using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;

namespace System.IO.Packaging
{
    public abstract class PackageProperties : IDisposable
    {
        internal const string NSPackageProperties = "http://schemas.openxmlformats.org/package/2006/metadata/core-properties";
        internal const string NSPackagePropertiesRelation = "http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties";
        internal const string PackagePropertiesContentType = "application/vnd.openxmlformats-package.core-properties+xml";


        static int uuid;

        protected PackageProperties()
        {

        }

        public abstract string Category { get; set; }
        public abstract string ContentStatus { get; set; }
        public abstract string ContentType { get; set; }
        public abstract DateTime? Created { get; set; }
        public abstract string Creator { get; set; }
        public abstract string Description { get; set; }
        public abstract string Identifier { get; set; }
        public abstract string Keywords { get; set; }
        public abstract string Language { get; set; }
        public abstract string LastModifiedBy { get; set; }
        public abstract DateTime? LastPrinted { get; set; }
        public abstract DateTime? Modified { get; set; }
        internal Package Package { get; set; }
        internal PackagePart Part { get; set; }
        public abstract string Revision { get; set; }
        public abstract string Subject { get; set; }
        public abstract string Title { get; set; }
        public abstract string Version { get; set; }


        public void Dispose()
        {
            Dispose(true);
        }

        protected virtual void Dispose(bool disposing)
        {
            // Nothing
        }

        internal void Flush()
        {
            using (MemoryStream temp = new MemoryStream())
            {
                using (XmlTextWriter writer = new XmlTextWriter(temp, System.Text.Encoding.UTF8))
                {
                    WriteTo(writer);
                    writer.Flush();
                    if (temp.Length == 0)
                        return;
                }
            }

            if (Part == null)
            {
                int id = System.Threading.Interlocked.Increment(ref uuid);
                Uri uri = new Uri(string.Format("/package/services/metadata/core-properties/{0}.psmdcp", id), UriKind.Relative);
                Part = Package.CreatePart(uri, PackagePropertiesContentType);
                PackageRelationship rel = Package.CreateRelationship(uri, TargetMode.Internal, NSPackagePropertiesRelation);
            }

            using (Stream s = Part.GetStream(FileMode.Create))
            using (XmlTextWriter writer = new XmlTextWriter(s, System.Text.Encoding.UTF8))
                WriteTo(writer);
        }

        internal virtual void LoadFrom(Stream stream)
        {

        }

        internal virtual void WriteTo(XmlTextWriter writer)
        {

        }
    }
}