using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;

namespace AsbCloudInfrastructure.Services.DetectOperations.Detectors
{
#nullable enable
    internal class FragmentDetector : IFragmentDetector
    {
        private int fragmentLength = 12;
        private int stepLength = 3;
        protected IEnumerable<IDetector> detectors = Enumerable.Empty<IDetector>();

        protected Func<DetectableTelemetry[], int, bool> detectStart;
        protected Func<DetectableTelemetry[], int, bool> detectEnd;

        public string Name { get; set; }

        public int FragmentLength { get => fragmentLength; set => fragmentLength = value; }
        public int StepLength { get => stepLength; set => stepLength = value; }

        public FragmentDetector(
            string name,
            Func<DetectableTelemetry[], int, bool> detectStart,
            IFragmentDetector detector,
            params IFragmentDetector[] detectors)
        {
            this.detectStart = detectStart;
            this.detectors = JoinDetectors(detector, detectors);
            detectEnd = (f, i) => !detectStart(f, i);
            Name = name;
        }
        public FragmentDetector(
            string name,
            Func<DetectableTelemetry[], int, bool> detectStart,
            Func<DetectableTelemetry[], int, bool> detectEnd,
            IFragmentDetector detector,
            params IFragmentDetector[] detectors)
        {
            this.detectStart = detectStart;
            this.detectEnd = detectEnd;
            this.detectors = JoinDetectors(detector, detectors);
            Name = name;
        }

        public FragmentDetector(
            string name,
            Func<DetectableTelemetry[], int, bool> detectStart,
            IOperationDetector operation)
        {
            this.detectStart = detectStart;
            detectors = new IOperationDetector[] { operation };
            detectEnd = (f, i) => !detectStart(f, i);
            Name = name;
        }

        public FragmentDetector(
            string name,
            Func<DetectableTelemetry[], int, bool> detectStart,
            Func<DetectableTelemetry[], int, bool> detectEnd,
            IOperationDetector operation)
        {
            this.detectStart = detectStart;
            this.detectEnd = detectEnd;
            detectors = new IOperationDetector[] { operation };
            Name = name;
        }

        private static IEnumerable<IFragmentDetector> JoinDetectors(IFragmentDetector detector, params IFragmentDetector[] detectors)
        {
            var joined = new IFragmentDetector[1 + detectors.Length];
            joined[0] = detector;
            if (detectors.Length > 0)
                detectors.CopyTo(joined, 1);
            return joined;
        }

        public static Func<DetectableTelemetry[], int, bool> MakeInstantDelegate(
            Func<DetectableTelemetry, bool> instantValueCondition
            )
        {
            var detect = (DetectableTelemetry[] telemetry, int position) =>
            {
                var firstItem = telemetry[position];
                var result = instantValueCondition(firstItem);
                return result;
            };
            return detect;
        }

        public static Func<DetectableTelemetry[], int, bool> MakeInterpolationDelegate(
            Func<DetectableTelemetry, double> yGetter,
            Func<InterpolationLine, bool> interpolationValueCondition,
            int fragmentLength)
        {
            var detect = (DetectableTelemetry[] telemetry, int position) =>
            {
                DetectableTelemetry[] data;
                if (fragmentLength > 0 && (position + fragmentLength) < telemetry.Length)
                    data = telemetry[position..(position + fragmentLength)];
                else
                    data = telemetry[position..];
                var line = new InterpolationLine(data.Select(d => (yGetter(d), (d.DateTime - telemetry[0].DateTime).TotalHours)));
                var result = interpolationValueCondition(line);
                return result;
            };
            return detect;
        }

        public bool TryDetect(int idTelemetry, DetectableTelemetry[] telemetry, int begin, int end, out IEnumerable<OperationDetectorResult> results)
        {
            List<OperationDetectorResult>? totaltResultList = null;
            var positionBegin = begin;
            // Поиск начала соответствия критерию начала операции
            while (end > positionBegin + fragmentLength + stepLength)
            {
                if (detectStart(telemetry, positionBegin))
                {
                    // Поиск окончания соответствия критерию
                    var positionEnd = positionBegin;
                    while (positionEnd < end)
                    {
                        positionEnd += stepLength;
                        if ((positionEnd > end))
                            positionEnd = end;

                        if ((positionEnd == end) || detectEnd(telemetry, positionEnd))
                        {
                            totaltResultList = totaltResultList ?? new List<OperationDetectorResult>();
                            var detectorsEnumerator = detectors.GetEnumerator();
                            while (detectorsEnumerator.MoveNext())
                                if (detectorsEnumerator.Current.TryDetect(idTelemetry, telemetry, positionBegin, positionEnd, out IEnumerable<OperationDetectorResult> innerResult))
                                    totaltResultList.AddRange(innerResult);

                            break;
                        }
                    }
                    positionBegin = positionEnd;
                }
                else
                {
                    positionBegin += stepLength;
                }
            }

            if(totaltResultList?.Any() == true)
            {
                results = totaltResultList!;
                return true;
            }
            else
            {
                results = Enumerable.Empty<OperationDetectorResult>();
                return false;
            }            
        }
        public override string ToString()
        => $"frame detector {Name}";
    }
#nullable disable
}