using System.Collections.Generic;
using Ichni.Menu.UI;
using Ichni.UI;
using Sirenix.OdinInspector;
using UnityEngine;

namespace Ichni.Story.UI
{
    /// <summary>
    /// 剧情与菜单共用的弹窗页面。
    /// MessageBox 与 SelectionBox 共用同一遮罩、容器和显示队列：两者不会重叠，
    /// 后续系统只需向本页提交“消息”或“选项”请求，无需再创建平行的 UIPage。
    /// </summary>
    public class MessageUIPage : UIPageBase
    {
        public static MessageUIPage instance;

        [Header("Prefabs & Containers")]
        [Tooltip("默认使用的 MessageBox 预制体（请从 Project 中拖拽，而非场景中的实例）")]
        public MessageBox defaultMessageBoxPrefab;
        
        [Tooltip("生成的 MessageBox 挂载在哪？如果不填，默认挂载在自己身上")]
        public Transform messageContainer;

        [Tooltip("通用多选弹窗预制体。TutorialBlock、奖励选择等系统都通过本页动态生成它。")]
        public SelectionBox defaultSelectionBoxPrefab;

        private enum PopupType
        {
            Message,
            Selection
        }

        // 用于统一排队的内部弹窗数据结构。
        private struct PendingPopup
        {
            public PopupType type;
            public string title;
            public string content;
            public MessageBox messagePrefab;
            public List<SelectionBoxOption> selectionOptions;
        }

        private readonly Queue<PendingPopup> _popupQueue = new();
        private MessageBox _currentMessageBox;
        private SelectionBox _currentSelectionBox;
        private bool _isPageActive = false;

        protected override void Awake()
        {
            base.Awake();
            
            if (instance == null)
            {
                instance = this;
            }
            else
            {
                Debug.LogWarning("[StoryMessageBoxUIPage] 场景中存在多个实例，正在销毁多余的实例。");
                Destroy(gameObject);
                return;
            }

            if (messageContainer == null)
            {
                messageContainer = this.transform;
            }
        }

        /// <summary>
        /// 将歌曲解锁提示加入弹窗队列。
        /// </summary>
        public void ShowUnlockMessage(string songUnlockKey)
        {
            string title = "New Song Unlocked!";
            string content = $"You have unlocked the song: {songUnlockKey}!";
            EnqueueMessage(title, content, defaultMessageBoxPrefab);
        }

        /// <summary>
        /// 将自定义文本提示加入弹窗队列。
        /// </summary>
        public void ShowCustomMessage(string title, string content)
        {
            EnqueueMessage(title, content, defaultMessageBoxPrefab);
        }

        /// <summary>
        /// Inspector 专用的运行时调试入口。
        /// 通过正常队列创建一条基础测试文本，因此可以同时验证新 Prefab 的布局、
        /// 入退场动画、输入拦截与队列收尾，而不会绕过正式流程或污染剧情数据。
        /// </summary>
        [Button("调试：创建空 MessageBox", ButtonSizes.Medium)]
        private void DebugCreateEmptyMessageBox()
        {
            if (!Application.isPlaying)
            {
                Debug.LogWarning("[MessageUIPage] 空 MessageBox 调试按钮只能在 Play Mode 中使用。", this);
                return;
            }

            ShowCustomMessage(
                "MessageBox Debug",
                "这是一条用于检查基础布局、文本换行与 Rail 动效的测试文本。\n\n" +
                "This is a basic MessageBox test message.");
        }

        /// <summary>
        /// Inspector 专用的运行时调试入口。
        /// 通过正常队列创建一条基础测试文本，因此可以同时验证新 Prefab 的布局、
        /// 入退场动画、输入拦截与队列收尾，而不会绕过正式流程或污染剧情数据。
        /// </summary>
        [Button("调试：创建空 SelectionBox", ButtonSizes.Medium)]
        private void DebugCreateEmptySelectionBox()
        {
            if (!Application.isPlaying)
            {
                Debug.LogWarning("[MessageUIPage] 空 SelectionBox 调试按钮只能在 Play Mode 中使用。", this);
                return;
            }

            ShowSelectionBox(
                "SelectionBox Debug",
                "这是一条用于检查基础布局、文本换行与 Rail 动效的测试文本。\n\n" +
                "This is a basic SelectionBox test message.",
                new List<SelectionBoxOption>
                {
                    new SelectionBoxOption("Option 1", () => Debug.Log("Option 1 selected")),
                    new SelectionBoxOption("Option 2", () => Debug.Log("Option 2 selected")),
                    new SelectionBoxOption("Option 3", () => Debug.Log("Option 3 selected"))
                });
        }

