Wire kage pack and kage open into the CLI

pack packs a mirror to a zim file or a runnable viewer, accepting a bare
host that it resolves against the default output directory. open serves a
zim over http like serve does for a folder. Execute checks for an appended
archive first, so a packed kage runs as an offline viewer on an ephemeral
port and ignores its arguments.

cli/root.go

@@ -7,15 +7,28 @@ package cli
 import (
 	"context"
 	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"os"
 
 	"github.com/charmbracelet/fang"
 	"github.com/spf13/cobra"
+
+	"github.com/tamnd/kage/pack"
+	"github.com/tamnd/kage/zim"
 )
 
 // Execute builds the root command and runs it through fang. main passes the
 // signal-aware context so Ctrl-C cancels the in-flight clone and flushes resume
 // state. It returns the process exit code.
 func Execute(ctx context.Context) int {
+	// A kage binary with a ZIM appended runs as an offline viewer for that site,
+	// ignoring its arguments. A normal build has no trailer and falls through.
+	if ra, size, ok := pack.Embedded(); ok {
+		return runEmbeddedViewer(ctx, ra, size)
+	}
+
 	root := newRoot()
 	opts := []fang.Option{
 		fang.WithVersion(Version),
@@ -41,5 +54,38 @@ func newRoot() *cobra.Command {
 	}
 	root.AddCommand(newCloneCmd())
 	root.AddCommand(newServeCmd())
+	root.AddCommand(newPackCmd())
+	root.AddCommand(newOpenCmd())
 	return root
 }
+
+// runEmbeddedViewer serves the ZIM appended to this executable on an ephemeral
+// local port and opens the browser. It runs until the context is cancelled
+// (Ctrl-C) and ignores all command-line arguments: a packed binary is the site,
+// not the kage CLI.
+func runEmbeddedViewer(ctx context.Context, ra io.ReaderAt, size int64) int {
+	r, err := zim.NewReader(ra, size)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "kage: corrupt embedded archive:", err)
+		return 1
+	}
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "kage: cannot start viewer:", err)
+		return 1
+	}
+	url := "http://" + ln.Addr().String()
+	fmt.Fprintln(os.Stderr, "serving offline site at "+url+"  (Ctrl-C to stop)")
+	_ = pack.OpenInBrowser(url)
+
+	srv := &http.Server{Handler: pack.Handler(r)}
+	go func() {
+		<-ctx.Done()
+		_ = srv.Close()
+	}()
+	if err := srv.Serve(ln); err != nil && err != http.ErrServerClosed {
+		fmt.Fprintln(os.Stderr, "kage:", err)
+		return 1
+	}
+	return 0
+}