FileView.cshtml.cs

using KaiChat.Services;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;

namespace KaiChat.Pages;

public class FileViewModel : PageModel
{
    private readonly IFileService _file;

    public FileViewModel(IFileService file)
    {
        _file = file;
    }

    public string FileName { get; set; } = "";
    public string CurrentFolder { get; set; } = "";
    public string FileContent { get; set; } = "";
    public string FileSize { get; set; } = "";
    public DateTime LastModified { get; set; }

    public IActionResult OnGet(string? path)
    {
        if (string.IsNullOrEmpty(path))
            return RedirectToPage("Files");

        var relativePath = path.TrimStart('/');
        FileName = Path.GetFileName(relativePath);
        CurrentFolder = Path.GetDirectoryName(relativePath)?.Replace('\\', '/') ?? "";

        var fullPath = Path.Combine(
            HttpContext.RequestServices.GetRequiredService<IConfiguration>().GetValue<string>("KaiChat:BaseFolder")!,
            relativePath);

        if (!System.IO.File.Exists(fullPath))
            return NotFound();

        var fileInfo = new FileInfo(fullPath);
        FileSize = FormatSize(fileInfo.Length);
        LastModified = fileInfo.LastWriteTime;
        FileContent = _file.ReadFile(relativePath);

        return Page();
    }

    private static string FormatSize(long bytes) => bytes switch
    {
        < 1024 => $"{bytes} B",
        < 1024 * 1024 => $"{bytes / 1024.0:F1} KB",
        < 1024 * 1024 * 1024 => $"{bytes / (1024.0 * 1024):F1} MB",
        _ => $"{bytes / (1024.0 * 1024 * 1024):F1} GB"
    };
}