From 508ec41fb4ecbb4d8caead8e35415a55691a732b Mon Sep 17 00:00:00 2001
From: Alexander Rosenberg <zanderpkg@pm.me>
Date: Thu, 1 Feb 2024 12:47:49 -0800
Subject: [PATCH] Add module caching for eshell-starship

---
 elisp/eshell-starship.el | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/elisp/eshell-starship.el b/elisp/eshell-starship.el
index 6447341..66b6ca7 100644
--- a/elisp/eshell-starship.el
+++ b/elisp/eshell-starship.el
@@ -12,8 +12,11 @@
 This should be an alist of (name function).  The macro
 `eshell-starship-defmodule' can help modify this list.")
 
+(defvar eshell-starship--module-cache (make-hash-table :test 'eq)
+  "Hash table to hold module cache for eshell-starship.")
+
 (cl-defmacro eshell-starship-defmodule (name &key pred files dirs exts icon color
-                                             allow-remote action)
+                                             allow-remote action reload-on)
   "Define an eshell-starship module called NAME.
 The module will be added to `eshell-starship-modules'.
   :PRED - a function that should return t if the module should be run
@@ -24,10 +27,12 @@ The module will be added to `eshell-starship-modules'.
   :ICON - this is the string to print before the modules text
   :COLOR - the color to print the modules text in
   :ALLOW-REMOTE - weather to allow the module to run on remote machines
-  :ACTION - a function that will return the module text, or nil"
+  :ACTION - a function that will return the module text, or nil
+  :RELOAD-ON - when to re-run the module.  Can be one of `'cwd' or `'always'
+               (same as nil)"
   (declare (indent defun))
   `(setf (alist-get ',name eshell-starship-modules)
-         ,(list 'list pred files dirs exts icon color allow-remote action)))
+         ,(list 'list pred files dirs exts icon color allow-remote action reload-on)))
 
 (cl-defmacro eshell-starship-find-version-function (command pattern
                                                     &rest format)
@@ -48,6 +53,7 @@ arguments to pass to `concat' to format the output."
   :icon "C"
   :color "green yellow"
   :allow-remote nil
+  :reload-on 'cwd
   :action (eshell-starship-find-version-function
             ("cc" "-v")
             "^\\([-a-zA-Z]+\\) version \\([0-9]+\\.[0-9]+\\.[0-9]+\\)"
@@ -58,11 +64,19 @@ arguments to pass to `concat' to format the output."
   :icon "󰔶"
   :color "blue"
   :allow-remote nil
+  :reload-on 'cwd
   :action (eshell-starship-find-version-function
             ("cmake" "--version")
             "cmake version \\([0-9]+\\.[0-9]+\\.[0-9]+\\)"
             "v" (match-string 1)))
 
+(defun eshell-starship--cwd-clear-caches ()
+  "Clear caches that should be cleared on cwd for eshell-starship."
+  (dolist (module eshell-starship-modules)
+    (if-let ((reload-on (nth 9 module))
+             ((eq reload-on 'cwd)))
+      (puthash (car module) nil eshell-starship--module-cache))))
+
 (defun eshell-starship--exts-exist-p (&rest exts)
   "Test if any files with EXTS at the end of their name exist in default dir."
   (catch 'found
@@ -89,16 +103,21 @@ arguments to pass to `concat' to format the output."
 (defun eshell-starship--execute-modules ()
   "Execute all the modules in `eshell-starship-modules'."
   (cl-loop
-   for (_ pred files dirs exts icon color allow-remote action)
+   for (name pred files dirs exts icon color allow-remote action reload-on)
    in eshell-starship-modules
    when (and (or allow-remote (not (file-remote-p default-directory)))
              (or (and files (apply 'eshell-starship--files-exist-p files))
                  (and dirs (apply' eshell-starship--dirs-exist-p dirs))
                  (and exts (apply' eshell-starship--exts-exist-p exts))
                  (and pred (funcall pred))))
-   concat (if-let (result (funcall action))
-              (concat " via " (propertize (concat icon " " result)
-                                          'face `(:foreground ,color))))))
+   concat (if-let (cache-val (gethash name eshell-starship--module-cache))
+              cache-val
+            (if-let ((result (funcall action))
+                     (mod-string (concat " via " (propertize (concat icon " " result)
+                                                             'face `(:foreground ,color)))))
+                (unless (or (not reload-on) (eq reload-on 'always))
+                  (puthash name mod-string eshell-starship--module-cache))
+              result))))
 
 (defun eshell-starship--replace-home-with-tilda (path)
   "If PATH beings with $HOME (the environment variable), replace it with ~."
@@ -336,6 +355,9 @@ END-TIME is the time when the command finished executing."
 (defvar-local ehsell-starship--restore-state nil
   "State of various variables set by `eshell-starship-prompt-mode'.")
 
+;;;###autoload
+(add-hook 'eshell-directory-change-hook #'eshell-starship--cwd-clear-caches)
+
 ;;;###autoload
 (define-minor-mode eshell-starship-prompt-mode
   "Minor mode to make eshell prompts look like starship (https://starship.rs)."