// ============================================================================
// LabPicUrlPreview.cs  （C# 7.3 / DevExpress 15.2 兼容）
// - 公用方法封装在一个类里
// - 事件绑定在一个地方 Attach(view)
// - 线程安全缓存 + 并发限流 + LRU 清理
// - 只在同步阶段写 e.Value；异步完成后刷新单元格
// ============================================================================
using System;
using System.Collections.Generic;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

using DevExpress.Data;
using DevExpress.XtraEditors.Controls;
using DevExpress.XtraEditors.Repository;
using DevExpress.XtraGrid;
using DevExpress.XtraGrid.Columns;
using DevExpress.XtraGrid.Views.Base;
using DevExpress.XtraGrid.Views.Grid;
using DevExpress.XtraGrid.Views.BandedGrid;
using Lskj.Business;
using Lskj.Control.Model;
// 若命名空间不同，请改成正确的 using

public static class LabPicUrlPreview
{
    // ====== 对外：初始化图片列（创建 RepositoryItemPictureEdit、设为 Unbound） ======
    public static void InitPicColumn(GridControl gridControl, GridColumn gridColumn, GridColumnModel model)
    {
        if (gridControl == null || gridColumn == null || model == null) return;

        gridColumn.AppearanceCell.Options.UseTextOptions = true;
        gridColumn.AppearanceCell.TextOptions.HAlignment = DevExpress.Utils.HorzAlignment.Center;
        gridColumn.OptionsColumn.AllowEdit = false;

        // 唯一列名（保持你原逻辑）
        gridColumn.FieldName = string.Format("{0}{1}", model.FieldName, Guid.NewGuid());
        gridColumn.Tag = model; // 事件里取模型

        RepositoryItemPictureEdit pictureEdit = new RepositoryItemPictureEdit();
        pictureEdit.ShowMenu = false;
        pictureEdit.NullText = " ";
        pictureEdit.SizeMode = PictureSizeMode.Zoom;

        gridControl.RepositoryItems.Add(pictureEdit);
        gridColumn.UnboundType = UnboundColumnType.Object;
        gridColumn.ColumnEdit = pictureEdit;
    }

    // ====== 对外：统一事件绑定入口（只需调用一次） ======
    public static void Attach(ColumnView view)
    {
        if (view == null) return;
        view.CustomUnboundColumnData -= OnCustomUnboundColumnData;
        view.CustomUnboundColumnData += OnCustomUnboundColumnData;
    }

    // ====== 事件实现（只在同步阶段写 e.Value；异步完成后刷新该单元格） ======
    private static void OnCustomUnboundColumnData(object sender, CustomColumnDataEventArgs e)
    {
        ColumnView view = sender as ColumnView;
        if (view == null) return;

        GridColumnModel m = e.Column.Tag as GridColumnModel;
        if (m == null || m.FieldType != ControlType.LabPicUrl || !e.IsGetData) return;

        // 1) 用 ListSourceRowIndex → RowHandle（兼容 DevExpress 15.2）
        int listIndex = e.ListSourceRowIndex;
        int rowHandle = view.GetRowHandle(listIndex);

        // 2) 读取原始 URL（优先 ListSource；兜底 e.Row）
        string raw = null;
        try
        {
            object val = view.GetListSourceRowCellValue(listIndex, m.FieldName);
            raw = val == null ? null : Convert.ToString(val);
        }
        catch
        {
            DataRowView drv = e.Row as DataRowView;
            if (drv != null && drv.Row != null && drv.Row.Table != null && drv.Row.Table.Columns.Contains(m.FieldName))
                raw = Convert.ToString(drv.Row[m.FieldName]);
        }
        if (string.IsNullOrWhiteSpace(raw)) return;

        // 3) 拼接完整 URL（相对路径 -> OA 根地址）
        string url = ResolveFullUrl(raw);

        // 4) 目标高（属性或方法都兼容；<=18 则用 30）
        int targetHeight = NormalizeHeight(m);

        // 5) 缓存命中：当次赋值（只在同步阶段写 e.Value）
        Image img;
        if (UrlImageCacheCompat.TryGet(url, targetHeight, out img))
        {
            e.Value = img;
            return;
        }

        // 6) 未命中：安排异步下载；完成后刷新该单元格（不要在异步线程里改 e.Value）
        System.Windows.Forms.Control invoker = view.GridControl; // UI 回调对象
        UrlImageCacheCompat.GetOrCreateAsync(url, targetHeight, invoker, delegate ()
        {
            RefreshCellCompat(view, rowHandle, e.Column);
        });
    }

    // ====== 视图安全刷新：GridView/BandedGridView 定向刷新，其他降级为 RefreshData ======
    private static void RefreshCellCompat(ColumnView view, int rowHandle, GridColumn column)
    {
        try
        {
            GridView gv = view as GridView;
            if (gv != null)
            {
                if (rowHandle >= 0) gv.RefreshRowCell(rowHandle, column);
                else gv.RefreshData();
                return;
            }

            BandedGridView bgv = view as BandedGridView;
            if (bgv != null)
            {
                if (rowHandle >= 0) bgv.RefreshRowCell(rowHandle, column);
                else bgv.RefreshData();
                return;
            }

            view.RefreshData();
        }
        catch
        {
            try { view.RefreshData(); } catch { }
        }
    }

    // ====== 兼容“属性或无参方法”的高度读取（避免 m.LabPicUrlHeight 被当作方法组出错） ======
    private static int NormalizeHeight(object model)
    {
        try
        {
            var t = model.GetType();

            // 属性
            var pi = t.GetProperty("LabPicUrlHeight");
            if (pi != null)
            {
                int v = Convert.ToInt32(pi.GetValue(model, null));
                return v <= 18 ? 30 : v;
            }

