//******************************************************************************************************
//  AngleDifferenceCalculator.cs - Gbtc
//
//  Copyright © 2016, Grid Protection Alliance.  All Rights Reserved.
//
//  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See
//  the NOTICE file distributed with this work for additional information regarding copyright ownership.
//  The GPA licenses this file to you under the MIT License (MIT), the "License"; you may
//  not use this file except in compliance with the License. You may obtain a copy of the License at:
//
//      http://opensource.org/licenses/MIT
//
//  Unless agreed to in writing, the subject software distributed under the License is distributed on an
//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the
//  License for the specific language governing permissions and limitations.
//
//  Code Modification History:
//  ----------------------------------------------------------------------------------------------------
//  10/26/2016 - J. Ritchie Carroll
//       Generated original version of source code.
//
//******************************************************************************************************

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using GSF;
using GSF.Collections;
using GSF.TimeSeries;
using GSF.TimeSeries.Adapters;
using GSF.Units.EE;
using PhasorProtocolAdapters;

namespace PowerCalculations
{
    /// <summary>
    /// Calculates a composed angle difference.
    /// </summary>
    [Description("Angle Difference Calculator: Safely calculates a difference between two angles, unwrapping source angles as needed")]
    public class AngleDifferenceCalculator : CalculatedMeasurementBase
    {
        #region [ Members ]

        // Constants
        private const int ValuesToShow = 4;
        private const double PhaseResetAngle = 720.0D;

        // Fields
        private double[] m_lastAngles;
        private double[] m_unwrapOffsets;
        private List<double> m_latestCalculatedAngles;
        private IMeasurement[] m_measurements;

        #endregion

        #region [ Properties ]

        /// <summary>
        /// Gets or sets flag indicating whether or not this adapter will produce a result for all calculations. If this value is true and a calculation fails,
        /// the adapter will produce NaN for that calculation. If this value is false and a calculation fails, the adapter will not produce any result.
        /// </summary>
        [ConnectionStringParameter]
        [Description("Defines flag that determines if adapter should always produce a result. When true, adapter will produce NaN for calculations that fail.")]
        [DefaultValue(false)]
        public bool AlwaysProduceResult { get; set; }
        
        /// <summary>
        /// Returns the detailed status of the <see cref="AngleDifferenceCalculator"/> calculator.
        /// </summary>
        public override string Status
        {
            get
            {
                StringBuilder status = new StringBuilder();

                status.AppendFormat("  Last " + ValuesToShow + " calculated angles:");

                lock (m_latestCalculatedAngles)
                {
                    if (m_latestCalculatedAngles.Count > ValuesToShow)
                        status.Append(m_latestCalculatedAngles.GetRange(m_latestCalculatedAngles.Count - ValuesToShow, ValuesToShow).Select(v => v.ToString("0.00°")).ToDelimitedString(", "));
                    else
                        status.Append("Not enough values calculated yet ...");
                }

                status.AppendLine();
                status.Append(base.Status);

                return status.ToString();
            }
        }

        #endregion

        #region [ Methods ]

        /// <summary>
        /// Initializes the <see cref="AngleDifferenceCalculator"/> calculator.
        /// </summary>
        public override void Initialize()
        {
            base.Initialize();

            // Validate input measurements
            List<MeasurementKey> validInputMeasurementKeys = new List<MeasurementKey>();
            SignalType keyType;

            for (int i = 0; i < InputMeasurementKeys.Length; i++)
            {
                keyType = InputMeasurementKeyTypes[i];

                // Make sure measurement key type is a phase angle
                if (keyType == SignalType.VPHA || keyType == SignalType.IPHA)
                    validInputMeasurementKeys.Add(InputMeasurementKeys[i]);
            }

            // Make sure only phase angles are used as input
            if (validInputMeasurementKeys.Count == 0)
                throw new InvalidOperationException("No valid phase angles were specified as inputs to the angle difference calculator.");

            if (InputMeasurementKeyTypes.Count(s => s == SignalType.VPHA) > 0 && InputMeasurementKeyTypes.Count(s => s == SignalType.IPHA) > 0)
                throw new InvalidOperationException("A mixture of voltage and current phase angles were specified as inputs to the angle difference calculator - you must specify one or the other: only voltage phase angles or only current phase angles.");

            if (validInputMeasurementKeys.Count != 2)
                throw new InvalidOperationException($"Expected exactly two phase angles as inputs to the angle difference calculator, got {validInputMeasurementKeys.Count}.");

