using UnityEditor;
using UnityEditor.UI;
using UnityEngine;
using System.Collections.Generic;
using System.Linq;
using UnityEditorInternal;
using UnityEngine.UI;

namespace Coffee.UIExtensions
{
    [CustomEditor(typeof(UIParticle))]
    [CanEditMultipleObjects]
    internal class UIParticleEditor : GraphicEditor
    {
        //################################
        // Constant or Static Members.
        //################################
        private static readonly GUIContent s_ContentRenderingOrder = new GUIContent("Rendering Order");
        private static readonly GUIContent s_ContentRefresh = new GUIContent("Refresh");
        private static readonly GUIContent s_ContentFix = new GUIContent("Fix");
        private static readonly GUIContent s_ContentMaterial = new GUIContent("Material");
        private static readonly GUIContent s_ContentTrailMaterial = new GUIContent("Trail Material");
        private static readonly GUIContent s_Content3D = new GUIContent("3D");
        private static readonly GUIContent s_ContentScale = new GUIContent("Scale");

        private SerializedProperty _spMaskable;
        private SerializedProperty _spScale;
        private SerializedProperty _spIgnoreCanvasScaler;
        private SerializedProperty _spAnimatableProperties;
        private SerializedProperty _spShrinkByMaterial;

        private ReorderableList _ro;
        private bool _xyzMode;
        private bool _showMaterials;

        private static readonly List<string> s_MaskablePropertyNames = new List<string>
        {
            "_Stencil",
            "_StencilComp",
            "_StencilOp",
            "_StencilWriteMask",
            "_StencilReadMask",
            "_ColorMask",
        };


        //################################
        // Public/Protected Members.
        //################################
        /// <summary>
        /// This function is called when the object becomes enabled and active.
        /// </summary>
        protected override void OnEnable()
        {
            base.OnEnable();
            _spMaskable = serializedObject.FindProperty("m_Maskable");
            _spScale = serializedObject.FindProperty("m_Scale3D");
            _spIgnoreCanvasScaler = serializedObject.FindProperty("m_IgnoreCanvasScaler");
            _spAnimatableProperties = serializedObject.FindProperty("m_AnimatableProperties");
            _spShrinkByMaterial = serializedObject.FindProperty("m_ShrinkByMaterial");
            _showMaterials = EditorPrefs.GetBool("Coffee.UIExtensions.UIParticleEditor._showMaterials", true);

            var sp = serializedObject.FindProperty("m_Particles");
            _ro = new ReorderableList(sp.serializedObject, sp, true, true, true, true);
            _ro.elementHeight = EditorGUIUtility.singleLineHeight * 3 + 4;
            _ro.elementHeightCallback = _ => _showMaterials
                ? 3 * (EditorGUIUtility.singleLineHeight + 2)
                : EditorGUIUtility.singleLineHeight + 2;
            _ro.drawElementCallback = (rect, index, active, focused) =>
            {
                EditorGUI.BeginDisabledGroup(sp.hasMultipleDifferentValues);
                rect.y += 1;
                rect.height = EditorGUIUtility.singleLineHeight;
                var p = sp.GetArrayElementAtIndex(index);
                EditorGUI.ObjectField(rect, p, GUIContent.none);
                if (!_showMaterials) return;

                rect.x += 15;
                rect.width -= 15;
                var ps = p.objectReferenceValue as ParticleSystem;
                var materials = ps
                    ? new SerializedObject(ps.GetComponent<ParticleSystemRenderer>()).FindProperty("m_Materials")
                    : null;
                rect.y += rect.height + 1;
                MaterialField(rect, s_ContentMaterial, materials, 0);
                rect.y += rect.height + 1;
                MaterialField(rect, s_ContentTrailMaterial, materials, 1);
                EditorGUI.EndDisabledGroup();
                if (materials != null)
                {
                    materials.serializedObject.ApplyModifiedProperties();
                }
            };
            _ro.drawHeaderCallback += rect =>
            {
#if !UNITY_2019_3_OR_NEWER
                rect.y -= 1;
#endif
                EditorGUI.LabelField(new Rect(rect.x, rect.y, 150, rect.height), s_ContentRenderingOrder);

                var content = EditorGUIUtility.IconContent(_showMaterials ? "VisibilityOn" : "VisibilityOff");
                _showMaterials = GUI.Toggle(new Rect(rect.width - 55, rect.y, 24, 20), _showMaterials, content, EditorStyles.label);

                if (GUI.Button(new Rect(rect.width - 35, rect.y, 60, rect.height), s_ContentRefresh, EditorStyles.miniButton))
                {
                    foreach (UIParticle t in targets)
                    {
                        t.RefreshParticles();
                    }
                }
            };
        }

        private static void MaterialField(Rect rect, GUIContent label, SerializedProperty sp, int index)
        {
            if (sp == null || sp.arraySize <= index)
            {
                EditorGUI.BeginDisabledGroup(true);
                EditorGUI.ObjectField(rect, label, null, typeof(Material), true);
                EditorGUI.EndDisabledGroup();
            }
            else
            {
                EditorGUI.PropertyField(rect, sp.GetArrayElementAtIndex(index), label);
            }
        }

