FFMpegCore/FFMpegCore/FFMpeg/Arguments/AudioGateArgument.cs

using System.Globalization;

namespace FFMpegCore.Arguments;

public class AudioGateArgument : IAudioFilterArgument
{
    private readonly Dictionary<string, string> _arguments = new();

    /// <summary>
    ///     Audio Gate. <see href="https://ffmpeg.org/ffmpeg-filters.html#agate" />
    /// </summary>
    /// <param name="levelIn">Set input level before filtering. Default is 1. Allowed range is from 0.015625 to 64.</param>
    /// <param name="mode">
    ///     Set the mode of operation. Can be upward or downward. Default is downward. If set to upward mode, higher parts of signal
    ///     will be amplified, expanding dynamic range in upward direction. Otherwise, in case of downward lower parts of signal will be reduced.
    /// </param>
    /// <param name="range">
    ///     Set the level of gain reduction when the signal is below the threshold. Default is 0.06125. Allowed range is from 0 to
    ///     1. Setting this to 0 disables reduction and then filter behaves like expander.
    /// </param>
    /// <param name="threshold">If a signal rises above this level the gain reduction is released. Default is 0.125. Allowed range is from 0 to 1.</param>
    /// <param name="ratio">Set a ratio by which the signal is reduced. Default is 2. Allowed range is from 1 to 9000.</param>
    /// <param name="attack">
    ///     Amount of milliseconds the signal has to rise above the threshold before gain reduction stops. Default is 20
    ///     milliseconds. Allowed range is from 0.01 to 9000.
    /// </param>
    /// <param name="release">
    ///     Amount of milliseconds the signal has to fall below the threshold before the reduction is increased again. Default is
    ///     250 milliseconds. Allowed range is from 0.01 to 9000.
    /// </param>
    /// <param name="makeup">Set amount of amplification of signal after processing. Default is 1. Allowed range is from 1 to 64.</param>
    /// <param name="knee">
    ///     Curve the sharp knee around the threshold to enter gain reduction more softly. Default is 2.828427125. Allowed range is
    ///     from 1 to 8.
    /// </param>
    /// <param name="detection">Choose if exact signal should be taken for detection or an RMS like one. Default is rms. Can be peak or rms.</param>
    /// <param name="link">
    ///     Choose if the average level between all channels or the louder channel affects the reduction. Default is average. Can be
    ///     average or maximum.
    /// </param>
    public AudioGateArgument(double levelIn = 1, string mode = "downward", double range = 0.06125, double threshold = 0.125, int ratio = 2,
        double attack = 20, double release = 250, int makeup = 1, double knee = 2.828427125, string detection = "rms", string link = "average")
    {
        if (levelIn is < 0.015625 or > 64)
        {
            throw new ArgumentOutOfRangeException(nameof(levelIn), "Level in must be between 0.015625 to 64");
        }

        if (mode != "upward" && mode != "downward")
        {
            throw new ArgumentOutOfRangeException(nameof(mode), "Mode must be either upward or downward");
        }

        if (range is <= 0 or > 1)
        {
            throw new ArgumentOutOfRangeException(nameof(range));
        }

        if (threshold is < 0 or > 1)
        {
            throw new ArgumentOutOfRangeException(nameof(threshold), "Threshold must be between 0 and 1");
        }

        if (ratio is < 1 or > 9000)
        {
            throw new ArgumentOutOfRangeException(nameof(ratio), "Ratio must be between 1 and 9000");
        }

        if (attack is < 0.01 or > 9000)
        {
            throw new ArgumentOutOfRangeException(nameof(attack), "Attack must be between 0.01 and 9000");
        }

        if (release is < 0.01 or > 9000)
        {
            throw new ArgumentOutOfRangeException(nameof(release), "Release must be between 0.01 and 9000");
        }

        if (makeup is < 1 or > 64)
        {
            throw new ArgumentOutOfRangeException(nameof(makeup), "Makeup Gain must be between 1 and 64");
        }

        if (knee is < 1 or > 64)
        {
            throw new ArgumentOutOfRangeException(nameof(makeup), "Knee must be between 1 and 8");
        }

        if (detection != "peak" && detection != "rms")
        {
            throw new ArgumentOutOfRangeException(nameof(detection), "Detection must be either peak or rms");
        }

        if (link != "average" && link != "maximum")
        {
            throw new ArgumentOutOfRangeException(nameof(link), "Link must be either average or maximum");
        }

        _arguments.Add("level_in", levelIn.ToString("0.00", CultureInfo.InvariantCulture));
        _arguments.Add("mode", mode);
        _arguments.Add("range", range.ToString("0.00", CultureInfo.InvariantCulture));
        _arguments.Add("threshold", threshold.ToString("0.00", CultureInfo.InvariantCulture));
        _arguments.Add("ratio", ratio.ToString());
        _arguments.Add("attack", attack.ToString("0.00", CultureInfo.InvariantCulture));
        _arguments.Add("release", release.ToString("0.00", CultureInfo.InvariantCulture));
        _arguments.Add("makeup", makeup.ToString());
        _arguments.Add("knee", knee.ToString("0.00", CultureInfo.InvariantCulture));
        _arguments.Add("detection", detection);
        _arguments.Add("link", link);
    }

    public string Key { get; } = "agate";

    public string Value => string.Join(":", _arguments.Select(pair => $"{pair.Key}={pair.Value}"));
}