using System.Collections;
using System.Collections.Generic;
using UnityEditor;
using UnityEngine;


namespace Beyond
{
    public static class Extensions
    {
        public static bool IsAncestor(this Transform trans, Transform ancestor)
        {
            if (trans.parent == null)
                return false;
            if (trans.parent == ancestor)
                return true;
            return trans.parent.IsAncestor(ancestor);
        }
        public static void SetLayer(this Transform trans, int layer)
        {
            trans.gameObject.layer = layer;
            foreach (Transform child in trans)
                child.SetLayer(layer);
        }
/*
        public static List<T> FindComponentsDownHierarchy<T>(this GameObject g) where T : Component
        {
            List<T> result = new List<T>();
            T component;
            component = g.GetComponent<T>();
            if (component == null)
                component = g.GetComponentInChildren<T>();
            return component;
        }
  */      
        public static T FindComponentDownHierarchy<T>(this GameObject g) where T : Component
        {
            T component;
            component = g.GetComponent<T>();
            if (component == null)
                component = g.GetComponentInChildren<T>();
            return component;
        }
        public static T FindComponentUpHierarchy<T>(this GameObject g) where T : Component
        {
            T component;
            component = g.GetComponent<T>();
            if (component == null && g.transform.parent != null)
            {
                component = FindComponentUpHierarchy<T>(g.transform.parent.gameObject);
            }
            return component;
        }

        public static void EnableRendererRecursivly(this GameObject g, bool enable)
        {
            g.GetComponent<Renderer>().enabled = enable;
            for (int i = 0; i < g.transform.childCount; i++)
            {
                EnableRendererRecursivly(g.transform.GetChild(i).gameObject, enable);
            }
        }

        public static T[] GetAllObjectsOnlyInScene<T>() where T : MonoBehaviour
        {
#if UNITY_EDITOR
            List<T> objectsInScene = new List<T>();
            foreach (T go in Resources.FindObjectsOfTypeAll(typeof(T)) as T[])
            {
                if (!EditorUtility.IsPersistent(go.transform.root.gameObject) && !(go.hideFlags == HideFlags.NotEditable || go.hideFlags == HideFlags.HideAndDontSave))
                    objectsInScene.Add(go);
            }
            return objectsInScene.ToArray();
#else
        return Resources.FindObjectsOfTypeAll(typeof(T)) as T[];
#endif
        }
    }


    public static class Vector2Extension
    {
        // positive if v2 is on the left side of v1
        public static float SignedAngle(this Vector2 v1, Vector2 v2)
        {
            Vector2 n1 = v1.normalized;
            Vector2 n2 = v2.normalized;

            float dot = Vector2.Dot(n1, n2);
            if (dot > 1.0f)
                dot = 1.0f;
            if (dot < -1.0f)
                dot = -1.0f;

            float theta = Mathf.Acos(dot);
            float sgn = Vector2.Dot(new Vector2(-n1.y, n1.x), n2);
            if (sgn >= 0f)
                return theta;
            else
                return -theta;
        }

        public static Vector2 Rotate(this Vector2 v, float theta)
        {
            float cs = Mathf.Cos(theta);
            float sn = Mathf.Sin(theta);
            float x1 = v.x * cs - v.y * sn;
            float y1 = v.x * sn + v.y * cs;
            return new Vector2(x1, y1);
        }
    }

    public static class Vector3Extension
    {
        public static Vector3 WithX(this Vector3 v, float x)
        {
            return new Vector3(x, v.y, v.z);
        }

        public static Vector3 WithY(this Vector3 v, float y)
        {
            return new Vector3(v.x, y, v.z);
        }

        public static Vector3 WithZ(this Vector3 v, float z)
        {
            return new Vector3(v.x, v.y, z);
        }
    }

    public static class Matrix4x4Extension
    {
        public static Matrix4x4 GetPerspectiveProjection(float left, float right, float bottom, float top, float near, float far)
        {
            float x = (2.0f * near) / (right - left);
            float y = (2.0f * near) / (top - bottom);
            float a = (right + left) / (right - left);
            float b = (top + bottom) / (top - bottom);
            float c = -(far + near) / (far - near);
            float d = -(2.0f * far * near) / (far - near);
            float e = -1.0f;

