ambrevar/shell: Add draft wrapper to start ncurses "visual" programs.

.local/share/common-lisp/source/ambrevar/shell.lisp

@@ -223,6 +223,65 @@ Example:
   "Like `cmd-' but return a stream."
   (apply #'%cmd- #'cmd> args))
 
+(defvar *visual-command* '("htop"))
+(defvar *command-wrappers* '("sudo" "env"))
+(defun visual-command-p (command)
+  "Return true if the COMMAND list runs one of the programs in `*visual-command*'.
+`*command-wrappers*' are supported, i.e.
+
+  env FOO=BAR sudo -i powertop
+
+works."
+  (labels ((basename (arg)
+             (namestring (pathname-name arg)))
+           (flag? (arg)
+             (str:starts-with? "-" arg))
+           (variable? (arg)
+             (and (< 1 (length arg))
+                  (str:contains? "=" (subseq arg 1))))
+           (first-positional-argument (command)
+             "Return the argument that's not a flag, not a variable setting and
+not in `*command-wrappers*'."
+             (when command
+               (if (or (flag? (first command))
+                       (variable? (first command))
+                       (find (basename (first command))
+                             *command-wrappers*
+                             :test #'string=))
+                   (first-positional-argument (rest command))
+                   (first command)))))
+    (sera:and-let* ((cmd (first-positional-argument command)))
+      (find (basename cmd)
+            *visual-command*
+            :test #'string=))))
+
+(defun vterm-terminal (cmd)
+  (list
+   "emacsclient" "--eval"
+   (let ((*print-case* :downcase))
+     (write-to-string
+      `(progn
+         (vterm)
+         (vterm-insert ,(str:join " " cmd))
+         (vterm-send-return))))))
+
+(defvar *terminal* '("/gnu/store/751mcahyg3b5dpwkbfvzg6x1vdn9i49a-xterm-363/bin/xterm" "-e")
+  "The terminal is either a list of arguments after which will be prepended to
+the visual command to run, or a function of one argument, the list of commands,
+returning the new list of commands.")
+
+(defun maybe-launch-visual-command (cmd)
+  (if (visual-command-p cmd)
+      (cmd:cmd
+       (if (functionp *terminal*)
+           (funcall *terminal* cmd)
+           (append *terminal* cmd)))
+      (cmd:cmd cmd)))
+
+(setf *terminal* #'vterm-terminal)
+
+;; (maybe-launch-visual-command '("htop"))
+
 (export-always 'tee)
 (defun tee (input-stream)               ; TODO: Real `tee' with separate process.
   "Return the INPUT-STREAM and its string representation as a second value."