using System;

namespace Barotrauma.Sounds
{
    /* This code is adapted from CSCore (.NET Audio Library) which is under a Microsoft Public License (Ms-PL) license.*/

    /*
    Microsoft Public License (Ms-PL)

    This license governs use of the accompanying software. If you use the software, you accept this license. If you do not accept the license, do not use the software.

    1. Definitions
    The terms "reproduce," "reproduction," "derivative works," and "distribution" have the same meaning here as under U.S. copyright law.

    A "contribution" is the original software, or any additions or changes to the software.

    A "contributor" is any person that distributes its contribution under this license.

    "Licensed patents" are a contributor's patent claims that read directly on its contribution.

    2. Grant of Rights
    (A) Copyright Grant- Subject to the terms of this license, including the license conditions and limitations in section 3, each contributor grants you a non-exclusive, worldwide, royalty-free copyright license to reproduce its contribution, prepare derivative works of its contribution, and distribute its contribution or any derivative works that you create.

    (B) Patent Grant- Subject to the terms of this license, including the license conditions and limitations in section 3, each contributor grants you a non-exclusive, worldwide, royalty-free license under its licensed patents to make, have made, use, sell, offer for sale, import, and/or otherwise dispose of its contribution in the software or derivative works of the contribution in the software.

    3. Conditions and Limitations
    (A) No Trademark License- This license does not grant you rights to use any contributors' name, logo, or trademarks.

    (B) If you bring a patent claim against any contributor over patents that you claim are infringed by the software, your patent license from such contributor to the software ends automatically.

    (C) If you distribute any portion of the software, you must retain all copyright, patent, trademark, and attribution notices that are present in the software.

    (D) If you distribute any portion of the software in source code form, you may do so only under this license by including a complete copy of this license with your distribution. If you distribute any portion of the software in compiled or object code form, you may only do so under a license that complies with this license.

    (E) The software is licensed "as-is." You bear the risk of using it. The contributors give no express warranties, guarantees or conditions. You may have additional consumer rights under your local laws which this license cannot change. To the extent permitted under your local laws, the contributors exclude the implied warranties of merchantability, fitness for a particular purpose and non-infringement. 
    */

    /*
    * These implementations are based on http://www.earlevel.com/main/2011/01/02/biquad-formulas/
    */

    /// <summary>
    /// Represents a biquad-filter.
    /// </summary>
    public abstract class BiQuad
    {
        /// <summary>
        /// The a0 value.
        /// </summary>
        protected double A0;
        /// <summary>
        /// The a1 value.
        /// </summary>
        protected double A1;
        /// <summary>
        /// The a2 value.
        /// </summary>
        protected double A2;
        /// <summary>
        /// The b1 value.
        /// </summary>
        protected double B1;
        /// <summary>
        /// The b2 value.
        /// </summary>
        protected double B2;
        /// <summary>
        /// The q value.
        /// </summary>
        private double _q;
        /// <summary>
        /// The gain value in dB.
        /// </summary>
        private double _gainDB;
        /// <summary>
        /// The z1 value.
        /// </summary>
        protected double Z1;
        /// <summary>
        /// The z2 value.
        /// </summary>
        protected double Z2;

        private double _frequency;

        /// <summary>
        /// Gets or sets the frequency.
        /// </summary>
        /// <exception cref="System.ArgumentOutOfRangeException">value;The samplerate has to be bigger than 2 * frequency.</exception>
        public double Frequency
        {
            get { return _frequency; }
            set
            {
                if (SampleRate < value * 2)
                {
                    throw new ArgumentOutOfRangeException("value", "The samplerate has to be bigger than 2 * frequency.");
                }
                _frequency = value;
                CalculateBiQuadCoefficients();
            }
        }

        /// <summary>
        /// Gets the sample rate.
        /// </summary>
        public int SampleRate { get; private set; }

        /// <summary>
        /// The q value.
        /// </summary>
        public double Q
        {
            get { return _q; }
            set
            {
                if (value <= 0)
                {
                    throw new ArgumentOutOfRangeException("value");
                }
                _q = value;
                CalculateBiQuadCoefficients();
            }
        }

        /// <summary>
        /// Gets or sets the gain value in dB.
        /// </summary>
        public double GainDB
        {
            get { return _gainDB; }
            set
            {
                _gainDB = value;
                CalculateBiQuadCoefficients();
            }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="BiQuad"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The frequency.</param>
        /// <exception cref="System.ArgumentOutOfRangeException">
        /// sampleRate
        /// or
        /// frequency
        /// or
        /// q
        /// </exception>
        protected BiQuad(int sampleRate, double frequency)
            : this(sampleRate, frequency, 1.0 / Math.Sqrt(2))
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="BiQuad"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The frequency.</param>
        /// <param name="q">The q.</param>
        /// <exception cref="System.ArgumentOutOfRangeException">
        /// sampleRate
        /// or
        /// frequency
        /// or
        /// q
        /// </exception>
        protected BiQuad(int sampleRate, double frequency, double q)
        {
            if (sampleRate <= 0)
                throw new ArgumentOutOfRangeException("sampleRate");
            if (frequency <= 0)
                throw new ArgumentOutOfRangeException("frequency");
            if (q <= 0)
                throw new ArgumentOutOfRangeException("q");
            SampleRate = sampleRate;
            Frequency = frequency;
            Q = q;
            GainDB = 6;
        }

