using System;
using System.Collections.Generic;
using System.Linq;
using DTS.Common.DAS.Concepts;

namespace DTS.Serialization
{
    /// <summary>
    /// A collection of a channel and associated metadata that will all be needed together when
    /// this file format starts laying down bytes.
    /// </summary>
    public class ChannelWithMeta
    {
        /// <summary>
        /// Get/set the <see cref="DTS.Serialization.Test.Module.Channel"/> to be serialized.
        /// </summary>
        public Test.Module.Channel Channel { get; }

        /// <summary>
        /// Get/set the <see cref="DataScaler"/> associated with the
        /// specified channel.
        /// </summary>
        public DataScaler Scaler { get; }

        /// <summary>
        /// Get/set the <see cref="double"/> sample rate associated with the specified channel.
        /// </summary>
        public double SampleRate { get; }

        /// <summary>
        /// Get/set the <see cref="double"/> start time associated with the specified channel.
        /// </summary>
        public double StartTime { get; }

        /// <summary>
        /// Initialize an instance of the ChannelWithMeta class.
        /// </summary>
        /// 
        /// <param name="channel">
        /// A <see cref="DTS.Serialization.Test.Module.Channel"/> to be serialized.
        /// </param>
        /// 
        /// <param name="scaler">
        /// The <see cref="DataScaler"/> containing scaling information for 
        /// the specified channel.
        /// </param>
        /// 
        /// <param name="samplerate">
        /// The <see cref="double"/> sample rate of the associated channel.
        /// </param>
        /// 
        /// <param name="starttime">
        /// The <see cref="double"/> start time of the associated channel.
        /// </param>
        /// 
        public ChannelWithMeta(DTS.Serialization.Test.Module.Channel channel, DataScaler scaler, double samplerate, double starttime)
        {
            Channel = channel;
            Scaler = scaler;
            SampleRate = samplerate;
            StartTime = starttime;
        }

        public static double GetMinStartTime(double start, IList<ChannelWithMeta> channelsWithMeta)
        {
            // Start is a generally a negative value, so to get the value for the start time of the minimum common data set, run Max()
            return Math.Max(start, channelsWithMeta.Min(cwm => cwm.StartTime));
        }

        public static double GetMinStopTime(double stop, IList<ChannelWithMeta> channelsWithMeta)
        {
            // To get the value for the stop time of the minimum common data set, run Min()
            // LINQ statement will sometimes hand back float-rounding error numbers (4.999999999999995 v 5.0), so cast to decimals.
            return (double)Math.Min((decimal)stop,
                                    channelsWithMeta.Min(cwm =>
                                        (decimal)cwm.StartTime + (cwm.Channel.PersistentChannelInfo.Length - 1) * 1m / (decimal)cwm.SampleRate));
        }
    }
}