using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.Concurrent;
using System.Xml;

namespace Differ
{
	public class FileSystem
	{
		#region .ctor
		#endregion

		#region Methods
		public void Parse(string rootPath) {
			Root = new Folder(rootPath);
		}
		public void SaveToXmlFile(string path) {
			XmlDocument doc = new XmlDocument();
			doc.AppendChild(Root.GetXmlNode(doc));
			doc.Save(path);
		}
		public void ParseFromXml(string path) {
			XmlDocument doc = new XmlDocument();
			nodesWithParentToParse = new ConcurrentQueue<KeyValuePair<XmlNode, Folder>>();
			doc.Load(path);

			foreach (XmlNode node in doc) {
				if(node.Name == "Folder")
					nodesWithParentToParse.Enqueue(new KeyValuePair<XmlNode, Folder>(node, null));
			}
			ParseXmlNodes();
		}
		private void ParseXmlNodes() {
			while (nodesWithParentToParse.Count > 0) {
				KeyValuePair<XmlNode, Folder> pair;
				if(!nodesWithParentToParse.TryDequeue(out pair))
					continue;
				Folder f = new Folder {Parent = pair.Value};
				f.ParseFromXmlNode(pair.Key);
				if(pair.Value != null)
					pair.Value.Folders.Add(f);
				else
					this.Root = f;
				foreach (XmlNode n in pair.Key.ChildNodes)
					if (n.Name == "Folder")
						nodesWithParentToParse.Enqueue(new KeyValuePair<XmlNode, Folder>(n, f));
					else if (n.Name == "File") {
						File file = new File();
						file.ParseFromXmlNode(n);
						file.Parent = f;
						f.Files.Add(file);
					}
			}
		}

		public IEnumerable<Difference> GetDiffs(FileSystem target) {
			List<Difference> diffs = new List<Difference>();
			ConcurrentQueue<Folder.FolderParser> workerQueue = new ConcurrentQueue<Folder.FolderParser>();
			Folder.FolderParser parserRoot = new Folder.FolderParser(Root, target.Root, workerQueue.Enqueue);
			workerQueue.Enqueue(parserRoot);

			Folder.FolderParser result;
			while (workerQueue.TryDequeue(out result)) {
				result.Run();
				diffs.AddRange(result.Diffs);
			}

			return diffs;
		}
		#endregion

		#region Propertys
		public Folder Root { get; private set; }
		#endregion

		#region Variables

		private ConcurrentQueue<KeyValuePair<XmlNode, Folder>> nodesWithParentToParse;

		#endregion
	}
}