package synth

import "github.com/netsynth/netsynth/classify"

const (
	SampleRate       = 44100                              // D-13: CD quality
	WindowMs         = 500                                // matches aggregate.DefaultWindowMs
	SamplesPerWindow = SampleRate * WindowMs / 1000       // 22050
	WhisperFloor     = 0.03                               // D-08/D-09: 3% of max amplitude
)

// WaveformType selects the harmonic preset for a synthesis layer.
// The zero value WaveformCustom preserves existing hand-tuned harmonics in FreqConfig.Harmonics.
type WaveformType int

const (
	WaveformCustom   WaveformType = iota // zero value: use FreqConfig.Harmonics as-is
	WaveformSine                         // pure fundamental, single harmonic
	WaveformSquare                       // odd harmonics with 1/k amplitude (bandlimited)
	WaveformSawtooth                     // all harmonics with 1/k amplitude (bandlimited)
	WaveformTriangle                     // odd harmonics with alternating 1/k^2 amplitude (bandlimited)
)

// WaveformPresetHarmonics returns the bandlimited harmonic series for the given waveform type
// at the given base frequency and sample rate. Returns nil for WaveformCustom.
// All returned harmonics are below Nyquist (sampleRate/2).
func WaveformPresetHarmonics(wt WaveformType, baseHz float64, sampleRate int) []HarmonicDef {
	nyquist := float64(sampleRate) / 2.0
	switch wt {
	case WaveformCustom:
		return nil
	case WaveformSine:
		return []HarmonicDef{{Ratio: 1, Amplitude: 1.0}}
	case WaveformSquare:
		var harmonics []HarmonicDef
		for k := 1; float64(k)*baseHz < nyquist; k += 2 {
			harmonics = append(harmonics, HarmonicDef{Ratio: k, Amplitude: 1.0 / float64(k)})
		}
		return harmonics
	case WaveformSawtooth:
		var harmonics []HarmonicDef
		for k := 1; float64(k)*baseHz < nyquist; k++ {
			harmonics = append(harmonics, HarmonicDef{Ratio: k, Amplitude: 1.0 / float64(k)})
		}
		return harmonics
	case WaveformTriangle:
		var harmonics []HarmonicDef
		sign := 1.0
		for k := 1; float64(k)*baseHz < nyquist; k += 2 {
			harmonics = append(harmonics, HarmonicDef{Ratio: k, Amplitude: sign / float64(k*k)})
			sign = -sign
		}
		return harmonics
	default:
		return nil
	}
}

// HarmonicDef defines one partial in an additive synthesizer.
type HarmonicDef struct {
	Ratio     int     // harmonic number: 1=fundamental, 2=octave, 3=fifth+octave, etc.
	Amplitude float64 // relative weight
}

// FreqConfig holds synthesis parameters for one traffic class.
type FreqConfig struct {
	BaseHz       float64
	Harmonics    []HarmonicDef
	Pan          float64      // [-1, 1]: -1=full left, 0=center, +1=full right
	WaveformType WaveformType // zero value WaveformCustom uses Harmonics as-is
}

// ClassFreqConfigs maps each traffic class to its synthesis parameters.
// Frequencies use musical intervals per D-02/D-03. Harmonics per D-05/D-06.
// Pan positions per D-12.
var ClassFreqConfigs = map[classify.TrafficClass]FreqConfig{
	classify.ClassICMP:     {BaseHz: 65.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.4}, {3, 0.15}}, Pan: 0.0},
	classify.ClassDNS:      {BaseHz: 110.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.5}, {3, 0.25}}, Pan: -0.2},
	classify.ClassHTTPS:    {BaseHz: 175.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.6}, {3, 0.3}}, Pan: 0.2},
	classify.ClassHTTP:     {BaseHz: 220.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.5}, {4, 0.2}}, Pan: -0.35},
	classify.ClassSSH:      {BaseHz: 330.0, Harmonics: []HarmonicDef{{1, 1.0}, {3, 0.6}, {5, 0.3}}, Pan: 0.35},
	classify.ClassSMTP:     {BaseHz: 440.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.3}, {3, 0.1}}, Pan: -0.55},
	classify.ClassNTP:      {BaseHz: 520.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.25}}, Pan: 0.55},
	classify.ClassDHCP:     {BaseHz: 600.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.35}, {3, 0.15}}, Pan: -0.75},
	classify.ClassOtherTCP: {BaseHz: 700.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.2}}, Pan: 0.75},
	classify.ClassOtherUDP: {BaseHz: 780.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.2}}, Pan: -0.75},
	// D-05: Unknown buckets in 850-1100 Hz dissonant range, detuned intervals
	// D-06: Same dissonant harmonic character {1,1.0},{2,0.8},{3,0.4} for all 4
	classify.ClassUnknown1: {BaseHz: 862.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: 0.6},
	classify.ClassUnknown2: {BaseHz: 920.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: -0.6},
	classify.ClassUnknown3: {BaseHz: 981.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: 0.9},
	classify.ClassUnknown4: {BaseHz: 1047.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: -0.9},
}