Initial commit

internal/dl/torrent.go

@@ -0,0 +1,90 @@
+package dl
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+var (
+	urlMatchRegex       = regexp.MustCompile(`(magnet|torrent\+https?):.*`)
+	ErrAria2NotFound    = errors.New("aria2 must be installed for torrent functionality")
+	ErrDestinationEmpty = errors.New("the destination directory is empty")
+)
+
+type TorrentDownloader struct{}
+
+// Name always returns "file"
+func (TorrentDownloader) Name() string {
+	return "torrent"
+}
+
+// MatchURL returns true if the URL is a magnet link
+// or an http(s) link with a "torrent+" prefix
+func (TorrentDownloader) MatchURL(u string) bool {
+	return urlMatchRegex.MatchString(u)
+}
+
+// Download downloads a file over the BitTorrent protocol.
+func (TorrentDownloader) Download(opts Options) (Type, string, error) {
+	aria2Path, err := exec.LookPath("aria2c")
+	if err != nil {
+		return 0, "", ErrAria2NotFound
+	}
+
+	opts.URL = strings.TrimPrefix(opts.URL, "torrent+")
+
+	cmd := exec.Command(aria2Path, "--summary-interval=0", "--log-level=warn", "--seed-time=0", "--dir="+opts.Destination, opts.URL)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	err = cmd.Run()
+	if err != nil {
+		return 0, "", fmt.Errorf("aria2c returned an error: %w", err)
+	}
+
+	err = removeTorrentFiles(opts.Destination)
+	if err != nil {
+		return 0, "", err
+	}
+
+	return determineType(opts.Destination)
+}
+
+func removeTorrentFiles(path string) error {
+	filePaths, err := filepath.Glob(filepath.Join(path, "*.torrent"))
+	if err != nil {
+		return err
+	}
+
+	for _, filePath := range filePaths {
+		err = os.Remove(filePath)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func determineType(path string) (Type, string, error) {
+	files, err := os.ReadDir(path)
+	if err != nil {
+		return 0, "", err
+	}
+
+	if len(files) > 1 {
+		return TypeDir, "", nil
+	} else if len(files) == 1 {
+		if files[0].IsDir() {
+			return TypeDir, files[0].Name(), nil
+		} else {
+			return TypeFile, files[0].Name(), nil
+		}
+	}
+
+	return 0, "", ErrDestinationEmpty
+}