core: add DL helper, apply to TrackArt OSD, DankLocationSearch

- unrelated change to add gsettingsOrDconf helpers

core/cmd/dms/commands_common.go

@@ -524,5 +524,6 @@ func getCommonCommands() []*cobra.Command {
 		chromaCmd,
 		doctorCmd,
 		configCmd,
+		dlCmd,
 	}
 }

core/cmd/dms/commands_download.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/spf13/cobra"
+)
+
+var dlOutput string
+var dlUserAgent string
+var dlTimeout int
+var dlIPv4Only bool
+
+var dlCmd = &cobra.Command{
+	Use:   "dl <url>",
+	Short: "Download a URL to stdout or file",
+	Args:  cobra.ExactArgs(1),
+	Run: func(cmd *cobra.Command, args []string) {
+		if err := runDownload(args[0]); err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+	},
+}
+
+func init() {
+	dlCmd.Flags().StringVarP(&dlOutput, "output", "o", "", "Output file path (default: stdout)")
+	dlCmd.Flags().StringVar(&dlUserAgent, "user-agent", "", "Custom User-Agent header")
+	dlCmd.Flags().IntVar(&dlTimeout, "timeout", 10, "Request timeout in seconds")
+	dlCmd.Flags().BoolVarP(&dlIPv4Only, "ipv4", "4", false, "Force IPv4 only")
+}
+
+func runDownload(url string) error {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(dlTimeout)*time.Second)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return fmt.Errorf("invalid request: %w", err)
+	}
+
+	switch {
+	case dlUserAgent != "":
+		req.Header.Set("User-Agent", dlUserAgent)
+	default:
+		req.Header.Set("User-Agent", "DankMaterialShell/1.0 (Linux)")
+	}
+
+	dialer := &net.Dialer{Timeout: 5 * time.Second}
+	transport := &http.Transport{DialContext: dialer.DialContext}
+	if dlIPv4Only {
+		transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
+			return dialer.DialContext(ctx, "tcp4", addr)
+		}
+	}
+	client := &http.Client{Transport: transport}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("download failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return fmt.Errorf("HTTP %d", resp.StatusCode)
+	}
+
+	if dlOutput == "" {
+		_, err = io.Copy(os.Stdout, resp.Body)
+		return err
+	}
+
+	if dir := filepath.Dir(dlOutput); dir != "." {
+		if err := os.MkdirAll(dir, 0755); err != nil {
+			return fmt.Errorf("mkdir failed: %w", err)
+		}
+	}
+
+	f, err := os.Create(dlOutput)
+	if err != nil {
+		return fmt.Errorf("create failed: %w", err)
+	}
+	defer f.Close()
+
+	if _, err := io.Copy(f, resp.Body); err != nil {
+		os.Remove(dlOutput)
+		return fmt.Errorf("write failed: %w", err)
+	}
+
+	fmt.Println(dlOutput)
+	return nil
+}