package transcode

import (
    "os"

    "github.com/go-audio/audio"
    "github.com/go-audio/wav"
)

func writePCM16WAV(path string, sampleRate int, channels int, samples []float64) error {
    if channels <= 0 {
        channels = 1
    }
    if err := os.MkdirAll(dirOf(path), 0o755); err != nil && dirOf(path) != "." {
        return err
    }
    f, err := os.Create(path)
    if err != nil {
        return err
    }
    defer f.Close()
    enc := wav.NewEncoder(f, sampleRate, 16, channels, 1)
    data := make([]int, len(samples))
    for i, s := range samples {
        data[i] = floatToInt16(s)
    }
    if err := enc.Write(&audio.IntBuffer{
        Format: &audio.Format{SampleRate: sampleRate, NumChannels: channels},
        Data:   data,
    }); err != nil {
        return err
    }
    return enc.Close()
}

func floatToInt16(f float64) int {
    if f > 1 {
        f = 1
    }
    if f < -1 {
        f = -1
    }
    return int(f * 32767)
}

func dirOf(path string) string {
    for i := len(path) - 1; i >= 0; i-- {
        if path[i] == '/' || path[i] == '\\' {
            return path[:i]
        }
    }
    return "."
}