htpack/cmd/htpacker/inspector.go

package main

import (
	"errors"
	"fmt"
	"os"

	"github.com/spf13/cobra"
	"src.lwithers.me.uk/go/htpack/packed"
)

var inspectCmd = &cobra.Command{
	Use:   "inspect",
	Short: "View contents of an htpack file",
	RunE: func(cmd *cobra.Command, args []string) error {
		if len(args) == 0 {
			return errors.New("must specify one or more files")
		}

		var exitCode int
		for _, filename := range args {
			if err := Inspect(filename); err != nil {
				fmt.Fprintf(os.Stderr, "%s: %v\n",
					filename, err)
				exitCode = 1
			}
		}
		os.Exit(exitCode)
		return nil
	},
}

// Inspect a packfile.
//  TODO: verify etag; verify integrity of compressed data.
func Inspect(filename string) error {
	f, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer f.Close()

	hdr, dir, err := packed.Load(f)
	if hdr != nil {
		fmt.Printf("Header: %#v\n", hdr)
	}
	if dir != nil {
		fmt.Printf("%d files:\n", len(dir.Files))
		for path, info := range dir.Files {
			fmt.Printf(" • %s\n"+
				"    · Etag:         %s\n"+
				"    · Content type: %s\n"+
				"    · Uncompressed: %s (offset %d)\n",
				path, info.Etag, info.ContentType,
				printSize(info.Uncompressed.Length),
				info.Uncompressed.Offset)

			if info.Gzip != nil {
				fmt.Printf("    · Gzipped:      %s (offset %d)\n",
					printSize(info.Gzip.Length), info.Gzip.Offset)
			}

			if info.Brotli != nil {
				fmt.Printf("    · Brotli:       %s (offset %d)\n",
					printSize(info.Brotli.Length), info.Brotli.Offset)
			}
		}
		inspectSummary(dir)
	}
	return err
}

func inspectSummary(dir *packed.Directory) {
	var (
		n, ngzip, nbrotli int
		s, sgzip, sbrotli uint64
	)

	for _, f := range dir.Files {
		n++
		s += f.Uncompressed.Length
		if f.Gzip != nil {
			ngzip++
			sgzip += f.Gzip.Length
		}
		if f.Brotli != nil {
			nbrotli++
			sbrotli += f.Brotli.Length
		}
	}

	fmt.Printf("Uncompressed:\n\tFiles: %d\n\tSize:  %s\n",
		n, printSize(s))
	if ngzip > 0 {
		fmt.Printf("gzip compressed:\n\tFiles: %d (%.1f%% of total)\n"+
			"\tSize:  %s\n\tRatio: %.1f%%\n",
			ngzip, 100*float64(ngzip)/float64(n),
			printSize(sgzip), 100*float64(sgzip)/float64(s))
	}
	if nbrotli > 0 {
		fmt.Printf("brotli compressed:\n\tFiles: %d (%.1f%% of total)\n"+
			"\tSize:  %s\n\tRatio: %.1f%%\n",
			nbrotli, 100*float64(nbrotli)/float64(n),
			printSize(sbrotli), 100*float64(sbrotli)/float64(s))
	}
}

func printSize(size uint64) string {
	switch {
	case size < 1<<10:
		return fmt.Sprintf("%d bytes", size)
	case size < 1<<15:
		return fmt.Sprintf("%.2f KiB", float64(size)/(1<<10))
	case size < 1<<20:
		return fmt.Sprintf("%.1f KiB", float64(size)/(1<<10))
	case size < 1<<25:
		return fmt.Sprintf("%.2f MiB", float64(size)/(1<<20))
	case size < 1<<30:
		return fmt.Sprintf("%.1f MiB", float64(size)/(1<<20))
	case size < 1<<35:
		return fmt.Sprintf("%.2f GiB", float64(size)/(1<<30))
	default:
		return fmt.Sprintf("%.1f GiB", float64(size)/(1<<30))
	}
}