using System;
using System.IO;
using System.Text.RegularExpressions;
using UnityEditor;
using UnityEditor.UIElements;
using UnityEngine;
using UnityEngine.UIElements;
using Ashwild.Inventory;
using Ashwild.Player;

namespace Ashwild.EditorTools
{
    /// <summary>
    /// The custom, context-aware editor for an ItemData shown in the right pane of the Ashwild
    /// Database. Replaces the default ScriptableObject inspector with a hero header (large icon, name,
    /// type badge) and a set of cards that reveal themselves only when relevant — the Tool card for
    /// tools/weapons, the Consumable card for consumables, fuel duration only when the item is fuel.
    /// All fields bind live to the asset, and the bottom card generates the world/hand prefabs by
    /// wrapping a chosen source object (see ItemAssetFactory).
    /// </summary>
    public class ItemEditorView
    {
        #region State

        public VisualElement Root { get; }

        private readonly ItemData item;
        private readonly SerializedObject so;
        private readonly Action onMetaChanged;
        private readonly Action onPrefabGenerated;

        private const int IconPickerControlId = 0x41534849;

        private VisualElement iconPreview;
        private VisualElement badgeHolder;
        private VisualElement toolCard;
        private VisualElement consumableCard;
        private VisualElement cookingCard;
        private VisualElement fuelCard;
        private VisualElement maxStackRow;
        private VisualElement fuelSecondsRow;
        private VisualElement generationCard;
        private ObjectField worldField;
        private ObjectField handField;
        private IMGUIContainer iconPickerProxy;
        private ItemType currentType;
        private GameObject pendingSource;

        #endregion

        #region Construction

        /// <summary>
        /// Builds the full editor tree for an item. <paramref name="onMetaChanged"/> is raised when the
        /// name, icon or type changes so the list can refresh that row; <paramref name="onPrefabGenerated"/>
        /// after a prefab is built so the view re-renders with the new reference.
        /// </summary>
        public ItemEditorView(ItemData item, Action onMetaChanged, Action onPrefabGenerated)
        {
            this.item = item;
            this.onMetaChanged = onMetaChanged;
            this.onPrefabGenerated = onPrefabGenerated;
            so = new SerializedObject(item);

            Root = new VisualElement();
            Root.Add(BuildHero());
            Root.Add(BuildIdentityCard());
            Root.Add(BuildStackingCard());
            Root.Add(BuildToolCard());
            Root.Add(BuildConsumableCard());
            Root.Add(BuildCookingCard());
            Root.Add(BuildFuelCard());
            Root.Add(BuildPrefabsCard());
            Root.Add(BuildAnimationCard());
            Root.Add(BuildGenerationCard());

            currentType = item.ItemType;
            ApplyTypeVisibility(currentType);
            SetRowVisible(maxStackRow, item.IsStackable);
            SetRowVisible(fuelSecondsRow, item.IsFuel);
            UpdateGenerationVisibility();
        }

        #endregion

        #region Hero

        /// <summary>
        /// Builds the hero header: a large icon preview, the editable item name, the type dropdown and
        /// the coloured type badge. Name/type changes notify the list; the badge and conditional cards
        /// react to the type 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 item icon";
            iconPreview.RegisterCallback<ClickEvent>(_ => OpenIconPicker());
            UpdateIconPreview(item.Icon);
            hero.Add(iconPreview);

            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 = item.ItemName };
            nameField.AddToClassList("ash-hero__name");
            nameField.BindProperty(so.FindProperty("itemName"));
            nameField.RegisterValueChangedCallback(_ => onMetaChanged?.Invoke());
            nameField.RegisterCallback<FocusOutEvent>(_ => RenameAssetToItemName());
            info.Add(AshwildUI.EditableNameRow(nameField));

            VisualElement typeRow = new VisualElement();
            typeRow.AddToClassList("ash-hero__typerow");

