package flac

import (
	"bytes"
	"fmt"
	"os/exec"
	"strconv"
)

type Metadata struct {
	SampleRate int64
	BPS        int64
	Channels   int64
	NumSamples int64 // Total length of file in samples (per channel).
}

func GetMetadata(path string) (md Metadata, err error) {
	cmd := exec.Command(
		"metaflac",
		"--show-sample-rate",
		"--show-bps",
		"--show-channels",
		"--show-total-samples",
		path)

	out, err := cmd.Output()
	if err != nil {
		return md, fmt.Errorf("Failed to open file: %w", err)
	}

	l := bytes.Split(out, []byte{'\n'})
	if len(l) != 5 {
		return md, fmt.Errorf("Output not understood:\n%s", out)
	}
	l = l[:4]

	md.SampleRate, err = strconv.ParseInt(string(l[0]), 10, 64)
	if err != nil {
		return md, fmt.Errorf("Invalid sample rate: %w", err)
	}

	md.BPS, err = strconv.ParseInt(string(l[1]), 10, 64)
	if err != nil {
		return md, fmt.Errorf("Invalid bps: %w", err)
	}

	md.Channels, err = strconv.ParseInt(string(l[2]), 10, 64)
	if err != nil {
		return md, fmt.Errorf("Invalid channels: %w", err)
	}

	md.NumSamples, err = strconv.ParseInt(string(l[3]), 10, 64)
	if err != nil {
		return md, fmt.Errorf("Invalid length: %w", err)
	}

	return md, nil
}

func Load(path string, nSamples int64) (L []float32, R []float32, err error) {
	// TODO!
	return
}