package cmd

import (
	"fmt"
	"io"
	"strings"
	"text/tabwriter"

	"gitea.hostxtra.co.uk/vantage/vantage-shared/backup"
	"github.com/spf13/cobra"
)

func newInspectCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "inspect ARCHIVE",
		Short: "Print an archive's manifest",
		Long: "inspect reads an archive and prints what it holds. It contacts no\n" +
			"database, so it is safe to run against an archive of unknown origin\n" +
			"and is the fastest way to find out whether one is worth anything.",
		Args: cobra.ExactArgs(1),
		RunE: func(c *cobra.Command, args []string) error {
			archive, err := backup.Open(args[0])
			if err != nil {
				return err
			}
			defer archive.Close()
			renderManifest(c.OutOrStdout(), archive.Manifest())
			return nil
		},
	}
}

// renderManifest prints a manifest for a human.
func renderManifest(w io.Writer, m backup.Manifest) {
	fmt.Fprintf(w, "Created       %s\n", m.CreatedAt.UTC().Format("2006-01-02 15:04:05 MST"))
	fmt.Fprintf(w, "Database      %s\n", m.MongoDB)
	fmt.Fprintf(w, "MongoDB       %s\n", m.MongoServerVersion)
	fmt.Fprintf(w, "Written by    vantagectl %s on %s\n", m.VantageVersion, m.Hostname)
	fmt.Fprintf(w, "Format        version %d\n", m.FormatVersion)

	if m.KeyFingerprint == nil {
		fmt.Fprintf(w, "Key           none recorded — this archive cannot be checked "+
			"against any KEY_ENCRYPTION_KEY\n")
	} else {
		fmt.Fprintf(w, "Key           %s\n", *m.KeyFingerprint)
	}
	if len(m.Excluded) > 0 {
		fmt.Fprintf(w, "Excluded      %s\n", strings.Join(m.Excluded, ", "))
	}

	var docs, bytes int64
	for _, c := range m.Collections {
		docs += c.Documents
		bytes += c.Bytes
	}
	fmt.Fprintf(w, "\n%d collections, %d documents, %s\n\n",
		len(m.Collections), docs, humanBytes(bytes))

	tw := tabwriter.NewWriter(w, 0, 0, 2, ' ', 0)
	fmt.Fprintln(tw, "COLLECTION\tDOCUMENTS\tSIZE")
	for _, c := range m.Collections {
		fmt.Fprintf(tw, "%s\t%d\t%s\n", c.Name, c.Documents, humanBytes(c.Bytes))
	}
	tw.Flush()
}

func humanBytes(n int64) string {
	const unit = 1024
	if n < unit {
		return fmt.Sprintf("%d B", n)
	}
	div, exp := int64(unit), 0
	for v := n / unit; v >= unit; v /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %cB", float64(n)/float64(div), "KMGTP"[exp])
}