97 lines
1.9 KiB
Go
97 lines
1.9 KiB
Go
package mv
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import (
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"fmt"
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"log"
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"os"
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"strings"
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"github.com/brtholomy/um/go/cat"
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"github.com/brtholomy/um/go/cmd"
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"github.com/brtholomy/um/go/flags"
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"github.com/brtholomy/um/go/next"
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"github.com/brtholomy/um/go/pipe"
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)
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const (
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CMD = cmd.Mv
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SUMMARY = "rename an um file descriptor field while updating its header"
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)
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type options struct {
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Filename flags.Arg
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Descriptor flags.Arg
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Help flags.Bool
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}
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func initOpts() options {
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return options{
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flags.Arg{"", "old filename"},
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flags.Arg{"", "new descriptor"},
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flags.Bool{"--help", "-h", false, "show help"},
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}
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}
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// generates new filename and its content with updated H1 header
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func newNameAndContent(olds string, opts options) (name string, content string, err error) {
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// name and title
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num, err := next.NumFromLast(opts.Filename.Val)
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if err != nil {
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return "", "", err
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}
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name = fmt.Sprintf("%s.%s.md", num, opts.Descriptor.Val)
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title := fmt.Sprintf("# %s", name)
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// content
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head, tail, ok := strings.Cut(olds, pipe.Newline)
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// the file has no newline at all?
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if !ok {
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tail = head
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}
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// there was no title in the original
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if !strings.HasPrefix(head, cat.H1) {
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tail = olds
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}
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return name, fmt.Sprintf("%s%s%s", title, pipe.Newline, tail), nil
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}
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// effectively does a mv to the new filename, while updating the H1 header to match.
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func mv(opts options) error {
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oldb, err := os.ReadFile(opts.Filename.Val)
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if err != nil {
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return err
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}
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olds := string(oldb)
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name, content, err := newNameAndContent(olds, opts)
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if err != nil {
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return err
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}
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// create
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newf, err := os.Create(name)
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if err != nil {
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return err
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}
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defer newf.Close()
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_, err = newf.WriteString(content)
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if err != nil {
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return err
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}
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// destroy
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err = os.Remove(opts.Filename.Val)
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if err != nil {
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return err
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}
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return nil
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}
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func Mv(args []string) {
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opts := initOpts()
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flags.ParseArgs(CMD, SUMMARY, args, &opts)
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err := mv(opts)
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if err != nil {
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log.Fatalf("um %s: %v", CMD, err)
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}
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}
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