Refactor forget and snapshots command

Implement filtering by using `FindFilteredSnapshots()` to iterate over the snapshots

Refactor cmd_snapshots' `PrintSnapshots()` so its pretty printing can be used from
both `forget` and `snapshots`.

Use contexts.

src/cmds/restic/cmd_forget.go

@@ -1,14 +1,12 @@
 package main
 
 import (
-	"encoding/hex"
+	"context"
 	"encoding/json"
 	"restic"
 	"sort"
 	"strings"
 
-	"restic/errors"
-
 	"github.com/spf13/cobra"
 )
 
@@ -33,7 +31,6 @@ type ForgetOptions struct {
 	Weekly   int
 	Monthly  int
 	Yearly   int
-
 	KeepTags []string
 
 	Host  string
@@ -83,32 +80,43 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 		return err
 	}
 
-	// Process all snapshot IDs given as arguments.
+	// group by hostname and dirs
-	if len(args) != 0 {
+	type key struct {
-		for _, s := range args {
+		Hostname string
-			// Parse argument as hex string.
+		Paths    []string
-			if _, err := hex.DecodeString(s); err != nil {
+		Tags     []string
-				Warnf("argument %q is not a snapshot ID, ignoring\n", s)
-				continue
-			}
-			id, err := restic.FindSnapshot(repo, s)
-			if err != nil {
-				Warnf("could not find a snapshot for ID %q, ignoring\n", s)
-				continue
 	}
+	snapshotGroups := make(map[string]restic.Snapshots)
 
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	for sn := range FindFilteredSnapshots(ctx, repo, opts.Host, opts.Tags, opts.Paths, args) {
+		if len(args) > 0 {
+			// When explicit snapshots args are given, remove them immediately.
 			if !opts.DryRun {
-				h := restic.Handle{Type: restic.SnapshotFile, Name: id.String()}
+				h := restic.Handle{Type: restic.SnapshotFile, Name: sn.ID().String()}
-				err = repo.Backend().Remove(h)
+				if err = repo.Backend().Remove(h); err != nil {
+					return err
+				}
+				Verbosef("removed snapshot %v\n", sn.ID().Str())
+			} else {
+				Verbosef("would have removed snapshot %v\n", sn.ID().Str())
+			}
+		} else {
+			var tags []string
+			if opts.GroupByTags {
+				tags = sn.Tags
+				sort.StringSlice(tags).Sort()
+			}
+			sort.StringSlice(sn.Paths).Sort()
+			k, err := json.Marshal(key{Hostname: sn.Hostname, Tags: tags, Paths: sn.Paths})
 			if err != nil {
 				return err
 			}
-
+			snapshotGroups[string(k)] = append(snapshotGroups[string(k)], sn)
-				Verbosef("removed snapshot %v\n", id.Str())
-			} else {
-				Verbosef("would remove snapshot %v\n", id.Str())
 		}
 	}
+	if len(args) > 0 {
 		return nil
 	}
 
@@ -122,53 +130,17 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 		Tags:    opts.KeepTags,
 	}
 
-	snapshots, err := restic.LoadAllSnapshots(repo)
-	if err != nil {
-		return err
-	}
-
-	// Group snapshots by hostname and dirs.
-	type key struct {
-		Hostname string
-		Paths    []string
-		Tags     []string
-	}
-
-	snapshotGroups := make(map[string]restic.Snapshots)
-
-	for _, sn := range snapshots {
-		if opts.Host != "" && sn.Hostname != opts.Host {
-			continue
-		}
-
-		if !sn.HasTags(opts.Tags) {
-			continue
-		}
-
-		if !sn.HasPaths(opts.Paths) {
-			continue
-		}
-
-		var tags []string
-		if opts.GroupByTags {
-			sort.StringSlice(sn.Tags).Sort()
-			tags = sn.Tags
-		}
-		sort.StringSlice(sn.Paths).Sort()
-		k, _ := json.Marshal(key{Hostname: sn.Hostname, Tags: tags, Paths: sn.Paths})
-		snapshotGroups[string(k)] = append(snapshotGroups[string(k)], sn)
-	}
-	if len(snapshotGroups) == 0 {
-		return errors.Fatal("no snapshots remained after filtering")
-	}
 	if policy.Empty() {
 		Verbosef("no policy was specified, no snapshots will be removed\n")
+		return nil
 	}
 
 	removeSnapshots := 0
 	for k, snapshotGroup := range snapshotGroups {
 		var key key
-		json.Unmarshal([]byte(k), &key)
+		if json.Unmarshal([]byte(k), &key) != nil {
+			return err
+		}
 		if opts.GroupByTags {
 			Printf("snapshots for host %v, tags [%v], paths: [%v]:\n\n", key.Hostname, strings.Join(key.Tags, ", "), strings.Join(key.Paths, ", "))
 		} else {

src/cmds/restic/cmd_snapshots.go

@@ -1,19 +1,19 @@
 package main
 
 import (
+	"context"
+	"encoding/json"
 	"fmt"
 	"io"
-	"restic/errors"
 	"sort"
 
