QuickLook/QuickLook.Plugin/QuickLook.Plugin.CsvViewer/CsvViewerPanel.xaml.cs

// Copyright © 2017-2026 QL-Win Contributors
//
// This file is part of QuickLook program.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using CsvHelper;
using CsvHelper.Configuration;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media;
using UtfUnknown;

namespace QuickLook.Plugin.CsvViewer;

public partial class CsvViewerPanel : UserControl
{
    public CsvViewerPanel()
    {
        InitializeComponent();
    }

    public List<string[]> Rows { get; private set; } = [];

    public void LoadFile(string path)
    {
        const int limit = 10000;
        var binded = false;

        var encoding = CharsetDetector.DetectFromFile(path).Detected?.Encoding ??
                       Encoding.Default;

        using var sr = new StreamReader(new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite), encoding);
      
        // Use fixed delimiters for known extensions to avoid mis-detection on small samples.
        var extension = Path.GetExtension(path);
        var delimiter = extension.Equals(".tsv", StringComparison.OrdinalIgnoreCase)
            ? "\t"
            : extension.Equals(".psv", StringComparison.OrdinalIgnoreCase)
                ? "|"
                : null;

        var conf = new CsvConfiguration(CultureInfo.CurrentUICulture)
        {
            MissingFieldFound = null,
            BadDataFound = null,
            DetectDelimiter = delimiter == null,
        };

        if (delimiter != null)
        {
            // Force delimiter for TSV/PSV so CsvHelper doesn't auto-detect incorrectly.
            conf.Delimiter = delimiter;
        }

        using var parser = new CsvParser(sr, conf);
        var i = 0;
        while (parser.Read())
        {
            var row = parser.Record;
            if (row == null)
                break;
            row = Concat([$"{i++ + 1}".PadLeft(6)], row);

            if (!binded)
            {
                SetupColumnBinding(row.Length);
                binded = true;
            }

            if (i > limit)
            {
                Rows.Add([.. Enumerable.Repeat("...", row.Length)]);
                break;
            }

            Rows.Add(row);
        }
    }

    private void SetupColumnBinding(int rowLength)
    {
        for (var i = 0; i < rowLength; i++)
        {
            var col = new DataGridTextColumn
            {
                FontFamily = new FontFamily("Consolas"),
                FontWeight = FontWeight.FromOpenTypeWeight(i == 0 ? 700 : 400),
                Binding = new Binding($"[{i}]")
            };
            dataGrid.Columns.Add(col);
        }
    }

    public static T[] Concat<T>(T[] x, T[] y)
    {
        if (x == null) throw new ArgumentNullException("x");
        if (y == null) throw new ArgumentNullException("y");
        var oldLen = x.Length;
        Array.Resize(ref x, x.Length + y.Length);
        Array.Copy(y, 0, x, oldLen, y.Length);
        return x;
    }
}