package audio

import (
	"os/exec"
	"fmt"
	"regexp"
)


type MicStreamConfig struct {
	Format string
	Device string
	Encoding string
	Bitrate int
	Channels int
}

func StreamMic(config MicStreamConfig) *exec.Cmd {
	cmd := exec.Command("ffmpeg", "-re",
		"-f", config.Format,
		"-i", config.Device,
		"-f", config.Encoding,
		"-ar", fmt.Sprintf("%d", config.Bitrate),
		"-ac", fmt.Sprintf("%d", config.Channels),
		"-",
	)
	return cmd
}

func GetMicDevice() (string, error) {
	cmd := exec.Command("ffmpeg",
		"-f", "avfoundation",
		"-list_devices", "true",
		"-i", "\"\"",
	)
	// ignore error, this ffmpeg command returns exit status 1
	outputBytes, _ := cmd.CombinedOutput()
	output := string(outputBytes)
	parsedOutput := parseDeviceNumber(output)
	if parsedOutput == "" {
		return "", fmt.Errorf("Command: %s\nFailed to parse FFmpeg output:\n%s", cmd, output)
	}
	return parsedOutput, nil
}

func parseDeviceNumber(ffmpegOutput string) string {
	re := regexp.MustCompile(`\[(\d)\].*?[Mm]icrophone`)
	matches := re.FindStringSubmatch(ffmpegOutput)	
	if (len(matches) == 2) {
		return matches[1]
	}
	return ""
}