Setup corfu indexed to work similar to company mode

nix/modules/completion/default.nix

@@ -29,7 +29,10 @@ let
     optionals (cfg.backend == "corfu") [
       corfu
       cape
-    ] ++ optionals (cfg.backend == "company") [
+    ] ++ optionals (config.fg42.graphics.enable && cfg.backend == "corfu") [
+      nerd-icons-corfu
+    ]
+    ++ optionals (cfg.backend == "company") [
       company
       company-box
     ]);

nix/modules/completion/lisp/fg42/completion.el

@@ -63,16 +63,41 @@ The current candidates are shown in a popup below or above the point. The candid
 can be selected by moving up and down. Corfu is the minimalistic in-buffer completion
 counterpart of the Vertico minibuffer UI."
     :custom
-    (corfu-cycle t)                ;; Enable cycling for `corfu-next/previous'
-    (corfu-auto t)                 ;; Enable auto completion
-    (corfu-separator ?\s)          ;; Orderless field separator
-    (corfu-quit-at-boundary nil)   ;; Never quit at completion boundary
-    ;; (corfu-quit-no-match nil)      ;; Never quit, even if there is no match
-    (corfu-preview-current nil)    ;; Disable current candidate preview
-    (corfu-preselect 'prompt)      ;; Preselect the prompt
-    (corfu-on-exact-match nil)     ;; Configure handling of exact matches
+    (corfu-cycle t)      ;; Enable cycling for `corfu-next/previous'
+    (corfu-auto t)       ;; Enable auto completion
+    (corfu-separator ?*) ;; Orderless field separator
+    (corfu-quit-no-match 'separator)
+    (corfu-quit-at-boundary 'separator)
+    (corfu-quit-no-match t)
+    (corfu-preview-current 'insert) ;; Disable current candidate preview
+    (corfu-preselect 'first)        ;; Preselect the prompt
+    (corfu-on-exact-match 'insert) ;; Configure handling of exact matches
     (corfu-scroll-margin 5)        ;; Use scroll margin
-    :hook (emacs-startup . global-corfu-mode)))
+    (corfu-left-margin-width 2.0)
+    (corfu-right-margin-width 2.0)
+
+    :bind
+    (:map corfu-map ("<escape>" . corfu-quit))
+    (:map corfu-map ("M-SPC" . corfu-insert-separator))
+    :hook
+    (emacs-startup . global-corfu-mode)
+    (corfu-mode . (lambda ()
+                    (require 'corfu-popupinfo)
+                    (require 'corfu-indexed)
+
+                    (corfu-popupinfo-mode)
+                    (corfu-indexed-mode)
+                    (dotimes (i 10)
+                      (define-key corfu-mode-map
+                                  (kbd (format "M-%s" i))
+                                  (kbd (format "C-%s <tab>" i)))))))
+
+  (with-config "graphics"
+    (use! nerd-icons-corfu
+      "Nerd icon integration with corfu."
+      :after corfu
+      :config
+      (add-to-list 'corfu-margin-formatters #'nerd-icons-corfu-formatter))))
 
 
 ;;;###autoload