using System;
using System.Collections.Generic;
using UnityEngine;
using Ashwild.UI;

namespace Ashwild.Building
{
    /// <summary>
    /// The construction menu window — a pure view driven by the GameUIManager panel stack (its
    /// Build kind locks input and shows the cursor while the world keeps running, like the
    /// inventory). It has no knowledge of the buildable data: a manager pushes a card payload in
    /// through <see cref="Populate"/> and the menu renders exactly that, reporting a pick back by
    /// index. The controller object stays active so Show/Hide only toggle the visible window,
    /// mirroring InventoryUI.
    /// </summary>
    public class BuildMenuUI : UIPanel
    {
        /// <summary>
        /// Marks this panel as the construction menu: input is locked and the cursor shows, but
        /// the world keeps running (unlike the pause menu).
        /// </summary>
        public override PanelKind Kind => PanelKind.Build;

        #region Serialized Fields

        [Header("References")]
        [SerializeField] private GameObject menuRoot;
        [SerializeField] private Transform cardContainer;
        [SerializeField] private BuildMenuCardUI cardPrefab;

        #endregion

        #region State

        /// <summary>
        /// The card views currently spawned in the grid, destroyed and rebuilt on each populate.
        /// </summary>
        private readonly List<BuildMenuCardUI> cards = new List<BuildMenuCardUI>();

        #endregion

        #region Unity Lifecycle

        /// <summary>
        /// Parks the window closed; the grid is filled later by the manager through Populate.
        /// </summary>
        private void Start()
        {
            if (menuRoot != null)
                menuRoot.SetActive(false);
        }

        #endregion

        #region Public API

        /// <summary>
        /// Rebuilds the card grid from the payload a manager pushes in. The menu is a pure view:
        /// it renders exactly these cards and reports a pick back by index through the callback,
        /// never resolving what a card represents itself.
        /// </summary>
        public void Populate(IReadOnlyList<BuildCardView> views, Action<int> onSelected)
        {
            ClearCards();

            if (cardPrefab == null || cardContainer == null)
            {
                Debug.LogError("[BuildMenuUI] Card prefab or container not assigned — cannot build the menu.", this);
                return;
            }
            if (views == null) return;

            for (int i = 0; i < views.Count; i++)
            {
                BuildMenuCardUI card = Instantiate(cardPrefab, cardContainer);
                card.Initialize(views[i], i, onSelected);
                cards.Add(card);
            }
        }

        #endregion

        #region Grid

        /// <summary>
        /// Destroys the previously spawned cards so a re-populate never stacks duplicates.
        /// </summary>
        private void ClearCards()
        {
            foreach (BuildMenuCardUI card in cards)
                if (card != null) Destroy(card.gameObject);
            cards.Clear();
        }

        #endregion

        #region Panel Show/Hide

        /// <summary>
        /// Opens the menu window (called by the GameUIManager panel stack).
        /// </summary>
        public override void Show()
        {
            if (menuRoot != null)
                menuRoot.SetActive(true);
        }

        /// <summary>
        /// Closes the menu window.
        /// </summary>
        public override void Hide()
        {
            if (menuRoot != null)
                menuRoot.SetActive(false);
        }

        /// <summary>
        /// Instant close used when the manager initializes panels — just parks the window closed.
        /// </summary>
        public override void HideInstant()
        {
            if (menuRoot != null)
                menuRoot.SetActive(false);
        }

        #endregion
    }
}