using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Net.Http.Headers;
using RadicadeServer.RecNet.CDN;

namespace RadicadeServer.Storage
{
	[Route("storage")]
	public class StorageAPI : Controller
	{
		private const long MaxUploadBytes = 256L * 1024 * 1024;
		private const int MaxMultipartPreambleBytes = 1024 * 1024;

		private static async Task<long?> FindFirstBoundaryAsync(Stream body, string boundary, CancellationToken cancellationToken)
		{
			var marker = System.Text.Encoding.ASCII.GetBytes("--" + boundary);
			if (marker.Length > MaxMultipartPreambleBytes) return null;
			var failure = new int[marker.Length];
			for (var i = 1; i < marker.Length; i++)
			{
				var matched = failure[i - 1];
				while (matched > 0 && marker[i] != marker[matched]) matched = failure[matched - 1];
				if (marker[i] == marker[matched]) matched++;
				failure[i] = matched;
			}

			var buffer = new byte[8192];
			var matchedBytes = 0;
			long scanned = 0;
			while (scanned <= MaxMultipartPreambleBytes)
			{
				var read = await body.ReadAsync(buffer.AsMemory(), cancellationToken);
				if (read == 0) break;
				var endOfBuffer = scanned + read;
				for (var i = 0; i < read; i++)
				{
					while (matchedBytes > 0 && buffer[i] != marker[matchedBytes])
						matchedBytes = failure[matchedBytes - 1];
					if (buffer[i] == marker[matchedBytes]) matchedBytes++;
					if (matchedBytes != marker.Length) continue;

					var markerStart = scanned + i + 1 - marker.Length;
					body.Position = markerStart + marker.Length;
					var nextByte = body.ReadByte();
					var secondByte = body.ReadByte();
					body.Position = endOfBuffer;
					if (markerStart <= MaxMultipartPreambleBytes &&
						(nextByte == 13 && secondByte == 10 || nextByte == 45 && secondByte == 45) &&
						(markerStart == 0 || ReadByteAt(body, markerStart - 1) == 10))
					{
						body.Position = markerStart;
						return markerStart;
					}
					matchedBytes = failure[matchedBytes - 1];
				}
				scanned = endOfBuffer;
			}
			return null;
		}

		private static int ReadByteAt(Stream body, long position)
		{
			var currentPosition = body.Position;
			body.Position = position;
			var value = body.ReadByte();
			body.Position = currentPosition;
			return value;
		}

		[HttpPost("upload/unityassets"), Authorize]
		[RequestSizeLimit(MaxUploadBytes)]
		public async Task<IActionResult> UploadUnityAssets()
		{
			if (!Request.HasFormContentType) return BadRequest(new { error = "multipart files required" });




			var contentType = MediaTypeHeaderValue.Parse(Request.ContentType!);
			var boundary = HeaderUtilities.RemoveQuotes(contentType.Boundary).Value;
			if (string.IsNullOrWhiteSpace(boundary)) return BadRequest(new { error = "multipart boundary required" });
			if (boundary.Length > 200) return BadRequest(new { error = "multipart boundary too long" });




			var contentEncoding = Request.Headers["Content-Encoding"].ToString().Trim();
			var isGzip = string.Equals(contentEncoding, "gzip", StringComparison.OrdinalIgnoreCase);
			if (!string.IsNullOrEmpty(contentEncoding) && !isGzip)
				return StatusCode(StatusCodes.Status415UnsupportedMediaType, new { error = "unsupported content encoding" });

			Stream multipartBody;
			await using var decompressedBody = isGzip
				? new FileStream(Path.Combine(Path.GetTempPath(), Guid.NewGuid() + ".studio-upload"), FileMode.CreateNew,
					FileAccess.ReadWrite, FileShare.None, 81920, FileOptions.Asynchronous | FileOptions.DeleteOnClose)
				: null;
			if (decompressedBody != null)
			{
				await using (var gzip = new System.IO.Compression.GZipStream(Request.Body, System.IO.Compression.CompressionMode.Decompress, leaveOpen: true))
				{
					var buffer = new byte[81920];
					long total = 0;
					int read;
					while ((read = await gzip.ReadAsync(buffer.AsMemory(), HttpContext.RequestAborted)) > 0)
					{
						total += read;
						if (total > MaxUploadBytes) return StatusCode(StatusCodes.Status413PayloadTooLarge);
						await decompressedBody.WriteAsync(buffer.AsMemory(0, read), HttpContext.RequestAborted);
					}
				}
				decompressedBody.Position = 0;
				multipartBody = decompressedBody;
			}
			else
			{
				Request.EnableBuffering();
				multipartBody = Request.Body;
			}

