cmd/httptap/cmd/doctor.go

package cmd

import (
	"fmt"
	"io"
	"os"
	"runtime"

	"github.com/spf13/cobra"

	"mercemay.top/httptap/internal/filter"
)

func newDoctorCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "doctor",
		Short: "Print diagnostic information about the environment",
		RunE: func(c *cobra.Command, args []string) error {
			return doctor(os.Stdout)
		},
	}
}

// doctor runs a handful of non-destructive probes and prints results to
// w. Each check is a separate function for easy table-driven testing.
func doctor(w io.Writer) error {
	for _, chk := range []func() (string, bool){
		checkSocket,
		checkHomeTTY,
		checkFilterFields,
		checkGo,
	} {
		msg, ok := chk()
		prefix := " OK "
		if !ok {
			prefix = "WARN"
		}
		fmt.Fprintf(w, "[%s] %s\n", prefix, msg)
	}
	return nil
}

func checkSocket() (string, bool) {
	if _, err := os.Stat(globalOpts.SocketPath); err != nil {
		return fmt.Sprintf("socket %s: %v", globalOpts.SocketPath, err), false
	}
	return fmt.Sprintf("socket exists at %s", globalOpts.SocketPath), true
}

func checkHomeTTY() (string, bool) {
	if home, _ := os.UserHomeDir(); home == "" {
		return "$HOME is not set", false
	}
	if !isatty(os.Stdout) {
		return "stdout is not a TTY; the TUI will not render", false
	}
	return "stdout is a TTY", true
}

func checkFilterFields() (string, bool) {
	if _, err := filter.Compile("method=GET"); err != nil {
		return fmt.Sprintf("filter compile: %v", err), false
	}
	return fmt.Sprintf("filter grammar: %d known fields", len(filter.KnownFields)), true
}

func checkGo() (string, bool) {
	return fmt.Sprintf("Go runtime %s on %s/%s",
		runtime.Version(), runtime.GOOS, runtime.GOARCH), true
}

// isatty is a POSIX-only shortcut; on Windows we always return false
// because we expect a Unix-y environment anyway.
func isatty(f *os.File) bool {
	fi, err := f.Stat()
	if err != nil {
		return false
	}
	return (fi.Mode() & os.ModeCharDevice) != 0
}