvas.renderMode = RenderMode.ScreenSpaceOverlay;
        root.AddComponent<CanvasScaler>();
        root.AddComponent<GraphicRaycaster>();
        Undo.RegisterCreatedObjectUndo(root, "Create " + root.name);

        // if there is no event system add one...
        CreateEventSystem(false);
        return root;
    }

    private static void CreateEventSystem(bool select)
    {
        CreateEventSystem(select, null);
    }

    private static void CreateEventSystem(bool select, GameObject parent)
    {
        var esys = Object.FindObjectOfType<EventSystem>();
        if (esys == null)
        {
            var eventSystem = new GameObject("EventSystem");
            GameObjectUtility.SetParentAndAlign(eventSystem, parent);
            esys = eventSystem.AddComponent<EventSystem>();
            eventSystem.AddComponent<StandaloneInputModule>();
            //eventSystem.AddComponent<TouchInputModule>();

            Undo.RegisterCreatedObjectUndo(eventSystem, "Create " + eventSystem.name);
        }

        if (select && esys != null)
        {
            Selection.activeGameObject = esys.gameObject;
        }
    }

    // Helper function that returns a Canvas GameObject; preferably a parent of the selection, or other existing Canvas.
    static public GameObject GetOrCreateCanvasGameObject()
    {
        GameObject selectedGo = Selection.activeGameObject;

        // Try to find a gameobject that is the selected GO or one if its parents.
        Canvas canvas = (selectedGo != null) ? selectedGo.GetComponentInParent<Canvas>() : null;
        if (canvas != null && canvas.gameObject.activeInHierarchy)
            return canvas.gameObject;

        // No canvas in selection or its parents? Then use just any canvas..
        canvas = Object.FindObjectOfType(typeof(Canvas)) as Canvas;
        if (canvas != null && canvas.gameObject.activeInHierarchy)
            return canvas.gameObject;

        // No canvas in the scene at all? Then create a new one.
        return CreateNewUI();
    }
}