package snapcast

import (
	"context"
	"io"
	"log"
	"os"
	"os/exec"
	"strconv"
	"sync"

	"github.com/gopxl/beep"
)

type Stream struct {
	sync.Mutex

	Out    io.ReadCloser
	Cancel context.CancelFunc
	Cmd    *exec.Cmd

	f   beep.Format
	buf []byte
}

func New(host string, port int) (ff beep.Streamer, err error) {
	st := new(Stream)
	ctx, cancel := context.WithCancel(context.Background())
	st.Cancel = cancel

	st.Cmd = exec.CommandContext(
		ctx,
		"/usr/bin/snapclient",
		"-h", host,
		"-p", strconv.Itoa(port),
		"--player", "file:filename=stderr",
		"--logfilter", "*:error",
	)

	st.Cmd.Stdout = os.Stdin

	st.Out, err = st.Cmd.StderrPipe()
	if err != nil {
		return nil, err
	}

	err = st.Cmd.Start()
	if err != nil {
		return nil, err
	}

	st.buf = make([]byte, 4)
	st.f = beep.Format{
		SampleRate:  beep.SampleRate(48000),
		NumChannels: 2,
		Precision:   2,
	}

	return st, nil
}

func (d *Stream) Stream(samples [][2]float64) (n int, ok bool) {
	for i := range samples {
		_, err := d.Out.Read(d.buf)
		if err != nil {
			log.Println(err)
			ok = false
			break
		}
		samples[i], _ = d.f.DecodeSigned(d.buf)
		ok = true
	}

	return len(samples), ok
}

func (d *Stream) Err() error {
	return nil
}