using UnityEditor;
using UnityEditor.UI;
using UnityEngine;
using System.Collections.Generic;
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 List<UIParticle> s_TempParents = new List<UIParticle>();
        private static readonly List<UIParticle> s_TempChildren = new List<UIParticle>();

        private SerializedProperty _spScale;
        private SerializedProperty _spIgnoreCanvasScaler;
        private SerializedProperty _spAnimatableProperties;

        private ReorderableList _ro;

        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();
            _spScale = serializedObject.FindProperty("m_Scale");
            _spIgnoreCanvasScaler = serializedObject.FindProperty("m_IgnoreCanvasScaler");
            _spAnimatableProperties = serializedObject.FindProperty("m_AnimatableProperties");

            var sp = serializedObject.FindProperty("m_Particles");
            _ro = new ReorderableList(sp.serializedObject, sp, true, true, false, false);
            _ro.elementHeight = EditorGUIUtility.singleLineHeight + 4;
            _ro.drawElementCallback = (rect, index, active, focused) =>
            {
                rect.y += 1;
                rect.height = EditorGUIUtility.singleLineHeight;
                EditorGUI.ObjectField(rect, sp.GetArrayElementAtIndex(index), GUIContent.none);
            };
            _ro.drawHeaderCallback += rect =>
            {
                EditorGUI.LabelField(new Rect(rect.x, rect.y, 150, rect.height), s_ContentRenderingOrder);

                if (GUI.Button(new Rect(rect.width - 80, rect.y - 1, 80, rect.height), s_ContentRefresh, EditorStyles.miniButton))
                {
                    foreach (UIParticle t in targets)
                    {
                        t.RefreshParticles();
                    }
                }
            };
        }

        /// <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();

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

            // Scale
            EditorGUILayout.PropertyField(_spScale);

            // AnimatableProperties
            AnimatedPropertiesEditor.DrawAnimatableProperties(_spAnimatableProperties, current.material);

            _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;
            }
            current.GetComponentsInParent(true, s_TempParents);
            if (FixButton(1 < s_TempParents.Count,"This UIParticle component should be removed. The parent UIParticle exists."))
            {
                DestroyUIParticle(current);
                return;
            }
            current.GetComponentsInChildren(true, s_TempChildren);
            if (FixButton(1 < s_TempChildren.Count,"The children UIParticle component should be removed."))
            {
                s_TempChildren.ForEach(child => DestroyUIParticle(child, true));
            }
        }

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

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

        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));
                }
            }
        }
    }
}