FileShare/Avalonia-API/Extensions/FileStreamEndpointExtensions.cs

using Avalonia_Services.Services.FileLibrary;

namespace Avalonia_API.Extensions
{
    /// <summary>
    /// API-only raw file stream endpoints used by browser media elements.
    /// </summary>
    public static class FileStreamEndpointExtensions
    {
        /// <summary>
        /// Map the media URL emitted by <see cref="FileRecordDto"/>.
        /// </summary>
        public static IEndpointRouteBuilder MapFileStreamEndpoints(this IEndpointRouteBuilder app)
        {
            app.MapMethods(
                    "/api/files/{id:int}/stream",
                    ["GET", "HEAD"],
                    async (int id, IFileStreamService fileStreamService, HttpContext httpContext) =>
                    {
                        var fileResponse = await fileStreamService.GetFileStreamAsync(id);
                        if (fileResponse is null)
                        {
                            return Results.NotFound();
                        }

                        var stream = System.IO.File.Open(
                            fileResponse.FilePath,
                            FileMode.Open,
                            FileAccess.Read,
                            FileShare.ReadWrite);

                        httpContext.Response.Headers.ContentDisposition =
                            $"inline; filename=\"{Uri.EscapeDataString(fileResponse.FileName)}\"";
                        httpContext.Response.Headers.AcceptRanges = "bytes";
                        httpContext.Response.Headers.CacheControl = "public, max-age=3600";

                        return Results.File(
                            stream,
                            contentType: fileResponse.ContentType,
                            lastModified: fileResponse.LastModified,
                            enableRangeProcessing: true);
                    })
                .WithName("StreamManagedFileById")
                .WithTags("FileLibrary");

            return app;
        }
    }
}