using System;
using UnityEditor;
using UnityEditor.UIElements;
using UnityEngine;
using UnityEngine.UIElements;
using Ashwild.Building;

namespace Ashwild.EditorTools
{
    /// <summary>
    /// The custom editor for a BuildableData shown in the right pane of the Ashwild Database. Replaces
    /// the default ScriptableObject inspector with a hero header (large clickable icon, editable name,
    /// "Buildable" badge) and cards for the identity (description) and the ghost/built prefabs the
    /// construction menu and placement ghost consume. All fields bind live to the asset; changing the
    /// name or icon notifies the list so the row updates without a full rebuild.
    /// </summary>
    public class BuildableEditorView
    {
        #region State

        public VisualElement Root { get; }

        private const int IconPickerControlId = 0x41534842;

        private readonly BuildableData buildable;
        private readonly SerializedObject so;
        private readonly Action onMetaChanged;

        private VisualElement iconPreview;

        #endregion

        #region Construction

        /// <summary>
        /// Builds the full editor tree for a buildable. <paramref name="onMetaChanged"/> is raised when
        /// the display name or icon changes so the list can refresh that row.
        /// </summary>
        public BuildableEditorView(BuildableData buildable, Action onMetaChanged)
        {
            this.buildable = buildable;
            this.onMetaChanged = onMetaChanged;
            so = new SerializedObject(buildable);

            Root = new VisualElement();
            Root.Add(BuildHero());
            Root.Add(BuildIdentityCard());
            Root.Add(BuildPrefabsCard());
        }

        #endregion

        #region Hero

        /// <summary>
        /// Builds the hero header: a large clickable icon preview, the editable display name and the
        /// "Buildable" badge. Name/icon changes notify the list so its row follows immediately.
        /// </summary>
        private VisualElement BuildHero()
        {
            VisualElement hero = new VisualElement();
            hero.AddToClassList("ash-hero");

            iconPreview = new VisualElement();
            iconPreview.AddToClassList("ash-hero__icon");
            iconPreview.AddToClassList("ash-hero__icon--clickable");
            iconPreview.tooltip = "Click to change the buildable icon";
            iconPreview.RegisterCallback<ClickEvent>(_ => OpenIconPicker());
            UpdateIconPreview(buildable.Icon);
            hero.Add(iconPreview);

            IMGUIContainer iconPickerProxy = new IMGUIContainer(HandleIconPickerCommands);
            iconPickerProxy.style.position = Position.Absolute;
            iconPickerProxy.style.width = 1;
            iconPickerProxy.style.height = 1;
            hero.Add(iconPickerProxy);

            VisualElement info = new VisualElement();
            info.AddToClassList("ash-hero__info");

            TextField nameField = new TextField { value = buildable.DisplayName };
            nameField.AddToClassList("ash-hero__name");
            nameField.BindProperty(so.FindProperty("displayName"));
            nameField.RegisterValueChangedCallback(_ => onMetaChanged?.Invoke());
            info.Add(AshwildUI.EditableNameRow(nameField));

            VisualElement typeRow = new VisualElement();
            typeRow.AddToClassList("ash-hero__typerow");
            typeRow.Add(AshwildUI.Badge("Buildable", AshwildUI.BuildableColor));
            info.Add(typeRow);

            hero.Add(info);
            return hero;
        }

        /// <summary>
        /// Shows the buildable's icon in the hero preview, or a neutral placeholder when none is set.
        /// </summary>
        private void UpdateIconPreview(Sprite sprite)
        {
            iconPreview.style.backgroundImage = sprite != null ? new StyleBackground(sprite) : new StyleBackground();
        }

        /// <summary>
        /// Opens Unity's sprite object picker, seeded with the current icon, so the designer can change
        /// the buildable icon by clicking the hero preview directly.
        /// </summary>
        private void OpenIconPicker()
        {
            EditorGUIUtility.ShowObjectPicker<Sprite>(buildable.Icon, false, string.Empty, IconPickerControlId);
        }

        /// <summary>
        /// Listens (through the hidden IMGUI proxy) for the picker selecting/closing on our control id
        /// and applies the chosen sprite live, so the hero preview and the list row update immediately.
        /// </summary>
        private void HandleIconPickerCommands()
        {
            Event evt = Event.current;
            if (evt == null || evt.type != EventType.ExecuteCommand) return;
            if (EditorGUIUtility.GetObjectPickerControlID() != IconPickerControlId) return;
            if (evt.commandName != "ObjectSelectorUpdated" && evt.commandName != "ObjectSelectorClosed") return;

            AssignIcon(EditorGUIUtility.GetObjectPickerObject() as Sprite);
        }

        /// <summary>
        /// Writes the picked icon onto the asset (no-op when unchanged) and refreshes the hero preview
        /// and the list row.
        /// </summary>
        private void AssignIcon(Sprite sprite)
        {
            SerializedProperty iconProp = so.FindProperty("icon");
            if (iconProp.objectReferenceValue == sprite) return;

            iconProp.objectReferenceValue = sprite;
            so.ApplyModifiedProperties();
            UpdateIconPreview(sprite);
            onMetaChanged?.Invoke();
        }

        #endregion

        #region Cards

        /// <summary>
        /// Identity card: the description shown on the menu card, plus the icon field (kept in sync
        /// with the hero preview and the list row when edited here).
        /// </summary>
        private VisualElement BuildIdentityCard()
        {
            VisualElement card = AshwildUI.Card("Identity");

            TextField description = new TextField("Description") { multiline = true };
            description.AddToClassList("ash-description");
            description.BindProperty(so.FindProperty("description"));
            card.Add(description);

            ObjectField icon = new ObjectField("Icon") { objectType = typeof(Sprite), allowSceneObjects = false };
            icon.BindProperty(so.FindProperty("icon"));
            icon.RegisterValueChangedCallback(evt =>
            {
                UpdateIconPreview(evt.newValue as Sprite);
                onMetaChanged?.Invoke();
            });
            card.Add(icon);

            return card;
        }

        /// <summary>
        /// Prefabs card: the semi-transparent ghost spawned while positioning and the real structure
        /// spawned once placement is confirmed.
        /// </summary>
        private VisualElement BuildPrefabsCard()
        {
            VisualElement card = AshwildUI.Card("Prefabs");

            ObjectField ghost = new ObjectField("Ghost Prefab") { objectType = typeof(GameObject), allowSceneObjects = false };
            ghost.BindProperty(so.FindProperty("ghostPrefab"));
            card.Add(ghost);

            ObjectField built = new ObjectField("Built Prefab") { objectType = typeof(GameObject), allowSceneObjects = false };
            built.BindProperty(so.FindProperty("builtPrefab"));
            card.Add(built);

            return card;
        }

        #endregion
    }
}