ObjectToZipConverter.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using Waher.Runtime.Collections;
using Waher.Runtime.Inventory;
 
namespace Waher.Content.Zip
{
    public class ObjectToZipConverter : IContentConverter
    {
        private readonly static Dictionary<string, bool> protectedContentTypes = new Dictionary<string, bool>(StringComparer.OrdinalIgnoreCase);
        private static string[] canConvertFrom = null;
 
        public static void ProtectContentType(string ContentType)
        {
            lock (protectedContentTypes)
            {
                protectedContentTypes[ContentType] = true;
                canConvertFrom = null;
            }
        }
 
        public static bool IsProtected(string ContentType)
        {
            lock (protectedContentTypes)
            {
                return protectedContentTypes.TryGetValue(ContentType, out bool Protected) && Protected;
            }
        }
 
        public ObjectToZipConverter()
        {
        }
 
        public string[] FromContentTypes
        {
            get
            {
                string[] Result = canConvertFrom;
                if (!(Result is null))
                    return Result;
 
                ChunkedList<string> Supported = new ChunkedList<string>();
                string[] ZipTypes = ZipCodec.ZipFileContentTypes;
 
                foreach (string ContentType in InternetContent.CanEncodeContentTypes)
                {
                    if (!IsProtected(ContentType) && Array.IndexOf(ZipTypes, ContentType) < 0)
                        Supported.Add(ContentType);
                }
 
                canConvertFrom = Result = Supported.ToArray();
 
                return Result;
            }
        }
 
        public string[] ToContentTypes => ZipCodec.ZipFileContentTypes;
 
        public virtual Grade ConversionGrade => Grade.Barely;
 
        public async Task<bool> ConvertAsync(ConversionState State)
        {
            if (State is null)
                return true;
 
            string SourceFileName = State.FromFileName;
 
            if (string.IsNullOrEmpty(SourceFileName))
                SourceFileName = "File." + InternetContent.GetFileExtension(State.FromContentType);
 
            byte[] Data;
 
            using (MemoryStream Output = new MemoryStream())
            {
                await Zip.CreateZipFile(SourceFileName, State.From, DateTime.Now, Output);
                Data = Output.ToArray();
            }
 
            await State.To.WriteAsync(Data, 0, Data.Length);
 
            return false;
        }
    }
}