using DTS.Common.Enums.Hardware;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel.DataAnnotations;
using System.IO;
using System.Linq;
using System.Xml;
using System.Xml.Serialization;

namespace DTS.Common.Classes.DSP
{
    /// <summary>
    /// collection for all dsp filters
    /// </summary>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Minor Code Smell", "S101:Types should be named in PascalCase", Justification = "Acronym")]
    public class DSPFilterCollection : Collection<DSPFilterType>
    {
        private static readonly object MyLock = new object();
        private static DSPFilterCollection _instance = null;
        public static DSPFilterCollection GetDSPFilterCollection()
        {
            lock (MyLock)
            {
                if (null != _instance) { return _instance; }
                WriteDefaultFileIfMissing(DSP_FILTER_XML_FILE);
                _instance =  ReadFile(DSP_FILTER_XML_FILE);
            }
            return _instance;
        }
        private const string DSP_FILTER_XML_FILE = "DSPFilters.xml";
        
        private DSPFilterCollection(DSPFilterType[] filters)
        {
            foreach (var filter in filters) { Add(filter); }
        }
        public DSPFilterCollection() { }

        public const int BUTTERWORTH = 13;
        public const int FIR45TAP = 14;
        public const int NONE = 0;

        public enum DSPFilterDefaults
        {
            [Display(Name ="None", Description = "Default and legacy setting for streaming")]
            [Scaler(double.NaN)]
            None = NONE,
            [Display(Name = "6th IIR Butterworth", Description = "6 - pole IIR Butterworth Low Pass")]
            [Scaler(double.NaN)]
            Butterworth = BUTTERWORTH,
            [Display(Name = "45-Tap FIR", Description = "finite impulse response filter with 45 taps")]
            [Scaler(double.NaN)]
            FIR = FIR45TAP
        }
        
        private static DSPFilterCollection CreateDefaultCollection()
        {
            var list = new List<DSPFilterType>
            {
                new DSPFilterType(DSPFilterDefaults.None, new DASRestriction[] { new DASRestriction() }),
                new DSPFilterType(DSPFilterDefaults.Butterworth, new DASRestriction[] { new DASRestriction(HardwareTypes.SLICE6_AIR.ToString(), 28), new DASRestriction(HardwareTypes.SLICE6_AIR_BR.ToString(), -1) }),
                new DSPFilterType(DSPFilterDefaults.FIR, new DASRestriction[] { new DASRestriction(HardwareTypes.SLICE6_AIR.ToString(), 28), new DASRestriction(HardwareTypes.SLICE6_AIR_BR.ToString(), -1) })
            };

            var collection = new DSPFilterCollection(list.ToArray());
            return collection;
        }

        private static void WriteDefaultFileIfMissing(string filePath)
        {
            if (File.Exists(filePath)) { return; }
            var collection = CreateDefaultCollection();

            var serializer = new XmlSerializer(typeof(DSPFilterCollection));
            var settings = new XmlWriterSettings() { Indent = true };

            using (var writer = XmlWriter.Create(filePath, settings))
            {
                serializer.Serialize(writer, collection);
            }
        }

        private static DSPFilterCollection ReadFile(string filePath)
        {
            var deserializer = new XmlSerializer(typeof(DSPFilterCollection));
            using (var fs = new FileStream(filePath, FileMode.Open))
            {
                var cs = (DSPFilterCollection)deserializer.Deserialize(fs);
                return cs;
            }
        }
        /// <summary>
        /// returns the matching filter, or None if not found, or if none isn't found then the first entry
        /// </summary>
        /// <param name="s"></param>
        /// <returns></returns>
        public DSPFilterType GetFilter(string s)
        {
            var match = Items.FirstOrDefault(x => x.DisplayString == s);
            if (null != match) { return match; }
            match = Items.FirstOrDefault(x => x.EnumValue == 0);
            if (null != match) { return match; }
            return Items[0];
        }
    }
}