feat(windows): rewrite NSIS installer, add pgtidy update command

cmd/pgtidy/update.go

@@ -0,0 +1,158 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"time"
+
+	"git.warky.dev/wdevs/pgtidy/pkg/updatecheck"
+)
+
+// windowsInstallerAsset is the release asset built by the NSIS installer step.
+const windowsInstallerAsset = "pgtidy-setup-windows-amd64.exe"
+
+// cmdUpdate implements `pgtidy update`: check the latest release and, on
+// Windows, offer to download and run the installer.
+func cmdUpdate(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
+	var checkOnly, assumeYes bool
+	for _, a := range args {
+		switch a {
+		case "--check":
+			checkOnly = true
+		case "-y", "--yes":
+			assumeYes = true
+		case "-h", "--help":
+			_, _ = fmt.Fprint(stdout, `pgtidy update — check for a newer release
+
+Usage:
+  pgtidy update [--check] [-y|--yes]
+
+  --check    Only report whether an update is available
+  -y, --yes  Update without prompting
+
+On Windows the installer is downloaded and started; elsewhere the release
+page URL is shown.
+`)
+			return 0
+		default:
+			_, _ = fmt.Fprintf(stderr, "pgtidy update: unknown flag %q\n", a)
+			return 2
+		}
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Minute)
+	defer cancel()
+	err := runUpdate(ctx, updateOptions{
+		current:   version,
+		apiURL:    updatecheck.DefaultAPIURL,
+		goos:      runtime.GOOS,
+		checkOnly: checkOnly,
+		assumeYes: assumeYes,
+		in:        stdin,
+		out:       stdout,
+		install:   downloadAndRunInstaller,
+	})
+	if err != nil {
+		_, _ = fmt.Fprintf(stderr, "pgtidy update: %v\n", err)
+		return 1
+	}
+	return 0
+}
+
+type updateOptions struct {
+	current   string
+	apiURL    string
+	goos      string
+	checkOnly bool
+	assumeYes bool
+	in        io.Reader
+	out       io.Writer
+	// install downloads and starts the installer found at url.
+	install func(ctx context.Context, url string, out io.Writer) error
+}
+
+func runUpdate(ctx context.Context, o updateOptions) error {
+	rel, err := updatecheck.Latest(ctx, nil, o.apiURL)
+	if err != nil {
+		return err
+	}
+
+	if !updatecheck.IsNewer(o.current, rel.Tag) {
+		_, _ = fmt.Fprintf(o.out, "PgTidy %s is up to date (latest release: %s)\n", o.current, rel.Tag)
+		return nil
+	}
+
+	_, _ = fmt.Fprintf(o.out, "A newer PgTidy is available: %s (installed: %s)\n", rel.Tag, o.current)
+	if o.checkOnly {
+		_, _ = fmt.Fprintf(o.out, "Release: %s\n", rel.URL)
+		return nil
+	}
+
+	installer, canInstall := rel.FindAsset(windowsInstallerAsset)
+	if o.goos != "windows" || !canInstall {
+		_, _ = fmt.Fprintf(o.out, "Download it from: %s\n", rel.URL)
+		return nil
+	}
+
+	if !o.assumeYes && !confirm(o.in, o.out, "Download and run the installer now?") {
+		_, _ = fmt.Fprintf(o.out, "Skipped. Release: %s\n", rel.URL)
+		return nil
+	}
+	return o.install(ctx, installer.URL, o.out)
+}
+
+// confirm asks a yes/no question, defaulting to no.
+func confirm(in io.Reader, out io.Writer, question string) bool {
+	_, _ = fmt.Fprintf(out, "%s [y/N]: ", question)
+	line, _ := bufio.NewReader(in).ReadString('\n')
+	switch strings.ToLower(strings.TrimSpace(line)) {
+	case "y", "yes":
+		return true
+	}
+	return false
+}
+
+// downloadAndRunInstaller saves the installer to a temp directory and starts
+// it detached so this process can exit and release pgtidy.exe.
+func downloadAndRunInstaller(ctx context.Context, url string, out io.Writer) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("downloading installer: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("downloading installer: unexpected status %s", resp.Status)
+	}
+
+	dir, err := os.MkdirTemp("", "pgtidy-update-")
+	if err != nil {
+		return err
+	}
+	path := filepath.Join(dir, windowsInstallerAsset)
+	f, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	if _, err := io.Copy(f, resp.Body); err != nil {
+		_ = f.Close()
+		return fmt.Errorf("downloading installer: %w", err)
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+
+	_, _ = fmt.Fprintf(out, "Starting installer: %s\n", path)
+	return exec.Command(path).Start()
+}