Show diff or file content in fzf_search_git_status

functions/__fzf_preview_changed_file.fish

@@ -0,0 +1,23 @@
+function __fzf_preview_changed_file
+    set git_status (string sub --length 2 $argv[1])
+
+    # path has been renamed and looks like "R LICENSE -> LICENSE.md"
+    # extract the renamed path
+    if test (string sub --length 1 $git_status) = 'R'
+        set path (string split -- "-> " $argv[2])[-1]
+    else
+        set path $argv[2]
+    end
+
+    switch $status
+        # Untracked filed
+        case '\?\?'
+            bat $path
+        # Deleted files, show the file content in previous commit
+        case '?D' 'D?'
+            git show HEAD:$path
+        # Other files, show the diff compared to last commit (unstaged & staged changes)
+        case '*'
+            git diff --color HEAD $path
+    end
+end

functions/__fzf_search_git_status.fish

@@ -5,7 +5,9 @@ function __fzf_search_git_status --description "Search the output of git status.
         set selected_paths (
             # Pass configuration color.status=always to force status to use colors even though output is sent to a pipe
             git -c color.status=always status --short |
-            fzf --ansi --multi --query=(commandline --current-token)
+            fzf --ansi --multi \
+                --query=(commandline --current-token) \
+                --preview="__fzf_preview_changed_file {} {2..}"
         )
         if test $status -eq 0
             # git status --short automatically escapes the paths of most files for us so not going to bother trying to handle