using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using BuzzGUI.Interfaces;
using BuzzGUI.Common;
using Sanford.Multimedia.Midi;
using Microsoft.Win32;
using System.Windows;

namespace BuzzGUI.SequenceEditor
{
	class MIDIExporter
	{
		const int TimeBase = 960;	// used by IPattern.PatternEditorMachineMIDIEvents

		public static void ExportMIDI(ISong s)
		{
			var fn = GetFilename();
			if (fn == null) return;
			ExportMIDI(s.Sequences, fn);
		}

		public static void ExportMIDI(ISequence s)
		{
			var fn = GetFilename();
			if (fn == null) return;
			ExportMIDI(LinqExtensions.Return(s), fn);
		}

		static string GetFilename()
		{
			var dlg = new SaveFileDialog();
			dlg.Filter = "Standard MIDI file|*.mid";
			dlg.DefaultExt = ".mid";

			if ((bool)dlg.ShowDialog())
				return dlg.FileName;
			else
				return null;
		}


		static void ExportMIDI(IEnumerable<ISequence> seqs, string path)
		{
			try
			{
				var ms = new Sequence(4 * TimeBase);

				foreach (var s in seqs)
					ms.Add(ExportTrack(s));

				ms.Save(path);
			}
			catch (Exception e)
			{
				MessageBox.Show(e.Message);
			}
		}

		static Track ExportTrack(ISequence s)
		{
			var mt = new Track();
			var tname = new MetaTextBuilder(MetaType.TrackName, s.Machine.Name);
			tname.Build();
			mt.Insert(0, tname.Result);

			foreach (var se in s.Events)
			{
				int setime = se.Key * TimeBase;

				if (se.Value.Type == SequenceEventType.PlayPattern)
				{
					var p = se.Value.Pattern;
					var me = p.PatternEditorMachineMIDIEvents;

					for (int i = 0; i < me.Length / 2; i++)
						mt.Insert(setime + me[2 * i + 0], new ChannelMessage(me[2 * i + 1]));
				}
			}

			return mt;
		}
	}
}