using System;
using System.Collections.Generic;
using Sandbox;

namespace SFXR;

[Title( "ADSR Envelope" )]
[Category( "SFXR Effects" )]
[Icon( "mail_outline" )]
public class SFXREnvelope : SFXREffect
{
    /// <summary>
    /// Time the sound takes to reach its peak amplitude
    /// (Default: 0)
    /// </summary>
    [Property, Range( 0, 10 )]
    public float Attack { get; set; } = 0;

    /// <summary>
    /// The time taken for the sound to fade to the sustain level
    /// </summary>
    [Property, Range( 0, 10 )]
    public float Decay { get; set; } = 0;

    /// <summary>
    /// The level maintained until release is triggered
    /// (Default: 1)
    /// </summary>
    [Property, Range( 0, 1 )]
    public float Sustain { get; set; } = 1f;

    /// <summary>
    /// The time taken for the sound to fade to zero after the sustain
    /// (Default: 0.3)
    /// </summary>
    [Property, Range( 0, 10 )]
    public float SustainTime { get; set; } = 0.3f;

    /// <summary>
    /// The time taken for the sound to fade to zero after the release
    /// (Default: 0.4)
    /// </summary>
    [Property, Range( 0, 10 )]
    public float Release { get; set; } = 0.4f;

    /// <summary>
    /// Returns the amplitude of the envelope at a given time
    /// </summary>
    /// <param name="time">Time in seconds</param>
    /// <returns>Amplitude of the envelope at the given time</returns>
    public float GetAmplitude( float time )
    {
        return GetCurve().Evaluate( time / GetLength() );
    }

    public override short[] Apply( short[] samples, SFXRComponent sound )
    {
        // Calculate the envelope amplitude for each sample
        for ( int i = 0; i < samples.Length; i++ )
        {
            float t = i / (float)sound.SampleRate;
            float amplitude = GetAmplitude( t );
            samples[i] = (short)(samples[i] * amplitude);
        }

        return samples;
    }

    public float GetLength()
    {
        return Attack + Decay + SustainTime + Release;
    }

    public Curve GetCurve()
    {
        Curve curve = new();

        List<Vector2> points = new();

        // Add the attack curve
        points.Add( new Vector2( 0, 0 ) );
        points.Add( new Vector2( Attack, 1 ) );

        // Add the decay curve
        points.Add( new Vector2( Attack + Decay, Sustain ) );

        // Add the sustain curve
        points.Add( new Vector2( Attack + Decay + SustainTime, Sustain ) );

        // Add the release curve
        points.Add( new Vector2( Attack + Decay + SustainTime + Release, 0 ) );

        // Normalize the curve to 0-1 in the x
        for ( int i = 0; i < points.Count; i++ )
        {
            points[i] = new Vector2( points[i].x / (Attack + Decay + SustainTime + Release), points[i].y );
        }

        // Add the points to the curve
        foreach ( var point in points )
        {
            curve.AddPoint( point.x, point.y );
        }

        return curve;
    }
}