        /// <summary>
        /// Implement this function to make a custom inspector.
        /// </summary>
        public override void OnInspectorGUI()
        {
            var current = target as UIParticle;
            if (current == null) return;

            serializedObject.Update();

            // Maskable
            EditorGUILayout.PropertyField(_spMaskable);

            // IgnoreCanvasScaler
            using (var ccs = new EditorGUI.ChangeCheckScope())
            {
                EditorGUILayout.PropertyField(_spIgnoreCanvasScaler);
                if (ccs.changed)
                {
                    foreach (UIParticle p in targets)
                    {
                        p.ignoreCanvasScaler = _spIgnoreCanvasScaler.boolValue;
                    }
                }
            }

            // Scale
            _xyzMode = DrawFloatOrVector3Field(_spScale, _xyzMode);

            // AnimatableProperties
            var mats = current.particles
                .Where(x => x)
                .Select(x => x.GetComponent<ParticleSystemRenderer>().sharedMaterial)
                .Where(x => x)
                .ToArray();

            // Animated properties
            EditorGUI.BeginChangeCheck();
            AnimatedPropertiesEditor.DrawAnimatableProperties(_spAnimatableProperties, mats);
            if (EditorGUI.EndChangeCheck())
            {
                foreach (UIParticle t in targets)
                    t.SetMaterialDirty();
            }

            // ShrinkByMaterial
            EditorGUILayout.PropertyField(_spShrinkByMaterial);

            // Target ParticleSystems.
            _ro.DoLayoutList();

            serializedObject.ApplyModifiedProperties();

            // Does the shader support UI masks?
            if (current.maskable && current.GetComponentInParent<Mask>())
            {
                foreach (var mat in current.materials)
                {
                    if (!mat || !mat.shader) continue;
                    var shader = mat.shader;
                    foreach (var propName in s_MaskablePropertyNames)
                    {
                        if (mat.HasProperty(propName)) continue;

                        EditorGUILayout.HelpBox(string.Format("Shader '{0}' doesn't have '{1}' property. This graphic cannot be masked.", shader.name, propName), MessageType.Warning);
                        break;
                    }
                }
            }

            // Does the shader support UI masks?

            if (FixButton(current.m_IsTrail, "This UIParticle component should be removed. The UIParticle for trails is no longer needed."))
            {
                DestroyUIParticle(current);
                return;
            }
        }

        void DestroyUIParticle(UIParticle p, bool ignoreCurrent = false)
        {
            if (!p || ignoreCurrent && target == p) return;

            var cr = p.canvasRenderer;
            DestroyImmediate(p);
            DestroyImmediate(cr);

#if UNITY_2018_3_OR_NEWER
            var stage = UnityEditor.Experimental.SceneManagement.PrefabStageUtility.GetCurrentPrefabStage();
            if (stage != null && stage.scene.isLoaded)
            {
#if UNITY_2020_1_OR_NEWER
                string prefabAssetPath = stage.assetPath;
#else
                string prefabAssetPath = stage.prefabAssetPath;
#endif
                PrefabUtility.SaveAsPrefabAsset(stage.prefabContentsRoot, prefabAssetPath);
            }
#endif
        }

        bool FixButton(bool show, string text)
        {
            if (!show) return false;
            using (new EditorGUILayout.HorizontalScope(GUILayout.ExpandWidth(true)))
            {
                EditorGUILayout.HelpBox(text, MessageType.Warning, true);
                using (new EditorGUILayout.VerticalScope())
                {
                    return GUILayout.Button(s_ContentFix, GUILayout.Width(30));
                }
            }
        }

        private static bool DrawFloatOrVector3Field(SerializedProperty sp, bool showXyz)
        {
            var x = sp.FindPropertyRelative("x");
            var y = sp.FindPropertyRelative("y");
            var z = sp.FindPropertyRelative("z");

            showXyz |= !Mathf.Approximately(x.floatValue, y.floatValue) ||
                       !Mathf.Approximately(y.floatValue, z.floatValue) ||
                       y.hasMultipleDifferentValues ||
                       z.hasMultipleDifferentValues;

            EditorGUILayout.BeginHorizontal();
            if (showXyz)
            {
                EditorGUI.BeginChangeCheck();
                EditorGUILayout.PropertyField(sp);
                if (EditorGUI.EndChangeCheck())
                {
                    x.floatValue = Mathf.Max(0.001f, x.floatValue);
                    y.floatValue = Mathf.Max(0.001f, y.floatValue);
                    z.floatValue = Mathf.Max(0.001f, z.floatValue);
                }
            }
            else
            {
                EditorGUI.BeginChangeCheck();
                EditorGUILayout.PropertyField(x, s_ContentScale);
                if (EditorGUI.EndChangeCheck())
                {
                    x.floatValue = Mathf.Max(0.001f, x.floatValue);
                    y.floatValue = Mathf.Max(0.001f, x.floatValue);
                    z.floatValue = Mathf.Max(0.001f, x.floatValue);
                }
            }

            EditorGUI.BeginChangeCheck();
            showXyz = GUILayout.Toggle(showXyz, s_Content3D, EditorStyles.miniButton, GUILayout.Width(30));
            if (EditorGUI.EndChangeCheck() && !showXyz)
                z.floatValue = y.floatValue = x.floatValue;
            EditorGUILayout.EndHorizontal();

            return showXyz;
        }
    }
}