Add “smart replace” functionality to the fish shell widget

shell/navi.plugin.fish

@@ -1,5 +1,3 @@
-#!/usr/bin/env fish
-
 function __call_navi
     navi --print
 end 
@@ -16,7 +14,37 @@ function navi-widget -d "Show cheat sheets"
   commandline -f repaint
 end
 
-bind \cg navi-widget
+# set -g navi_last_cmd ""
+
+function smart_replace
+  set -l current_process (commandline -p)
+
+  if [ $current_process = "" ]
+    commandline -p (navi --print)
+    commandline -f repaint
+  else
+    set -l best_match (navi --print --best-match --query $current_process)
+
+    if not [ $best_match > /dev/null ];
+      commandline -p $current_process
+      commandline -f repaint
+      return
+    end
+
+    if [ $best_match = "" ]
+        commandline -p (navi --print --query $current_process)
+        commandline -f repaint
+    else if [ $current_process != $best_match ]
+      commandline -p $best_match
+      commandline -f repaint
+    else if [ $current_process = $best_match ]
+      commandline -p (navi --print --query $current_process)
+      commandline -f repaint
+    end
+  end
+end
+
+bind \cg smart_replace
 if bind -M insert > /dev/null 2>&1
-  bind -M insert \cg navi-widget
+  bind -M insert \cg smart_replace
 end