using UnityEngine;
using UnityEngine.Rendering.Universal;

namespace UnityEditor.Rendering.Universal
{
    [CustomPropertyDrawer(typeof(StencilStateData), true)]
    internal class StencilStateDataDrawer : PropertyDrawer
    {
        class Styles
        {
            public static readonly GUIContent overrideStencil =
                new GUIContent("Stencil", "Override stencil rendering.");

            public static readonly GUIContent stencilValue = new GUIContent("Value",
                "The stencil index to write to.");

            public static readonly GUIContent stencilFunction = new GUIContent("Compare Function",
                "Choose the comparison function against the stencil value on screen.");

            public static readonly GUIContent stencilPass =
                new GUIContent("Pass", "What happens to the stencil value when passing.");

            public static readonly GUIContent stencilFail =
                new GUIContent("Fail", "What happens the the stencil value when failing.");

            public static readonly GUIContent stencilZFail =
                new GUIContent("Z Fail", "What happens the the stencil value when failing Z testing.");
        }

        private bool firstTime = true;

        //Stencil rendering
        private const int stencilBits = 4;
        private const int minStencilValue = 0;
        private const int maxStencilValue = (1 << stencilBits) - 1;

        //Stencil props
        private SerializedProperty m_OverrideStencil;
        private SerializedProperty m_StencilIndex;
        private SerializedProperty m_StencilFunction;
        private SerializedProperty m_StencilPass;
        private SerializedProperty m_StencilFail;
        private SerializedProperty m_StencilZFail;

        void Init(SerializedProperty property)
        {
            //Stencil
            m_OverrideStencil = property.FindPropertyRelative("overrideStencilState");
            m_StencilIndex = property.FindPropertyRelative("stencilReference");
            m_StencilFunction = property.FindPropertyRelative("stencilCompareFunction");
            m_StencilPass = property.FindPropertyRelative("passOperation");
            m_StencilFail = property.FindPropertyRelative("failOperation");
            m_StencilZFail = property.FindPropertyRelative("zFailOperation");

            firstTime = false;
        }

        public override void OnGUI(Rect rect, SerializedProperty property, GUIContent label)
        {
            if(firstTime)
                Init(property);

            rect.height = EditorGUIUtility.singleLineHeight;

            EditorGUI.PropertyField(rect, m_OverrideStencil, Styles.overrideStencil);
            if (m_OverrideStencil.boolValue)
            {
                EditorGUI.indentLevel++;
                rect.y += EditorUtils.Styles.defaultLineSpace;
                //Stencil value
                EditorGUI.BeginChangeCheck();
                var stencilVal = m_StencilIndex.intValue;
                stencilVal = EditorGUI.IntSlider(rect, Styles.stencilValue, stencilVal, minStencilValue, maxStencilValue);
                if (EditorGUI.EndChangeCheck())
                    m_StencilIndex.intValue = stencilVal;
                rect.y += EditorUtils.Styles.defaultLineSpace;
                //Stencil compare options
                EditorGUI.PropertyField(rect, m_StencilFunction, Styles.stencilFunction);
                rect.y += EditorUtils.Styles.defaultLineSpace;
                EditorGUI.indentLevel++;
                EditorGUI.PropertyField(rect, m_StencilPass, Styles.stencilPass);
                rect.y += EditorUtils.Styles.defaultLineSpace;
                EditorGUI.PropertyField(rect, m_StencilFail, Styles.stencilFail);
                rect.y += EditorUtils.Styles.defaultLineSpace;
                EditorGUI.indentLevel--;
                //Stencil compare options
                EditorGUI.PropertyField(rect, m_StencilZFail, Styles.stencilZFail);
                EditorGUI.indentLevel--;
            }
        }

        public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
        {
            if (m_OverrideStencil != null && m_OverrideStencil.boolValue)
                return EditorUtils.Styles.defaultLineSpace * 6;
            return EditorUtils.Styles.defaultLineSpace * 1;
        }
    }
}