ytdlp_navidrome/internal/ytdlp/ytdlp.go

package ytdlp

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"os/exec"
	"strings"
	"time"
)

// SearchResult is a single entry from yt-dlp flat playlist output.
type SearchResult struct {
	ID       string
	Title    string
	Duration string
	Channel  string
}

// RunSearch executes yt-dlp with a search query and returns parsed results.
func RunSearch(ctx context.Context, ytdlpPath, query string, limit int, proxyURL string, timeoutSeconds int) ([]SearchResult, error) {
	searchQuery := fmt.Sprintf("ytsearch%d:%s", limit, query)

	args := []string{
		searchQuery,
		"--flat-playlist",
		"--print", "%(id)s\t%(title)s\t%(duration_string)s\t%(channel)s",
	}
	if proxyURL != "" {
		args = append(args, "--proxy", proxyURL)
	}

	cmdCtx, cancel := context.WithTimeout(ctx, toDuration(timeoutSeconds))
	defer cancel()

	cmd := exec.CommandContext(cmdCtx, ytdlpPath, args...)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		if cmdCtx.Err() != nil {
			return nil, fmt.Errorf("search timed out after %ds: %s", timeoutSeconds, stderr.String())
		}
		return nil, fmt.Errorf("yt-dlp search failed: %w\nstderr: %s", err, strings.TrimSpace(stderr.String()))
	}

	return parseSearchOutput(stdout.String()), nil
}

func parseSearchOutput(output string) []SearchResult {
	lines := strings.Split(strings.TrimSpace(output), "\n")
	var results []SearchResult
	for _, line := range lines {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		parts := strings.SplitN(line, "\t", 4)
		if len(parts) < 3 {
			continue
		}
		r := SearchResult{
			ID:       parts[0],
			Title:    parts[1],
			Duration: parts[2],
		}
		if len(parts) >= 4 {
			r.Channel = parts[3]
		}
		results = append(results, r)
	}
	return results
}

// DownloadPreview downloads a single track as audio preview (lower quality) to tmpDir.
// Returns the path to the downloaded file.
func DownloadPreview(ctx context.Context, ytdlpPath, videoID, tmpDir, audioFormat string, quality, timeoutSeconds int, proxyURL string) (string, error) {
	outputTmpl := fmt.Sprintf("%s/%s.%%%%(ext)s", tmpDir, videoID)
	url := fmt.Sprintf("https://www.youtube.com/watch?v=%s", videoID)

	args := []string{
		url,
		"-x",
		"--audio-format", audioFormat,
		"--audio-quality", fmt.Sprintf("%d", quality),
		"--output", outputTmpl,
		"--no-embed-thumbnail",
		"--no-add-metadata",
	}
	if proxyURL != "" {
		args = append(args, "--proxy", proxyURL)
	}

	cmdCtx, cancel := context.WithTimeout(ctx, toDuration(timeoutSeconds))
	defer cancel()

	cmd := exec.CommandContext(cmdCtx, ytdlpPath, args...)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		if cmdCtx.Err() != nil {
			return "", fmt.Errorf("preview download timed out after %ds", timeoutSeconds)
		}
		return "", fmt.Errorf("yt-dlp preview failed: %w\nstderr: %s", err, strings.TrimSpace(stderr.String()))
	}

	// yt-dlp outputs to {tmpDir}/{videoID}.{ext}
	ext := audioFormat
	if ext == "opus" {
		ext = "opus"
	}
	// Try common extensions
	for _, e := range []string{audioFormat, "opus", "m4a", "webm"} {
		path := fmt.Sprintf("%s/%s.%s", tmpDir, videoID, e)
		if fileExists(path) {
			return path, nil
		}
	}

	return fmt.Sprintf("%s/%s.%s", tmpDir, videoID, audioFormat), nil
}

// DownloadFinal downloads a track at best quality with metadata into musicDir.
// Returns the final file path.
func DownloadFinal(ctx context.Context, ytdlpPath, videoID, musicDir, audioFormat string, quality, timeoutSeconds int, proxyURL string) (string, error) {
	outputTmpl := fmt.Sprintf("%s/%%%%(artist)s - %%%%(title)s.%%%%(ext)s", musicDir)
	url := fmt.Sprintf("https://www.youtube.com/watch?v=%s", videoID)

	args := []string{
		url,
		"-x",
		"--audio-format", audioFormat,
		"--audio-quality", fmt.Sprintf("%d", quality),
		"--embed-thumbnail",
		"--add-metadata",
		"--output", outputTmpl,
		"--no-playlist",
	}
	if proxyURL != "" {
		args = append(args, "--proxy", proxyURL)
	}

	cmdCtx, cancel := context.WithTimeout(ctx, toDuration(timeoutSeconds))
	defer cancel()

	cmd := exec.CommandContext(cmdCtx, ytdlpPath, args...)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		if cmdCtx.Err() != nil {
			return "", fmt.Errorf("final download timed out after %ds", timeoutSeconds)
		}
		return "", fmt.Errorf("yt-dlp final download failed: %w\nstderr: %s", err, strings.TrimSpace(stderr.String()))
	}

	// Return the output template pattern — caller will need to find the actual file
	return outputTmpl, nil
}

func toDuration(seconds int) time.Duration {
	return time.Duration(seconds) * time.Second
}

func fileExists(path string) bool {
	_, err := os.Stat(path)
	return err == nil
}