using System;
using System.Collections.Generic;
using Core.Components.Charting.Data;
using OxyPlot;
using OxyPlot.Series;

namespace Core.Components.OxyPlot.Converter
{
    /// <summary>
    /// Provides an abstract base class for transforming <see cref="ChartData"/> in specific
    /// <see cref="Series"/> instances.
    /// </summary>
    public abstract class ChartDataConverter<T> : IChartDataConverter where T : ChartData
    {
        public bool CanConvertSeries(ChartData data)
        {
            return data.GetType() == typeof(T);
        }

        public IList<Series> Convert(ChartData data)
        {
            if (data == null)
            {
                throw new ArgumentNullException("Null data cannot be converted into series.");
            }
            if (!CanConvertSeries(data))
            {
                var message = string.Format("The data of type {0} cannot be converted by this converter.", data.GetType());
                throw new ArgumentException(message);
            }
            return Convert((T) data);
        }

        /// <summary>
        /// Transforms a given object into a <see cref="DataPoint"/>. Can be used as a 
        /// <see cref="DataPointSeries.Mapping"/>.
        /// </summary>
        /// <param name="obj">The object to convert into a <see cref="DataPoint"/>.</param>
        /// <returns>A new <see cref="DataPoint"/> based on <paramref name="obj"/>.</returns>
        /// <exception cref="InvalidCastException">Thrown when <paramref name="obj"/> is not
        /// of type <see cref="Tuple"/> of <see cref="double"/>.</exception>
        protected static DataPoint TupleToDataPoint(object obj)
        {
            var point = (Tuple<double, double>) obj;
            return new DataPoint(point.Item1, point.Item2);
        }

        /// <summary>
        /// Creates one or more <see cref="Series"/> based on the <paramref name="data"/> that was given.
        /// </summary>
        /// <param name="data">The data to transform into a <see cref="Series"/>.</param>
        /// <returns>A new <see cref="IList{T}"/> of <see cref="Series"/>.</returns>
        protected abstract IList<Series> Convert(T data);
    }
}