package asteriskws

import (
	"encoding/binary"
	"math"
	"time"

	"ai-operator/internal/audio"
	"ai-operator/internal/media"
)

func GenerateSilence(codec media.Codec, duration time.Duration, sampleRate int) []byte {
	if duration <= 0 || sampleRate <= 0 {
		return nil
	}
	switch codec {
	case media.CodecSLIN16:
	case media.CodecULaw:
		samples := int(duration.Seconds() * float64(sampleRate))
		out := make([]byte, samples)
		for i := range out {
			out[i] = 0xff
		}
		return out
	default:
		return nil
	}
	samples := int(duration.Seconds() * float64(sampleRate))
	return make([]byte, samples*2)
}

func GenerateSineToneSLIN16(frequencyHz float64, duration time.Duration, sampleRate int, amplitude float64) []byte {
	if frequencyHz <= 0 || duration <= 0 || sampleRate <= 0 {
		return nil
	}
	if amplitude < 0 {
		amplitude = 0
	}
	if amplitude > 1 {
		amplitude = 1
	}
	samples := int(duration.Seconds() * float64(sampleRate))
	out := make([]byte, samples*2)
	for i := 0; i < samples; i++ {
		v := int16(math.Sin(2*math.Pi*frequencyHz*float64(i)/float64(sampleRate)) * amplitude * math.MaxInt16)
		binary.LittleEndian.PutUint16(out[i*2:], uint16(v))
	}
	return out
}

func GenerateSineTone(codec media.Codec, frequencyHz float64, duration time.Duration, sampleRate int, amplitude float64) []byte {
	pcm := GenerateSineToneSLIN16(frequencyHz, duration, sampleRate, amplitude)
	if codec == media.CodecULaw {
		return audio.EncodeULaw(pcm)
	}
	if codec == media.CodecSLIN16 {
		return pcm
	}
	return nil
}