using PepLib.Models;
using System.IO.Compression;
using System.Text.RegularExpressions;

namespace PepLib.IO
{
    public sealed class DrawingReader
    {
        public Drawing Drawing { get; private set; }

        public DrawingReader()
        {
            Drawing = new Drawing();
        }

        public DrawingReader(Drawing drawing)
        {
            Drawing = drawing;
        }

        public void Read(Stream stream)
        {
            using (var zip = new ZipArchive(stream, ZipArchiveMode.Read, leaveOpen: true))
            {
                foreach (var entry in zip.Entries)
                {
                    using var entryStream = entry.Open();
                    var memstream = new MemoryStream();
                    entryStream.CopyTo(memstream);
                    memstream.Seek(0, SeekOrigin.Begin);

                    var extension = Path.GetExtension(entry.FullName);

                    switch (extension)
                    {
                        case ".dir":
                            LoadInfo(memstream);
                            memstream.Close();
                            continue;

                        case ".loop-info":
                        case ".cadsnapshot":
                            memstream.Close();
                            continue;
                    }

                    if (Regex.IsMatch(extension, "loop-\\d\\d\\d"))
                        Drawing.Loops.Add(ReadLoop(entry.FullName, memstream));

                    memstream.Close();
                }
            }

            if (Drawing.Info == null)
                Drawing.Info = DeriveInfoFromLoops();

            Drawing.ResolveLoops();
        }

        public void Read(string nestFile)
        {
            if (!File.Exists(nestFile))
            {
                var msg = string.Format("File Not Found: {0}", nestFile);
                throw new FileNotFoundException(msg);
            }

            Stream stream = null;

            try
            {
                stream = new FileStream(nestFile, FileMode.Open, FileAccess.Read, FileShare.Read);
                Read(stream);
            }
            finally
            {
                if (stream != null)
                    stream.Close();
            }
        }

        private void LoadInfo(Stream stream)
        {
            Drawing.Info = DrawingInfo.Load(stream);
        }

        private DrawingInfo DeriveInfoFromLoops()
        {
            var info = new DrawingInfo();

            if (Drawing.Loops.Count > 0)
            {
                // Loop names follow the pattern "{DrawingName}.loop-XXX"
                var loopName = Drawing.Loops[0].Name;
                var suffix = loopName.LastIndexOf(".loop-", StringComparison.OrdinalIgnoreCase);
                info.Name = suffix >= 0 ? loopName.Substring(0, suffix) : loopName;
            }

            return info;
        }

        private Loop ReadLoop(string name, Stream stream)
        {
            var reader = new LoopReader();
            reader.Read(name, stream);

            return reader.Loop;
        }
    }
}