using System;
using Chernobyl.App.Core;
using Chernobyl.Collections.Generic;
using Chernobyl.Extensions;
using Chernobyl.Generation;
using Chernobyl.Generation.Old;
using Chernobyl.Mathematics.Space;
using GalaSoft.MvvmLight.CommandWpf;
using LiveCharts;
using LiveCharts.Wpf;

namespace Chernobyl.App.Audio
{
    /// <summary>
    /// A view model representing a song.
    /// </summary>
    public class SongViewModel : ViewModel
    {
        /// <summary>
        /// Constructor.
        /// </summary>
        public SongViewModel(IWavePlayerFactory wavePlayerFactory)
        {
            // TODO: SongViewModel should take the IPlayer, not the factory. Need a View/Model that handles creation.
            Player = wavePlayerFactory.Create(CreateWavePlayerConfig());

            CreateMusicCommand = new RelayCommand(CreateMusic);
            PlayMusicCommand = new RelayCommand(Play);
            StopMusicCommand = new RelayCommand(Stop);
            TimeAxisFormatter = value => (value * TimeInterval.TotalSeconds).ToString();

            CreateMusic();
        }

        WavePlayerConfig CreateWavePlayerConfig()
        {
            var sampleRate = 16000;
            var amplitude = 0.25f;
            var halfSecond = sampleRate / 6;

            var available = new IPattern[]
            {
                new BasicPattern(200),
                new BasicPattern(225),
                new BasicPattern(250),
                new BasicPattern(275),
                new BasicPattern(300),
                new BasicPattern(325),
                new BasicPattern(350),
                new BasicPattern(375),
                new BasicPattern(400),
            };

            // Give each frequency 'beat' a position in the wave.
            var frequencyPattern = available.CreateParent(new Random()).Data
                .GetEnumerator().AsFunc().Select(freq => Tuple.Create(freq, halfSecond));

            var waveFunc = Generation.Audio.CreateSinOscillator(frequencyPattern.Square(), () => sampleRate, () => amplitude)
                .Select(Convert.ToSingle);

            return new WavePlayerConfig(waveFunc, sampleRate);
        }

        /// <inheritdoc />
        public override void Cleanup()
        {
            Player.Dispose();
            base.Cleanup();
        }

        /// <summary>
        /// The instance that plays music.
        /// </summary>
        public IPlayer Player { get; set; }

        /// <summary>
        /// The time between each beat of the song in seconds.
        /// </summary>
        public TimeSpan TimeInterval => TimeSpan.FromMilliseconds(500);

        /// <summary>
        /// The indicators current location as an floating point index. For example, 0 is the first
        /// data point, 1 is the second, .5 is halfway between the first and second data points.
        /// </summary>
        public double CurrentDatumIndex => Player.Position.TotalSeconds * 2;

        void CreateMusic()
        {
            Stop();

            MusicSeries.Clear();
            MusicSeries.Add(new LineSeries
            {
                Title = "Beat 1",
                //Values = new ChartValues<double>(Wave.Sin.Step(.1).Select(value => (value + 37 * 2)).AsEnumerable().Take(150).ToArray())
                Values = new ChartValues<double>()
            });

            Reset();
        }

        void Play()
        {
            Player.Play();
        }

        void Stop()
        {
            Player.Stop();
        }

        /// <summary>
        /// Sets the player to the start of the song.
        /// </summary>
        void Reset()
        {
        }

        /// <summary>
        /// The command to create music.
        /// </summary>
        public RelayCommand CreateMusicCommand { get; }

        /// <summary>
        /// Plays the current music when invoked.
        /// </summary>
        public RelayCommand PlayMusicCommand { get; }

        /// <summary>
        /// Stops the current music when invoked.
        /// </summary>
        public RelayCommand StopMusicCommand { get; }

        /// <summary>
        /// The data representing the music.
        /// </summary>
        public SeriesCollection MusicSeries { get; } = new SeriesCollection();

        /// <summary>
        /// The instance that formats the time series.
        /// </summary>
        public Func<double, string> TimeAxisFormatter { get; }
    }
}