        /// <summary>
        /// 将一组运行时选项加入通用弹窗队列。
        /// 若 MessageBox 或其它 SelectionBox 正在显示，选项会按提交顺序等待，而不会叠在同一遮罩上。
        /// </summary>
        public bool ShowSelectionBox(string title, string content, IReadOnlyList<SelectionBoxOption> options)
        {
            if (defaultSelectionBoxPrefab == null)
            {
                Debug.LogError("[MessageUIPage] 未配置 defaultSelectionBoxPrefab，无法显示选项框。");
                return false;
            }

            if (options == null || options.Count == 0)
            {
                Debug.LogWarning("[MessageUIPage] 未提供任何 SelectionBoxOption，忽略空选项框。");
                return false;
            }

            _popupQueue.Enqueue(new PendingPopup
            {
                type = PopupType.Selection,
                title = title,
                content = content,
                // 复制调用方传入的列表，防止调用方随后改动集合而改变已排队的玩家选择。
                selectionOptions = new List<SelectionBoxOption>(options)
            });

            BeginQueueIfNeeded();
            return true;
        }

        /// <summary>
        /// 将指定消息入队。如果是空闲状态，则唤醒大页面并开始处理队列。
        /// </summary>
        private void EnqueueMessage(string title, string content, MessageBox prefab)
        {
            if (prefab == null)
            {
                Debug.LogError("[StoryMessageBoxUIPage] 没有可用的 MessageBox 预制体！");
                return;
            }

            _popupQueue.Enqueue(new PendingPopup
            {
                type = PopupType.Message,
                title = title,
                content = content,
                messagePrefab = prefab
            });

            BeginQueueIfNeeded();
        }

        /// <summary>
        /// 若当前没有弹窗，激活共享遮罩后开始依次显示队列。遮罩从出现瞬间拦截输入，
        /// 避免 UIPageBase 默认淡入结束前的短暂底层点击窗口。
        /// </summary>
        private void BeginQueueIfNeeded()
        {
            if (_isPageActive) return;

            _isPageActive = true;
            mainCanvasGroup.gameObject.SetActive(true);
            mainCanvasGroup.interactable = true;
            mainCanvasGroup.blocksRaycasts = true;
            FadeIn(0f, false, ShowNextInQueue);
        }

        /// <summary>
        /// 从队列中取出一个并实例化显示。
        /// </summary>
        private void ShowNextInQueue()
        {
            if (_popupQueue.Count == 0)
            {
                // 队列处理完毕，大页面整体退场。
                _currentMessageBox = null;
                _currentSelectionBox = null;
                _isPageActive = false;
                FadeOut(0f);
                return;
            }

            PendingPopup popup = _popupQueue.Dequeue();
            if (popup.type == PopupType.Selection)
            {
                ShowSelectionPopup(popup);
                return;
            }

            ShowMessagePopup(popup);
        }

        private void ShowMessagePopup(PendingPopup popup)
        {
            if (popup.messagePrefab == null)
            {
                Debug.LogError("[MessageUIPage] 队列中的 MessageBox Prefab 已丢失，跳过该消息。");
                ShowNextInQueue();
                return;
            }

            MessageBox messageBox = Instantiate(popup.messagePrefab, messageContainer);
            _currentMessageBox = messageBox;

            // MessageBox 只显示一条消息；队列顺序始终由本页统一管理。
            messageBox.Closed += HandleMessageBoxClosed;
            messageBox.gameObject.SetActive(true);
            messageBox.SetUp(popup.title, popup.content);
        }

        private void HandleMessageBoxClosed(MessageBox messageBox)
        {
            messageBox.Closed -= HandleMessageBoxClosed;
            Destroy(messageBox.gameObject);

            if (_currentMessageBox == messageBox)
                _currentMessageBox = null;

            ShowNextInQueue();
        }

        private void ShowSelectionPopup(PendingPopup popup)
        {
            if (defaultSelectionBoxPrefab == null)
            {
                Debug.LogError("[MessageUIPage] 队列中的 SelectionBox Prefab 已丢失，跳过该选项框。");
                ShowNextInQueue();
                return;
            }

            SelectionBox selectionBox = Instantiate(defaultSelectionBoxPrefab, messageContainer);
            _currentSelectionBox = selectionBox;
            selectionBox.Closed += HandleSelectionBoxClosed;

            if (!selectionBox.SetUp(popup.title, popup.content, popup.selectionOptions))
            {
                selectionBox.Closed -= HandleSelectionBoxClosed;
                Destroy(selectionBox.gameObject);
                _currentSelectionBox = null;
                ShowNextInQueue();
            }
        }

        private void HandleSelectionBoxClosed(SelectionBox selectionBox)
        {
            if (selectionBox != _currentSelectionBox) return;

            selectionBox.Closed -= HandleSelectionBoxClosed;
            Destroy(selectionBox.gameObject);
            _currentSelectionBox = null;
            ShowNextInQueue();
        }
    }
}