convmv: add convmv command

convmv supports advanced path name transformations for converting and renaming
files and directories by applying prefixes, suffixes, and other alterations.

For example:

rclone convmv "stories/The Quick Brown Fox!.txt" --name-transform "all,uppercase"
// Output: STORIES/THE QUICK BROWN FOX!.TXT

See help doc for complete details.

lib/transform/help.go

@@ -0,0 +1,132 @@
+package transform
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/lib/encoder"
+)
+
+type commands struct {
+	command     string
+	description string
+}
+
+type example struct {
+	path  string
+	flags []string
+}
+
+var commandList = []commands{
+	{command: "--name-transform prefix=XXXX", description: "Prepends XXXX to the file name."},
+	{command: "--name-transform suffix=XXXX", description: "Appends XXXX to the file name after the extension."},
+	{command: "--name-transform suffix_keep_extension=XXXX", description: "Appends XXXX to the file name while preserving the original file extension."},
+	{command: "--name-transform trimprefix=XXXX", description: "Removes XXXX if it appears at the start of the file name."},
+	{command: "--name-transform trimsuffix=XXXX", description: "Removes XXXX if it appears at the end of the file name."},
+	{command: "--name-transform regex=/pattern/replacement/", description: "Applies a regex-based transformation."},
+	{command: "--name-transform replace=old:new", description: "Replaces occurrences of old with new in the file name."},
+	{command: "--name-transform date=YYYYMMDD", description: "Appends or prefixes the specified date format."},
+	{command: "--name-transform truncate=N", description: "Truncates the file name to a maximum of N characters."},
+	{command: "--name-transform base64encode", description: "Encodes the file name in Base64."},
+	{command: "--name-transform base64decode", description: "Decodes a Base64-encoded file name."},
+	{command: "--name-transform encoder=ENCODING", description: "Converts the file name to the specified encoding (e.g., ISO-8859-1, Windows-1252, Macintosh)."},
+	{command: "--name-transform decoder=ENCODING", description: "Decodes the file name from the specified encoding."},
+	{command: "--name-transform charmap=MAP", description: "Applies a character mapping transformation."},
+	{command: "--name-transform lowercase", description: "Converts the file name to lowercase."},
+	{command: "--name-transform uppercase", description: "Converts the file name to UPPERCASE."},
+	{command: "--name-transform titlecase", description: "Converts the file name to Title Case."},
+	{command: "--name-transform ascii", description: "Strips non-ASCII characters."},
+	{command: "--name-transform url", description: "URL-encodes the file name."},
+	{command: "--name-transform nfc", description: "Converts the file name to NFC Unicode normalization form."},
+	{command: "--name-transform nfd", description: "Converts the file name to NFD Unicode normalization form."},
+	{command: "--name-transform nfkc", description: "Converts the file name to NFKC Unicode normalization form."},
+	{command: "--name-transform nfkd", description: "Converts the file name to NFKD Unicode normalization form."},
+	{command: "--name-transform command=/path/to/my/programfile names.", description: "Executes an external program to transform"},
+}
+
+var examples = []example{
+	{"stories/The Quick Brown Fox!.txt", []string{"all,uppercase"}},
+	{"stories/The Quick Brown Fox!.txt", []string{"all,replace=Fox:Turtle", "all,replace=Quick:Slow"}},
+	{"stories/The Quick Brown Fox!.txt", []string{"all,base64encode"}},
+	{"c3Rvcmllcw==/VGhlIFF1aWNrIEJyb3duIEZveCEudHh0", []string{"all,base64decode"}},
+	{"stories/The Quick Brown 🦊 Fox Went to the Café!.txt", []string{"all,nfc"}},
+	{"stories/The Quick Brown 🦊 Fox Went to the Café!.txt", []string{"all,nfd"}},
+	{"stories/The Quick Brown 🦊 Fox!.txt", []string{"all,ascii"}},
+	{"stories/The Quick Brown Fox!.txt", []string{"all,trimsuffix=.txt"}},
+	{"stories/The Quick Brown Fox!.txt", []string{"all,prefix=OLD_"}},
+	{"stories/The Quick Brown 🦊 Fox Went to the Café!.txt", []string{"all,charmap=ISO-8859-7"}},
+	{"stories/The Quick Brown Fox: A Memoir [draft].txt", []string{"all,encoder=Colon,SquareBracket"}},
+	{"stories/The Quick Brown 🦊 Fox Went to the Café!.txt", []string{"all,truncate=21"}},
+}
+
+func (e example) command() string {
+	s := fmt.Sprintf(`rclone convmv %q`, e.path)
+	for _, f := range e.flags {
+		s += fmt.Sprintf(" --name-transform %q", f)
+	}
+	return s
+}
+
+func (e example) output() string {
+	err := SetOptions(context.Background(), e.flags...)
+	if err != nil {
+		fs.Errorf(nil, "error generating help text: %v", err)
+	}
+	return Path(e.path, false)
+}
+
+// go run ./ convmv --help
+func sprintExamples() string {
+	s := "Examples: \n\n"
+	for _, e := range examples {
+		s += fmt.Sprintf("```\n%s\n", e.command())
+		s += fmt.Sprintf("// Output: %s\n```\n\n", e.output())
+	}
+	Opt = Options{} // reset
+	return s
+}
+
+func commandTable() string {
+	s := `| Command | Description |
+|------|------|`
+	for _, c := range commandList {
+		s += fmt.Sprintf("\n| `%s` | %s |", c.command, c.description)
+	}
+	s += "\n\n\n"
+	return s
+}
+
+// SprintList returns the example help text as a string
+func SprintList() string {
+	var algos transformAlgo
+	var charmaps fs.Enum[cmapChoices]
+	s := commandTable()
+	s += fmt.Sprintln("Conversion modes:  \n```")
+	for _, v := range algos.Choices() {
+		s += fmt.Sprintln(v + "  ")
+	}
+	s += fmt.Sprintln("```")
+
+	s += fmt.Sprintln("Char maps:  \n```")
+	for _, v := range charmaps.Choices() {
+		s += fmt.Sprintln(v + "  ")
+	}
+	s += fmt.Sprintln("```")
+
+	s += fmt.Sprintln("Encoding masks:  \n```")
+	for _, v := range strings.Split(encoder.ValidStrings(), ",") {
+		s += fmt.Sprintln(v + "  ")
+	}
+	s += fmt.Sprintln("```")
+
+	s += sprintExamples()
+
+	return s
+}
+
+// PrintList prints the example help text to stdout
+func PrintList() {
+	fmt.Println(SprintList())
+}

lib/transform/options.go

@@ -47,7 +47,7 @@ const (
 var OptionsInfo = fs.Options{{
 	Name:    "name_transform",
 	Default: []string{},
-	Help:    "TODO",
+	Help:    "`--name-transform` introduces path name transformations for `rclone copy`, `rclone sync`, and `rclone move`. These transformations enable modifications to source and destination file names by applying prefixes, suffixes, and other alterations during transfer operations. For detailed docs and examples, see [`convmv`](/commands/rclone_convmv/).",
 	Groups:  "Filter",
 }}