Find similar file by replacing path tokens with minibuffer text

find-similar-file.el

(require 'cl-lib)

(setq find-similar-file-separators '("-" "_" "/" "."))

(defvar find-similar-file--cur-file nil)

(defun find-similar-file-zip (separators tokens)
  (let ((seps (cl-copy-list separators)))
    (mapconcat
     (lambda (token) (concat (pop seps) token))
     tokens
     "")))

(defun find-similar-file-collection (new pred flag)
  (let* ((tokens (split-string find-similar-file--cur-file
                               (rx (eval (append '(or) find-similar-file-separators)))
                               t))
         (separators (split-string find-similar-file--cur-file
                                   (rx (one-or-more (eval (list 'not (append '(or) find-similar-file-separators)))))
                                   t)))
    (cond
     ((eq flag 'metadata) '(metadata (category . file)))
     ((eq flag 'lambda) (funcall (or pred 'file-exists-p) new))
     (t
      (if-let ((file (catch 'found-file
                       (dolist (old tokens)
                         (let ((file (find-similar-file-zip
                                      separators
                                      (cl-substitute new old tokens :test #'string=))))
                           (if (file-exists-p file)
                               (throw 'found-file file)))))))
          (list file)
        nil)))))

(defun find-similar-file ()
  (interactive)
  (let ((find-similar-file--cur-file buffer-file-name))
    (funcall-interactively
     'find-file
     (completing-read "File: " 'find-similar-file-collection nil t))))