R rebuilds every pane detached; r refreshes data; Author gains guidance and preview; Repair gains the rebuild log

tui/rebuild.go

@@ -0,0 +1,90 @@
+package main
+
+// Rebuilding and refreshing, and the difference between them.
+//
+//   r  read the data again in this panel. Nothing is closed, nothing moves.
+//   R  rebuild every workspace and pane from the project file: close what the
+//      layout owns, then build it again in order.
+//
+// A rebuild must survive the panel that started it, because that panel is one of
+// the things being replaced. So the rebuild runs detached, in its own session,
+// with its output in a log the Repair workspace can show.
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"syscall"
+	"time"
+)
+
+func rebuildLogPath() string {
+	return filepath.Join(os.TempDir(), "paperclip-harness-rebuild.log")
+}
+
+// startRebuild launches bin/board --replace for this folder and returns at once.
+func startRebuild(folder string) error {
+	board := filepath.Join(exeDir(), "board")
+	if _, err := os.Stat(board); err != nil {
+		return fmt.Errorf("no bin/board next to the program (%s)", board)
+	}
+	log, err := os.Create(rebuildLogPath())
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(log, "rebuild started %s\n", time.Now().Format("2006-01-02 15:04:05"))
+
+	cmd := exec.Command(board, "--folder", folder, "--replace")
+	cmd.Stdout = log
+	cmd.Stderr = log
+	cmd.Stdin = nil
+	// Its own session, so closing this pane does not take the rebuild with it.
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
+	if err := cmd.Start(); err != nil {
+		log.Close()
+		return err
+	}
+	go func() {
+		cmd.Wait()
+		fmt.Fprintf(log, "rebuild finished %s\n", time.Now().Format("15:04:05"))
+		log.Close()
+	}()
+	return nil
+}
+
+func exeDir() string {
+	p, err := os.Executable()
+	if err != nil {
+		return "."
+	}
+	return filepath.Dir(p)
+}
+
+// rebuildLogTail returns the end of the last rebuild, for the Repair workspace.
+func rebuildLogTail(lines int) []string {
+	b, err := os.ReadFile(rebuildLogPath())
+	if err != nil {
+		return []string{"", " no rebuild has been run since this machine started"}
+	}
+	all := splitLines(string(b))
+	start := max(0, len(all)-lines)
+	return all[start:]
+}
+
+func splitLines(s string) []string {
+	var out []string
+	cur := ""
+	for _, r := range s {
+		if r == '\n' {
+			out = append(out, cur)
+			cur = ""
+			continue
+		}
+		cur += string(r)
+	}
+	if cur != "" {
+		out = append(out, cur)
+	}
+	return out
+}