        /// <summary>
        /// Processes a single <paramref name="input"/> sample and returns the result.
        /// </summary>
        /// <param name="input">The input sample to process.</param>
        /// <returns>The result of the processed <paramref name="input"/> sample.</returns>
        public float Process(float input)
        {
            double o = input * A0 + Z1;
            Z1 = input * A1 + Z2 - B1 * o;
            Z2 = input * A2 - B2 * o;
            return (float)o;
        }

        /// <summary>
        /// Processes multiple <paramref name="input"/> samples.
        /// </summary>
        /// <param name="input">The input samples to process.</param>
        /// <remarks>The result of the calculation gets stored within the <paramref name="input"/> array.</remarks>
        public void Process(float[] input)
        {
            for (int i = 0; i < input.Length; i++)
            {
                input[i] = Process(input[i]);
            }
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected abstract void CalculateBiQuadCoefficients();
    }

    /// <summary>
    /// Used to apply a lowpass-filter to a signal.
    /// </summary>
    public class LowpassFilter : BiQuad
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="LowpassFilter"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The filter's corner frequency.</param>
        public LowpassFilter(int sampleRate, double frequency)
            : base(sampleRate, frequency)
        {
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected override void CalculateBiQuadCoefficients()
        {
            double k = Math.Tan(Math.PI * Frequency / SampleRate);
            var norm = 1 / (1 + k / Q + k * k);
            A0 = k * k * norm;
            A1 = 2 * A0;
            A2 = A0;
            B1 = 2 * (k * k - 1) * norm;
            B2 = (1 - k / Q + k * k) * norm;
        }
    }

    /// <summary>
    /// Used to apply a highpass-filter to a signal.
    /// </summary>
    public class HighpassFilter : BiQuad
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="HighpassFilter"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The filter's corner frequency.</param>
        public HighpassFilter(int sampleRate, double frequency)
            : base(sampleRate, frequency)
        {
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected override void CalculateBiQuadCoefficients()
        {
            double k = Math.Tan(Math.PI * Frequency / SampleRate);
            var norm = 1 / (1 + k / Q + k * k);
            A0 = 1 * norm;
            A1 = -2 * A0;
            A2 = A0;
            B1 = 2 * (k * k - 1) * norm;
            B2 = (1 - k / Q + k * k) * norm;
        }
    }

    /// <summary>
    /// Used to apply a bandpass-filter to a signal.
    /// </summary>
    public class BandpassFilter : BiQuad
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="BandpassFilter"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The filter's corner frequency.</param>
        public BandpassFilter(int sampleRate, double frequency)
            : base(sampleRate, frequency)
        {
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected override void CalculateBiQuadCoefficients()
        {
            double k = Math.Tan(Math.PI * Frequency / SampleRate);
            double norm = 1 / (1 + k / Q + k * k);
            A0 = k / Q * norm;
            A1 = 0;
            A2 = -A0;
            B1 = 2 * (k * k - 1) * norm;
            B2 = (1 - k / Q + k * k) * norm;
        }
    }

    /// <summary>
    /// Used to apply a notch-filter to a signal.
    /// </summary>
    public class NotchFilter : BiQuad
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="NotchFilter"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The filter's corner frequency.</param>
        public NotchFilter(int sampleRate, double frequency)
            : base(sampleRate, frequency)
        {
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected override void CalculateBiQuadCoefficients()
        {
            double k = Math.Tan(Math.PI * Frequency / SampleRate);
            double norm = 1 / (1 + k / Q + k * k);
            A0 = (1 + k * k) * norm;
            A1 = 2 * (k * k - 1) * norm;
            A2 = A0;
            B1 = A1;
            B2 = (1 - k / Q + k * k) * norm;
        }
    }

