lib/transform: add transform library and --name-transform flag

lib/transform adds the transform library, supporting advanced path name
transformations for converting and renaming files and directories by applying
prefixes, suffixes, and other alterations.

It also adds the --name-transform flag for use with sync, copy, and move.

Multiple transformations can be used in sequence, applied in the order they are
specified on the command line.

By default --name-transform will only apply to file names. The means only the leaf
file name will be transformed. However some of the transforms would be better
applied to the whole path or just directories. To choose which which part of the
file path is affected some tags can be added to the --name-transform:

file	Only transform the leaf name of files (DEFAULT)
dir	Only transform name of directories - these may appear anywhere in the path
all	Transform the entire path for files and directories

Example syntax:
--name-transform file,prefix=ABC
--name-transform dir,prefix=DEF

cmd/bisync/bilib/names.go

@@ -5,8 +5,6 @@ import (
 	"os"
 	"sort"
 	"strconv"
-	"strings"
-	"time"
 )
 
 // Names comprises a set of file names
@@ -85,81 +83,3 @@ func (am AliasMap) Alias(name1 string) string {
 	}
 	return name1
 }
-
-// ParseGlobs determines whether a string contains {brackets}
-// and returns the substring (including both brackets) for replacing
-// substring is first opening bracket to last closing bracket --
-// good for {{this}} but not {this}{this}
-func ParseGlobs(s string) (hasGlobs bool, substring string) {
-	open := strings.Index(s, "{")
-	close := strings.LastIndex(s, "}")
-	if open >= 0 && close > open {
-		return true, s[open : close+1]
-	}
-	return false, ""
-}
-
-// TrimBrackets converts {{this}} to this
-func TrimBrackets(s string) string {
-	return strings.Trim(s, "{}")
-}
-
-// TimeFormat converts a user-supplied string to a Go time constant, if possible
-func TimeFormat(timeFormat string) string {
-	switch timeFormat {
-	case "Layout":
-		timeFormat = time.Layout
-	case "ANSIC":
-		timeFormat = time.ANSIC
-	case "UnixDate":
-		timeFormat = time.UnixDate
-	case "RubyDate":
-		timeFormat = time.RubyDate
-	case "RFC822":
-		timeFormat = time.RFC822
-	case "RFC822Z":
-		timeFormat = time.RFC822Z
-	case "RFC850":
-		timeFormat = time.RFC850
-	case "RFC1123":
-		timeFormat = time.RFC1123
-	case "RFC1123Z":
-		timeFormat = time.RFC1123Z
-	case "RFC3339":
-		timeFormat = time.RFC3339
-	case "RFC3339Nano":
-		timeFormat = time.RFC3339Nano
-	case "Kitchen":
-		timeFormat = time.Kitchen
-	case "Stamp":
-		timeFormat = time.Stamp
-	case "StampMilli":
-		timeFormat = time.StampMilli
-	case "StampMicro":
-		timeFormat = time.StampMicro
-	case "StampNano":
-		timeFormat = time.StampNano
-	case "DateTime":
-		// timeFormat = time.DateTime // missing in go1.19
-		timeFormat = "2006-01-02 15:04:05"
-	case "DateOnly":
-		// timeFormat = time.DateOnly // missing in go1.19
-		timeFormat = "2006-01-02"
-	case "TimeOnly":
-		// timeFormat = time.TimeOnly // missing in go1.19
-		timeFormat = "15:04:05"
-	case "MacFriendlyTime", "macfriendlytime", "mac":
-		timeFormat = "2006-01-02 0304PM" // not actually a Go constant -- but useful as macOS filenames can't have colons
-	}
-	return timeFormat
-}
-
-// AppyTimeGlobs converts "myfile-{DateOnly}.txt" to "myfile-2006-01-02.txt"
-func AppyTimeGlobs(s string, t time.Time) string {
-	hasGlobs, substring := ParseGlobs(s)
-	if !hasGlobs {
-		return s
-	}
-	timeString := t.Local().Format(TimeFormat(TrimBrackets(substring)))
-	return strings.ReplaceAll(s, substring, timeString)
-}

cmd/bisync/resolve.go

@@ -4,8 +4,6 @@ import (
 	"context"
 	"fmt"
 	"math"
-	"mime"
-	"path"
 	"strings"
 	"time"
 
@@ -13,6 +11,7 @@ import (
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/operations"
 	"github.com/rclone/rclone/lib/terminal"
+	"github.com/rclone/rclone/lib/transform"
 )
 
 // Prefer describes strategies for resolving sync conflicts
@@ -97,8 +96,8 @@ func (b *bisyncRun) setResolveDefaults(ctx context.Context) error {
 	}
 	// replace glob variables, if any
 	t := time.Now() // capture static time here so it is the same for all files throughout this run
-	b.opt.ConflictSuffix1 = bilib.AppyTimeGlobs(b.opt.ConflictSuffix1, t)
-	b.opt.ConflictSuffix2 = bilib.AppyTimeGlobs(b.opt.ConflictSuffix2, t)
+	b.opt.ConflictSuffix1 = transform.AppyTimeGlobs(b.opt.ConflictSuffix1, t)
+	b.opt.ConflictSuffix2 = transform.AppyTimeGlobs(b.opt.ConflictSuffix2, t)
 
 	// append dot (intentionally allow more than one)
 	b.opt.ConflictSuffix1 = "." + b.opt.ConflictSuffix1
@@ -130,6 +129,7 @@ type (
 		path2 namePair
 	}
 )
+
 type namePair struct {
 	oldName string
 	newName string
@@ -240,24 +240,7 @@ func SuffixName(ctx context.Context, remote, suffix string) string {
 	}
 	ci := fs.GetConfig(ctx)
 	if ci.SuffixKeepExtension {
-		var (
-			base  = remote
-			exts  = ""
-			first = true
-			ext   = path.Ext(remote)
-		)
-		for ext != "" {
-			// Look second and subsequent extensions in mime types.
-			// If they aren't found then don't keep it as an extension.
-			if !first && mime.TypeByExtension(ext) == "" {
-				break
-			}
-			base = base[:len(base)-len(ext)]
-			exts = ext + exts
-			first = false
-			ext = path.Ext(base)
-		}
-		return base + suffix + exts
+		return transform.SuffixKeepExtension(remote, suffix)
 	}
 	return remote + suffix
 }