Merge pull request 'Built #25 new template builder' (#26) from dev/25-template-builder into v0.3.0

Reviewed-on: https://git.cer.sh/Axodouble/QUptime/pulls/26

Author: Axodouble

internal/cli/builder.go

@@ -0,0 +1,96 @@
+package cli
+
+import (
+	_ "embed"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"git.cer.sh/axodouble/quptime/internal/alerts"
+)
+
+//go:embed builder.html
+var builderHTML string
+
+// addBuilderCmd registers `qu builder`, which materialises a standalone
+// HTML page that operators can use to compose alert message templates
+// interactively. The page is self-contained — no network calls, no
+// external assets — so it can be opened straight from disk or copied
+// to a workstation that has no qu binary installed.
+//
+// The default templates baked into the page are injected from
+// internal/alerts at build (actually at command-run) time, so the
+// builder always offers the same starting points the daemon would
+// render itself.
+func addBuilderCmd(root *cobra.Command) {
+	var output string
+	cmd := &cobra.Command{
+		Use:   "builder",
+		Short: "Generate a standalone HTML alert-template builder",
+		Long: `Write a self-contained HTML page that helps you compose subject and
+body templates for ` + "`qu alert`" + ` channels. The page bundles a
+drag-and-drop variable palette, a live preview rendered against
+editable sample data, and the per-check-type defaults you can use as a
+starting point. It runs entirely offline once written to disk.
+
+Pass ` + "`-o -`" + ` to write the HTML to stdout instead of a file.`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			rendered, err := renderBuilderHTML()
+			if err != nil {
+				return err
+			}
+			if output == "-" {
+				_, err := cmd.OutOrStdout().Write([]byte(rendered))
+				return err
+			}
+			if err := os.WriteFile(output, []byte(rendered), 0o644); err != nil {
+				return fmt.Errorf("write %s: %w", output, err)
+			}
+			abs, _ := filepath.Abs(output)
+			fmt.Fprintf(cmd.OutOrStdout(), "wrote %s\n", abs)
+			fmt.Fprintf(cmd.OutOrStdout(), "open it in a browser to start composing templates.\n")
+			return nil
+		},
+	}
+	cmd.Flags().StringVarP(&output, "output", "o", "quptime-template-builder.html",
+		"output path for the generated HTML (use - for stdout)")
+	root.AddCommand(cmd)
+}
+
+// renderBuilderHTML substitutes the placeholder tokens in builder.html
+// with JSON-encoded copies of the current default templates. JSON
+// encoding is exactly what we want for JS string literals — it handles
+// the embedded backticks, backslashes, and newlines in the Go template
+// constants without further escaping.
+func renderBuilderHTML() (string, error) {
+	subs := map[string]string{
+		"__QU_DEFAULT_HTTP_SUBJECT__":    alerts.DefaultSubjectHTTP,
+		"__QU_DEFAULT_HTTP_BODY__":       alerts.DefaultBodyHTTP,
+		"__QU_DEFAULT_TLS_SUBJECT__":     alerts.DefaultSubjectTLS,
+		"__QU_DEFAULT_TLS_BODY__":        alerts.DefaultBodyTLS,
+		"__QU_DEFAULT_TCP_SUBJECT__":     alerts.DefaultSubjectTCP,
+		"__QU_DEFAULT_TCP_BODY__":        alerts.DefaultBodyTCP,
+		"__QU_DEFAULT_ICMP_SUBJECT__":    alerts.DefaultSubjectICMP,
+		"__QU_DEFAULT_ICMP_BODY__":       alerts.DefaultBodyICMP,
+		"__QU_DEFAULT_DNS_SUBJECT__":     alerts.DefaultSubjectDNS,
+		"__QU_DEFAULT_DNS_BODY__":        alerts.DefaultBodyDNS,
+		"__QU_DEFAULT_GENERIC_SUBJECT__": alerts.DefaultSubjectGeneric,
+		"__QU_DEFAULT_GENERIC_BODY__":    alerts.DefaultBodyGeneric,
+	}
+	out := builderHTML
+	for marker, value := range subs {
+		encoded, err := json.Marshal(value)
+		if err != nil {
+			return "", fmt.Errorf("encode %s: %w", marker, err)
+		}
+		if !strings.Contains(out, marker) {
+			return "", fmt.Errorf("builder.html missing placeholder %s", marker)
+		}
+		out = strings.ReplaceAll(out, marker, string(encoded))
+	}
+	return out, nil
+}