            InputMeasurementKeys = validInputMeasurementKeys.ToArray();

            // Validate output measurements
            if (OutputMeasurements.Length < 1)
                throw new InvalidOperationException("An output measurement was not specified for the angle difference calculator - one measurement is expected to represent the \"Calculated Angle Difference\" value.");

            Dictionary<string, string> settings = Settings;
            string setting;

            if (settings.TryGetValue("AlwaysProduceResult", out setting))
                AlwaysProduceResult = setting.ParseBoolean();
            
            // Initialize member fields
            m_lastAngles = new double[2];
            m_unwrapOffsets = new double[2];
            m_latestCalculatedAngles = new List<double>();

            // Set last angles as uninitialized
            m_lastAngles[0] = double.NaN;
            m_lastAngles[1] = double.NaN;
        }

        /// <summary>
        /// Calculates an angle difference.
        /// </summary>
        /// <param name="frame">Single frame of measurement data within one second samples</param>
        /// <param name="index">Index of frame within the one second samples</param>
        protected override void PublishFrame(IFrame frame, int index)
        {
            Measurement calculatedMeasurement = Measurement.Clone(OutputMeasurements[0], frame.Timestamp);
            double angle, deltaAngle, angleDifference, lastAngle, unwrapOffset, angle1 = double.NaN, angle2 = double.NaN;

            // Attempt to get minimum needed reporting set of composite angles used to calculate angle difference
            if (TryGetMinimumNeededMeasurements(frame, ref m_measurements))
            {
                // Get both phase angles, unwrapping as necessary
                for (int i = 0; i < m_measurements.Length; i++)
                {
                    // Get current angle value
                    angle = m_measurements[i].AdjustedValue;

                    // Get the unwrap offset for this angle
                    unwrapOffset = m_unwrapOffsets[i];

                    // Get angle value from last run, if there was a last run
                    lastAngle = m_lastAngles[i];

                    if (!double.IsNaN(lastAngle))
                    {
                        // Calculate the angle difference from last run
                        deltaAngle = angle - lastAngle;

                        // Adjust angle unwrap offset if needed
                        if (deltaAngle > 300)
                            unwrapOffset -= 360;
                        else if (deltaAngle < -300)
                            unwrapOffset += 360;

                        // Reset angle unwrap offset if needed
                        if (unwrapOffset > PhaseResetAngle)
                            unwrapOffset -= PhaseResetAngle;
                        else if (unwrapOffset < -PhaseResetAngle)
                            unwrapOffset += PhaseResetAngle;

                        // Record last angle unwrap offset
                        m_unwrapOffsets[i] = unwrapOffset;
                    }

                    // Pick off unwrapped angles
                    if (i == 0)
                        angle1 = angle + unwrapOffset;
                    else
                        angle2 = angle + unwrapOffset;
                }

                // We use modulus function to make sure angle is in range of 0 to 360
                angleDifference = (angle1 - angle2) % 360.0D;

                // Record last angles for next run
                for (int i = 0; i < m_measurements.Length; i++)
                    m_lastAngles[i] = m_measurements[i].AdjustedValue;
            }
            else
            {
                angleDifference = double.NaN;
                calculatedMeasurement.StateFlags |= MeasurementStateFlags.BadData;
            }

            // Convert angle value to the range of -180 to 180
            if (angleDifference > 180)
                angleDifference -= 360;

            if (angleDifference <= -180)
                angleDifference += 360;

            if (double.IsNaN(angleDifference) && !AlwaysProduceResult)
                return;

            calculatedMeasurement.Value = angleDifference;

            // Expose calculated value
            OnNewMeasurements(new IMeasurement[] { calculatedMeasurement });

            // Track last few calculated reference angles
            lock (m_latestCalculatedAngles)
            {
                m_latestCalculatedAngles.Add(angleDifference);

                while (m_latestCalculatedAngles.Count > ValuesToShow)
                    m_latestCalculatedAngles.RemoveAt(0);
            }
        }

        #endregion
    }
}