using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using BetterPatchFileCreator.Code;
using Differ;
using PatcherShared;

namespace BetterPatchFileCreator.XAML.Pages
{
	/// <summary>
	/// Interaction logic for CreatingPatch.xaml
	/// </summary>
	public partial class CreatingPatch : Page {
		private PatchConfig config;
		private TaskScheduler uiScheduler;
		private TaskFactory uiFactory;

		private FileSystem oldFileSys;
		private FileSystem newFileSys;
		private IEnumerable<Difference> diffs;
		private PatchFile patchFile;

		public CreatingPatch(PatchConfig config) {
			uiScheduler = TaskScheduler.FromCurrentSynchronizationContext();
			uiFactory = new TaskFactory(uiScheduler);
			this.config = config;
			InitializeComponent();
			Task.Factory.StartNew(CreatePatch);
		}

		#region Create-Patch Methods

		public void CreatePatch()
		{
			ReadIndexOfOldClient();
			IndexCurrentClient();
			CalculatedDiffs();
			if(!CheckForDiffs()) return;	// No diffs.
			EncodePatchFile();
			SavePatchFile();
			SaveIndex();

			SetStatus("Finished.");
			Finish();
		}

		private void ReadIndexOfOldClient() {
			SetStatus("Reading index...");
			string oldXmlPath = GetXmlPath();
			oldFileSys = new FileSystem();
			oldFileSys.ParseFromXml(oldXmlPath);
			SetProgress(0.1);
		}
		private void IndexCurrentClient() {
			SetStatus("Indexing client...");
			newFileSys = new FileSystem();
			newFileSys.Parse(config.ClientPath);
			SetProgress(1.3);
		}
		private void CalculatedDiffs() {
			SetStatus("Calculating differences...");
			diffs = newFileSys.GetDiffs(oldFileSys);
			SetProgress(1.6);
		}
		private bool CheckForDiffs() {
			if (diffs.Count() == 0)
			{
				SetStatus("Finished. No changes detected.");
				SetProgress(2.0);					// complete
				Finish();
				return false;
			}
			return true;
		}
		private void EncodePatchFile() {
			SetStatus("Encoding to patchfile...");
			DiffToPatchfileEncoder encoder = new DiffToPatchfileEncoder();
			patchFile = encoder.Encode(diffs);
			SetProgress(1.8);	
		}
		private void SavePatchFile() {
			SetStatus("Saving patchfile...");
			if (MessageBox.Show("Patcherpatch?", "Patcherpatch", MessageBoxButton.YesNo, MessageBoxImage.Question) == MessageBoxResult.Yes) {
				patchFile.SelfPatch = true;
			} else {
				patchFile.SelfPatch = false;
			}
			patchFile.Write(GetPatchFilePath());
			SetProgress(1.9);
		}
		private void SaveIndex() {
			SetStatus("Saving Index...");
			Interlocked.Increment(ref config._v);
			newFileSys.SaveToXmlFile(GetXmlPath());
			SetProgress(2.0);
		}

		private string GetXmlPath() {
			StringBuilder builder = new StringBuilder();
			builder.Append(config.XmlPath);
			builder.Append('\\');
			builder.Append(config.Name);
			builder.Append('-');
			builder.Append(config.Version);
			builder.Append(".xml");

			return builder.ToString();
		}
		private string GetPatchFilePath() {
			StringBuilder builder = new StringBuilder();
			builder.Append(config.PatchFilePath);
			builder.Append('\\');
			builder.Append(config.Name);
			builder.Append('-');
			builder.Append(config.Version);
			builder.Append(".spf");

			return builder.ToString();
		}

		#endregion
		#region Methods

		#endregion

		#region UI-ThreadSafe Methods
		private void Finish()
		{
			uiFactory.StartNew(() => btFinish.Visibility = Visibility.Visible);
		}
		private void SetProgress(double progress)
		{
			uiFactory.StartNew(() => Progress.Value = progress);
		}
		private void SetStatus(string status)
		{
			uiFactory.StartNew(() => State.Text = status);
		} 
		#endregion
	}
}