            // 无参方法
            var mi = t.GetMethod("LabPicUrlHeight", Type.EmptyTypes);
            if (mi != null)
            {
                int v = Convert.ToInt32(mi.Invoke(model, null));
                return v <= 18 ? 30 : v;
            }
        }
        catch { }
        return 30;
    }

    // ====== 解析完整 URL：相对路径 -> SystemInfo.Instance.OAUrl + 相对 ======
    private static string ResolveFullUrl(string raw)
    {
        if (string.IsNullOrEmpty(raw)) return raw;
        if (raw.StartsWith("http", StringComparison.OrdinalIgnoreCase)) return raw;

        try
        {
            // 直接使用你项目里的 SystemInfo（若没有可替换为你自己的配置）
            string oa = SystemInfo.Instance.OAUrl;
            if (string.IsNullOrEmpty(oa)) return raw.TrimStart('/');
            if (!oa.EndsWith("/")) oa += "/";
            return oa + raw.TrimStart('/');
        }
        catch
        {
            return raw.TrimStart('/');
        }
    }

    // ====== 线程安全缓存（WebClient + Dictionary + Semaphore，C# 7.3 兼容） ======
    private static class UrlImageCacheCompat
    {
        private class CacheEntry
        {
            public Image Image;
            public DateTime LastHitUtc;
        }

        private static readonly object _lock = new object();
        private static readonly Dictionary<string, CacheEntry> _cache =
            new Dictionary<string, CacheEntry>(StringComparer.OrdinalIgnoreCase);
        private static readonly Dictionary<string, Task<Image>> _tasks =
            new Dictionary<string, Task<Image>>(StringComparer.OrdinalIgnoreCase);

        // 旧框架用传统 Semaphore，限制并发下载数量
        private static readonly Semaphore _throttle = new Semaphore(4, 4); // 同时最多 4 个下载
        private const int Capacity = 300; // 最多缓存 300 张缩略图

        static UrlImageCacheCompat()
        {
            // 尽量启用 TLS1.2（老系统需要）
            try
            {
                const System.Security.Authentication.SslProtocols _Tls12 =
                    (System.Security.Authentication.SslProtocols)0x00000C00;
                ServicePointManager.SecurityProtocol |= (SecurityProtocolType)_Tls12;
            }
            catch { }
        }

        private static string MakeKey(string url, int h)
        {
            return url + "#h=" + h.ToString();
        }

        public static bool TryGet(string url, int targetHeight, out Image image)
        {
            string key = MakeKey(url, targetHeight);
            lock (_lock)
            {
                CacheEntry e;
                if (_cache.TryGetValue(key, out e) && e != null && e.Image != null)
                {
                    e.LastHitUtc = DateTime.UtcNow;
                    _cache[key] = e;
                    image = e.Image;
                    return true;
                }
            }
            image = null;
            return false;
        }

        public static void GetOrCreateAsync(string url, int targetHeight, System.Windows.Forms.Control uiInvoker, Action onReady)
        {
            string key = MakeKey(url, targetHeight);

            lock (_lock)
            {
                // 已缓存：直接回调
                if (_cache.ContainsKey(key))
                {
                    BeginInvokeSafe(uiInvoker, onReady);
                    return;
                }

                // 同 key 只下载一次：已有任务则挂回调
                Task<Image> exist;
                if (_tasks.TryGetValue(key, out exist))
                {
                    exist.ContinueWith(delegate { BeginInvokeSafe(uiInvoker, onReady); }, TaskScheduler.Default);
                    return;
                }

                // 启动新任务（受限流）
                Task<Image> task = Task.Factory.StartNew<Image>(delegate
                {
                    _throttle.WaitOne();
                    try
                    {
                        using (WebClient wc = new WebClient())
                        {
                            byte[] bytes = wc.DownloadData(url);
                            using (MemoryStream ms = new MemoryStream(bytes))
                            using (Bitmap bmp = new Bitmap(ms))
                            {
                                return ScaleBitmap(bmp, targetHeight);
                            }
                        }
                    }
                    catch
                    {
                        return null;
                    }
                    finally
                    {
                        try { _throttle.Release(); } catch { }
                    }
                }, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default).ContinueWith<Image>(delegate (Task<Image> t)
                {
                    Image result = t.Result;
                    lock (_lock)
                    {
                        _tasks.Remove(key);
                        if (result != null)
                        {
                            _cache[key] = new CacheEntry { Image = result, LastHitUtc = DateTime.UtcNow };
                            TrimIfNeededUnsafe();
                        }
                    }
                    return result;
                }, TaskScheduler.Default);

                _tasks[key] = task;

                task.ContinueWith(delegate { BeginInvokeSafe(uiInvoker, onReady); }, TaskScheduler.Default);
            }
        }

        private static Image ScaleBitmap(Bitmap bmp, int targetHeight)
        {
            int h = targetHeight <= 0 ? 30 : targetHeight;
            if (h < 18) h = 18;

            double ratio = (double)h / (double)bmp.Height;
            int w = (int)Math.Round((double)bmp.Width * ratio);
            if (w < 1) w = 1;

            // 只缓存缩略图，避免内存暴涨
            return new Bitmap(bmp, new Size(w, h));
        }

        private static void TrimIfNeededUnsafe()
        {
            if (_cache.Count <= Capacity) return;

            // 简单 LRU：移除最早命中的 10%
            List<KeyValuePair<string, CacheEntry>> list = _cache.ToList();
            list.Sort(delegate (KeyValuePair<string, CacheEntry> a, KeyValuePair<string, Ca