using System.Collections.Generic;
using Ichni.Story.Dialogue;
using UnityEngine;
using UnityEngine.UI;

namespace Ichni.Story.UI
{
    /// <summary>
    /// 对话记录覆盖面板。
    /// <para>它不是独立 UIPage：打开时覆盖在 DialogUIPage 上方，并由全屏 Raycast Target 阻断底层输入；
    /// 关闭后仅恢复对话画面，不推进 Yarn 对话。</para>
    /// </summary>
    public class DialogueHistoryPage : MonoBehaviour
    {
        [Header("References")]
        [Tooltip("覆盖全屏的 CanvasGroup。根物体应位于 DialogCanvas 顶层，并包含可接收 Raycast 的全屏透明 Image。")]
        [SerializeField] private CanvasGroup canvasGroup;
        [SerializeField] private ScrollRect scrollRect;
        [SerializeField] private RectTransform entryContainer;
        [SerializeField] private DialogueHistoryEntryView entryPrefab;
        [SerializeField] private Button closeButton;

        /// <summary>当前覆盖层是否正在显示并拦截 DialogUIPage 输入。</summary>
        public bool IsOpen => _isOpen;

        private readonly List<DialogueHistoryEntryView> _spawnedEntries = new();
        private bool _isOpen;

        private void Awake()
        {
            if (closeButton != null)
                closeButton.onClick.AddListener(Close);

            SetVisible(false);
        }

        private void OnDestroy()
        {
            if (closeButton != null)
                closeButton.onClick.RemoveListener(Close);
        }

        /// <summary>以当前一次 TextBlock 对话的内存记录刷新并打开覆盖面板。</summary>
        public void Open(IReadOnlyList<DialogueHistoryEntry> entries)
        {
            RebuildEntries(entries);
            SetVisible(true);
            Canvas.ForceUpdateCanvases();

            // 记录按时间从上到下排列；打开后停在最早一条，玩家可向下浏览最新内容。
            if (scrollRect != null)
                scrollRect.verticalNormalizedPosition = 1f;
        }

        /// <summary>关闭覆盖面板，不修改当前 Yarn 进度或选项状态。</summary>
        public void Close() => SetVisible(false);

        private void RebuildEntries(IReadOnlyList<DialogueHistoryEntry> entries)
        {
            foreach (DialogueHistoryEntryView view in _spawnedEntries)
                if (view != null)
                    Destroy(view.gameObject);
            _spawnedEntries.Clear();

            if (entries == null || entryPrefab == null || entryContainer == null)
                return;

            foreach (DialogueHistoryEntry entry in entries)
            {
                DialogueHistoryEntryView view = Instantiate(entryPrefab, entryContainer);
                view.SetUp(entry);
                _spawnedEntries.Add(view);
            }
        }

        private void SetVisible(bool visible)
        {
            _isOpen = visible;
            if (canvasGroup == null)
                return;

            canvasGroup.alpha = visible ? 1f : 0f;
            canvasGroup.interactable = visible;
            canvasGroup.blocksRaycasts = visible;
        }
    }
}