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

namespace PackingPress.Common
{
    internal class UpgradePackageWriter
    {
        private readonly string _filePath;
        private readonly List<UpgradePackage> _packages = new List<UpgradePackage>();

        public IReadOnlyList<UpgradePackage> Packages => _packages;


        public UpgradePackageWriter(string filePath)
        {
            _filePath = filePath;
        }


        public void AddPackage(UpgradePackage package)
        {
            var existing = _packages.FirstOrDefault(x => x.Platform == package.Platform && x.Type == package.Type);
            if (existing == null)
            {
                _packages.Add(package);
            }
        }

        public void RemovePackage(PackagePlatform platform, PackageType type)
        {
            var existing = _packages.FirstOrDefault(x => x.Platform == platform && x.Type == type);
            if (existing != null)
            {
                _packages.Remove(existing);
            }
        }

        public void Save()
        {
            using (var stream = new FileStream(_filePath, FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite))
            {
                var writer = new UpgradePackageStreamWriter(stream);
                writer.WriteString("VUP");
                writer.WriteInt(_packages.Count);
                foreach (var package in _packages)
                {
                    writer.WriteInt((int)package.Platform);
                    writer.WriteInt((int)package.Type);
                    writer.WriteString(package.Version.ToString());
                    writer.WriteString(package.Description);
                    writer.WriteBytes(package.FileData);
                    writer.WriteBytes(package.FileMD5);
                }
            }
        }

        private class UpgradePackageStreamWriter
        {
            private readonly Stream _stream;

            public UpgradePackageStreamWriter(Stream stream)
            {
                _stream = stream;
            }

            /// <summary>
            /// Write a string to stream.
            /// </summary>
            /// <param name="value"></param>
            public void WriteString(string value)
            {
                var data = Encoding.Unicode.GetBytes(value);
                WriteInt(data.Length);
                _stream.Write(data, 0, data.Length);
            }

            /// <summary>
            /// Write a int32 value to stream.
            /// </summary>
            /// <param name="value"></param>
            public void WriteInt(int value)
            {
                _stream.Write(BitConverter.GetBytes(value), 0, sizeof(int));
            }

            /// <summary>
            /// Write a array in to stream.
            /// </summary>
            public void WriteBytes(byte[] value)
            {
                WriteInt(value.Length);
                _stream.Write(value, 0, value.Length);
            }
        }
    }
}