namespace HaWeb.Controllers;
using Microsoft.AspNetCore.Mvc;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Extensions.Configuration;
using Microsoft.Net.Http.Headers;
using HaWeb.Filters;
using HaWeb.FileHelpers;
using HaWeb.XMLParser;
using System.Text.Json.Serialization;
using System.Text.Json;
using HaDocument.Interfaces;
using HaXMLReader.Interfaces;
using Microsoft.FeatureManagement.Mvc;
using System.Runtime.InteropServices;
using Microsoft.AspNetCore.Http.Features;

// Controlling all the API-Endpoints
public class APIController : Controller {

    // DI
    private ILibrary _lib;
    private IReaderService _readerService;
    private readonly long _fileSizeLimit;
    private readonly string _targetFilePath;
    private readonly IXMLService _xmlService;

    // Options
    private static readonly string[] _permittedExtensions = { ".xml" };
    private static readonly FormOptions _defaultFormOptions = new FormOptions();


    public APIController(ILibrary lib, IReaderService readerService, IXMLService xmlService, IConfiguration config) {
        _lib = lib;
        _readerService = readerService;
        _xmlService = xmlService;
        _fileSizeLimit = config.GetValue<long>("FileSizeLimit");
        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
            _targetFilePath = config.GetValue<string>("StoredFilePathWindows");
        } else {
            _targetFilePath = config.GetValue<string>("StoredFilePathLinux");
        }
    }

    [HttpGet]
    [Route("API/Syntaxcheck/{id}")]
    [DisableFormValueModelBinding]
    [ValidateAntiForgeryToken]
    [FeatureGate(Features.AdminService)]
    public async Task<IActionResult> SyntaxCheck(string id) {
        return Ok();
    }

    //// UPLOAD ////
    [HttpPost]
    [Route("API/Upload")]
    [DisableFormValueModelBinding]
    [ValidateAntiForgeryToken]
    [FeatureGate(Features.UploadService)]
    public async Task<IActionResult> Upload(string? id) {
        List<XMLRootDocument>? docs = null;
        //// 1. Stage: Check Request format and request spec
        // Checks the Content-Type Field (must be multipart + Boundary)
        if (!MultipartRequestHelper.IsMultipartContentType(Request.ContentType)) {
            ModelState.AddModelError("Error", $"Wrong / No Content Type on the Request");
            return BadRequest(ModelState);
        }

        // Divides the multipart document into it's sections and sets up a reader
        var boundary = MultipartRequestHelper.GetBoundary(MediaTypeHeaderValue.Parse(Request.ContentType), _defaultFormOptions.MultipartBoundaryLengthLimit);
        var reader = new MultipartReader(boundary, HttpContext.Request.Body);
        MultipartSection? section = null;
        try {
            section = await reader.ReadNextSectionAsync();
        } catch (Exception ex) {
            ModelState.AddModelError("Error", "The Request is bad: " + ex.Message);
        }

        while (section != null) {
            // Multipart document content disposition header read for a section:
            // Starts with boundary, contains field name, content-dispo, filename, content-type
            var hasContentDispositionHeader = ContentDispositionHeaderValue.TryParse(section.ContentDisposition, out var contentDisposition);

            if (contentDisposition != null && contentDisposition.Name == "__RequestVerificationToken") {
                try {
                    section = await reader.ReadNextSectionAsync();
                } catch (Exception ex) {
                    ModelState.AddModelError("Error", "The Request is bad: " + ex.Message);
                }
                continue;
            }

            if (hasContentDispositionHeader && contentDisposition != null) {
                // Checks if it is a section with content-disposition, name, filename
                if (!MultipartRequestHelper.HasFileContentDisposition(contentDisposition)) {
                    ModelState.AddModelError("Error", $"Wrong Content-Dispostion Headers in Multipart Document");
                    return BadRequest(ModelState);
                }

                //// 2. Stage: Check File. Sanity checks on the file on a byte level, extension checking, is it empty etc.
                var streamedFileContent = await XMLFileHelpers.ProcessStreamedFile(
                    section, contentDisposition, ModelState,
                    _permittedExtensions, _fileSizeLimit);
                if (!ModelState.IsValid || streamedFileContent == null)
                    return BadRequest(ModelState);

                //// 3. Stage: Valid XML checking using a simple XDocument.Load()
                var xdocument = await XDocumentFileHelper.ProcessStreamedFile(streamedFileContent, ModelState);
                if (!ModelState.IsValid || xdocument == null)
                    return UnprocessableEntity(ModelState);

                //// 4. Stage: Is it a Hamann-Document? What kind?
                var retdocs = await _xmlService.ProbeHamannFile(xdocument, ModelState);
                if (!ModelState.IsValid || retdocs == null || !retdocs.Any())
                    return UnprocessableEntity(ModelState);

                //// 5. Stage: Saving the File(s)
                foreach (var doc in retdocs) {
                    await _xmlService.UpdateAvailableFiles(doc, _targetFilePath, ModelState);
                    if (!ModelState.IsValid) return StatusCode(500, ModelState);
                    if (docs == null) docs = new List<XMLRootDocument>();
                    docs.Add(doc);
                }
            }

            try {
                section = await reader.ReadNextSectionAsync();
            } catch (Exception ex) {
                ModelState.AddModelError("Error", "The Request is bad: " + ex.Message);
            }
        }

        // 6. Stage: Success! Returning Ok, and redirecting 
        JsonSerializerOptions options = new() {
            ReferenceHandler = ReferenceHandler.Preserve,
            Converters = {
                new IdentificationStringJSONConverter()
            }
        };

        string json = JsonSerializer.Serialize(docs);
        return Created(nameof(UploadController), json);
    }
}