using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HeuristicLab.Problems.Instances.DataAnalysis.Regression.Matlab.Api.Types {
  using TMLTimeseriesValueDT = IMLValueVariable<IList<KeyValuePair<double, double[]>>>;
  public class MLTimeseries : IMLValueVariable<IList<KeyValuePair<double, double[]>>>, IMLTimeseries {
    private readonly object _locker = new object();

    private string[] _dataHeaders;

    protected MLTimeseries() {
      Data = new List<KeyValuePair<double, double[]>>();
      Name = string.Empty;
    }

    /// <summary>
    /// Creates a new timeseries from the given collection of timeseries.
    /// All values will be merged into one time series.
    /// </summary>
    /// <param name="timeseries"></param>
    public MLTimeseries(IEnumerable<MLTimeseries> timeseries) : this() {
      var dataHeaders = new List<string>();
      var times = new SortedSet<double>(); // The time values have to be unique and sorted.

      foreach (var item in timeseries) {
        foreach (var dataHeader in item.DataHeader) {
          dataHeaders.Add(dataHeader);
        }

        foreach (var time in item.Times) {
          times.Add(time);
        }
      }

      var numberOfElements = dataHeaders.Count;
      Parallel.ForEach(times, (time) => {
        //foreach (var time in times) {
        var values = new double[numberOfElements];
        int idx = 0;
        foreach (var item in timeseries) {
          double[] vs = item.GetValuesByTime(time);

          foreach (var v in vs) {
            values[idx++] = v;
          }
        }
        lock (_locker) {
          Data.Add(new KeyValuePair<double, double[]>(time, values));
        }
      });

      _dataHeaders = dataHeaders.ToArray();
    }

    public MLTimeseries(string name, object times, object data) : this() {
      Name = name;

      if (!(times is double[,]) || !(data is double[,])) {
        throw new ArgumentException(string.Format("Invalid datatype: times={0}, data={1}", times.GetType(), data.GetType()));
      }

      var t = times as double[,];
      var d = data as double[,];

      if (t.GetLength(0) != d.GetLength(0)) {
        throw new ArgumentException(string.Format("Number of elements are not equal: times={0}, data={1}", t.GetLength(0), d.GetLength(0)));
      }

      var valueColumns = d.GetLength(1);
      _dataHeaders = new string[valueColumns];

      for (int i = 0; i < valueColumns; i++) {
        _dataHeaders[i] = string.Format("{0}:{1}", Name, i);
      }

      for (int i = 0; i < t.GetLength(0); i++) {
        var time = t[i, 0];
        var vals = new double[valueColumns];
        for (int j = 0; j < valueColumns; j++) {
          vals[j] = d[i, j];
        }
        Data.Add(new KeyValuePair<double, double[]>(time, vals));
      }
    }

    private MLTimeseries(IMLTimeseries original) : this() {
      Name = ((TMLTimeseriesValueDT)original).Name;

      _dataHeaders = (string[])original.DataHeader.Clone();

      foreach (var entry in ((TMLTimeseriesValueDT)original).Data) {
        Data.Add(new KeyValuePair<double, double[]>(entry.Key, entry.Value));
      }
    }

    public string Name { get; set; }

    public IList<KeyValuePair<double, double[]>> Data { get; set; }

    public MLDatatype Datatype {
      get { return MLDatatype.Timeseries; }
    }

    public string[] DataHeader {
      get { return _dataHeaders; }
    }

    public double[] this[int idx] {
      get {
        var entry = Data[idx];
        var values = new double[entry.Value.Length + 1];
        values[0] = Data[idx].Key;
        for (int i = 1; i < values.Length; i++) {
          values[i] = entry.Value[i - 1];
        }
        return values;
      }
    }

    public double[] Times {
      get {
        return Data.Select(x => x.Key).ToArray();
      }
    }

    public double GetTimeAt(int idx) {
      if (idx < Data.Count) {
        return Data[idx].Key;
      }

      return double.MaxValue;
    }

    public int Count {
      get {
        return Data.Count;
      }
    }

    public double[] GetValuesByTime(double time) {
      double[] value;
      if (Data.Count < 0) {
        value = new double[] { 0.0 };
      }
      value = Data.Where(x => x.Key <= time).LastOrDefault().Value;
      if (value == null) {
        return new double[Data[0].Value.Length];
      }
      return value;
    }

    public IMLTimeseries ToTimeseries() {
      return new MLTimeseries(this);
    }
  }
}