 	"github.com/spf13/cobra"
 
-	"encoding/json"
 	"restic"
 )
 
 var cmdSnapshots = &cobra.Command{
-	Use:   "snapshots",
+	Use:   "snapshots [snapshotID ...]",
 	Short: "list all snapshots",
 	Long: `
 The "snapshots" command lists all snapshots stored in the repository.
@@ -26,6 +26,7 @@ The "snapshots" command lists all snapshots stored in the repository.
 // SnapshotOptions bundles all options for the snapshots command.
 type SnapshotOptions struct {
 	Host  string
+	Tags  []string
 	Paths []string
 }
 
@@ -35,15 +36,12 @@ func init() {
 	cmdRoot.AddCommand(cmdSnapshots)
 
 	f := cmdSnapshots.Flags()
-	f.StringVar(&snapshotOptions.Host, "host", "", "only print snapshots for this host")
+	f.StringVarP(&snapshotOptions.Host, "host", "H", "", "only consider snapshots for this `host`")
-	f.StringSliceVar(&snapshotOptions.Paths, "path", []string{}, "only print snapshots for this `path` (can be specified multiple times)")
+	f.StringSliceVar(&snapshotOptions.Tags, "tag", nil, "only consider snapshots which include this `tag` (can be specified multiple times)")
+	f.StringSliceVar(&snapshotOptions.Paths, "path", nil, "only consider snapshots for this `path` (can be specified multiple times)")
 }
 
 func runSnapshots(opts SnapshotOptions, gopts GlobalOptions, args []string) error {
-	if len(args) != 0 {
-		return errors.Fatal("wrong number of arguments")
-	}
-
 	repo, err := OpenRepository(gopts)
 	if err != nil {
 		return err
@@ -57,32 +55,14 @@ func runSnapshots(opts SnapshotOptions, gopts GlobalOptions, args []string) erro
 		}
 	}
 
-	done := make(chan struct{})
+	ctx, cancel := context.WithCancel(gopts.ctx)
-	defer close(done)
+	defer cancel()
 
-	list := []*restic.Snapshot{}
+	var list restic.Snapshots
-	for id := range repo.List(restic.SnapshotFile, done) {
+	for sn := range FindFilteredSnapshots(ctx, repo, opts.Host, opts.Tags, opts.Paths, args) {
-		sn, err := restic.LoadSnapshot(repo, id)
-		if err != nil {
-			Warnf("error loading snapshot %s: %v\n", id, err)
-			continue
-		}
-
-		if (opts.Host == "" || opts.Host == sn.Hostname) && sn.HasPaths(opts.Paths) {
-			pos := sort.Search(len(list), func(i int) bool {
-				return list[i].Time.After(sn.Time)
-			})
-
-			if pos < len(list) {
-				list = append(list, nil)
-				copy(list[pos+1:], list[pos:])
-				list[pos] = sn
-			} else {
 		list = append(list, sn)
 	}
-		}
+	sort.Sort(sort.Reverse(list))
-
-	}
 
 	if gopts.JSON {
 		err := printSnapshotsJSON(gopts.stdout, list)
@@ -97,7 +77,7 @@ func runSnapshots(opts SnapshotOptions, gopts GlobalOptions, args []string) erro
 }
 
 // PrintSnapshots prints a text table of the snapshots in list to stdout.
-func PrintSnapshots(stdout io.Writer, list []*restic.Snapshot) {
+func PrintSnapshots(stdout io.Writer, list restic.Snapshots) {
 
 	// Determine the max widths for host and tag.
 	maxHost, maxTag := 10, 6
@@ -165,7 +145,7 @@ func PrintSnapshots(stdout io.Writer, list []*restic.Snapshot) {
 	tab.Write(stdout)
 }
 
-// Snapshot helps to print Snaphots as JSON
+// Snapshot helps to print Snaphots as JSON with their ID included.
 type Snapshot struct {
 	*restic.Snapshot
 
@@ -173,7 +153,7 @@ type Snapshot struct {
 }
 
 // printSnapshotsJSON writes the JSON representation of list to stdout.
-func printSnapshotsJSON(stdout io.Writer, list []*restic.Snapshot) error {
+func printSnapshotsJSON(stdout io.Writer, list restic.Snapshots) error {
 
 	var snapshots []Snapshot
 
@@ -187,5 +167,4 @@ func printSnapshotsJSON(stdout io.Writer, list []*restic.Snapshot) error {
 	}
 
 	return json.NewEncoder(stdout).Encode(snapshots)
-
 }