            EnumField typeField = new EnumField(item.ItemType);
            typeField.AddToClassList("ash-hero__type");
            typeField.BindProperty(so.FindProperty("itemType"));
            typeField.RegisterValueChangedCallback(evt =>
            {
                currentType = (ItemType)evt.newValue;
                ApplyTypeVisibility(currentType);
                RebuildBadge(currentType);
                UpdateGenerationVisibility();
                onMetaChanged?.Invoke();
            });
            typeRow.Add(typeField);

            badgeHolder = new VisualElement();
            badgeHolder.AddToClassList("ash-hero__badge");
            RebuildBadge(item.ItemType);
            typeRow.Add(badgeHolder);

            info.Add(typeRow);
            hero.Add(info);

            return hero;
        }

        /// <summary>
        /// Paints the type badge for the given type, replacing any previous one.
        /// </summary>
        private void RebuildBadge(ItemType type)
        {
            badgeHolder.Clear();
            badgeHolder.Add(AshwildUI.Badge(type.ToString(), AshwildUI.TypeColor(type)));
        }

        /// <summary>
        /// Shows the item'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 item icon by clicking the hero preview directly.
        /// </summary>
        private void OpenIconPicker()
        {
            EditorGUIUtility.ShowObjectPicker<Sprite>(item.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. ObjectSelectorUpdated fires on each highlight, so the
        /// hero, the bound Icon field and the list all preview the change 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 Asset Naming

        /// <summary>
        /// Renames the underlying asset file to match the authored item name (spaces → underscores) so
        /// the ScriptableObject on disk reads like the item it holds instead of the generic "NewItem".
        /// Runs on focus-out, not per keystroke, so the file is renamed once the name is committed; a
        /// blank name, an unchanged name, or a rename collision is skipped (the latter logged).
        /// </summary>
        private void RenameAssetToItemName()
        {
            string path = AssetDatabase.GetAssetPath(item);
            if (string.IsNullOrEmpty(path)) return;

            string desired = ToAssetFileName(item.ItemName);
            if (string.IsNullOrEmpty(desired)) return;

            if (string.Equals(Path.GetFileNameWithoutExtension(path), desired, StringComparison.Ordinal)) return;

            string error = AssetDatabase.RenameAsset(path, desired);
            if (!string.IsNullOrEmpty(error))
            {
                Debug.LogError($"[ItemEditorView] Could not rename asset to '{desired}': {error}", item);
                return;
            }

            onMetaChanged?.Invoke();
        }

        /// <summary>
        /// Turns an authored item name into a valid asset file name: trims, collapses every whitespace
        /// run to a single underscore, and drops characters the filesystem forbids in a file name.
        /// </summary>
        private static string ToAssetFileName(string itemName)
        {
            if (string.IsNullOrWhiteSpace(itemName)) return string.Empty;

            string underscored = Regex.Replace(itemName.Trim(), @"\s+", "_");
            foreach (char invalid in Path.GetInvalidFileNameChars())
                underscored = underscored.Replace(invalid.ToString(), string.Empty);
            return underscored;
        }

        #endregion

        #region Cards

        /// <summary>
        /// Identity card: description and icon. Editing the icon updates the hero preview and the list.
        /// </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>
        /// Stacking card: the stackable toggle and a max-stack field that only shows while stackable.
        /// </summary>
        private VisualElement BuildStackingCard()
        {
            VisualElement card = AshwildUI.Card("Stacking");

            Toggle stackable = new Toggle("Is Stackable");
            stackable.BindProperty(so.FindProperty("isStackable"));
            stackable.RegisterValueChangedCallback(evt => SetRowVisible(maxStackRow, evt.newValue));
            card.Add(stackable);

            maxStackRow = new IntegerField("Max Stack Size");
            ((IntegerField)maxStackRow).BindProperty(so.FindProperty("maxStackSize"));
            card.Add(maxStackRow);

            return card;
        }

        /// <summary>
        /// Tool card: harvest type and tool power. Only shown for tools and weapons.
        /// </summary>
        private VisualElement BuildToolCard()
        {
            toolCard = AshwildUI.Card("Tool");

