CodePreviewHandler.cs

using System;
using System.IO;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Xml.Linq;
using System.Text;
using SharpShell.Attributes;
using SharpShell.SharpPreviewHandler;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace XML_JSON_Preview
{
    [ComVisible(true)]
    [Guid("A3D6E521-1234-4B5C-9D8E-F0A1B2C3D4E5")]
    [COMServerAssociation(AssociationType.Class, ".xml")]
    [COMServerAssociation(AssociationType.Class, ".json")]
    [PreviewHandler]
    public class CodePreviewHandler : SharpPreviewHandler
    {
        public CodePreviewHandler() { }

        protected override PreviewHandlerControl DoPreview()
        {
            return new CodePreviewControl(SelectedFilePath);
        }
    }

    public class CodePreviewControl : PreviewHandlerControl
    {
        private TreeView _treeView;

        public CodePreviewControl(string filePath)
        {
            this.BackColor = Color.White;
            _treeView = new TreeView();
            _treeView.Dock = DockStyle.Fill;
            _treeView.BorderStyle = BorderStyle.None;
            _treeView.Font = new Font("Consolas", 10);
            this.Controls.Add(_treeView);

            SafeLoad(filePath);
        }

        private void SafeLoad(string filePath)
        {
            try
            {
                _treeView.Nodes.Clear();
                if (string.IsNullOrEmpty(filePath))
                {
                    _treeView.Nodes.Add("Error: Path is empty.");
                    return;
                }
                LoadData(filePath);
            }
            catch (Exception ex)
            {
                _treeView.Nodes.Add("Global Exception: " + ex.Message);
            }
        }

        private void LoadData(string filePath)
        {
            string content = "";
            try
            {
                // Čtení souboru, které neblokuje ostatní procesy a poradí si s kódováním
                using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                using (var reader = new StreamReader(stream, Encoding.UTF8, true))
                {
                    content = reader.ReadToEnd();
                }
            }
            catch (Exception ex)
            {
                _treeView.Nodes.Add("File Access Error: " + ex.Message);
                return;
            }

            if (string.IsNullOrWhiteSpace(content))
            {
                _treeView.Nodes.Add("File is empty.");
                return;
            }

            string trimmed = content.Trim();
            bool loaded = false;

            // 1. Zkoušíme JSON
            if (trimmed.StartsWith("{") || trimmed.StartsWith("["))
            {
                try
                {
                    JToken token = JToken.Parse(trimmed);
                    AddJsonNode(token, "JSON Root", _treeView.Nodes);
                    loaded = true;
                }
                catch (Exception ex) { _treeView.Nodes.Add("JSON Parse Hint: " + ex.Message); }
            }

            // 2. Zkoušíme XML
            if (!loaded)
            {
                try
                {
                    int xmlStart = trimmed.IndexOf('<');
                    if (xmlStart >= 0)
                    {
                        string cleanXml = trimmed.Substring(xmlStart);
                        XDocument doc = XDocument.Parse(cleanXml);
                        if (doc.Root != null)
                        {
                            AddXmlNode(doc.Root, _treeView.Nodes);
                            loaded = true;
                        }
                    }
                }
                catch (Exception ex) { _treeView.Nodes.Add("XML Parse Hint: " + ex.Message); }
            }

            // 3. Poslední záchrana: TEXT
            if (!loaded)
            {
                _treeView.Nodes.Add("--- Parsing failed, showing raw text ---");
                TreeNode textRoot = _treeView.Nodes.Add(Path.GetFileName(filePath));
                string[] lines = content.Split(new[] { "\r\n", "\r", "\n" }, StringSplitOptions.None);
                for (int i = 0; i < Math.Min(lines.Length, 1000); i++)
                {
                    textRoot.Nodes.Add(lines[i]);
                }
            }

            _treeView.ExpandAll();
            if (_treeView.Nodes.Count > 0) _treeView.Nodes[0].EnsureVisible();
        }

        private void AddJsonNode(JToken token, string name, TreeNodeCollection nodes)
        {
            try
            {
                if (token is JValue) nodes.Add($"{name}: {token}");
                else if (token is JObject obj)
                {
                    TreeNode newNode = nodes.Add(name);
                    foreach (var prop in obj.Properties()) AddJsonNode(prop.Value, prop.Name, newNode.Nodes);
                }
                else if (token is JArray array)
                {
                    TreeNode newNode = nodes.Add($"{name} [array]");
                    for (int i = 0; i < array.Count; i++) AddJsonNode(array[i], $"[{i}]", newNode.Nodes);
                }
            }
            catch { }
        }

        private void AddXmlNode(XElement element, TreeNodeCollection nodes)
        {
            try
            {
                string nodeText = element.Name.LocalName;
                if (!element.HasElements && !string.IsNullOrEmpty(element.Value)) nodeText += ": " + element.Value.Trim();
                TreeNode newNode = nodes.Add(nodeText);
                foreach (var attr in element.Attributes()) newNode.Nodes.Add($"@{attr.Name}: {attr.Value}");
                foreach (var sub in element.Elements()) AddXmlNode(sub, newNode.Nodes);
            }
            catch { }
        }
    }
}