EnvelopeGenerator/EnvelopeGenerator.Web/Handler/FileHandler.cs

using DigitalData.Modules.Database;
using DigitalData.Modules.Logging;
using EnvelopeGenerator.Common;
using EnvelopeGenerator.Common.My.Resources;
using EnvelopeGenerator.Web.Services;
using Microsoft.Extensions.Primitives;
using System.IO.Pipelines;
using System.Reflection.Metadata.Ecma335;
using System.Text;

namespace EnvelopeGenerator.Web.Handler
{
     public class FileHandler
    {
        /// <summary>
        /// URL: GET /api/envelope/{envelopeKey}
        /// 
        /// Returns a
        /// </summary>
        /// <returns></returns>
        public IResult HandleGetEnvelope(HttpContext ctx, DatabaseService database, LoggingService logging)
        {
            var logger = logging.LogConfig.GetLogger("FileHandler");

            try
            {
                logger.Info("Handling envelope loading.");

                // Load Envelope from EnvelopeKey
                string envelopeKey = EnsureValidEnvelopeKey(logger, ctx.Request);
                EnvelopeResponse r = database.LoadEnvelope(envelopeKey);

                // Return the envelope and additional data as json
                return Results.Json(r);

            }
            catch (Exception e)
            {
                // Better error handling & reporting
                logger.Error(e);
                return Results.Problem(e.Message);

            }
        }

        /// <summary>
        /// URL: GET /api/document/{envelopeKey}?index={documentIndex}
        /// 
        /// Returns a document for the supplied EnvelopeKey and Document Id / Index
        /// </summary>
        /// <returns>file buffer of the requested document</returns>
        public async Task<IResult> HandleGetDocument(HttpContext ctx, DatabaseService database, LoggingService logging)
        {
            var logger = logging.LogConfig.GetLogger("FileHandler");

            try
            {
                logger.Info("Handling file download.");

                // Load Envelope from EnvelopeKey
                string envelopeKey = EnsureValidEnvelopeKey(logger, ctx.Request);
                EnvelopeResponse r = database.LoadEnvelope(envelopeKey);

                // Get the document Index
                int documentId = EnsureValidDocumentIndex(logger, ctx.Request);
                var document = GetDocument(r.Envelope, documentId);              

                // Load the document from disk
                var bytes = await File.ReadAllBytesAsync(document.Filepath);
                logger.Info("Serving file, size: [{0}]", bytes.Length);

                // Return the document as bytes
                return Results.File(bytes);
            }
            catch (Exception e)
            {
                // Better error handling & reporting
                logger.Error(e);
                return Results.Problem();

            }
        }

        public async Task<IResult> HandlePostDocument(HttpContext ctx, DatabaseService database, LoggingService logging)
        {
            var logger = logging.LogConfig.GetLogger("FileHandler");

            try
            {
                logger.Info("Handling file upload.");

                // Load Envelope from EnvelopeKey
                string envelopeKey = EnsureValidEnvelopeKey(logger, ctx.Request);
                EnvelopeResponse r = database.LoadEnvelope(envelopeKey);

                // Get the document Index
                int documentId = EnsureValidDocumentIndex(logger, ctx.Request);
                var document = GetDocument(r.Envelope, documentId);

                using FileStream fs = new(document.Filepath, FileMode.Open);
                await ctx.Request.Body.CopyToAsync(fs);
                fs.Flush();

                return Results.Ok();
            }
            catch (Exception e)
            {
                // Better error handling & reporting
                logger.Error(e);
                return Results.Problem();
            }
        }

        public async Task<IResult> HandlePostEnvelope(HttpContext ctx, DatabaseService database, LoggingService logging)
        {
            var logger = logging.LogConfig.GetLogger("FileHandler");

            try
            {
                logger.Info("Handling envelope saving.");

                // Load Envelope from EnvelopeKey
                string envelopeKey = EnsureValidEnvelopeKey(logger, ctx.Request);
                EnvelopeResponse r = database.LoadEnvelope(envelopeKey);

                // Get the document Index
                int documentId = EnsureValidDocumentIndex(logger, ctx.Request);
                var document = GetDocument(r.Envelope, documentId);        

                string? annotationData = await EnsureValidAnnotationData(logger, ctx.Request);

                if (annotationData == null)
                {
                    throw new ArgumentNullException("AnnotationData");
                }

                State state = GetState(logging.LogConfig, database.MSSQL);
                DocumentStatusModel model = new(state);

                model.InsertOrUpdate(new DocumentStatus()
                {
                     EnvelopeId = r.Envelope.Id,
                     ReceiverId = r.ReceiverId,
                     Value = annotationData,
                     Status = Common.Constants.DocumentStatus.Signed
                });

                return Results.Ok();
            }
            catch (Exception e)
            {
                // Better error handling & reporting
                logger.Error(e);
                return Results.Problem();
            }
        }

        private State GetState(LogConfig LogConfig, MSSQLServer Database)
        {
            return new State
            {
                LogConfig = LogConfig,
                Database = Database,
            };
        }

        private int EnsureValidDocumentIndex(Logger logger, HttpRequest request)
        {
            if (request.Query.TryGetValue("index", out StringValues documentIndexString))
            {
                try
                {
                    return int.Parse(documentIndexString.First());
                }
                catch (Exception e)
                {
                    throw new ArgumentNullException("DocumentIndex", e);
                }              
            }
            else
            {
                throw new ArgumentNullException("DocumentIndex");
            }
        }

        private string EnsureValidEnvelopeKey(Logger logger, HttpRequest request)
        {
            logger.Debug("Parsing EnvelopeKey..");
            var envelopeKey = request.RouteValues["envelopeKey"] as string;

            if (string.IsNullOrEmpty(envelopeKey))
                throw new ArgumentNullException("EnvelopeKey");

            Tuple<string, string> result = Helpers.DecodeEnvelopeReceiverId(envelopeKey);
            logger.Debug("EnvelopeUUID: [{0}]", result.Item1);
            logger.Debug("ReceiverSignature: [{0}]", result.Item2);

            if (string.IsNullOrEmpty(result.Item1))
                throw new ArgumentNullException("EnvelopeUUID");

            if (string.IsNullOrEmpty(result.Item2))
                throw new ArgumentNullException("ReceiverSignature");

            return envelopeKey;
        }

        private async Task<string?> EnsureValidAnnotationData(Logger logger, HttpRequest request)
        {
            logger.Debug("Parsing AnnotationData..");

            try
            {
                using MemoryStream ms = new();
                await request.BodyReader.CopyToAsync(ms);
                var bytes = ms.ToArray();

                return Encoding.UTF8.GetString(bytes);
            }
            catch (Exception e)
            {
                logger.Error(e);
                return null;
            }
            
        }

        private EnvelopeDocument GetDocument(Common.Envelope envelope, int documentId)
        {
            var document = envelope.Documents.
                Where(d => d.Id == documentId).
                FirstOrDefault();

            if (document == null)
                throw new ArgumentException("DocumentId");

            return document;
        }
    }
}