            EnumField harvest = new EnumField("Harvest Type", item.HarvestType);
            harvest.BindProperty(so.FindProperty("harvestType"));
            toolCard.Add(harvest);

            FloatField power = new FloatField("Tool Power");
            power.BindProperty(so.FindProperty("toolPower"));
            toolCard.Add(power);

            return toolCard;
        }

        /// <summary>
        /// Consumable card: the restore values. Only shown for consumables.
        /// </summary>
        private VisualElement BuildConsumableCard()
        {
            consumableCard = AshwildUI.Card("Consumable");
            consumableCard.Add(BoundFloat("Health Restore", "healthRestore"));
            consumableCard.Add(BoundFloat("Hunger Restore", "hungerRestore"));
            consumableCard.Add(BoundFloat("Thirst Restore", "thirstRestore"));
            return consumableCard;
        }

        /// <summary>
        /// Cooking card: the cooked result item and its cook time (applies to any item that can cook).
        /// </summary>
        private VisualElement BuildCookingCard()
        {
            cookingCard = AshwildUI.Card("Cooking");

            ObjectField cooked = new ObjectField("Cooked Result") { objectType = typeof(ItemData), allowSceneObjects = false };
            cooked.BindProperty(so.FindProperty("cookedResult"));
            cookingCard.Add(cooked);

            cookingCard.Add(BoundFloat("Cook Time", "cookTime"));
            return cookingCard;
        }

        /// <summary>
        /// Fuel card: the fuel toggle and a burn-duration field revealed only while the item is fuel.
        /// </summary>
        private VisualElement BuildFuelCard()
        {
            fuelCard = AshwildUI.Card("Fuel");

            Toggle isFuel = new Toggle("Is Fuel");
            isFuel.BindProperty(so.FindProperty("isFuel"));
            isFuel.RegisterValueChangedCallback(evt => SetRowVisible(fuelSecondsRow, evt.newValue));
            fuelCard.Add(isFuel);

            fuelSecondsRow = BoundFloat("Fuel Seconds", "fuelSeconds");
            fuelCard.Add(fuelSecondsRow);

            return fuelCard;
        }

        /// <summary>
        /// Prefabs card: the world and hand prefab references (auto-filled by generation, editable here).
        /// </summary>
        private VisualElement BuildPrefabsCard()
        {
            VisualElement card = AshwildUI.Card("Prefabs");

            worldField = new ObjectField("World Prefab") { objectType = typeof(GameObject), allowSceneObjects = false };
            worldField.BindProperty(so.FindProperty("worldPrefab"));
            worldField.RegisterValueChangedCallback(_ => UpdateGenerationVisibility());
            card.Add(worldField);

            handField = new ObjectField("Hand Prefab") { objectType = typeof(GameObject), allowSceneObjects = false };
            handField.BindProperty(so.FindProperty("handPrefab"));
            handField.RegisterValueChangedCallback(_ => UpdateGenerationVisibility());
            card.Add(handField);

            return card;
        }

        /// <summary>
        /// Animation card: the clip sets this item imposes on each rig while it is held. Both are
        /// optional — an item that leaves them empty simply keeps the bare-hand animations, which is the
        /// right answer for every material and most consumables.
        /// </summary>
        private VisualElement BuildAnimationCard()
        {
            VisualElement card = AshwildUI.Card("Animation");

            ObjectField armsField = new ObjectField("Arms Set") { objectType = typeof(PlayerAnimationSet), allowSceneObjects = false };
            armsField.BindProperty(so.FindProperty("armsAnimationSet"));
            card.Add(armsField);