            Matrix4x4 m = new Matrix4x4();
            m[0, 0] = x; m[0, 1] = 0; m[0, 2] = a; m[0, 3] = 0;
            m[1, 0] = 0; m[1, 1] = y; m[1, 2] = b; m[1, 3] = 0;
            m[2, 0] = 0; m[2, 1] = 0; m[2, 2] = c; m[2, 3] = d;
            m[3, 0] = 0; m[3, 1] = 0; m[3, 2] = e; m[3, 3] = 0;
            return m;
        }
    }

    public static class GameObjectExt
    {
        public static void SetLayerRecursively(this GameObject obj, int layer)
        {
            obj.layer = layer;
            foreach (Transform t in obj.transform)
            {
                t.gameObject.SetLayerRecursively(layer);
            }
        }
    }

    public static class QuaternionExt
    {
        public static Quaternion Mul(this Quaternion quat, float a)
        {
            Quaternion res = quat;
            res.x *= a;
            res.y *= a;
            res.z *= a;
            res.w *= a;
            return res;
        }

        public static Quaternion Normalize(this Quaternion quat)
        {
            float s = Mathf.Sqrt(quat.x * quat.x + quat.y * quat.y + quat.z * quat.z + quat.w * quat.w);
            return quat.Mul(1.0f / s);
        }

        public static Quaternion Add(this Quaternion lhs, Quaternion rhs)
        {
            Quaternion res = lhs;
            res.x += rhs.x;
            res.y += rhs.y;
            res.z += rhs.z;
            res.w += rhs.w;
            return res;
        }
    }

    public static class CameraExtension
    {
        public static Matrix4x4 GetPerspectiveProjection(this Camera camera)
        {
            return GetPerspectiveProjection(camera, 0f, 0f);
        }

        public static Matrix4x4 GetPerspectiveProjection(this Camera camera, float texelOffsetX, float texelOffsetY)
        {
            if (camera == null)
                return Matrix4x4.identity;

            float oneExtentY = Mathf.Tan(0.5f * Mathf.Deg2Rad * camera.fieldOfView);
            float oneExtentX = oneExtentY * camera.aspect;
            float texelSizeX = oneExtentX / (0.5f * camera.pixelWidth);
            float texelSizeY = oneExtentY / (0.5f * camera.pixelHeight);
            float oneJitterX = texelSizeX * texelOffsetX;
            float oneJitterY = texelSizeY * texelOffsetY;

            float cf = camera.farClipPlane;
            float cn = camera.nearClipPlane;
            float xm = (oneJitterX - oneExtentX) * cn;
            float xp = (oneJitterX + oneExtentX) * cn;
            float ym = (oneJitterY - oneExtentY) * cn;
            float yp = (oneJitterY + oneExtentY) * cn;

            return Matrix4x4Extension.GetPerspectiveProjection(xm, xp, ym, yp, cn, cf);
        }

        public static Vector4 GetPerspectiveProjectionCornerRay(this Camera camera)
        {
            return GetPerspectiveProjectionCornerRay(camera, 0f, 0f);
        }

        public static Vector4 GetPerspectiveProjectionCornerRay(this Camera camera, float texelOffsetX, float texelOffsetY)
        {
            if (camera == null)
                return Vector4.zero;

            float oneExtentY = Mathf.Tan(0.5f * Mathf.Deg2Rad * camera.fieldOfView);
            float oneExtentX = oneExtentY * camera.aspect;
            float texelSizeX = oneExtentX / (0.5f * camera.pixelWidth);
            float texelSizeY = oneExtentY / (0.5f * camera.pixelHeight);
            float oneJitterX = texelSizeX * texelOffsetX;
            float oneJitterY = texelSizeY * texelOffsetY;

            return new Vector4(oneExtentX, oneExtentY, oneJitterX, oneJitterY);
        }
    }
}