    /// <summary>
    /// Used to apply a lowshelf-filter to a signal.
    /// </summary>
    public class LowShelfFilter : BiQuad
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="LowShelfFilter"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The filter's corner frequency.</param>
        /// <param name="gainDB">Gain value in dB.</param>
        public LowShelfFilter(int sampleRate, double frequency, double gainDB)
            : base(sampleRate, frequency)
        {
            GainDB = gainDB;
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected override void CalculateBiQuadCoefficients()
        {
            const double sqrt2 = 1.4142135623730951;
            double k = Math.Tan(Math.PI * Frequency / SampleRate);
            double v = Math.Pow(10, Math.Abs(GainDB) / 20.0);
            double norm;
            if (GainDB >= 0)
            {    // boost
                norm = 1 / (1 + sqrt2 * k + k * k);
                A0 = (1 + Math.Sqrt(2 * v) * k + v * k * k) * norm;
                A1 = 2 * (v * k * k - 1) * norm;
                A2 = (1 - Math.Sqrt(2 * v) * k + v * k * k) * norm;
                B1 = 2 * (k * k - 1) * norm;
                B2 = (1 - sqrt2 * k + k * k) * norm;
            }
            else
            {    // cut
                norm = 1 / (1 + Math.Sqrt(2 * v) * k + v * k * k);
                A0 = (1 + sqrt2 * k + k * k) * norm;
                A1 = 2 * (k * k - 1) * norm;
                A2 = (1 - sqrt2 * k + k * k) * norm;
                B1 = 2 * (v * k * k - 1) * norm;
                B2 = (1 - Math.Sqrt(2 * v) * k + v * k * k) * norm;
            }
        }
    }

    /// <summary>
    /// Used to apply a highshelf-filter to a signal.
    /// </summary>
    public class HighShelfFilter : BiQuad
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="HighShelfFilter"/> class.
        /// </summary>
        /// <param name="sampleRate">The sample rate.</param>
        /// <param name="frequency">The filter's corner frequency.</param>
        /// <param name="gainDB">Gain value in dB.</param>
        public HighShelfFilter(int sampleRate, double frequency, double gainDB)
            : base(sampleRate, frequency)
        {
            GainDB = gainDB;
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected override void CalculateBiQuadCoefficients()
        {
            const double sqrt2 = 1.4142135623730951;
            double k = Math.Tan(Math.PI * Frequency / SampleRate);
            double v = Math.Pow(10, Math.Abs(GainDB) / 20.0);
            double norm;
            if (GainDB >= 0)
            {    // boost
                norm = 1 / (1 + sqrt2 * k + k * k);
                A0 = (v + Math.Sqrt(2 * v) * k + k * k) * norm;
                A1 = 2 * (k * k - v) * norm;
                A2 = (v - Math.Sqrt(2 * v) * k + k * k) * norm;
                B1 = 2 * (k * k - 1) * norm;
                B2 = (1 - sqrt2 * k + k * k) * norm;
            }
            else
            {    // cut
                norm = 1 / (v + Math.Sqrt(2 * v) * k + k * k);
                A0 = (1 + sqrt2 * k + k * k) * norm;
                A1 = 2 * (k * k - 1) * norm;
                A2 = (1 - sqrt2 * k + k * k) * norm;
                B1 = 2 * (k * k - v) * norm;
                B2 = (v - Math.Sqrt(2 * v) * k + k * k) * norm;
            }
        }
    }

    /// <summary>
    /// Used to apply an peak-filter to a signal.
    /// </summary>
    public class PeakFilter : BiQuad
    {
        /// <summary>
        /// Gets or sets the bandwidth.
        /// </summary>
        public double BandWidth
        {
            get { return Q; }
            set
            {
                if (value <= 0)
                    throw new ArgumentOutOfRangeException("value");
                Q = value;
            }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="PeakFilter"/> class.
        /// </summary>
        /// <param name="sampleRate">The sampleRate of the audio data to process.</param>
        /// <param name="frequency">The center frequency to adjust.</param>
        /// <param name="bandWidth">The bandWidth.</param>
        /// <param name="peakGainDB">The gain value in dB.</param>
        public PeakFilter(int sampleRate, double frequency, double bandWidth, double peakGainDB)
            : base(sampleRate, frequency, bandWidth)
        {
            GainDB = peakGainDB;
        }

        /// <summary>
        /// Calculates all coefficients.
        /// </summary>
        protected override void CalculateBiQuadCoefficients()
        {
            double norm;
            double v = Math.Pow(10, Math.Abs(GainDB) / 20.0);
            double k = Math.Tan(Math.PI * Frequency / SampleRate);
            double q = Q;

            if (GainDB >= 0) //boost
            {
                norm = 1 / (1 + 1 / q * k + k * k);
                A0 = (1 + v / q * k + k * k) * norm;
                A1 = 2 * (k * k - 1) * norm;
                A2 = (1 - v / q * k + k * k) * norm;
                B1 = A1;
                B2 = (1 - 1 / q * k + k * k) * norm;
            }
            else //cut
            {
                norm = 1 / (1 + v / q * k + k * k);
                A0 = (1 + 1 / q * k + k * k) * norm;
                A1 = 2 * (k * k - 1) * norm;
                A2 = (1 - 1 / q * k + k * k) * norm;
                B1 = A1;
                B2 = (1 - v / q * k + k * k) * norm;
            }
        }
    }

}