            ObjectField bodyField = new ObjectField("Body Set") { objectType = typeof(PlayerAnimationSet), allowSceneObjects = false };
            bodyField.BindProperty(so.FindProperty("bodyAnimationSet"));
            card.Add(bodyField);

            return card;
        }

        /// <summary>
        /// Generation card: pick a source prefab, then build both the world pickup (always) and the
        /// in-hand prefab (tools/weapons only) from it with one button, creating only the ones still
        /// missing.
        /// </summary>
        private VisualElement BuildGenerationCard()
        {
            generationCard = AshwildUI.Card("Prefab Generation");
            generationCard.AddToClassList("ash-card--accent");

            ObjectField source = new ObjectField("Source Prefab") { objectType = typeof(GameObject), allowSceneObjects = false };
            source.tooltip = "The set-up prefab (meshes + materials). Generation saves a Prefab Variant of it with the gameplay components added.";
            source.RegisterValueChangedCallback(evt => pendingSource = evt.newValue as GameObject);
            generationCard.Add(source);

            VisualElement buttons = new VisualElement();
            buttons.AddToClassList("ash-buttons");

            Button generate = new Button(GeneratePrefabs) { text = "Generate Prefab" };
            generate.AddToClassList("ash-btn");
            generate.AddToClassList("ash-btn--primary");
            buttons.Add(generate);

            generationCard.Add(buttons);
            return generationCard;
        }

        #endregion

        #region Actions

        /// <summary>
        /// Builds every prefab still missing for the item from the chosen source: the world pickup when
        /// none is set, and the in-hand prefab when the item is a tool/weapon and none is set. Re-renders
        /// once if anything was generated so the view reflects the new references and hides the card when
        /// nothing is left to build.
        /// </summary>
        private void GeneratePrefabs()
        {
            bool generated = false;

            if (worldField.value == null)
                generated |= ItemAssetFactory.GenerateWorldPrefab(item, pendingSource) != null;

            bool isToolLike = currentType == ItemType.Tool || currentType == ItemType.Weapon;
            if (isToolLike && handField.value == null)
                generated |= ItemAssetFactory.GenerateHandPrefab(item, pendingSource) != null;

            if (generated) onPrefabGenerated?.Invoke();
        }

        #endregion

        #region Conditional Visibility

        /// <summary>
        /// Reveals only the cards that make sense for the item type: Tool for tools/weapons; Consumable
        /// for consumables; Cooking for consumables (food) and materials (smelting ore → ingot), but
        /// never for a tool or weapon; and Fuel for materials only (a consumable is never burned).
        /// </summary>
        private void ApplyTypeVisibility(ItemType type)
        {
            SetRowVisible(toolCard, type == ItemType.Tool || type == ItemType.Weapon);
            SetRowVisible(consumableCard, type == ItemType.Consumable);
            SetRowVisible(cookingCard, type == ItemType.Consumable || type == ItemType.Material);
            SetRowVisible(fuelCard, type == ItemType.Material);
        }

        /// <summary>
        /// Collapses the whole generation card once every prefab the item needs already exists — the
        /// world pickup for any item, plus the hand prefab for tools/weapons — so a fully wired item
        /// shows no redundant tooling. Re-evaluated when the type or a prefab field changes.
        /// </summary>
        private void UpdateGenerationVisibility()
        {
            if (worldField == null || handField == null || generationCard == null) return;

            bool isToolLike = currentType == ItemType.Tool || currentType == ItemType.Weapon;
            bool needWorld = worldField.value == null;
            bool needHand = isToolLike && handField.value == null;

            SetRowVisible(generationCard, needWorld || needHand);
        }

        /// <summary>
        /// Collapses or shows an element without leaving a gap when hidden.
        /// </summary>
        private static void SetRowVisible(VisualElement element, bool visible)
        {
            if (element != null) element.style.display = visible ? DisplayStyle.Flex : DisplayStyle.None;
        }

        /// <summary>
        /// Builds a float field already bound to a serialized property.
        /// </summary>
        private FloatField BoundFloat(string label, string property)
        {
            FloatField field = new FloatField(label);
            field.BindProperty(so.FindProperty(property));
            return field;
        }

        #endregion
    }
}