			var preambleLength = await FindFirstBoundaryAsync(multipartBody, boundary, HttpContext.RequestAborted);
			if (preambleLength is null)
				return BadRequest(new { error = "multipart boundary not found within the preamble limit" });
			if (preambleLength > 0)
				Console.WriteLine($"[StudioUpload] skipped {preambleLength} multipart preamble bytes");

			var reader = new MultipartReader(boundary, multipartBody)
			{



				BodyLengthLimit = null,
				HeadersLengthLimit = 64 * 1024
			};
			var responses = new List<object>();
			MultipartSection? section;
			while ((section = await reader.ReadNextSectionAsync(HttpContext.RequestAborted)) != null)
			{
				if (!ContentDispositionHeaderValue.TryParse(section.ContentDisposition, out var disposition) ||
					!string.Equals(disposition.DispositionType.Value, "form-data", StringComparison.OrdinalIgnoreCase))
					continue;

				var fileName = HeaderUtilities.RemoveQuotes(disposition.FileNameStar.HasValue
					? disposition.FileNameStar
					: disposition.FileName).Value;
				if (string.IsNullOrWhiteSpace(fileName)) continue;

				responses.Add(await StudioAssetStorage.Save(section.Body, HttpContext.RequestAborted));
			}

			if (responses.Count == 0) return BadRequest(new { error = "no files supplied" });
			return Ok(responses);
		}

		[HttpPost("upload"), Authorize]
		[RequestSizeLimit(MaxUploadBytes)]
		public async Task<ActionResult<UploadResponse?>> Upload()
		{
			var boundaryHeader = Request.ContentType == null ? null : MediaTypeHeaderValue.Parse(Request.ContentType).Boundary;
			var boundary = HeaderUtilities.RemoveQuotes(boundaryHeader).Value;
			if (string.IsNullOrWhiteSpace(boundary)) return BadRequest(new { error = "multipart boundary required" });

			var contentEncoding = Request.Headers["Content-Encoding"].ToString().Trim();
			var isGzip = string.Equals(contentEncoding, "gzip", StringComparison.OrdinalIgnoreCase);
			if (!string.IsNullOrEmpty(contentEncoding) && !isGzip)
				return StatusCode(StatusCodes.Status415UnsupportedMediaType, new { error = "unsupported content encoding" });

			Stream multipartBody;
			await using var decompressedBody = isGzip
				? new FileStream(Path.Combine(Path.GetTempPath(), Guid.NewGuid() + ".studio-upload"), FileMode.CreateNew,
					FileAccess.ReadWrite, FileShare.None, 81920, FileOptions.Asynchronous | FileOptions.DeleteOnClose)
				: null;
			if (decompressedBody != null)
			{
				await using (var gzip = new System.IO.Compression.GZipStream(Request.Body, System.IO.Compression.CompressionMode.Decompress, leaveOpen: true))
				{
					var buffer = new byte[81920];
					long total = 0;
					int read;
					while ((read = await gzip.ReadAsync(buffer.AsMemory(), HttpContext.RequestAborted)) > 0)
					{
						total += read;
						if (total > MaxUploadBytes) return StatusCode(StatusCodes.Status413PayloadTooLarge);
						await decompressedBody.WriteAsync(buffer.AsMemory(0, read), HttpContext.RequestAborted);
					}
				}
				decompressedBody.Position = 0;
				multipartBody = decompressedBody;
			}
			else
			{
				Request.EnableBuffering();
				multipartBody = Request.Body;
			}

			var preambleLength = await FindFirstBoundaryAsync(multipartBody, boundary, HttpContext.RequestAborted);
			if (preambleLength is null) return BadRequest(new { error = "multipart boundary not found within the preamble limit" });

			var reader = new MultipartReader(boundary, multipartBody)
			{
				BodyLengthLimit = null,
				HeadersLengthLimit = 64 * 1024
			};
			MultipartSection? section;
			while ((section = await reader.ReadNextSectionAsync(HttpContext.RequestAborted)) != null)
			{
				if (!ContentDispositionHeaderValue.TryParse(section.ContentDisposition, out var disposition) ||
					!string.Equals(disposition.DispositionType.Value, "form-data", StringComparison.OrdinalIgnoreCase)) continue;

				var fileName = HeaderUtilities.RemoveQuotes(disposition.FileNameStar.HasValue
					? disposition.FileNameStar
					: disposition.FileName).Value;
				if (string.IsNullOrWhiteSpace(fileName)) continue;

				var stored = await StudioAssetStorage.Save(section.Body, HttpContext.RequestAborted);
				if (stored.Length <= 0) return BadRequest(new { error = "empty upload" });
				return new UploadResponse(stored.Filename);
			}
			return BadRequest(new { error = "no file supplied" });
		}
	}
}